// SPDX-License-Identifier: GPL-2.0-only
// Copyright (C) 2017 Broadcom

/*
 * Broadcom FlexRM Mailbox Driver
 *
 * Each Broadcom FlexSparx4 offload engine is implemented as an
 * extension to Broadcom FlexRM ring manager. The FlexRM ring
 * manager provides a set of rings which can be used to submit
 * work to a FlexSparx4 offload engine.
 *
 * This driver creates a mailbox controller using a set of FlexRM
 * rings where each mailbox channel represents a separate FlexRM ring.
 */

#include <asm/barrier.h>
#include <asm/byteorder.h>
#include <linux/atomic.h>
#include <linux/bitmap.h>
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/mailbox_controller.h>
#include <linux/mailbox/brcm-message.h>
#include <linux/module.h>
#include <linux/msi.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>

/* ====== FlexRM register defines ===== */

/* FlexRM configuration */
#define RING_REGS_SIZE                                  0x10000
#define RING_DESC_SIZE                                  8
#define RING_DESC_INDEX(offset)                         \
                        ((offset) / RING_DESC_SIZE)
#define RING_DESC_OFFSET(index)                         \
                        ((index) * RING_DESC_SIZE)
#define RING_MAX_REQ_COUNT                              1024
#define RING_BD_ALIGN_ORDER                             12
#define RING_BD_ALIGN_CHECK(addr)                       \
                        (!((addr) & ((0x1 << RING_BD_ALIGN_ORDER) - 1)))
#define RING_BD_TOGGLE_INVALID(offset)                  \
                        (((offset) >> RING_BD_ALIGN_ORDER) & 0x1)
#define RING_BD_TOGGLE_VALID(offset)                    \
                        (!RING_BD_TOGGLE_INVALID(offset))
#define RING_BD_DESC_PER_REQ                            32
#define RING_BD_DESC_COUNT                              \
                        (RING_MAX_REQ_COUNT * RING_BD_DESC_PER_REQ)
#define RING_BD_SIZE                                    \
                        (RING_BD_DESC_COUNT * RING_DESC_SIZE)
#define RING_CMPL_ALIGN_ORDER                           13
#define RING_CMPL_DESC_COUNT                            RING_MAX_REQ_COUNT
#define RING_CMPL_SIZE                                  \
                        (RING_CMPL_DESC_COUNT * RING_DESC_SIZE)
#define RING_VER_MAGIC                                  0x76303031

/* Per-Ring register offsets */
#define RING_VER                                        0x000
#define RING_BD_START_ADDR                              0x004
#define RING_BD_READ_PTR                                0x008
#define RING_BD_WRITE_PTR                               0x00c
#define RING_BD_READ_PTR_DDR_LS                         0x010
#define RING_BD_READ_PTR_DDR_MS                         0x014
#define RING_CMPL_START_ADDR                            0x018
#define RING_CMPL_WRITE_PTR                             0x01c
#define RING_NUM_REQ_RECV_LS                            0x020
#define RING_NUM_REQ_RECV_MS                            0x024
#define RING_NUM_REQ_TRANS_LS                           0x028
#define RING_NUM_REQ_TRANS_MS                           0x02c
#define RING_NUM_REQ_OUTSTAND                           0x030
#define RING_CONTROL                                    0x034
#define RING_FLUSH_DONE                                 0x038
#define RING_MSI_ADDR_LS                                0x03c
#define RING_MSI_ADDR_MS                                0x040
#define RING_MSI_CONTROL                                0x048
#define RING_BD_READ_PTR_DDR_CONTROL                    0x04c
#define RING_MSI_DATA_VALUE                             0x064

/* Register RING_BD_START_ADDR fields */
#define BD_LAST_UPDATE_HW_SHIFT                         28
#define BD_LAST_UPDATE_HW_MASK                          0x1
#define BD_START_ADDR_VALUE(pa)                         \
        ((u32)((((dma_addr_t)(pa)) >> RING_BD_ALIGN_ORDER) & 0x0fffffff))
#define BD_START_ADDR_DECODE(val)                       \
        ((dma_addr_t)((val) & 0x0fffffff) << RING_BD_ALIGN_ORDER)

/* Register RING_CMPL_START_ADDR fields */
#define CMPL_START_ADDR_VALUE(pa)                       \
        ((u32)((((u64)(pa)) >> RING_CMPL_ALIGN_ORDER) & 0x07ffffff))

/* Register RING_CONTROL fields */
#define CONTROL_MASK_DISABLE_CONTROL                    12
#define CONTROL_FLUSH_SHIFT                             5
#define CONTROL_ACTIVE_SHIFT                            4
#define CONTROL_RATE_ADAPT_MASK                         0xf
#define CONTROL_RATE_DYNAMIC                            0x0
#define CONTROL_RATE_FAST                               0x8
#define CONTROL_RATE_MEDIUM                             0x9
#define CONTROL_RATE_SLOW                               0xa
#define CONTROL_RATE_IDLE                               0xb

/* Register RING_FLUSH_DONE fields */
#define FLUSH_DONE_MASK                                 0x1

/* Register RING_MSI_CONTROL fields */
#define MSI_TIMER_VAL_SHIFT                             16
#define MSI_TIMER_VAL_MASK                              0xffff
#define MSI_ENABLE_SHIFT                                15
#define MSI_ENABLE_MASK                                 0x1
#define MSI_COUNT_SHIFT                                 0
#define MSI_COUNT_MASK                                  0x3ff

/* Register RING_BD_READ_PTR_DDR_CONTROL fields */
#define BD_READ_PTR_DDR_TIMER_VAL_SHIFT                 16
#define BD_READ_PTR_DDR_TIMER_VAL_MASK                  0xffff
#define BD_READ_PTR_DDR_ENABLE_SHIFT                    15
#define BD_READ_PTR_DDR_ENABLE_MASK                     0x1

/* ====== FlexRM ring descriptor defines ===== */

/* Completion descriptor format */
#define CMPL_OPAQUE_SHIFT                       0
#define CMPL_OPAQUE_MASK                        0xffff
#define CMPL_ENGINE_STATUS_SHIFT                16
#define CMPL_ENGINE_STATUS_MASK                 0xffff
#define CMPL_DME_STATUS_SHIFT                   32
#define CMPL_DME_STATUS_MASK                    0xffff
#define CMPL_RM_STATUS_SHIFT                    48
#define CMPL_RM_STATUS_MASK                     0xffff

/* Completion DME status code */
#define DME_STATUS_MEM_COR_ERR                  BIT(0)
#define DME_STATUS_MEM_UCOR_ERR                 BIT(1)
#define DME_STATUS_FIFO_UNDERFLOW               BIT(2)
#define DME_STATUS_FIFO_OVERFLOW                BIT(3)
#define DME_STATUS_RRESP_ERR                    BIT(4)
#define DME_STATUS_BRESP_ERR                    BIT(5)
#define DME_STATUS_ERROR_MASK                   (DME_STATUS_MEM_COR_ERR | \
                                                 DME_STATUS_MEM_UCOR_ERR | \
                                                 DME_STATUS_FIFO_UNDERFLOW | \
                                                 DME_STATUS_FIFO_OVERFLOW | \
                                                 DME_STATUS_RRESP_ERR | \
                                                 DME_STATUS_BRESP_ERR)

/* Completion RM status code */
#define RM_STATUS_CODE_SHIFT                    0
#define RM_STATUS_CODE_MASK                     0x3ff
#define RM_STATUS_CODE_GOOD                     0x0
#define RM_STATUS_CODE_AE_TIMEOUT               0x3ff

/* General descriptor format */
#define DESC_TYPE_SHIFT                         60
#define DESC_TYPE_MASK                          0xf
#define DESC_PAYLOAD_SHIFT                      0
#define DESC_PAYLOAD_MASK                       0x0fffffffffffffff

/* Null descriptor format  */
#define NULL_TYPE                               0
#define NULL_TOGGLE_SHIFT                       58
#define NULL_TOGGLE_MASK                        0x1

