// SPDX-License-Identifier: GPL-2.0-only
// Copyright (c) 2021 Intel Corporation

#include <linux/bug.h>
#include <linux/export.h>
#include <linux/pci.h>
#include <linux/peci.h>
#include <linux/slab.h>
#include <linux/types.h>

#include <linux/unaligned.h>

#include "internal.h"

#define PECI_GET_DIB_CMD                0xf7
#define  PECI_GET_DIB_WR_LEN            1
#define  PECI_GET_DIB_RD_LEN            8

#define PECI_GET_TEMP_CMD               0x01
#define  PECI_GET_TEMP_WR_LEN           1
#define  PECI_GET_TEMP_RD_LEN           2

#define PECI_RDPKGCFG_CMD               0xa1
#define  PECI_RDPKGCFG_WR_LEN           5
#define  PECI_RDPKGCFG_RD_LEN_BASE      1
#define PECI_WRPKGCFG_CMD               0xa5
#define  PECI_WRPKGCFG_WR_LEN_BASE      6
#define  PECI_WRPKGCFG_RD_LEN           1

#define PECI_RDIAMSR_CMD                0xb1
#define  PECI_RDIAMSR_WR_LEN            5
#define  PECI_RDIAMSR_RD_LEN            9
#define PECI_WRIAMSR_CMD                0xb5
#define PECI_RDIAMSREX_CMD              0xd1
#define  PECI_RDIAMSREX_WR_LEN          6
#define  PECI_RDIAMSREX_RD_LEN          9

#define PECI_RDPCICFG_CMD               0x61
#define  PECI_RDPCICFG_WR_LEN           6
#define  PECI_RDPCICFG_RD_LEN           5
#define  PECI_RDPCICFG_RD_LEN_MAX       24
#define PECI_WRPCICFG_CMD               0x65

#define PECI_RDPCICFGLOCAL_CMD                  0xe1
#define  PECI_RDPCICFGLOCAL_WR_LEN              5
#define  PECI_RDPCICFGLOCAL_RD_LEN_BASE         1
#define PECI_WRPCICFGLOCAL_CMD                  0xe5
#define  PECI_WRPCICFGLOCAL_WR_LEN_BASE         6
#define  PECI_WRPCICFGLOCAL_RD_LEN              1

#define PECI_ENDPTCFG_TYPE_LOCAL_PCI            0x03
#define PECI_ENDPTCFG_TYPE_PCI                  0x04
#define PECI_ENDPTCFG_TYPE_MMIO                 0x05
#define PECI_ENDPTCFG_ADDR_TYPE_PCI             0x04
#define PECI_ENDPTCFG_ADDR_TYPE_MMIO_D          0x05
#define PECI_ENDPTCFG_ADDR_TYPE_MMIO_Q          0x06
#define PECI_RDENDPTCFG_CMD                     0xc1
#define  PECI_RDENDPTCFG_PCI_WR_LEN             12
#define  PECI_RDENDPTCFG_MMIO_WR_LEN_BASE       10
#define  PECI_RDENDPTCFG_MMIO_D_WR_LEN          14
#define  PECI_RDENDPTCFG_MMIO_Q_WR_LEN          18
#define  PECI_RDENDPTCFG_RD_LEN_BASE            1
#define PECI_WRENDPTCFG_CMD                     0xc5
#define  PECI_WRENDPTCFG_PCI_WR_LEN_BASE        13
#define  PECI_WRENDPTCFG_MMIO_D_WR_LEN_BASE     15
#define  PECI_WRENDPTCFG_MMIO_Q_WR_LEN_BASE     19
#define  PECI_WRENDPTCFG_RD_LEN                 1

