// SPDX-License-Identifier: GPL-2.0-only
/*
 * System Control and Power Interface (SCPI) Message Protocol driver
 *
 * SCPI Message Protocol is used between the System Control Processor(SCP)
 * and the Application Processors(AP). The Message Handling Unit(MHU)
 * provides a mechanism for inter-processor communication between SCP's
 * Cortex M3 and AP.
 *
 * SCP offers control and management of the core/cluster power states,
 * various power domain DVFS including the core/cluster, certain system
 * clocks configuration, thermal sensors and many others.
 *
 * Copyright (C) 2015 ARM Ltd.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/bitmap.h>
#include <linux/bitfield.h>
#include <linux/cleanup.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/mailbox_client.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/printk.h>
#include <linux/property.h>
#include <linux/pm_opp.h>
#include <linux/scpi_protocol.h>
#include <linux/slab.h>
#include <linux/sort.h>
#include <linux/spinlock.h>

#define CMD_ID_MASK             GENMASK(6, 0)
#define CMD_TOKEN_ID_MASK       GENMASK(15, 8)
#define CMD_DATA_SIZE_MASK      GENMASK(24, 16)
#define CMD_LEGACY_DATA_SIZE_MASK       GENMASK(28, 20)
#define PACK_SCPI_CMD(cmd_id, tx_sz)            \
        (FIELD_PREP(CMD_ID_MASK, cmd_id) |      \
        FIELD_PREP(CMD_DATA_SIZE_MASK, tx_sz))
#define PACK_LEGACY_SCPI_CMD(cmd_id, tx_sz)     \
        (FIELD_PREP(CMD_ID_MASK, cmd_id) |      \
        FIELD_PREP(CMD_LEGACY_DATA_SIZE_MASK, tx_sz))

#define CMD_SIZE(cmd)   FIELD_GET(CMD_DATA_SIZE_MASK, cmd)
#define CMD_UNIQ_MASK   (CMD_TOKEN_ID_MASK | CMD_ID_MASK)
#define CMD_XTRACT_UNIQ(cmd)    ((cmd) & CMD_UNIQ_MASK)

#define SCPI_SLOT               0

#define MAX_DVFS_DOMAINS        8
#define MAX_DVFS_OPPS           16

#define PROTO_REV_MAJOR_MASK    GENMASK(31, 16)
#define PROTO_REV_MINOR_MASK    GENMASK(15, 0)

#define FW_REV_MAJOR_MASK       GENMASK(31, 24)
#define FW_REV_MINOR_MASK       GENMASK(23, 16)
#define FW_REV_PATCH_MASK       GENMASK(15, 0)

#define MAX_RX_TIMEOUT          (msecs_to_jiffies(30))

enum scpi_error_codes {
        SCPI_SUCCESS = 0, /* Success */
        SCPI_ERR_PARAM = 1, /* Invalid parameter(s) */
        SCPI_ERR_ALIGN = 2, /* Invalid alignment */
        SCPI_ERR_SIZE = 3, /* Invalid size */
        SCPI_ERR_HANDLER = 4, /* Invalid handler/callback */
        SCPI_ERR_ACCESS = 5, /* Invalid access/permission denied */
        SCPI_ERR_RANGE = 6, /* Value out of range */
        SCPI_ERR_TIMEOUT = 7, /* Timeout has occurred */
        SCPI_ERR_NOMEM = 8, /* Invalid memory area or pointer */
        SCPI_ERR_PWRSTATE = 9, /* Invalid power state */
        SCPI_ERR_SUPPORT = 10, /* Not supported or disabled */
        SCPI_ERR_DEVICE = 11, /* Device error */
        SCPI_ERR_BUSY = 12, /* Device busy */
        SCPI_ERR_MAX
};

/* SCPI Standard commands */
enum scpi_std_cmd {
        SCPI_CMD_INVALID                = 0x00,
        SCPI_CMD_SCPI_READY             = 0x01,
        SCPI_CMD_SCPI_CAPABILITIES      = 0x02,
        SCPI_CMD_SET_CSS_PWR_STATE      = 0x03,
        SCPI_CMD_GET_CSS_PWR_STATE      = 0x04,
        SCPI_CMD_SET_SYS_PWR_STATE      = 0x05,
        SCPI_CMD_SET_CPU_TIMER          = 0x06,
        SCPI_CMD_CANCEL_CPU_TIMER       = 0x07,
        SCPI_CMD_DVFS_CAPABILITIES      = 0x08,
        SCPI_CMD_GET_DVFS_INFO          = 0x09,
        SCPI_CMD_SET_DVFS               = 0x0a,
        SCPI_CMD_GET_DVFS               = 0x0b,
        SCPI_CMD_GET_DVFS_STAT          = 0x0c,
        SCPI_CMD_CLOCK_CAPABILITIES     = 0x0d,
        SCPI_CMD_GET_CLOCK_INFO         = 0x0e,
        SCPI_CMD_SET_CLOCK_VALUE        = 0x0f,
        SCPI_CMD_GET_CLOCK_VALUE        = 0x10,
        SCPI_CMD_PSU_CAPABILITIES       = 0x11,
        SCPI_CMD_GET_PSU_INFO           = 0x12,
        SCPI_CMD_SET_PSU                = 0x13,
        SCPI_CMD_GET_PSU                = 0x14,
        SCPI_CMD_SENSOR_CAPABILITIES    = 0x15,
        SCPI_CMD_SENSOR_INFO            = 0x16,
        SCPI_CMD_SENSOR_VALUE           = 0x17,
        SCPI_CMD_SENSOR_CFG_PERIODIC    = 0x18,
        SCPI_CMD_SENSOR_CFG_BOUNDS      = 0x19,
        SCPI_CMD_SENSOR_ASYNC_VALUE     = 0x1a,
        SCPI_CMD_SET_DEVICE_PWR_STATE   = 0x1b,
        SCPI_CMD_GET_DEVICE_PWR_STATE   = 0x1c,
        SCPI_CMD_COUNT
};