/* Header descriptor format */
#define HEADER_TYPE                             1
#define HEADER_TOGGLE_SHIFT                     58
#define HEADER_TOGGLE_MASK                      0x1
#define HEADER_ENDPKT_SHIFT                     57
#define HEADER_ENDPKT_MASK                      0x1
#define HEADER_STARTPKT_SHIFT                   56
#define HEADER_STARTPKT_MASK                    0x1
#define HEADER_BDCOUNT_SHIFT                    36
#define HEADER_BDCOUNT_MASK                     0x1f
#define HEADER_BDCOUNT_MAX                      HEADER_BDCOUNT_MASK
#define HEADER_FLAGS_SHIFT                      16
#define HEADER_FLAGS_MASK                       0xffff
#define HEADER_OPAQUE_SHIFT                     0
#define HEADER_OPAQUE_MASK                      0xffff

/* Source (SRC) descriptor format */
#define SRC_TYPE                                2
#define SRC_LENGTH_SHIFT                        44
#define SRC_LENGTH_MASK                         0xffff
#define SRC_ADDR_SHIFT                          0
#define SRC_ADDR_MASK                           0x00000fffffffffff

/* Destination (DST) descriptor format */
#define DST_TYPE                                3
#define DST_LENGTH_SHIFT                        44
#define DST_LENGTH_MASK                         0xffff
#define DST_ADDR_SHIFT                          0
#define DST_ADDR_MASK                           0x00000fffffffffff

/* Immediate (IMM) descriptor format */
#define IMM_TYPE                                4
#define IMM_DATA_SHIFT                          0
#define IMM_DATA_MASK                           0x0fffffffffffffff

/* Next pointer (NPTR) descriptor format */
#define NPTR_TYPE                               5
#define NPTR_TOGGLE_SHIFT                       58
#define NPTR_TOGGLE_MASK                        0x1
#define NPTR_ADDR_SHIFT                         0
#define NPTR_ADDR_MASK                          0x00000fffffffffff

/* Mega source (MSRC) descriptor format */
#define MSRC_TYPE                               6
#define MSRC_LENGTH_SHIFT                       44
#define MSRC_LENGTH_MASK                        0xffff
#define MSRC_ADDR_SHIFT                         0
#define MSRC_ADDR_MASK                          0x00000fffffffffff

/* Mega destination (MDST) descriptor format */
#define MDST_TYPE                               7
#define MDST_LENGTH_SHIFT                       44
#define MDST_LENGTH_MASK                        0xffff
#define MDST_ADDR_SHIFT                         0
#define MDST_ADDR_MASK                          0x00000fffffffffff

/* Source with tlast (SRCT) descriptor format */
#define SRCT_TYPE                               8
#define SRCT_LENGTH_SHIFT                       44
#define SRCT_LENGTH_MASK                        0xffff
#define SRCT_ADDR_SHIFT                         0
#define SRCT_ADDR_MASK                          0x00000fffffffffff

/* Destination with tlast (DSTT) descriptor format */
#define DSTT_TYPE                               9
#define DSTT_LENGTH_SHIFT                       44
#define DSTT_LENGTH_MASK                        0xffff
#define DSTT_ADDR_SHIFT                         0
#define DSTT_ADDR_MASK                          0x00000fffffffffff

/* Immediate with tlast (IMMT) descriptor format */
#define IMMT_TYPE                               10
#define IMMT_DATA_SHIFT                         0
#define IMMT_DATA_MASK                          0x0fffffffffffffff

/* Descriptor helper macros */
#define DESC_DEC(_d, _s, _m)                    (((_d) >> (_s)) & (_m))
#define DESC_ENC(_d, _v, _s, _m)                \
                        do { \
                                (_d) &= ~((u64)(_m) << (_s)); \
                                (_d) |= (((u64)(_v) & (_m)) << (_s)); \
                        } while (0)

/* ====== FlexRM data structures ===== */

struct flexrm_ring {
        /* Unprotected members */
        int num;
        struct flexrm_mbox *mbox;
        void __iomem *regs;
        bool irq_requested;
        unsigned int irq;
        cpumask_t irq_aff_hint;
        unsigned int msi_timer_val;
        unsigned int msi_count_threshold;
        struct brcm_message *requests[RING_MAX_REQ_COUNT];
        void *bd_base;
        dma_addr_t bd_dma_base;
        u32 bd_write_offset;
        void *cmpl_base;
        dma_addr_t cmpl_dma_base;
        /* Atomic stats */
        atomic_t msg_send_count;
        atomic_t msg_cmpl_count;
        /* Protected members */
        spinlock_t lock;
        DECLARE_BITMAP(requests_bmap, RING_MAX_REQ_COUNT);
        u32 cmpl_read_offset;
};

struct flexrm_mbox {
        struct device *dev;
        void __iomem *regs;
        u32 num_rings;
        struct flexrm_ring *rings;
        struct dma_pool *bd_pool;
        struct dma_pool *cmpl_pool;
        struct dentry *root;
        struct mbox_controller controller;
};

/* ====== FlexRM ring descriptor helper routines ===== */

static u64 flexrm_read_desc(void *desc_ptr)
{
        return le64_to_cpu(*((u64 *)desc_ptr));
}

static void flexrm_write_desc(void *desc_ptr, u64 desc)
{
        *((u64 *)desc_ptr) = cpu_to_le64(desc);
}

static u32 flexrm_cmpl_desc_to_reqid(u64 cmpl_desc)
{
        return (u32)(cmpl_desc & CMPL_OPAQUE_MASK);
}

static int flexrm_cmpl_desc_to_error(u64 cmpl_desc)
{
        u32 status;

        status = DESC_DEC(cmpl_desc, CMPL_DME_STATUS_SHIFT,
                          CMPL_DME_STATUS_MASK);
        if (status & DME_STATUS_ERROR_MASK)
                return -EIO;

        status = DESC_DEC(cmpl_desc, CMPL_RM_STATUS_SHIFT,
                          CMPL_RM_STATUS_MASK);
        status &= RM_STATUS_CODE_MASK;
        if (status == RM_STATUS_CODE_AE_TIMEOUT)
                return -ETIMEDOUT;

        return 0;
}

static bool flexrm_is_next_table_desc(void *desc_ptr)
{
        u64 desc = flexrm_read_desc(desc_ptr);
        u32 type = DESC_DEC(desc, DESC_TYPE_SHIFT, DESC_TYPE_MASK);

        return (type == NPTR_TYPE) ? true : false;
}

static u64 flexrm_next_table_desc(u32 toggle, dma_addr_t next_addr)
{
        u64 desc = 0;

        DESC_ENC(desc, NPTR_TYPE, DESC_TYPE_SHIFT, DESC_TYPE_MASK);
        DESC_ENC(desc, toggle, NPTR_TOGGLE_SHIFT, NPTR_TOGGLE_MASK);
        DESC_ENC(desc, next_addr, NPTR_ADDR_SHIFT, NPTR_ADDR_MASK);

        return desc;
}

static u64 flexrm_null_desc(u32 toggle)
{
        u64 desc = 0;

        DESC_ENC(desc, NULL_TYPE, DESC_TYPE_SHIFT, DESC_TYPE_MASK);
        DESC_ENC(desc, toggle, NULL_TOGGLE_SHIFT, NULL_TOGGLE_MASK);

        return desc;
}

static u32 flexrm_estimate_header_desc_count(u32 nhcnt)
{
        u32 hcnt = nhcnt / HEADER_BDCOUNT_MAX;

        if (!(nhcnt % HEADER_BDCOUNT_MAX))
                hcnt += 1;

        return hcnt;
}

static void flexrm_flip_header_toggle(void *desc_ptr)
{
        u64 desc = flexrm_read_desc(desc_ptr);

        if (desc & ((u64)0x1 << HEADER_TOGGLE_SHIFT))
                desc &= ~((u64)0x1 << HEADER_TOGGLE_SHIFT);
        else
                desc |= ((u64)0x1 << HEADER_TOGGLE_SHIFT);

        flexrm_write_desc(desc_ptr, desc);
}

static u64 flexrm_header_desc(u32 toggle, u32 startpkt, u32 endpkt,
                               u32 bdcount, u32 flags, u32 opaque)
{
        u64 desc = 0;