/* Device Specific Completion Code (CC) Definition */
#define PECI_CC_SUCCESS                         0x40
#define PECI_CC_NEED_RETRY                      0x80
#define PECI_CC_OUT_OF_RESOURCE                 0x81
#define PECI_CC_UNAVAIL_RESOURCE                0x82
#define PECI_CC_INVALID_REQ                     0x90
#define PECI_CC_MCA_ERROR                       0x91
#define PECI_CC_CATASTROPHIC_MCA_ERROR          0x93
#define PECI_CC_FATAL_MCA_ERROR                 0x94
#define PECI_CC_PARITY_ERR_GPSB_OR_PMSB         0x98
#define PECI_CC_PARITY_ERR_GPSB_OR_PMSB_IERR    0x9B
#define PECI_CC_PARITY_ERR_GPSB_OR_PMSB_MCA     0x9C

#define PECI_RETRY_BIT                  BIT(0)

#define PECI_RETRY_TIMEOUT              msecs_to_jiffies(700)
#define PECI_RETRY_INTERVAL_MIN         msecs_to_jiffies(1)
#define PECI_RETRY_INTERVAL_MAX         msecs_to_jiffies(128)

static u8 peci_request_data_cc(struct peci_request *req)
{
        return req->rx.buf[0];
}

/**
 * peci_request_status() - return -errno based on PECI completion code
 * @req: the PECI request that contains response data with completion code
 *
 * It can't be used for Ping(), GetDIB() and GetTemp() - for those commands we
 * don't expect completion code in the response.
 *
 * Return: -errno
 */
int peci_request_status(struct peci_request *req)
{
        u8 cc = peci_request_data_cc(req);

        if (cc != PECI_CC_SUCCESS)
                dev_dbg(&req->device->dev, "ret: %#02x\n", cc);

        switch (cc) {
        case PECI_CC_SUCCESS:
                return 0;
        case PECI_CC_NEED_RETRY:
        case PECI_CC_OUT_OF_RESOURCE:
        case PECI_CC_UNAVAIL_RESOURCE:
                return -EAGAIN;
        case PECI_CC_INVALID_REQ:
                return -EINVAL;
        case PECI_CC_MCA_ERROR:
        case PECI_CC_CATASTROPHIC_MCA_ERROR:
        case PECI_CC_FATAL_MCA_ERROR:
        case PECI_CC_PARITY_ERR_GPSB_OR_PMSB:
        case PECI_CC_PARITY_ERR_GPSB_OR_PMSB_IERR:
        case PECI_CC_PARITY_ERR_GPSB_OR_PMSB_MCA:
                return -EIO;
        }

        WARN_ONCE(1, "Unknown PECI completion code: %#02x\n", cc);

        return -EIO;
}
EXPORT_SYMBOL_NS_GPL(peci_request_status, "PECI");

static int peci_request_xfer(struct peci_request *req)
{
        struct peci_device *device = req->device;
        struct peci_controller *controller = to_peci_controller(device->dev.parent);
        int ret;

        mutex_lock(&controller->bus_lock);
        ret = controller->ops->xfer(controller, device->addr, req);
        mutex_unlock(&controller->bus_lock);

        return ret;
}

static int peci_request_xfer_retry(struct peci_request *req)
{
        long wait_interval = PECI_RETRY_INTERVAL_MIN;
        struct peci_device *device = req->device;
        struct peci_controller *controller = to_peci_controller(device->dev.parent);
        unsigned long start = jiffies;
        int ret;

        /* Don't try to use it for ping */
        if (WARN_ON(req->tx.len == 0))
                return 0;

        do {
                ret = peci_request_xfer(req);
                if (ret) {
                        dev_dbg(&controller->dev, "xfer error: %d\n", ret);
                        return ret;
                }

                if (peci_request_status(req) != -EAGAIN)
                        return 0;