/* SCPI Legacy Commands */
enum legacy_scpi_std_cmd {
        LEGACY_SCPI_CMD_INVALID                 = 0x00,
        LEGACY_SCPI_CMD_SCPI_READY              = 0x01,
        LEGACY_SCPI_CMD_SCPI_CAPABILITIES       = 0x02,
        LEGACY_SCPI_CMD_EVENT                   = 0x03,
        LEGACY_SCPI_CMD_SET_CSS_PWR_STATE       = 0x04,
        LEGACY_SCPI_CMD_GET_CSS_PWR_STATE       = 0x05,
        LEGACY_SCPI_CMD_CFG_PWR_STATE_STAT      = 0x06,
        LEGACY_SCPI_CMD_GET_PWR_STATE_STAT      = 0x07,
        LEGACY_SCPI_CMD_SYS_PWR_STATE           = 0x08,
        LEGACY_SCPI_CMD_L2_READY                = 0x09,
        LEGACY_SCPI_CMD_SET_AP_TIMER            = 0x0a,
        LEGACY_SCPI_CMD_CANCEL_AP_TIME          = 0x0b,
        LEGACY_SCPI_CMD_DVFS_CAPABILITIES       = 0x0c,
        LEGACY_SCPI_CMD_GET_DVFS_INFO           = 0x0d,
        LEGACY_SCPI_CMD_SET_DVFS                = 0x0e,
        LEGACY_SCPI_CMD_GET_DVFS                = 0x0f,
        LEGACY_SCPI_CMD_GET_DVFS_STAT           = 0x10,
        LEGACY_SCPI_CMD_SET_RTC                 = 0x11,
        LEGACY_SCPI_CMD_GET_RTC                 = 0x12,
        LEGACY_SCPI_CMD_CLOCK_CAPABILITIES      = 0x13,
        LEGACY_SCPI_CMD_SET_CLOCK_INDEX         = 0x14,
        LEGACY_SCPI_CMD_SET_CLOCK_VALUE         = 0x15,
        LEGACY_SCPI_CMD_GET_CLOCK_VALUE         = 0x16,
        LEGACY_SCPI_CMD_PSU_CAPABILITIES        = 0x17,
        LEGACY_SCPI_CMD_SET_PSU                 = 0x18,
        LEGACY_SCPI_CMD_GET_PSU                 = 0x19,
        LEGACY_SCPI_CMD_SENSOR_CAPABILITIES     = 0x1a,
        LEGACY_SCPI_CMD_SENSOR_INFO             = 0x1b,
        LEGACY_SCPI_CMD_SENSOR_VALUE            = 0x1c,
        LEGACY_SCPI_CMD_SENSOR_CFG_PERIODIC     = 0x1d,
        LEGACY_SCPI_CMD_SENSOR_CFG_BOUNDS       = 0x1e,
        LEGACY_SCPI_CMD_SENSOR_ASYNC_VALUE      = 0x1f,
        LEGACY_SCPI_CMD_COUNT
};

/* List all commands that are required to go through the high priority link */
static int legacy_hpriority_cmds[] = {
        LEGACY_SCPI_CMD_GET_CSS_PWR_STATE,
        LEGACY_SCPI_CMD_CFG_PWR_STATE_STAT,
        LEGACY_SCPI_CMD_GET_PWR_STATE_STAT,
        LEGACY_SCPI_CMD_SET_DVFS,
        LEGACY_SCPI_CMD_GET_DVFS,
        LEGACY_SCPI_CMD_SET_RTC,
        LEGACY_SCPI_CMD_GET_RTC,
        LEGACY_SCPI_CMD_SET_CLOCK_INDEX,
        LEGACY_SCPI_CMD_SET_CLOCK_VALUE,
        LEGACY_SCPI_CMD_GET_CLOCK_VALUE,
        LEGACY_SCPI_CMD_SET_PSU,
        LEGACY_SCPI_CMD_GET_PSU,
        LEGACY_SCPI_CMD_SENSOR_CFG_PERIODIC,
        LEGACY_SCPI_CMD_SENSOR_CFG_BOUNDS,
};