        DESC_ENC(desc, HEADER_TYPE, DESC_TYPE_SHIFT, DESC_TYPE_MASK);
        DESC_ENC(desc, toggle, HEADER_TOGGLE_SHIFT, HEADER_TOGGLE_MASK);
        DESC_ENC(desc, startpkt, HEADER_STARTPKT_SHIFT, HEADER_STARTPKT_MASK);
        DESC_ENC(desc, endpkt, HEADER_ENDPKT_SHIFT, HEADER_ENDPKT_MASK);
        DESC_ENC(desc, bdcount, HEADER_BDCOUNT_SHIFT, HEADER_BDCOUNT_MASK);
        DESC_ENC(desc, flags, HEADER_FLAGS_SHIFT, HEADER_FLAGS_MASK);
        DESC_ENC(desc, opaque, HEADER_OPAQUE_SHIFT, HEADER_OPAQUE_MASK);

        return desc;
}

static void flexrm_enqueue_desc(u32 nhpos, u32 nhcnt, u32 reqid,
                                 u64 desc, void **desc_ptr, u32 *toggle,
                                 void *start_desc, void *end_desc)
{
        u64 d;
        u32 nhavail, _toggle, _startpkt, _endpkt, _bdcount;

        /* Sanity check */
        if (nhcnt <= nhpos)
                return;

        /*
         * Each request or packet start with a HEADER descriptor followed
         * by one or more non-HEADER descriptors (SRC, SRCT, MSRC, DST,
         * DSTT, MDST, IMM, and IMMT). The number of non-HEADER descriptors
         * following a HEADER descriptor is represented by BDCOUNT field
         * of HEADER descriptor. The max value of BDCOUNT field is 31 which
         * means we can only have 31 non-HEADER descriptors following one
         * HEADER descriptor.
         *
         * In general use, number of non-HEADER descriptors can easily go
         * beyond 31. To tackle this situation, we have packet (or request)
         * extension bits (STARTPKT and ENDPKT) in the HEADER descriptor.
         *
         * To use packet extension, the first HEADER descriptor of request
         * (or packet) will have STARTPKT=1 and ENDPKT=0. The intermediate
         * HEADER descriptors will have STARTPKT=0 and ENDPKT=0. The last
         * HEADER descriptor will have STARTPKT=0 and ENDPKT=1. Also, the
         * TOGGLE bit of the first HEADER will be set to invalid state to
         * ensure that FlexRM does not start fetching descriptors till all
         * descriptors are enqueued. The user of this function will flip
         * the TOGGLE bit of first HEADER after all descriptors are
         * enqueued.
         */

        if ((nhpos % HEADER_BDCOUNT_MAX == 0) && (nhcnt - nhpos)) {
                /* Prepare the header descriptor */
                nhavail = (nhcnt - nhpos);
                _toggle = (nhpos == 0) ? !(*toggle) : (*toggle);
                _startpkt = (nhpos == 0) ? 0x1 : 0x0;
                _endpkt = (nhavail <= HEADER_BDCOUNT_MAX) ? 0x1 : 0x0;
                _bdcount = (nhavail <= HEADER_BDCOUNT_MAX) ?
                                nhavail : HEADER_BDCOUNT_MAX;
                if (nhavail <= HEADER_BDCOUNT_MAX)
                        _bdcount = nhavail;
                else
                        _bdcount = HEADER_BDCOUNT_MAX;
                d = flexrm_header_desc(_toggle, _startpkt, _endpkt,
                                        _bdcount, 0x0, reqid);

                /* Write header descriptor */
                flexrm_write_desc(*desc_ptr, d);

                /* Point to next descriptor */
                *desc_ptr += sizeof(desc);
                if (*desc_ptr == end_desc)
                        *desc_ptr = start_desc;

                /* Skip next pointer descriptors */
                while (flexrm_is_next_table_desc(*desc_ptr)) {
                        *toggle = (*toggle) ? 0 : 1;
                        *desc_ptr += sizeof(desc);
                        if (*desc_ptr == end_desc)
                                *desc_ptr = start_desc;
                }
        }

        /* Write desired descriptor */
        flexrm_write_desc(*desc_ptr, desc);

        /* Point to next descriptor */
        *desc_ptr += sizeof(desc);
        if (*desc_ptr == end_desc)
                *desc_ptr = start_desc;

        /* Skip next pointer descriptors */
        while (flexrm_is_next_table_desc(*desc_ptr)) {
                *toggle = (*toggle) ? 0 : 1;
                *desc_ptr += sizeof(desc);
                if (*desc_ptr == end_desc)
                        *desc_ptr = start_desc;
        }
}

static u64 flexrm_src_desc(dma_addr_t addr, unsigned int length)
{
        u64 desc = 0;

        DESC_ENC(desc, SRC_TYPE, DESC_TYPE_SHIFT, DESC_TYPE_MASK);
        DESC_ENC(desc, length, SRC_LENGTH_SHIFT, SRC_LENGTH_MASK);
        DESC_ENC(desc, addr, SRC_ADDR_SHIFT, SRC_ADDR_MASK);

        return desc;
}

static u64 flexrm_msrc_desc(dma_addr_t addr, unsigned int length_div_16)
{
        u64 desc = 0;

        DESC_ENC(desc, MSRC_TYPE, DESC_TYPE_SHIFT, DESC_TYPE_MASK);
        DESC_ENC(desc, length_div_16, MSRC_LENGTH_SHIFT, MSRC_LENGTH_MASK);
        DESC_ENC(desc, addr, MSRC_ADDR_SHIFT, MSRC_ADDR_MASK);

        return desc;
}

static u64 flexrm_dst_desc(dma_addr_t addr, unsigned int length)
{
        u64 desc = 0;

        DESC_ENC(desc, DST_TYPE, DESC_TYPE_SHIFT, DESC_TYPE_MASK);
        DESC_ENC(desc, length, DST_LENGTH_SHIFT, DST_LENGTH_MASK);
        DESC_ENC(desc, addr, DST_ADDR_SHIFT, DST_ADDR_MASK);

        return desc;
}

static u64 flexrm_mdst_desc(dma_addr_t addr, unsigned int length_div_16)
{
        u64 desc = 0;

        DESC_ENC(desc, MDST_TYPE, DESC_TYPE_SHIFT, DESC_TYPE_MASK);
        DESC_ENC(desc, length_div_16, MDST_LENGTH_SHIFT, MDST_LENGTH_MASK);
        DESC_ENC(desc, addr, MDST_ADDR_SHIFT, MDST_ADDR_MASK);

        return desc;
}

static u64 flexrm_imm_desc(u64 data)
{
        u64 desc = 0;

        DESC_ENC(desc, IMM_TYPE, DESC_TYPE_SHIFT, DESC_TYPE_MASK);
        DESC_ENC(desc, data, IMM_DATA_SHIFT, IMM_DATA_MASK);

        return desc;
}

static u64 flexrm_srct_desc(dma_addr_t addr, unsigned int length)
{
        u64 desc = 0;

        DESC_ENC(desc, SRCT_TYPE, DESC_TYPE_SHIFT, DESC_TYPE_MASK);
        DESC_ENC(desc, length, SRCT_LENGTH_SHIFT, SRCT_LENGTH_MASK);
        DESC_ENC(desc, addr, SRCT_ADDR_SHIFT, SRCT_ADDR_MASK);

        return desc;
}

static u64 flexrm_dstt_desc(dma_addr_t addr, unsigned int length)
{
        u64 desc = 0;

        DESC_ENC(desc, DSTT_TYPE, DESC_TYPE_SHIFT, DESC_TYPE_MASK);
        DESC_ENC(desc, length, DSTT_LENGTH_SHIFT, DSTT_LENGTH_MASK);
        DESC_ENC(desc, addr, DSTT_ADDR_SHIFT, DSTT_ADDR_MASK);

        return desc;
}

static u64 flexrm_immt_desc(u64 data)
{
        u64 desc = 0;