                /* Set the retry bit to indicate a retry attempt */
                req->tx.buf[1] |= PECI_RETRY_BIT;

                if (schedule_timeout_interruptible(wait_interval))
                        return -ERESTARTSYS;

                wait_interval = min_t(long, wait_interval * 2, PECI_RETRY_INTERVAL_MAX);
        } while (time_before(jiffies, start + PECI_RETRY_TIMEOUT));

        dev_dbg(&controller->dev, "request timed out\n");

        return -ETIMEDOUT;
}

/**
 * peci_request_alloc() - allocate &struct peci_requests
 * @device: PECI device to which request is going to be sent
 * @tx_len: TX length
 * @rx_len: RX length
 *
 * Return: A pointer to a newly allocated &struct peci_request on success or NULL otherwise.
 */
struct peci_request *peci_request_alloc(struct peci_device *device, u8 tx_len, u8 rx_len)
{
        struct peci_request *req;

        /*
         * TX and RX buffers are fixed length members of peci_request, this is
         * just a warn for developers to make sure to expand the buffers (or
         * change the allocation method) if we go over the current limit.
         */
        if (WARN_ON_ONCE(tx_len > PECI_REQUEST_MAX_BUF_SIZE || rx_len > PECI_REQUEST_MAX_BUF_SIZE))
                return NULL;
        /*
         * PECI controllers that we are using now don't support DMA, this
         * should be converted to DMA API once support for controllers that do
         * allow it is added to avoid an extra copy.
         */
        req = kzalloc_obj(*req);
        if (!req)
                return NULL;

        req->device = device;
        req->tx.len = tx_len;
        req->rx.len = rx_len;

        return req;
}
EXPORT_SYMBOL_NS_GPL(peci_request_alloc, "PECI");

/**
 * peci_request_free() - free peci_request
 * @req: the PECI request to be freed
 */
void peci_request_free(struct peci_request *req)
{
        kfree(req);
}
EXPORT_SYMBOL_NS_GPL(peci_request_free, "PECI");

struct peci_request *peci_xfer_get_dib(struct peci_device *device)
{
        struct peci_request *req;
        int ret;

        req = peci_request_alloc(device, PECI_GET_DIB_WR_LEN, PECI_GET_DIB_RD_LEN);
        if (!req)
                return ERR_PTR(-ENOMEM);

        req->tx.buf[0] = PECI_GET_DIB_CMD;

        ret = peci_request_xfer(req);
        if (ret) {
                peci_request_free(req);
                return ERR_PTR(ret);
        }

        return req;
}
EXPORT_SYMBOL_NS_GPL(peci_xfer_get_dib, "PECI");

struct peci_request *peci_xfer_get_temp(struct peci_device *device)
{
        struct peci_request *req;
        int ret;

        req = peci_request_alloc(device, PECI_GET_TEMP_WR_LEN, PECI_GET_TEMP_RD_LEN);
        if (!req)
                return ERR_PTR(-ENOMEM);

        req->tx.buf[0] = PECI_GET_TEMP_CMD;

        ret = peci_request_xfer(req);
        if (ret) {
                peci_request_free(req);
                return ERR_PTR(ret);
        }

        return req;
}
EXPORT_SYMBOL_NS_GPL(peci_xfer_get_temp, "PECI");

static struct peci_request *
__pkg_cfg_read(struct peci_device *device, u8 index, u16 param, u8 len)
{
        struct peci_request *req;
        int ret;

        req = peci_request_alloc(device, PECI_RDPKGCFG_WR_LEN, PECI_RDPKGCFG_RD_LEN_BASE + len);
        if (!req)
                return ERR_PTR(-ENOMEM);

        req->tx.buf[0] = PECI_RDPKGCFG_CMD;
        req->tx.buf[1] = 0;
        req->tx.buf[2] = index;
        put_unaligned_le16(param, &req->tx.buf[3]);

        ret = peci_request_xfer_retry(req);
        if (ret) {
                peci_request_free(req);
                return ERR_PTR(ret);
        }

        return req;
}

static u32 __get_pci_addr(u8 bus, u8 dev, u8 func, u16 reg)
{
        return reg | PCI_DEVID(bus, PCI_DEVFN(dev, func)) << 12;
}

static struct peci_request *
__pci_cfg_local_read(struct peci_device *device, u8 bus, u8 dev, u8 func, u16 reg, u8 len)
{
        struct peci_request *req;
        u32 pci_addr;
        int ret;