/* List all commands used by this driver, used as indexes */
enum scpi_drv_cmds {
        CMD_SCPI_CAPABILITIES = 0,
        CMD_GET_CLOCK_INFO,
        CMD_GET_CLOCK_VALUE,
        CMD_SET_CLOCK_VALUE,
        CMD_GET_DVFS,
        CMD_SET_DVFS,
        CMD_GET_DVFS_INFO,
        CMD_SENSOR_CAPABILITIES,
        CMD_SENSOR_INFO,
        CMD_SENSOR_VALUE,
        CMD_SET_DEVICE_PWR_STATE,
        CMD_GET_DEVICE_PWR_STATE,
        CMD_MAX_COUNT,
};

static int scpi_std_commands[CMD_MAX_COUNT] = {
        SCPI_CMD_SCPI_CAPABILITIES,
        SCPI_CMD_GET_CLOCK_INFO,
        SCPI_CMD_GET_CLOCK_VALUE,
        SCPI_CMD_SET_CLOCK_VALUE,
        SCPI_CMD_GET_DVFS,
        SCPI_CMD_SET_DVFS,
        SCPI_CMD_GET_DVFS_INFO,
        SCPI_CMD_SENSOR_CAPABILITIES,
        SCPI_CMD_SENSOR_INFO,
        SCPI_CMD_SENSOR_VALUE,
        SCPI_CMD_SET_DEVICE_PWR_STATE,
        SCPI_CMD_GET_DEVICE_PWR_STATE,
};

static int scpi_legacy_commands[CMD_MAX_COUNT] = {
        LEGACY_SCPI_CMD_SCPI_CAPABILITIES,
        -1, /* GET_CLOCK_INFO */
        LEGACY_SCPI_CMD_GET_CLOCK_VALUE,
        LEGACY_SCPI_CMD_SET_CLOCK_VALUE,
        LEGACY_SCPI_CMD_GET_DVFS,
        LEGACY_SCPI_CMD_SET_DVFS,
        LEGACY_SCPI_CMD_GET_DVFS_INFO,
        LEGACY_SCPI_CMD_SENSOR_CAPABILITIES,
        LEGACY_SCPI_CMD_SENSOR_INFO,
        LEGACY_SCPI_CMD_SENSOR_VALUE,
        -1, /* SET_DEVICE_PWR_STATE */
        -1, /* GET_DEVICE_PWR_STATE */
};

struct scpi_xfer {
        u32 slot; /* has to be first element */
        u32 cmd;
        u32 status;
        const void *tx_buf;
        void *rx_buf;
        unsigned int tx_len;
        unsigned int rx_len;
        struct list_head node;
        struct completion done;
};

struct scpi_chan {
        struct mbox_client cl;
        struct mbox_chan *chan;
        void __iomem *tx_payload;
        void __iomem *rx_payload;
        struct list_head rx_pending;
        struct list_head xfers_list;
        struct scpi_xfer *xfers;
        spinlock_t rx_lock; /* locking for the rx pending list */
        struct mutex xfers_lock;
        u8 token;
};

struct scpi_drvinfo {
        u32 protocol_version;
        u32 firmware_version;
        bool is_legacy;
        int num_chans;
        int *commands;
        DECLARE_BITMAP(cmd_priority, LEGACY_SCPI_CMD_COUNT);
        atomic_t next_chan;
        struct scpi_ops *scpi_ops;
        struct scpi_chan *channels;
        struct scpi_dvfs_info *dvfs[MAX_DVFS_DOMAINS];
};

/*
 * The SCP firmware only executes in little-endian mode, so any buffers
 * shared through SCPI should have their contents converted to little-endian
 */
struct scpi_shared_mem {
        __le32 command;
        __le32 status;
        u8 payload[];
} __packed;

struct legacy_scpi_shared_mem {
        __le32 status;
        u8 payload[];
} __packed;

struct scp_capabilities {
        __le32 protocol_version;
        __le32 event_version;
        __le32 platform_version;
        __le32 commands[4];
} __packed;

struct clk_get_info {
        __le16 id;
        __le16 flags;
        __le32 min_rate;
        __le32 max_rate;
        u8 name[20];
} __packed;

struct clk_set_value {
        __le16 id;
        __le16 reserved;
        __le32 rate;
} __packed;

struct legacy_clk_set_value {
        __le32 rate;
        __le16 id;
        __le16 reserved;
} __packed;

struct dvfs_info {
        u8 domain;
        u8 opp_count;
        __le16 latency;
        struct {
                __le32 freq;
                __le32 m_volt;
        } opps[MAX_DVFS_OPPS];
} __packed;

struct dvfs_set {
        u8 domain;
        u8 index;
} __packed;

struct _scpi_sensor_info {
        __le16 sensor_id;
        u8 class;
        u8 trigger_type;
        char name[20];
};

struct dev_pstate_set {
        __le16 dev_id;
        u8 pstate;
} __packed;

static struct scpi_drvinfo *scpi_info;