        DESC_ENC(desc, IMMT_TYPE, DESC_TYPE_SHIFT, DESC_TYPE_MASK);
        DESC_ENC(desc, data, IMMT_DATA_SHIFT, IMMT_DATA_MASK);

        return desc;
}

static bool flexrm_spu_sanity_check(struct brcm_message *msg)
{
        struct scatterlist *sg;

        if (!msg->spu.src || !msg->spu.dst)
                return false;
        for (sg = msg->spu.src; sg; sg = sg_next(sg)) {
                if (sg->length & 0xf) {
                        if (sg->length > SRC_LENGTH_MASK)
                                return false;
                } else {
                        if (sg->length > (MSRC_LENGTH_MASK * 16))
                                return false;
                }
        }
        for (sg = msg->spu.dst; sg; sg = sg_next(sg)) {
                if (sg->length & 0xf) {
                        if (sg->length > DST_LENGTH_MASK)
                                return false;
                } else {
                        if (sg->length > (MDST_LENGTH_MASK * 16))
                                return false;
                }
        }

        return true;
}

static u32 flexrm_spu_estimate_nonheader_desc_count(struct brcm_message *msg)
{
        u32 cnt = 0;
        unsigned int dst_target = 0;
        struct scatterlist *src_sg = msg->spu.src, *dst_sg = msg->spu.dst;

        while (src_sg || dst_sg) {
                if (src_sg) {
                        cnt++;
                        dst_target = src_sg->length;
                        src_sg = sg_next(src_sg);
                } else
                        dst_target = UINT_MAX;

                while (dst_target && dst_sg) {
                        cnt++;
                        if (dst_sg->length < dst_target)
                                dst_target -= dst_sg->length;
                        else
                                dst_target = 0;
                        dst_sg = sg_next(dst_sg);
                }
        }

        return cnt;
}

static int flexrm_spu_dma_map(struct device *dev, struct brcm_message *msg)
{
        int rc;

        rc = dma_map_sg(dev, msg->spu.src, sg_nents(msg->spu.src),
                        DMA_TO_DEVICE);
        if (!rc)
                return -EIO;

        rc = dma_map_sg(dev, msg->spu.dst, sg_nents(msg->spu.dst),
                        DMA_FROM_DEVICE);
        if (!rc) {
                dma_unmap_sg(dev, msg->spu.src, sg_nents(msg->spu.src),
                             DMA_TO_DEVICE);
                return -EIO;
        }

        return 0;
}

static void flexrm_spu_dma_unmap(struct device *dev, struct brcm_message *msg)
{
        dma_unmap_sg(dev, msg->spu.dst, sg_nents(msg->spu.dst),
                     DMA_FROM_DEVICE);
        dma_unmap_sg(dev, msg->spu.src, sg_nents(msg->spu.src),
                     DMA_TO_DEVICE);
}

static void *flexrm_spu_write_descs(struct brcm_message *msg, u32 nhcnt,
                                     u32 reqid, void *desc_ptr, u32 toggle,
                                     void *start_desc, void *end_desc)
{
        u64 d;
        u32 nhpos = 0;
        void *orig_desc_ptr = desc_ptr;
        unsigned int dst_target = 0;
        struct scatterlist *src_sg = msg->spu.src, *dst_sg = msg->spu.dst;

        while (src_sg || dst_sg) {
                if (src_sg) {
                        if (sg_dma_len(src_sg) & 0xf)
                                d = flexrm_src_desc(sg_dma_address(src_sg),
                                                     sg_dma_len(src_sg));
                        else
                                d = flexrm_msrc_desc(sg_dma_address(src_sg),
                                                      sg_dma_len(src_sg)/16);
                        flexrm_enqueue_desc(nhpos, nhcnt, reqid,
                                             d, &desc_ptr, &toggle,
                                             start_desc, end_desc);
                        nhpos++;
                        dst_target = sg_dma_len(src_sg);
                        src_sg = sg_next(src_sg);
                } else
                        dst_target = UINT_MAX;

                while (dst_target && dst_sg) {
                        if (sg_dma_len(dst_sg) & 0xf)
                                d = flexrm_dst_desc(sg_dma_address(dst_sg),
                                                     sg_dma_len(dst_sg));
                        else
                                d = flexrm_mdst_desc(sg_dma_address(dst_sg),
                                                      sg_dma_len(dst_sg)/16);
                        flexrm_enqueue_desc(nhpos, nhcnt, reqid,
                                             d, &desc_ptr, &toggle,
                                             start_desc, end_desc);
                        nhpos++;
                        if (sg_dma_len(dst_sg) < dst_target)
                                dst_target -= sg_dma_len(dst_sg);
                        else
                                dst_target = 0;
                        dst_sg = sg_next(dst_sg);
                }
        }

        /* Null descriptor with invalid toggle bit */
        flexrm_write_desc(desc_ptr, flexrm_null_desc(!toggle));

        /* Ensure that descriptors have been written to memory */
        wmb();

        /* Flip toggle bit in header */
        flexrm_flip_header_toggle(orig_desc_ptr);

        return desc_ptr;
}

static bool flexrm_sba_sanity_check(struct brcm_message *msg)
{
        u32 i;

        if (!msg->sba.cmds || !msg->sba.cmds_count)
                return false;

        for (i = 0; i < msg->sba.cmds_count; i++) {
                if (((msg->sba.cmds[i].flags & BRCM_SBA_CMD_TYPE_B) ||
                     (msg->sba.cmds[i].flags & BRCM_SBA_CMD_TYPE_C)) &&
                    (msg->sba.cmds[i].flags & BRCM_SBA_CMD_HAS_OUTPUT))
                        return false;
                if ((msg->sba.cmds[i].flags & BRCM_SBA_CMD_TYPE_B) &&
                    (msg->sba.cmds[i].data_len > SRCT_LENGTH_MASK))
                        return false;
                if ((msg->sba.cmds[i].flags & BRCM_SBA_CMD_TYPE_C) &&
                    (msg->sba.cmds[i].data_len > SRCT_LENGTH_MASK))
                        return false;
                if ((msg->sba.cmds[i].flags & BRCM_SBA_CMD_HAS_RESP) &&
                    (msg->sba.cmds[i].resp_len > DSTT_LENGTH_MASK))
                        return false;
                if ((msg->sba.cmds[i].flags & BRCM_SBA_CMD_HAS_OUTPUT) &&
                    (msg->sba.cmds[i].data_len > DSTT_LENGTH_MASK))
                        return false;
        }

        return true;
}

static u32 flexrm_sba_estimate_nonheader_desc_count(struct brcm_message *msg)
{
        u32 i, cnt;

        cnt = 0;
        for (i = 0; i < msg->sba.cmds_count; i++) {
                cnt++;

                if ((msg->sba.cmds[i].flags & BRCM_SBA_CMD_TYPE_B) ||
                    (msg->sba.cmds[i].flags & BRCM_SBA_CMD_TYPE_C))
                        cnt++;

                if (msg->sba.cmds[i].flags & BRCM_SBA_CMD_HAS_RESP)
                        cnt++;

                if (msg->sba.cmds[i].flags & BRCM_SBA_CMD_HAS_OUTPUT)
                        cnt++;
        }

        return cnt;
}

static void *flexrm_sba_write_descs(struct brcm_message *msg, u32 nhcnt,
                                     u32 reqid, void *desc_ptr, u32 toggle,
                                     void *start_desc, void *end_desc)
{
        u64 d;
        u32 i, nhpos = 0;
        struct brcm_sba_command *c;
        void *orig_desc_ptr = desc_ptr;