        req = peci_request_alloc(device, PECI_RDPCICFGLOCAL_WR_LEN,
                                 PECI_RDPCICFGLOCAL_RD_LEN_BASE + len);
        if (!req)
                return ERR_PTR(-ENOMEM);

        pci_addr = __get_pci_addr(bus, dev, func, reg);

        req->tx.buf[0] = PECI_RDPCICFGLOCAL_CMD;
        req->tx.buf[1] = 0;
        put_unaligned_le24(pci_addr, &req->tx.buf[2]);

        ret = peci_request_xfer_retry(req);
        if (ret) {
                peci_request_free(req);
                return ERR_PTR(ret);
        }

        return req;
}

static struct peci_request *
__ep_pci_cfg_read(struct peci_device *device, u8 msg_type, u8 seg,
                  u8 bus, u8 dev, u8 func, u16 reg, u8 len)
{
        struct peci_request *req;
        u32 pci_addr;
        int ret;

        req = peci_request_alloc(device, PECI_RDENDPTCFG_PCI_WR_LEN,
                                 PECI_RDENDPTCFG_RD_LEN_BASE + len);
        if (!req)
                return ERR_PTR(-ENOMEM);

        pci_addr = __get_pci_addr(bus, dev, func, reg);

        req->tx.buf[0] = PECI_RDENDPTCFG_CMD;
        req->tx.buf[1] = 0;
        req->tx.buf[2] = msg_type;
        req->tx.buf[3] = 0;
        req->tx.buf[4] = 0;
        req->tx.buf[5] = 0;
        req->tx.buf[6] = PECI_ENDPTCFG_ADDR_TYPE_PCI;
        req->tx.buf[7] = seg; /* PCI Segment */
        put_unaligned_le32(pci_addr, &req->tx.buf[8]);

        ret = peci_request_xfer_retry(req);
        if (ret) {
                peci_request_free(req);
                return ERR_PTR(ret);
        }

        return req;
}

static struct peci_request *
__ep_mmio_read(struct peci_device *device, u8 bar, u8 addr_type, u8 seg,
               u8 bus, u8 dev, u8 func, u64 offset, u8 tx_len, u8 len)
{
        struct peci_request *req;
        int ret;

        req = peci_request_alloc(device, tx_len, PECI_RDENDPTCFG_RD_LEN_BASE + len);
        if (!req)
                return ERR_PTR(-ENOMEM);

        req->tx.buf[0] = PECI_RDENDPTCFG_CMD;
        req->tx.buf[1] = 0;
        req->tx.buf[2] = PECI_ENDPTCFG_TYPE_MMIO;
        req->tx.buf[3] = 0; /* Endpoint ID */
        req->tx.buf[4] = 0; /* Reserved */
        req->tx.buf[5] = bar;
        req->tx.buf[6] = addr_type;
        req->tx.buf[7] = seg; /* PCI Segment */
        req->tx.buf[8] = PCI_DEVFN(dev, func);
        req->tx.buf[9] = bus; /* PCI Bus */

        if (addr_type == PECI_ENDPTCFG_ADDR_TYPE_MMIO_D)
                put_unaligned_le32(offset, &req->tx.buf[10]);
        else
                put_unaligned_le64(offset, &req->tx.buf[10]);

        ret = peci_request_xfer_retry(req);
        if (ret) {
                peci_request_free(req);
                return ERR_PTR(ret);
        }

        return req;
}

u8 peci_request_data_readb(struct peci_request *req)
{
        return req->rx.buf[1];
}
EXPORT_SYMBOL_NS_GPL(peci_request_data_readb, "PECI");

u16 peci_request_data_readw(struct peci_request *req)
{
        return get_unaligned_le16(&req->rx.buf[1]);
}
EXPORT_SYMBOL_NS_GPL(peci_request_data_readw, "PECI");