static int scpi_linux_errmap[SCPI_ERR_MAX] = {
        /* better than switch case as long as return value is continuous */
        0, /* SCPI_SUCCESS */
        -EINVAL, /* SCPI_ERR_PARAM */
        -ENOEXEC, /* SCPI_ERR_ALIGN */
        -EMSGSIZE, /* SCPI_ERR_SIZE */
        -EINVAL, /* SCPI_ERR_HANDLER */
        -EACCES, /* SCPI_ERR_ACCESS */
        -ERANGE, /* SCPI_ERR_RANGE */
        -ETIMEDOUT, /* SCPI_ERR_TIMEOUT */
        -ENOMEM, /* SCPI_ERR_NOMEM */
        -EINVAL, /* SCPI_ERR_PWRSTATE */
        -EOPNOTSUPP, /* SCPI_ERR_SUPPORT */
        -EIO, /* SCPI_ERR_DEVICE */
        -EBUSY, /* SCPI_ERR_BUSY */
};

static inline int scpi_to_linux_errno(int errno)
{
        if (errno >= SCPI_SUCCESS && errno < SCPI_ERR_MAX)
                return scpi_linux_errmap[errno];
        return -EIO;
}

static void scpi_process_cmd(struct scpi_chan *ch, u32 cmd)
{
        unsigned long flags;
        struct scpi_xfer *t, *match = NULL;

        spin_lock_irqsave(&ch->rx_lock, flags);
        if (list_empty(&ch->rx_pending)) {
                spin_unlock_irqrestore(&ch->rx_lock, flags);
                return;
        }

        /* Command type is not replied by the SCP Firmware in legacy Mode
         * We should consider that command is the head of pending RX commands
         * if the list is not empty. In TX only mode, the list would be empty.
         */
        if (scpi_info->is_legacy) {
                match = list_first_entry(&ch->rx_pending, struct scpi_xfer,
                                         node);
                list_del(&match->node);
        } else {
                list_for_each_entry(t, &ch->rx_pending, node)
                        if (CMD_XTRACT_UNIQ(t->cmd) == CMD_XTRACT_UNIQ(cmd)) {
                                list_del(&t->node);
                                match = t;
                                break;
                        }
        }
        /* check if wait_for_completion is in progress or timed-out */
        if (match && !completion_done(&match->done)) {
                unsigned int len;

                if (scpi_info->is_legacy) {
                        struct legacy_scpi_shared_mem __iomem *mem =
                                                        ch->rx_payload;

                        /* RX Length is not replied by the legacy Firmware */
                        len = match->rx_len;

                        match->status = ioread32(&mem->status);
                        memcpy_fromio(match->rx_buf, mem->payload, len);
                } else {
                        struct scpi_shared_mem __iomem *mem = ch->rx_payload;

                        len = min_t(unsigned int, match->rx_len, CMD_SIZE(cmd));

                        match->status = ioread32(&mem->status);
                        memcpy_fromio(match->rx_buf, mem->payload, len);
                }

                if (match->rx_len > len)
                        memset(match->rx_buf + len, 0, match->rx_len - len);
                complete(&match->done);
        }
        spin_unlock_irqrestore(&ch->rx_lock, flags);
}

static void scpi_handle_remote_msg(struct mbox_client *c, void *msg)
{
        struct scpi_chan *ch = container_of(c, struct scpi_chan, cl);
        struct scpi_shared_mem __iomem *mem = ch->rx_payload;
        u32 cmd = 0;

        if (!scpi_info->is_legacy)
                cmd = ioread32(&mem->command);

        scpi_process_cmd(ch, cmd);
}

static void scpi_tx_prepare(struct mbox_client *c, void *msg)
{
        unsigned long flags;
        struct scpi_xfer *t = msg;
        struct scpi_chan *ch = container_of(c, struct scpi_chan, cl);
        struct scpi_shared_mem __iomem *mem = ch->tx_payload;

        if (t->tx_buf) {
                if (scpi_info->is_legacy)
                        memcpy_toio(ch->tx_payload, t->tx_buf, t->tx_len);
                else
                        memcpy_toio(mem->payload, t->tx_buf, t->tx_len);
        }

        if (t->rx_buf) {
                if (!(++ch->token))
                        ++ch->token;
                t->cmd |= FIELD_PREP(CMD_TOKEN_ID_MASK, ch->token);
                spin_lock_irqsave(&ch->rx_lock, flags);
                list_add_tail(&t->node, &ch->rx_pending);
                spin_unlock_irqrestore(&ch->rx_lock, flags);
        }

        if (!scpi_info->is_legacy)
                iowrite32(t->cmd, &mem->command);
}

static struct scpi_xfer *get_scpi_xfer(struct scpi_chan *ch)
{
        struct scpi_xfer *t;

        mutex_lock(&ch->xfers_lock);
        if (list_empty(&ch->xfers_list)) {
                mutex_unlock(&ch->xfers_lock);
                return NULL;
        }
        t = list_first_entry(&ch->xfers_list, struct scpi_xfer, node);
        list_del(&t->node);
        mutex_unlock(&ch->xfers_lock);
        return t;
}