        /* Convert SBA commands into descriptors */
        for (i = 0; i < msg->sba.cmds_count; i++) {
                c = &msg->sba.cmds[i];

                if ((c->flags & BRCM_SBA_CMD_HAS_RESP) &&
                    (c->flags & BRCM_SBA_CMD_HAS_OUTPUT)) {
                        /* Destination response descriptor */
                        d = flexrm_dst_desc(c->resp, c->resp_len);
                        flexrm_enqueue_desc(nhpos, nhcnt, reqid,
                                             d, &desc_ptr, &toggle,
                                             start_desc, end_desc);
                        nhpos++;
                } else if (c->flags & BRCM_SBA_CMD_HAS_RESP) {
                        /* Destination response with tlast descriptor */
                        d = flexrm_dstt_desc(c->resp, c->resp_len);
                        flexrm_enqueue_desc(nhpos, nhcnt, reqid,
                                             d, &desc_ptr, &toggle,
                                             start_desc, end_desc);
                        nhpos++;
                }

                if (c->flags & BRCM_SBA_CMD_HAS_OUTPUT) {
                        /* Destination with tlast descriptor */
                        d = flexrm_dstt_desc(c->data, c->data_len);
                        flexrm_enqueue_desc(nhpos, nhcnt, reqid,
                                             d, &desc_ptr, &toggle,
                                             start_desc, end_desc);
                        nhpos++;
                }

                if (c->flags & BRCM_SBA_CMD_TYPE_B) {
                        /* Command as immediate descriptor */
                        d = flexrm_imm_desc(c->cmd);
                        flexrm_enqueue_desc(nhpos, nhcnt, reqid,
                                             d, &desc_ptr, &toggle,
                                             start_desc, end_desc);
                        nhpos++;
                } else {
                        /* Command as immediate descriptor with tlast */
                        d = flexrm_immt_desc(c->cmd);
                        flexrm_enqueue_desc(nhpos, nhcnt, reqid,
                                             d, &desc_ptr, &toggle,
                                             start_desc, end_desc);
                        nhpos++;
                }

                if ((c->flags & BRCM_SBA_CMD_TYPE_B) ||
                    (c->flags & BRCM_SBA_CMD_TYPE_C)) {
                        /* Source with tlast descriptor */
                        d = flexrm_srct_desc(c->data, c->data_len);
                        flexrm_enqueue_desc(nhpos, nhcnt, reqid,
                                             d, &desc_ptr, &toggle,
                                             start_desc, end_desc);
                        nhpos++;
                }
        }

        /* Null descriptor with invalid toggle bit */
        flexrm_write_desc(desc_ptr, flexrm_null_desc(!toggle));

        /* Ensure that descriptors have been written to memory */
        wmb();

        /* Flip toggle bit in header */
        flexrm_flip_header_toggle(orig_desc_ptr);

        return desc_ptr;
}

static bool flexrm_sanity_check(struct brcm_message *msg)
{
        if (!msg)
                return false;

        switch (msg->type) {
        case BRCM_MESSAGE_SPU:
                return flexrm_spu_sanity_check(msg);
        case BRCM_MESSAGE_SBA:
                return flexrm_sba_sanity_check(msg);
        default:
                return false;
        };
}

static u32 flexrm_estimate_nonheader_desc_count(struct brcm_message *msg)
{
        if (!msg)
                return 0;

        switch (msg->type) {
        case BRCM_MESSAGE_SPU:
                return flexrm_spu_estimate_nonheader_desc_count(msg);
        case BRCM_MESSAGE_SBA:
                return flexrm_sba_estimate_nonheader_desc_count(msg);
        default:
                return 0;
        };
}

static int flexrm_dma_map(struct device *dev, struct brcm_message *msg)
{
        if (!dev || !msg)
                return -EINVAL;

        switch (msg->type) {
        case BRCM_MESSAGE_SPU:
                return flexrm_spu_dma_map(dev, msg);
        default:
                break;
        }

        return 0;
}

static void flexrm_dma_unmap(struct device *dev, struct brcm_message *msg)
{
        if (!dev || !msg)
                return;

        switch (msg->type) {
        case BRCM_MESSAGE_SPU:
                flexrm_spu_dma_unmap(dev, msg);
                break;
        default:
                break;
        }
}

static void *flexrm_write_descs(struct brcm_message *msg, u32 nhcnt,
                                u32 reqid, void *desc_ptr, u32 toggle,
                                void *start_desc, void *end_desc)
{
        if (!msg || !desc_ptr || !start_desc || !end_desc)
                return ERR_PTR(-ENOTSUPP);

        if ((desc_ptr < start_desc) || (end_desc <= desc_ptr))
                return ERR_PTR(-ERANGE);

        switch (msg->type) {
        case BRCM_MESSAGE_SPU:
                return flexrm_spu_write_descs(msg, nhcnt, reqid,
                                               desc_ptr, toggle,
                                               start_desc, end_desc);
        case BRCM_MESSAGE_SBA:
                return flexrm_sba_write_descs(msg, nhcnt, reqid,
                                               desc_ptr, toggle,
                                               start_desc, end_desc);
        default:
                return ERR_PTR(-ENOTSUPP);
        };
}

/* ====== FlexRM driver helper routines ===== */

static void flexrm_write_config_in_seqfile(struct flexrm_mbox *mbox,
                                           struct seq_file *file)
{
        int i;
        const char *state;
        struct flexrm_ring *ring;

        seq_printf(file, "%-5s %-9s %-18s %-10s %-18s %-10s\n",
                   "Ring#", "State", "BD_Addr", "BD_Size",
                   "Cmpl_Addr", "Cmpl_Size");

        for (i = 0; i < mbox->num_rings; i++) {
                ring = &mbox->rings[i];
                if (readl(ring->regs + RING_CONTROL) &
                    BIT(CONTROL_ACTIVE_SHIFT))
                        state = "active";
                else
                        state = "inactive";
                seq_printf(file,
                           "%-5d %-9s 0x%016llx 0x%08x 0x%016llx 0x%08x\n",
                           ring->num, state,
                           (unsigned long long)ring->bd_dma_base,
                           (u32)RING_BD_SIZE,
                           (unsigned long long)ring->cmpl_dma_base,
                           (u32)RING_CMPL_SIZE);
        }
}

static void flexrm_write_stats_in_seqfile(struct flexrm_mbox *mbox,
                                          struct seq_file *file)
{
        int i;
        u32 val, bd_read_offset;
        struct flexrm_ring *ring;

        seq_printf(file, "%-5s %-10s %-10s %-10s %-11s %-11s\n",
                   "Ring#", "BD_Read", "BD_Write",
                   "Cmpl_Read", "Submitted", "Completed");

        for (i = 0; i < mbox->num_rings; i++) {
                ring = &mbox->rings[i];
                bd_read_offset = readl_relaxed(ring->regs + RING_BD_READ_PTR);
                val = readl_relaxed(ring->regs + RING_BD_START_ADDR);
                bd_read_offset *= RING_DESC_SIZE;
                bd_read_offset += (u32)(BD_START_ADDR_DECODE(val) -
                                        ring->bd_dma_base);
                seq_printf(file, "%-5d 0x%08x 0x%08x 0x%08x %-11d %-11d\n",
                           ring->num,
                           (u32)bd_read_offset,
                           (u32)ring->bd_write_offset,
                           (u32)ring->cmpl_read_offset,
                           (u32)atomic_read(&ring->msg_send_count),
                           (u32)atomic_read(&ring->msg_cmpl_count));
        }
}

static int flexrm_new_request(struct flexrm_ring *ring,
                                struct brcm_message *batch_msg,
                                struct brcm_message *msg)
{
        void *next;
        unsigned long flags;
        u32 val, count, nhcnt;
        u32 read_offset, write_offset;
        bool exit_cleanup = false;
        int ret = 0, reqid;

        /* Do sanity check on message */
        if (!flexrm_sanity_check(msg))
                return -EIO;
        msg->error = 0;

        /* If no requests possible then save data pointer and goto done. */
        spin_lock_irqsave(&ring->lock, flags);
        reqid = bitmap_find_free_region(ring->requests_bmap,
                                        RING_MAX_REQ_COUNT, 0);
        spin_unlock_irqrestore(&ring->lock, flags);
        if (reqid < 0)
                return -ENOSPC;
        ring->requests[reqid] = msg;