u32 peci_request_data_readl(struct peci_request *req)
{
        return get_unaligned_le32(&req->rx.buf[1]);
}
EXPORT_SYMBOL_NS_GPL(peci_request_data_readl, "PECI");

u64 peci_request_data_readq(struct peci_request *req)
{
        return get_unaligned_le64(&req->rx.buf[1]);
}
EXPORT_SYMBOL_NS_GPL(peci_request_data_readq, "PECI");

u64 peci_request_dib_read(struct peci_request *req)
{
        return get_unaligned_le64(&req->rx.buf[0]);
}
EXPORT_SYMBOL_NS_GPL(peci_request_dib_read, "PECI");

s16 peci_request_temp_read(struct peci_request *req)
{
        return get_unaligned_le16(&req->rx.buf[0]);
}
EXPORT_SYMBOL_NS_GPL(peci_request_temp_read, "PECI");

#define __read_pkg_config(x, type) \
struct peci_request *peci_xfer_pkg_cfg_##x(struct peci_device *device, u8 index, u16 param) \
{ \
        return __pkg_cfg_read(device, index, param, sizeof(type)); \
} \
EXPORT_SYMBOL_NS_GPL(peci_xfer_pkg_cfg_##x, "PECI")

__read_pkg_config(readb, u8);
__read_pkg_config(readw, u16);
__read_pkg_config(readl, u32);
__read_pkg_config(readq, u64);

#define __read_pci_config_local(x, type) \
struct peci_request * \
peci_xfer_pci_cfg_local_##x(struct peci_device *device, u8 bus, u8 dev, u8 func, u16 reg) \
{ \
        return __pci_cfg_local_read(device, bus, dev, func, reg, sizeof(type)); \
} \
EXPORT_SYMBOL_NS_GPL(peci_xfer_pci_cfg_local_##x, "PECI")

__read_pci_config_local(readb, u8);
__read_pci_config_local(readw, u16);
__read_pci_config_local(readl, u32);

#define __read_ep_pci_config(x, msg_type, type) \
struct peci_request * \
peci_xfer_ep_pci_cfg_##x(struct peci_device *device, u8 seg, u8 bus, u8 dev, u8 func, u16 reg) \
{ \
        return __ep_pci_cfg_read(device, msg_type, seg, bus, dev, func, reg, sizeof(type)); \
} \
EXPORT_SYMBOL_NS_GPL(peci_xfer_ep_pci_cfg_##x, "PECI")

__read_ep_pci_config(local_readb, PECI_ENDPTCFG_TYPE_LOCAL_PCI, u8);
__read_ep_pci_config(local_readw, PECI_ENDPTCFG_TYPE_LOCAL_PCI, u16);
__read_ep_pci_config(local_readl, PECI_ENDPTCFG_TYPE_LOCAL_PCI, u32);
__read_ep_pci_config(readb, PECI_ENDPTCFG_TYPE_PCI, u8);
__read_ep_pci_config(readw, PECI_ENDPTCFG_TYPE_PCI, u16);
__read_ep_pci_config(readl, PECI_ENDPTCFG_TYPE_PCI, u32);

#define __read_ep_mmio(x, y, addr_type, type1, type2) \
struct peci_request *peci_xfer_ep_mmio##y##_##x(struct peci_device *device, u8 bar, u8 seg, \
                                           u8 bus, u8 dev, u8 func, u64 offset) \
{ \
        return __ep_mmio_read(device, bar, addr_type, seg, bus, dev, func, \
                              offset, PECI_RDENDPTCFG_MMIO_WR_LEN_BASE + sizeof(type1), \
                              sizeof(type2)); \
} \
EXPORT_SYMBOL_NS_GPL(peci_xfer_ep_mmio##y##_##x, "PECI")

__read_ep_mmio(readl, 32, PECI_ENDPTCFG_ADDR_TYPE_MMIO_D, u32, u32);
__read_ep_mmio(readl, 64, PECI_ENDPTCFG_ADDR_TYPE_MMIO_Q, u64, u32);