static void put_scpi_xfer(struct scpi_xfer *t, struct scpi_chan *ch)
{
        mutex_lock(&ch->xfers_lock);
        list_add_tail(&t->node, &ch->xfers_list);
        mutex_unlock(&ch->xfers_lock);
}

static int scpi_send_message(u8 idx, void *tx_buf, unsigned int tx_len,
                             void *rx_buf, unsigned int rx_len)
{
        int ret;
        u8 chan;
        u8 cmd;
        struct scpi_xfer *msg;
        struct scpi_chan *scpi_chan;

        if (scpi_info->commands[idx] < 0)
                return -EOPNOTSUPP;

        cmd = scpi_info->commands[idx];

        if (scpi_info->is_legacy)
                chan = test_bit(cmd, scpi_info->cmd_priority) ? 1 : 0;
        else
                chan = atomic_inc_return(&scpi_info->next_chan) %
                        scpi_info->num_chans;
        scpi_chan = scpi_info->channels + chan;

        msg = get_scpi_xfer(scpi_chan);
        if (!msg)
                return -ENOMEM;

        if (scpi_info->is_legacy) {
                msg->cmd = PACK_LEGACY_SCPI_CMD(cmd, tx_len);
                msg->slot = msg->cmd;
        } else {
                msg->slot = BIT(SCPI_SLOT);
                msg->cmd = PACK_SCPI_CMD(cmd, tx_len);
        }
        msg->tx_buf = tx_buf;
        msg->tx_len = tx_len;
        msg->rx_buf = rx_buf;
        msg->rx_len = rx_len;
        reinit_completion(&msg->done);

        ret = mbox_send_message(scpi_chan->chan, msg);
        if (ret < 0 || !rx_buf)
                goto out;

        if (!wait_for_completion_timeout(&msg->done, MAX_RX_TIMEOUT))
                ret = -ETIMEDOUT;
        else
                /* first status word */
                ret = msg->status;
out:
        if (ret < 0 && rx_buf) /* remove entry from the list if timed-out */
                scpi_process_cmd(scpi_chan, msg->cmd);

        put_scpi_xfer(msg, scpi_chan);
        /* SCPI error codes > 0, translate them to Linux scale*/
        return ret > 0 ? scpi_to_linux_errno(ret) : ret;
}

static u32 scpi_get_version(void)
{
        return scpi_info->protocol_version;
}

static int
scpi_clk_get_range(u16 clk_id, unsigned long *min, unsigned long *max)
{
        int ret;
        struct clk_get_info clk;
        __le16 le_clk_id = cpu_to_le16(clk_id);

        ret = scpi_send_message(CMD_GET_CLOCK_INFO, &le_clk_id,
                                sizeof(le_clk_id), &clk, sizeof(clk));
        if (!ret) {
                *min = le32_to_cpu(clk.min_rate);
                *max = le32_to_cpu(clk.max_rate);
        }
        return ret;
}

static unsigned long scpi_clk_get_val(u16 clk_id)
{
        int ret;
        __le32 rate;
        __le16 le_clk_id = cpu_to_le16(clk_id);

        ret = scpi_send_message(CMD_GET_CLOCK_VALUE, &le_clk_id,
                                sizeof(le_clk_id), &rate, sizeof(rate));
        if (ret)
                return 0;

        return le32_to_cpu(rate);
}

static int scpi_clk_set_val(u16 clk_id, unsigned long rate)
{
        int stat;
        struct clk_set_value clk = {
                .id = cpu_to_le16(clk_id),
                .rate = cpu_to_le32(rate)
        };

        return scpi_send_message(CMD_SET_CLOCK_VALUE, &clk, sizeof(clk),
                                 &stat, sizeof(stat));
}

static int legacy_scpi_clk_set_val(u16 clk_id, unsigned long rate)
{
        int stat;
        struct legacy_clk_set_value clk = {
                .id = cpu_to_le16(clk_id),
                .rate = cpu_to_le32(rate)
        };

        return scpi_send_message(CMD_SET_CLOCK_VALUE, &clk, sizeof(clk),
                                 &stat, sizeof(stat));
}

static int scpi_dvfs_get_idx(u8 domain)
{
        int ret;
        u8 dvfs_idx;

        ret = scpi_send_message(CMD_GET_DVFS, &domain, sizeof(domain),
                                &dvfs_idx, sizeof(dvfs_idx));

        return ret ? ret : dvfs_idx;
}

static int scpi_dvfs_set_idx(u8 domain, u8 index)
{
        int stat;
        struct dvfs_set dvfs = {domain, index};

        return scpi_send_message(CMD_SET_DVFS, &dvfs, sizeof(dvfs),
                                 &stat, sizeof(stat));
}

static int opp_cmp_func(const void *opp1, const void *opp2)
{
        const struct scpi_opp *t1 = opp1, *t2 = opp2;

        return t1->freq - t2->freq;
}

static struct scpi_dvfs_info *scpi_dvfs_get_info(u8 domain)
{
        struct scpi_dvfs_info *info;
        struct scpi_opp *opp;
        struct dvfs_info buf;
        int ret, i;

        if (domain >= MAX_DVFS_DOMAINS)
                return ERR_PTR(-EINVAL);