        /* Do DMA mappings for the message */
        ret = flexrm_dma_map(ring->mbox->dev, msg);
        if (ret < 0) {
                ring->requests[reqid] = NULL;
                spin_lock_irqsave(&ring->lock, flags);
                bitmap_release_region(ring->requests_bmap, reqid, 0);
                spin_unlock_irqrestore(&ring->lock, flags);
                return ret;
        }

        /* Determine current HW BD read offset */
        read_offset = readl_relaxed(ring->regs + RING_BD_READ_PTR);
        val = readl_relaxed(ring->regs + RING_BD_START_ADDR);
        read_offset *= RING_DESC_SIZE;
        read_offset += (u32)(BD_START_ADDR_DECODE(val) - ring->bd_dma_base);

        /*
         * Number required descriptors = number of non-header descriptors +
         *                               number of header descriptors +
         *                               1x null descriptor
         */
        nhcnt = flexrm_estimate_nonheader_desc_count(msg);
        count = flexrm_estimate_header_desc_count(nhcnt) + nhcnt + 1;

        /* Check for available descriptor space. */
        write_offset = ring->bd_write_offset;
        while (count) {
                if (!flexrm_is_next_table_desc(ring->bd_base + write_offset))
                        count--;
                write_offset += RING_DESC_SIZE;
                if (write_offset == RING_BD_SIZE)
                        write_offset = 0x0;
                if (write_offset == read_offset)
                        break;
        }
        if (count) {
                ret = -ENOSPC;
                exit_cleanup = true;
                goto exit;
        }

        /* Write descriptors to ring */
        next = flexrm_write_descs(msg, nhcnt, reqid,
                        ring->bd_base + ring->bd_write_offset,
                        RING_BD_TOGGLE_VALID(ring->bd_write_offset),
                        ring->bd_base, ring->bd_base + RING_BD_SIZE);
        if (IS_ERR(next)) {
                ret = PTR_ERR(next);
                exit_cleanup = true;
                goto exit;
        }

        /* Save ring BD write offset */
        ring->bd_write_offset = (unsigned long)(next - ring->bd_base);

        /* Increment number of messages sent */
        atomic_inc_return(&ring->msg_send_count);

exit:
        /* Update error status in message */
        msg->error = ret;

        /* Cleanup if we failed */
        if (exit_cleanup) {
                flexrm_dma_unmap(ring->mbox->dev, msg);
                ring->requests[reqid] = NULL;
                spin_lock_irqsave(&ring->lock, flags);
                bitmap_release_region(ring->requests_bmap, reqid, 0);
                spin_unlock_irqrestore(&ring->lock, flags);
        }

        return ret;
}

static int flexrm_process_completions(struct flexrm_ring *ring)
{
        u64 desc;
        int err, count = 0;
        unsigned long flags;
        struct brcm_message *msg = NULL;
        u32 reqid, cmpl_read_offset, cmpl_write_offset;
        struct mbox_chan *chan = &ring->mbox->controller.chans[ring->num];

        spin_lock_irqsave(&ring->lock, flags);

        /*
         * Get current completion read and write offset
         *
         * Note: We should read completion write pointer at least once
         * after we get a MSI interrupt because HW maintains internal
         * MSI status which will allow next MSI interrupt only after
         * completion write pointer is read.
         */
        cmpl_write_offset = readl_relaxed(ring->regs + RING_CMPL_WRITE_PTR);
        cmpl_write_offset *= RING_DESC_SIZE;
        cmpl_read_offset = ring->cmpl_read_offset;
        ring->cmpl_read_offset = cmpl_write_offset;

        spin_unlock_irqrestore(&ring->lock, flags);

        /* For each completed request notify mailbox clients */
        reqid = 0;
        while (cmpl_read_offset != cmpl_write_offset) {
                /* Dequeue next completion descriptor */
                desc = *((u64 *)(ring->cmpl_base + cmpl_read_offset));

                /* Next read offset */
                cmpl_read_offset += RING_DESC_SIZE;
                if (cmpl_read_offset == RING_CMPL_SIZE)
                        cmpl_read_offset = 0;

                /* Decode error from completion descriptor */
                err = flexrm_cmpl_desc_to_error(desc);
                if (err < 0) {
                        dev_warn(ring->mbox->dev,
                        "ring%d got completion desc=0x%lx with error %d\n",
                        ring->num, (unsigned long)desc, err);
                }

                /* Determine request id from completion descriptor */
                reqid = flexrm_cmpl_desc_to_reqid(desc);

                /* Determine message pointer based on reqid */
                msg = ring->requests[reqid];
                if (!msg) {
                        dev_warn(ring->mbox->dev,
                        "ring%d null msg pointer for completion desc=0x%lx\n",
                        ring->num, (unsigned long)desc);
                        continue;
                }

                /* Release reqid for recycling */
                ring->requests[reqid] = NULL;
                spin_lock_irqsave(&ring->lock, flags);
                bitmap_release_region(ring->requests_bmap, reqid, 0);
                spin_unlock_irqrestore(&ring->lock, flags);

                /* Unmap DMA mappings */
                flexrm_dma_unmap(ring->mbox->dev, msg);

                /* Give-back message to mailbox client */
                msg->error = err;
                mbox_chan_received_data(chan, msg);

                /* Increment number of completions processed */
                atomic_inc_return(&ring->msg_cmpl_count);
                count++;
        }

        return count;
}

/* ====== FlexRM Debugfs callbacks ====== */

static int flexrm_debugfs_conf_show(struct seq_file *file, void *offset)
{
        struct flexrm_mbox *mbox = dev_get_drvdata(file->private);

        /* Write config in file */
        flexrm_write_config_in_seqfile(mbox, file);

        return 0;
}

static int flexrm_debugfs_stats_show(struct seq_file *file, void *offset)
{
        struct flexrm_mbox *mbox = dev_get_drvdata(file->private);

        /* Write stats in file */
        flexrm_write_stats_in_seqfile(mbox, file);

        return 0;
}

/* ====== FlexRM interrupt handler ===== */

static irqreturn_t flexrm_irq_thread(int irq, void *dev_id)
{
        flexrm_process_completions(dev_id);

        return IRQ_HANDLED;
}

/* ====== FlexRM mailbox callbacks ===== */

static int flexrm_send_data(struct mbox_chan *chan, void *data)
{
        int i, rc;
        struct flexrm_ring *ring = chan->con_priv;
        struct brcm_message *msg = data;

        if (msg->type == BRCM_MESSAGE_BATCH) {
                for (i = msg->batch.msgs_queued;
                     i < msg->batch.msgs_count; i++) {
                        rc = flexrm_new_request(ring, msg,
                                                 &msg->batch.msgs[i]);
                        if (rc) {
                                msg->error = rc;
                                return rc;
                        }
                        msg->batch.msgs_queued++;
                }
                return 0;
        }

        return flexrm_new_request(ring, NULL, data);
}

static bool flexrm_peek_data(struct mbox_chan *chan)
{
        int cnt = flexrm_process_completions(chan->con_priv);

        return (cnt > 0) ? true : false;
}

static int flexrm_startup(struct mbox_chan *chan)
{
        u64 d;
        u32 val, off;
        int ret = 0;
        dma_addr_t next_addr;
        struct flexrm_ring *ring = chan->con_priv;

        /* Allocate BD memory */
        ring->bd_base = dma_pool_alloc(ring->mbox->bd_pool,
                                       GFP_KERNEL, &ring->bd_dma_base);
        if (!ring->bd_base) {
                dev_err(ring->mbox->dev,
                        "can't allocate BD memory for ring%d\n",
                        ring->num);
                ret = -ENOMEM;
                goto fail;
        }

        /* Configure next table pointer entries in BD memory */
        for (off = 0; off < RING_BD_SIZE; off += RING_DESC_SIZE) {
                next_addr = off + RING_DESC_SIZE;
                if (next_addr == RING_BD_SIZE)
                        next_addr = 0;
                next_addr += ring->bd_dma_base;
                if (RING_BD_ALIGN_CHECK(next_addr))
                        d = flexrm_next_table_desc(RING_BD_TOGGLE_VALID(off),
                                                    next_addr);
                else
                        d = flexrm_null_desc(RING_BD_TOGGLE_INVALID(off));
                flexrm_write_desc(ring->bd_base + off, d);
        }

        /* Allocate completion memory */
        ring->cmpl_base = dma_pool_zalloc(ring->mbox->cmpl_pool,
                                         GFP_KERNEL, &ring->cmpl_dma_base);
        if (!ring->cmpl_base) {
                dev_err(ring->mbox->dev,
                        "can't allocate completion memory for ring%d\n",
                        ring->num);
                ret = -ENOMEM;
                goto fail_free_bd_memory;
        }

        /* Request IRQ */
        if (ring->irq == UINT_MAX) {
                dev_err(ring->mbox->dev,
                        "ring%d IRQ not available\n", ring->num);
                ret = -ENODEV;
                goto fail_free_cmpl_memory;
        }
        ret = request_threaded_irq(ring->irq, NULL, flexrm_irq_thread,
                                   IRQF_ONESHOT, dev_name(ring->mbox->dev), ring);
        if (ret) {
                dev_err(ring->mbox->dev,
                        "failed to request ring%d IRQ\n", ring->num);
                goto fail_free_cmpl_memory;
        }
        ring->irq_requested = true;

        /* Set IRQ affinity hint */
        ring->irq_aff_hint = CPU_MASK_NONE;
        val = ring->mbox->num_rings;
        val = (num_online_cpus() < val) ? val / num_online_cpus() : 1;
        cpumask_set_cpu((ring->num / val) % num_online_cpus(),
                        &ring->irq_aff_hint);
        ret = irq_update_affinity_hint(ring->irq, &ring->irq_aff_hint);
        if (ret) {
                dev_err(ring->mbox->dev,
                        "failed to set IRQ affinity hint for ring%d\n",
                        ring->num);
                goto fail_free_irq;
        }

        /* Disable/inactivate ring */
        writel_relaxed(0x0, ring->regs + RING_CONTROL);

        /* Program BD start address */
        val = BD_START_ADDR_VALUE(ring->bd_dma_base);
        writel_relaxed(val, ring->regs + RING_BD_START_ADDR);

        /* BD write pointer will be same as HW write pointer */
        ring->bd_write_offset =
                        readl_relaxed(ring->regs + RING_BD_WRITE_PTR);
        ring->bd_write_offset *= RING_DESC_SIZE;

        /* Program completion start address */
        val = CMPL_START_ADDR_VALUE(ring->cmpl_dma_base);
        writel_relaxed(val, ring->regs + RING_CMPL_START_ADDR);

        /* Completion read pointer will be same as HW write pointer */
        ring->cmpl_read_offset =
                        readl_relaxed(ring->regs + RING_CMPL_WRITE_PTR);
        ring->cmpl_read_offset *= RING_DESC_SIZE;

        /* Read ring Tx, Rx, and Outstanding counts to clear */
        readl_relaxed(ring->regs + RING_NUM_REQ_RECV_LS);
        readl_relaxed(ring->regs + RING_NUM_REQ_RECV_MS);
        readl_relaxed(ring->regs + RING_NUM_REQ_TRANS_LS);
        readl_relaxed(ring->regs + RING_NUM_REQ_TRANS_MS);
        readl_relaxed(ring->regs + RING_NUM_REQ_OUTSTAND);

        /* Configure RING_MSI_CONTROL */
        val = 0;
        val |= (ring->msi_timer_val << MSI_TIMER_VAL_SHIFT);
        val |= BIT(MSI_ENABLE_SHIFT);
        val |= (ring->msi_count_threshold & MSI_COUNT_MASK) << MSI_COUNT_SHIFT;
        writel_relaxed(val, ring->regs + RING_MSI_CONTROL);

        /* Enable/activate ring */
        val = BIT(CONTROL_ACTIVE_SHIFT);
        writel_relaxed(val, ring->regs + RING_CONTROL);

        /* Reset stats to zero */
        atomic_set(&ring->msg_send_count, 0);
        atomic_set(&ring->msg_cmpl_count, 0);

        return 0;

fail_free_irq:
        free_irq(ring->irq, ring);
        ring->irq_requested = false;
fail_free_cmpl_memory:
        dma_pool_free(ring->mbox->cmpl_pool,
                      ring->cmpl_base, ring->cmpl_dma_base);
        ring->cmpl_base = NULL;
fail_free_bd_memory:
        dma_pool_free(ring->mbox->bd_pool,
                      ring->bd_base, ring->bd_dma_base);
        ring->bd_base = NULL;
fail:
        return ret;
}

static void flexrm_shutdown(struct mbox_chan *chan)
{
        u32 reqid;
        unsigned int timeout;
        struct brcm_message *msg;
        struct flexrm_ring *ring = chan->con_priv;

        /* Disable/inactivate ring */
        writel_relaxed(0x0, ring->regs + RING_CONTROL);

        /* Set ring flush state */
        timeout = 1000; /* timeout of 1s */
        writel_relaxed(BIT(CONTROL_FLUSH_SHIFT),
                        ring->regs + RING_CONTROL);
        do {
                if (readl_relaxed(ring->regs + RING_FLUSH_DONE) &
                    FLUSH_DONE_MASK)
                        break;
                mdelay(1);
        } while (--timeout);
        if (!timeout)
                dev_err(ring->mbox->dev,
                        "setting ring%d flush state timedout\n", ring->num);

        /* Clear ring flush state */
        timeout = 1000; /* timeout of 1s */
        writel_relaxed(0x0, ring->regs + RING_CONTROL);
        do {
                if (!(readl_relaxed(ring->regs + RING_FLUSH_DONE) &
                      FLUSH_DONE_MASK))
                        break;
                mdelay(1);
        } while (--timeout);
        if (!timeout)
                dev_err(ring->mbox->dev,
                        "clearing ring%d flush state timedout\n", ring->num);

        /* Abort all in-flight requests */
        for (reqid = 0; reqid < RING_MAX_REQ_COUNT; reqid++) {
                msg = ring->requests[reqid];
                if (!msg)
                        continue;

                /* Release reqid for recycling */
                ring->requests[reqid] = NULL;

                /* Unmap DMA mappings */
                flexrm_dma_unmap(ring->mbox->dev, msg);

                /* Give-back message to mailbox client */
                msg->error = -EIO;
                mbox_chan_received_data(chan, msg);
        }

        /* Clear requests bitmap */
        bitmap_zero(ring->requests_bmap, RING_MAX_REQ_COUNT);

        /* Release IRQ */
        if (ring->irq_requested) {
                irq_update_affinity_hint(ring->irq, NULL);
                free_irq(ring->irq, ring);
                ring->irq_requested = false;
        }

        /* Free-up completion descriptor ring */
        if (ring->cmpl_base) {
                dma_pool_free(ring->mbox->cmpl_pool,
                              ring->cmpl_base, ring->cmpl_dma_base);
                ring->cmpl_base = NULL;
        }

        /* Free-up BD descriptor ring */
        if (ring->bd_base) {
                dma_pool_free(ring->mbox->bd_pool,
                              ring->bd_base, ring->bd_dma_base);
                ring->bd_base = NULL;
        }
}

static const struct mbox_chan_ops flexrm_mbox_chan_ops = {
        .send_data      = flexrm_send_data,
        .startup        = flexrm_startup,
        .shutdown       = flexrm_shutdown,
        .peek_data      = flexrm_peek_data,
};

static struct mbox_chan *flexrm_mbox_of_xlate(struct mbox_controller *cntlr,
                                        const struct of_phandle_args *pa)
{
        struct mbox_chan *chan;
        struct flexrm_ring *ring;

        if (pa->args_count < 3)
                return ERR_PTR(-EINVAL);

        if (pa->args[0] >= cntlr->num_chans)
                return ERR_PTR(-ENOENT);

        if (pa->args[1] > MSI_COUNT_MASK)
                return ERR_PTR(-EINVAL);

        if (pa->args[2] > MSI_TIMER_VAL_MASK)
                return ERR_PTR(-EINVAL);

        chan = &cntlr->chans[pa->args[0]];
        ring = chan->con_priv;
        ring->msi_count_threshold = pa->args[1];
        ring->msi_timer_val = pa->args[2];

        return chan;
}

/* ====== FlexRM platform driver ===== */

static void flexrm_mbox_msi_write(struct msi_desc *desc, struct msi_msg *msg)
{
        struct device *dev = msi_desc_to_dev(desc);
        struct flexrm_mbox *mbox = dev_get_drvdata(dev);
        struct flexrm_ring *ring = &mbox->rings[desc->msi_index];