        if (scpi_info->dvfs[domain])    /* data already populated */
                return scpi_info->dvfs[domain];

        ret = scpi_send_message(CMD_GET_DVFS_INFO, &domain, sizeof(domain),
                                &buf, sizeof(buf));
        if (ret)
                return ERR_PTR(ret);

        if (!buf.opp_count)
                return ERR_PTR(-ENOENT);

        info = kmalloc_obj(*info);
        if (!info)
                return ERR_PTR(-ENOMEM);

        info->count = buf.opp_count;
        info->latency = le16_to_cpu(buf.latency) * 1000; /* uS to nS */

        info->opps = kzalloc_objs(*opp, info->count);
        if (!info->opps) {
                kfree(info);
                return ERR_PTR(-ENOMEM);
        }

        for (i = 0, opp = info->opps; i < info->count; i++, opp++) {
                opp->freq = le32_to_cpu(buf.opps[i].freq);
                opp->m_volt = le32_to_cpu(buf.opps[i].m_volt);
        }

        sort(info->opps, info->count, sizeof(*opp), opp_cmp_func, NULL);

        scpi_info->dvfs[domain] = info;
        return info;
}

static int scpi_dev_domain_id(struct device *dev)
{
        struct of_phandle_args clkspec;

        if (of_parse_phandle_with_args(dev->of_node, "clocks", "#clock-cells",
                                       0, &clkspec))
                return -EINVAL;

        return clkspec.args[0];
}

static struct scpi_dvfs_info *scpi_dvfs_info(struct device *dev)
{
        int domain = scpi_dev_domain_id(dev);

        if (domain < 0)
                return ERR_PTR(domain);

        return scpi_dvfs_get_info(domain);
}

static int scpi_dvfs_get_transition_latency(struct device *dev)
{
        struct scpi_dvfs_info *info = scpi_dvfs_info(dev);

        if (IS_ERR(info))
                return PTR_ERR(info);

        return info->latency;
}

static int scpi_dvfs_add_opps_to_device(struct device *dev)
{
        int idx, ret;
        struct scpi_opp *opp;
        struct scpi_dvfs_info *info = scpi_dvfs_info(dev);

        if (IS_ERR(info))
                return PTR_ERR(info);

        if (!info->opps)
                return -EIO;

        for (opp = info->opps, idx = 0; idx < info->count; idx++, opp++) {
                ret = dev_pm_opp_add(dev, opp->freq, opp->m_volt * 1000);
                if (ret) {
                        dev_warn(dev, "failed to add opp %uHz %umV\n",
                                 opp->freq, opp->m_volt);
                        while (idx-- > 0)
                                dev_pm_opp_remove(dev, (--opp)->freq);
                        return ret;
                }
        }
        return 0;
}

static int scpi_sensor_get_capability(u16 *sensors)
{
        __le16 cap;
        int ret;

        ret = scpi_send_message(CMD_SENSOR_CAPABILITIES, NULL, 0, &cap,
                                sizeof(cap));
        if (!ret)
                *sensors = le16_to_cpu(cap);

        return ret;
}

static int scpi_sensor_get_info(u16 sensor_id, struct scpi_sensor_info *info)
{
        __le16 id = cpu_to_le16(sensor_id);
        struct _scpi_sensor_info _info;
        int ret;

        ret = scpi_send_message(CMD_SENSOR_INFO, &id, sizeof(id),
                                &_info, sizeof(_info));
        if (!ret) {
                memcpy(info, &_info, sizeof(*info));
                info->sensor_id = le16_to_cpu(_info.sensor_id);
        }

        return ret;
}

static int scpi_sensor_get_value(u16 sensor, u64 *val)
{
        __le16 id = cpu_to_le16(sensor);
        __le64 value;
        int ret;

        ret = scpi_send_message(CMD_SENSOR_VALUE, &id, sizeof(id),
                                &value, sizeof(value));
        if (ret)
                return ret;

        if (scpi_info->is_legacy)
                /* only 32-bits supported, upper 32 bits can be junk */
                *val = le32_to_cpup((__le32 *)&value);
        else
                *val = le64_to_cpu(value);

        return 0;
}

static int scpi_device_get_power_state(u16 dev_id)
{
        int ret;
        u8 pstate;
        __le16 id = cpu_to_le16(dev_id);

        ret = scpi_send_message(CMD_GET_DEVICE_PWR_STATE, &id,
                                sizeof(id), &pstate, sizeof(pstate));
        return ret ? ret : pstate;
}

static int scpi_device_set_power_state(u16 dev_id, u8 pstate)
{
        int stat;
        struct dev_pstate_set dev_set = {
                .dev_id = cpu_to_le16(dev_id),
                .pstate = pstate,
        };

        return scpi_send_message(CMD_SET_DEVICE_PWR_STATE, &dev_set,
                                 sizeof(dev_set), &stat, sizeof(stat));
}