        /* Configure per-Ring MSI registers */
        writel_relaxed(msg->address_lo, ring->regs + RING_MSI_ADDR_LS);
        writel_relaxed(msg->address_hi, ring->regs + RING_MSI_ADDR_MS);
        writel_relaxed(msg->data, ring->regs + RING_MSI_DATA_VALUE);
}

static int flexrm_mbox_probe(struct platform_device *pdev)
{
        int index, ret = 0;
        void __iomem *regs;
        void __iomem *regs_end;
        struct resource *iomem;
        struct flexrm_ring *ring;
        struct flexrm_mbox *mbox;
        struct device *dev = &pdev->dev;

        /* Allocate driver mailbox struct */
        mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL);
        if (!mbox) {
                ret = -ENOMEM;
                goto fail;
        }
        mbox->dev = dev;
        platform_set_drvdata(pdev, mbox);

        /* Get resource for registers and map registers of all rings */
        mbox->regs = devm_platform_get_and_ioremap_resource(pdev, 0, &iomem);
        if (!iomem || (resource_size(iomem) < RING_REGS_SIZE)) {
                ret = -ENODEV;
                goto fail;
        } else if (IS_ERR(mbox->regs)) {
                ret = PTR_ERR(mbox->regs);
                goto fail;
        }
        regs_end = mbox->regs + resource_size(iomem);

        /* Scan and count available rings */
        mbox->num_rings = 0;
        for (regs = mbox->regs; regs < regs_end; regs += RING_REGS_SIZE) {
                if (readl_relaxed(regs + RING_VER) == RING_VER_MAGIC)
                        mbox->num_rings++;
        }
        if (!mbox->num_rings) {
                ret = -ENODEV;
                goto fail;
        }

        /* Allocate driver ring structs */
        ring = devm_kcalloc(dev, mbox->num_rings, sizeof(*ring), GFP_KERNEL);
        if (!ring) {
                ret = -ENOMEM;
                goto fail;
        }
        mbox->rings = ring;

        /* Initialize members of driver ring structs */
        regs = mbox->regs;
        for (index = 0; index < mbox->num_rings; index++) {
                ring = &mbox->rings[index];
                ring->num = index;
                ring->mbox = mbox;
                while ((regs < regs_end) &&
                       (readl_relaxed(regs + RING_VER) != RING_VER_MAGIC))
                        regs += RING_REGS_SIZE;
                if (regs_end <= regs) {
                        ret = -ENODEV;
                        goto fail;
                }
                ring->regs = regs;
                regs += RING_REGS_SIZE;
                ring->irq = UINT_MAX;
                ring->irq_requested = false;
                ring->msi_timer_val = MSI_TIMER_VAL_MASK;
                ring->msi_count_threshold = 0x1;
                memset(ring->requests, 0, sizeof(ring->requests));
                ring->bd_base = NULL;
                ring->bd_dma_base = 0;
                ring->cmpl_base = NULL;
                ring->cmpl_dma_base = 0;
                atomic_set(&ring->msg_send_count, 0);
                atomic_set(&ring->msg_cmpl_count, 0);
                spin_lock_init(&ring->lock);
                bitmap_zero(ring->requests_bmap, RING_MAX_REQ_COUNT);
                ring->cmpl_read_offset = 0;
        }

        /* FlexRM is capable of 40-bit physical addresses only */
        ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(40));
        if (ret) {
                ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
                if (ret)
                        goto fail;
        }

        /* Create DMA pool for ring BD memory */
        mbox->bd_pool = dma_pool_create("bd", dev, RING_BD_SIZE,
                                        1 << RING_BD_ALIGN_ORDER, 0);
        if (!mbox->bd_pool) {
                ret = -ENOMEM;
                goto fail;
        }

        /* Create DMA pool for ring completion memory */
        mbox->cmpl_pool = dma_pool_create("cmpl", dev, RING_CMPL_SIZE,
                                          1 << RING_CMPL_ALIGN_ORDER, 0);
        if (!mbox->cmpl_pool) {
                ret = -ENOMEM;
                goto fail_destroy_bd_pool;
        }

        /* Allocate platform MSIs for each ring */
        ret = platform_device_msi_init_and_alloc_irqs(dev, mbox->num_rings,
                                                      flexrm_mbox_msi_write);
        if (ret)
                goto fail_destroy_cmpl_pool;

        /* Save alloced IRQ numbers for each ring */
        for (index = 0; index < mbox->num_rings; index++)
                mbox->rings[index].irq = msi_get_virq(dev, index);

        /* Check availability of debugfs */
        if (!debugfs_initialized())
                goto skip_debugfs;

        /* Create debugfs root entry */
        mbox->root = debugfs_create_dir(dev_name(mbox->dev), NULL);

        /* Create debugfs config entry */
        debugfs_create_devm_seqfile(mbox->dev, "config", mbox->root,
                                    flexrm_debugfs_conf_show);

        /* Create debugfs stats entry */
        debugfs_create_devm_seqfile(mbox->dev, "stats", mbox->root,
                                    flexrm_debugfs_stats_show);

skip_debugfs:

        /* Initialize mailbox controller */
        mbox->controller.txdone_irq = false;
        mbox->controller.txdone_poll = false;
        mbox->controller.ops = &flexrm_mbox_chan_ops;
        mbox->controller.dev = dev;
        mbox->controller.num_chans = mbox->num_rings;
        mbox->controller.of_xlate = flexrm_mbox_of_xlate;
        mbox->controller.chans = devm_kcalloc(dev, mbox->num_rings,
                                sizeof(*mbox->controller.chans), GFP_KERNEL);
        if (!mbox->controller.chans) {
                ret = -ENOMEM;
                goto fail_free_debugfs_root;
        }
        for (index = 0; index < mbox->num_rings; index++)
                mbox->controller.chans[index].con_priv = &mbox->rings[index];

        /* Register mailbox controller */
        ret = devm_mbox_controller_register(dev, &mbox->controller);
        if (ret)
                goto fail_free_debugfs_root;

        dev_info(dev, "registered flexrm mailbox with %d channels\n",
                        mbox->controller.num_chans);

        return 0;

fail_free_debugfs_root:
        debugfs_remove_recursive(mbox->root);
        platform_device_msi_free_irqs_all(dev);
fail_destroy_cmpl_pool:
        dma_pool_destroy(mbox->cmpl_pool);
fail_destroy_bd_pool:
        dma_pool_destroy(mbox->bd_pool);
fail:
        return ret;
}

static void flexrm_mbox_remove(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct flexrm_mbox *mbox = platform_get_drvdata(pdev);

        debugfs_remove_recursive(mbox->root);

        platform_device_msi_free_irqs_all(dev);

        dma_pool_destroy(mbox->cmpl_pool);
        dma_pool_destroy(mbox->bd_pool);
}

static const struct of_device_id flexrm_mbox_of_match[] = {
        { .compatible = "brcm,iproc-flexrm-mbox", },
        {},
};
MODULE_DEVICE_TABLE(of, flexrm_mbox_of_match);

static struct platform_driver flexrm_mbox_driver = {
        .driver = {
                .name = "brcm-flexrm-mbox",
                .of_match_table = flexrm_mbox_of_match,
        },
        .probe          = flexrm_mbox_probe,
        .remove         = flexrm_mbox_remove,
};
module_platform_driver(flexrm_mbox_driver);

MODULE_AUTHOR("Anup Patel <anup.patel@broadcom.com>");
MODULE_DESCRIPTION("Broadcom FlexRM mailbox driver");
MODULE_LICENSE("GPL v2");