static struct scpi_ops scpi_ops = {
        .get_version = scpi_get_version,
        .clk_get_range = scpi_clk_get_range,
        .clk_get_val = scpi_clk_get_val,
        .clk_set_val = scpi_clk_set_val,
        .dvfs_get_idx = scpi_dvfs_get_idx,
        .dvfs_set_idx = scpi_dvfs_set_idx,
        .dvfs_get_info = scpi_dvfs_get_info,
        .device_domain_id = scpi_dev_domain_id,
        .get_transition_latency = scpi_dvfs_get_transition_latency,
        .add_opps_to_device = scpi_dvfs_add_opps_to_device,
        .sensor_get_capability = scpi_sensor_get_capability,
        .sensor_get_info = scpi_sensor_get_info,
        .sensor_get_value = scpi_sensor_get_value,
        .device_get_power_state = scpi_device_get_power_state,
        .device_set_power_state = scpi_device_set_power_state,
};

struct scpi_ops *get_scpi_ops(void)
{
        return scpi_info ? scpi_info->scpi_ops : NULL;
}
EXPORT_SYMBOL_GPL(get_scpi_ops);

static int scpi_init_versions(struct scpi_drvinfo *info)
{
        int ret;
        struct scp_capabilities caps;

        ret = scpi_send_message(CMD_SCPI_CAPABILITIES, NULL, 0,
                                &caps, sizeof(caps));
        if (!ret) {
                info->protocol_version = le32_to_cpu(caps.protocol_version);
                info->firmware_version = le32_to_cpu(caps.platform_version);
        }
        /* Ignore error if not implemented */
        if (info->is_legacy && ret == -EOPNOTSUPP)
                return 0;

        return ret;
}

static ssize_t protocol_version_show(struct device *dev,
                                     struct device_attribute *attr, char *buf)
{
        struct scpi_drvinfo *scpi_info = dev_get_drvdata(dev);

        return sprintf(buf, "%lu.%lu\n",
                FIELD_GET(PROTO_REV_MAJOR_MASK, scpi_info->protocol_version),
                FIELD_GET(PROTO_REV_MINOR_MASK, scpi_info->protocol_version));
}
static DEVICE_ATTR_RO(protocol_version);

static ssize_t firmware_version_show(struct device *dev,
                                     struct device_attribute *attr, char *buf)
{
        struct scpi_drvinfo *scpi_info = dev_get_drvdata(dev);

        return sprintf(buf, "%lu.%lu.%lu\n",
                FIELD_GET(FW_REV_MAJOR_MASK, scpi_info->firmware_version),
                FIELD_GET(FW_REV_MINOR_MASK, scpi_info->firmware_version),
                FIELD_GET(FW_REV_PATCH_MASK, scpi_info->firmware_version));
}
static DEVICE_ATTR_RO(firmware_version);

static struct attribute *versions_attrs[] = {
        &dev_attr_firmware_version.attr,
        &dev_attr_protocol_version.attr,
        NULL,
};
ATTRIBUTE_GROUPS(versions);

static void scpi_free_channels(void *data)
{
        struct scpi_drvinfo *info = data;
        int i;

        for (i = 0; i < info->num_chans; i++)
                mbox_free_channel(info->channels[i].chan);
}

static void scpi_remove(struct platform_device *pdev)
{
        int i;
        struct scpi_drvinfo *info = platform_get_drvdata(pdev);

        scpi_info = NULL; /* stop exporting SCPI ops through get_scpi_ops */

        for (i = 0; i < MAX_DVFS_DOMAINS && info->dvfs[i]; i++) {
                kfree(info->dvfs[i]->opps);
                kfree(info->dvfs[i]);
        }
}

#define MAX_SCPI_XFERS          10
static int scpi_alloc_xfer_list(struct device *dev, struct scpi_chan *ch)
{
        int i;
        struct scpi_xfer *xfers;

        xfers = devm_kcalloc(dev, MAX_SCPI_XFERS, sizeof(*xfers), GFP_KERNEL);
        if (!xfers)
                return -ENOMEM;

        ch->xfers = xfers;
        for (i = 0; i < MAX_SCPI_XFERS; i++, xfers++) {
                init_completion(&xfers->done);
                list_add_tail(&xfers->node, &ch->xfers_list);
        }

        return 0;
}

static const struct of_device_id shmem_of_match[] __maybe_unused = {
        { .compatible = "amlogic,meson-gxbb-scp-shmem", },
        { .compatible = "amlogic,meson-axg-scp-shmem", },
        { .compatible = "arm,juno-scp-shmem", },
        { .compatible = "arm,scp-shmem", },
        { }
};

static int scpi_probe(struct platform_device *pdev)
{
        int count, idx, ret;
        struct resource res;
        struct device *dev = &pdev->dev;
        struct device_node *np = dev->of_node;
        struct scpi_drvinfo *scpi_drvinfo;

        scpi_drvinfo = devm_kzalloc(dev, sizeof(*scpi_drvinfo), GFP_KERNEL);
        if (!scpi_drvinfo)
                return -ENOMEM;

        scpi_drvinfo->is_legacy = !!device_get_match_data(dev);

        count = of_count_phandle_with_args(np, "mboxes", "#mbox-cells");
        if (count < 0) {
                dev_err(dev, "no mboxes property in '%pOF'\n", np);
                return -ENODEV;
        }

        scpi_drvinfo->channels =
                devm_kcalloc(dev, count, sizeof(struct scpi_chan), GFP_KERNEL);
        if (!scpi_drvinfo->channels)
                return -ENOMEM;

        ret = devm_add_action(dev, scpi_free_channels, scpi_drvinfo);
        if (ret)
                return ret;

        for (; scpi_drvinfo->num_chans < count; scpi_drvinfo->num_chans++) {
                resource_size_t size;
                int idx = scpi_drvinfo->num_chans;
                struct scpi_chan *pchan = scpi_drvinfo->channels + idx;
                struct mbox_client *cl = &pchan->cl;
                struct device_node *shmem __free(device_node) =
                        of_parse_phandle(np, "shmem", idx);

                if (!of_match_node(shmem_of_match, shmem))
                        return -ENXIO;

                ret = of_address_to_resource(shmem, 0, &res);
                if (ret) {
                        dev_err(dev, "failed to get SCPI payload mem resource\n");
                        return ret;
                }

                size = resource_size(&res);
                pchan->rx_payload = devm_ioremap(dev, res.start, size);
                if (!pchan->rx_payload) {
                        dev_err(dev, "failed to ioremap SCPI payload\n");
                        return -EADDRNOTAVAIL;
                }
                pchan->tx_payload = pchan->rx_payload + (size >> 1);

                cl->dev = dev;
                cl->rx_callback = scpi_handle_remote_msg;
                cl->tx_prepare = scpi_tx_prepare;
                cl->tx_block = true;
                cl->tx_tout = 20;
                cl->knows_txdone = false; /* controller can't ack */

                INIT_LIST_HEAD(&pchan->rx_pending);
                INIT_LIST_HEAD(&pchan->xfers_list);
                spin_lock_init(&pchan->rx_lock);
                mutex_init(&pchan->xfers_lock);

                ret = scpi_alloc_xfer_list(dev, pchan);
                if (!ret) {
                        pchan->chan = mbox_request_channel(cl, idx);
                        if (!IS_ERR(pchan->chan))
                                continue;
                        ret = PTR_ERR(pchan->chan);
                        if (ret != -EPROBE_DEFER)
                                dev_err(dev, "failed to get channel%d err %d\n",
                                        idx, ret);
                }
                return ret;
        }

        scpi_drvinfo->commands = scpi_std_commands;

        platform_set_drvdata(pdev, scpi_drvinfo);

        if (scpi_drvinfo->is_legacy) {
                /* Replace with legacy variants */
                scpi_ops.clk_set_val = legacy_scpi_clk_set_val;
                scpi_drvinfo->commands = scpi_legacy_commands;

                /* Fill priority bitmap */
                for (idx = 0; idx < ARRAY_SIZE(legacy_hpriority_cmds); idx++)
                        set_bit(legacy_hpriority_cmds[idx],
                                scpi_drvinfo->cmd_priority);
        }

        scpi_info = scpi_drvinfo;

        ret = scpi_init_versions(scpi_drvinfo);
        if (ret) {
                dev_err(dev, "incorrect or no SCP firmware found\n");
                scpi_info = NULL;
                return ret;
        }

        if (scpi_drvinfo->is_legacy && !scpi_drvinfo->protocol_version &&
            !scpi_drvinfo->firmware_version)
                dev_info(dev, "SCP Protocol legacy pre-1.0 firmware\n");
        else
                dev_info(dev, "SCP Protocol %lu.%lu Firmware %lu.%lu.%lu version\n",
                         FIELD_GET(PROTO_REV_MAJOR_MASK,
                                   scpi_drvinfo->protocol_version),
                         FIELD_GET(PROTO_REV_MINOR_MASK,
                                   scpi_drvinfo->protocol_version),
                         FIELD_GET(FW_REV_MAJOR_MASK,
                                   scpi_drvinfo->firmware_version),
                         FIELD_GET(FW_REV_MINOR_MASK,
                                   scpi_drvinfo->firmware_version),
                         FIELD_GET(FW_REV_PATCH_MASK,
                                   scpi_drvinfo->firmware_version));

        scpi_drvinfo->scpi_ops = &scpi_ops;

        ret = devm_of_platform_populate(dev);
        if (ret)
                scpi_info = NULL;

        return ret;
}

static const struct of_device_id scpi_of_match[] = {
        {.compatible = "arm,scpi"},
        {.compatible = "arm,scpi-pre-1.0", .data = (void *)1UL },
        {},
};

MODULE_DEVICE_TABLE(of, scpi_of_match);

static struct platform_driver scpi_driver = {
        .driver = {
                .name = "scpi_protocol",
                .of_match_table = scpi_of_match,
                .dev_groups = versions_groups,
        },
        .probe = scpi_probe,
        .remove = scpi_remove,
};
module_platform_driver(scpi_driver);

MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
MODULE_DESCRIPTION("ARM SCPI mailbox protocol driver");
MODULE_LICENSE("GPL v2");