/*
 * drivers/net/ethernet/mellanox/mlxsw/i2c.c
 * Copyright (c) 2016 Mellanox Technologies. All rights reserved.
 * Copyright (c) 2016 Vadim Pasternak <vadimp@mellanox.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the names of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/mutex.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/slab.h>

#include "cmd.h"
#include "core.h"
#include "i2c.h"

static const char mlxsw_i2c_driver_name[] = "mlxsw_i2c";

#define MLXSW_I2C_CIR2_BASE             0x72000
#define MLXSW_I2C_CIR_STATUS_OFF        0x18
#define MLXSW_I2C_CIR2_OFF_STATUS       (MLXSW_I2C_CIR2_BASE + \
                                         MLXSW_I2C_CIR_STATUS_OFF)
#define MLXSW_I2C_OPMOD_SHIFT           12
#define MLXSW_I2C_GO_BIT_SHIFT          23
#define MLXSW_I2C_CIR_CTRL_STATUS_SHIFT 24
#define MLXSW_I2C_GO_BIT                BIT(MLXSW_I2C_GO_BIT_SHIFT)
#define MLXSW_I2C_GO_OPMODE             BIT(MLXSW_I2C_OPMOD_SHIFT)
#define MLXSW_I2C_SET_IMM_CMD           (MLXSW_I2C_GO_OPMODE | \
                                         MLXSW_CMD_OPCODE_QUERY_FW)
#define MLXSW_I2C_PUSH_IMM_CMD          (MLXSW_I2C_GO_BIT | \
                                         MLXSW_I2C_SET_IMM_CMD)
#define MLXSW_I2C_SET_CMD               (MLXSW_CMD_OPCODE_ACCESS_REG)
#define MLXSW_I2C_PUSH_CMD              (MLXSW_I2C_GO_BIT | MLXSW_I2C_SET_CMD)
#define MLXSW_I2C_TLV_HDR_SIZE          0x10
#define MLXSW_I2C_ADDR_WIDTH            4
#define MLXSW_I2C_PUSH_CMD_SIZE         (MLXSW_I2C_ADDR_WIDTH + 4)
#define MLXSW_I2C_READ_SEMA_SIZE        4
#define MLXSW_I2C_PREP_SIZE             (MLXSW_I2C_ADDR_WIDTH + 28)
#define MLXSW_I2C_MBOX_SIZE             20
#define MLXSW_I2C_MBOX_OUT_PARAM_OFF    12
#define MLXSW_I2C_MAX_BUFF_SIZE         32
#define MLXSW_I2C_MBOX_OFFSET_BITS      20
#define MLXSW_I2C_MBOX_SIZE_BITS        12
#define MLXSW_I2C_ADDR_BUF_SIZE         4
#define MLXSW_I2C_BLK_MAX               32
#define MLXSW_I2C_RETRY                 5
#define MLXSW_I2C_TIMEOUT_MSECS         5000

/**
 * struct mlxsw_i2c - device private data:
 * @cmd.mb_size_in: input mailbox size;
 * @cmd.mb_off_in: input mailbox offset in register space;
 * @cmd.mb_size_out: output mailbox size;
 * @cmd.mb_off_out: output mailbox offset in register space;
 * @cmd.lock: command execution lock;
 * @dev: I2C device;
 * @core: switch core pointer;
 * @bus_info: bus info block;
 */
struct mlxsw_i2c {
        struct {
                u32 mb_size_in;
                u32 mb_off_in;
                u32 mb_size_out;
                u32 mb_off_out;
                struct mutex lock;
        } cmd;
        struct device *dev;
        struct mlxsw_core *core;
        struct mlxsw_bus_info bus_info;
};

#define MLXSW_I2C_READ_MSG(_client, _addr_buf, _buf, _len) {    \
        { .addr = (_client)->addr,                              \
          .buf = (_addr_buf),                                   \
          .len = MLXSW_I2C_ADDR_BUF_SIZE,                       \
          .flags = 0 },                                         \
        { .addr = (_client)->addr,                              \
          .buf = (_buf),                                        \
          .len = (_len),                                        \
          .flags = I2C_M_RD } }

#define MLXSW_I2C_WRITE_MSG(_client, _buf, _len)                \
        { .addr = (_client)->addr,                              \
          .buf = (u8 *)(_buf),                                  \
          .len = (_len),                                        \
          .flags = 0 }

/* Routine converts in and out mail boxes offset and size. */
static inline void
mlxsw_i2c_convert_mbox(struct mlxsw_i2c *mlxsw_i2c, u8 *buf)
{
        u32 tmp;

        /* Local in/out mailboxes: 20 bits for offset, 12 for size */
        tmp = be32_to_cpup((__be32 *) buf);
        mlxsw_i2c->cmd.mb_off_in = tmp &
                                   GENMASK(MLXSW_I2C_MBOX_OFFSET_BITS - 1, 0);
        mlxsw_i2c->cmd.mb_size_in = (tmp & GENMASK(31,
                                        MLXSW_I2C_MBOX_OFFSET_BITS)) >>
                                        MLXSW_I2C_MBOX_OFFSET_BITS;

        tmp = be32_to_cpup((__be32 *) (buf + MLXSW_I2C_ADDR_WIDTH));
        mlxsw_i2c->cmd.mb_off_out = tmp &
                                    GENMASK(MLXSW_I2C_MBOX_OFFSET_BITS - 1, 0);
        mlxsw_i2c->cmd.mb_size_out = (tmp & GENMASK(31,
                                        MLXSW_I2C_MBOX_OFFSET_BITS)) >>
                                        MLXSW_I2C_MBOX_OFFSET_BITS;
}

/* Routine obtains register size from mail box buffer. */
static inline int mlxsw_i2c_get_reg_size(u8 *in_mbox)
{
        u16  tmp = be16_to_cpup((__be16 *) (in_mbox + MLXSW_I2C_TLV_HDR_SIZE));

        return (tmp & 0x7ff) * 4 + MLXSW_I2C_TLV_HDR_SIZE;
}

/* Routine sets I2C device internal offset in the transaction buffer. */
static inline void mlxsw_i2c_set_slave_addr(u8 *buf, u32 off)
{
        __be32 *val = (__be32 *) buf;

        *val = htonl(off);
}

/* Routine waits until go bit is cleared. */
static int mlxsw_i2c_wait_go_bit(struct i2c_client *client,
                                 struct mlxsw_i2c *mlxsw_i2c, u8 *p_status)
{
        u8 addr_buf[MLXSW_I2C_ADDR_BUF_SIZE];
        u8 buf[MLXSW_I2C_READ_SEMA_SIZE];
        int len = MLXSW_I2C_READ_SEMA_SIZE;
        struct i2c_msg read_sema[] =
                MLXSW_I2C_READ_MSG(client, addr_buf, buf, len);
        bool wait_done = false;
        unsigned long end;
        int i = 0, err;

        mlxsw_i2c_set_slave_addr(addr_buf, MLXSW_I2C_CIR2_OFF_STATUS);

        end = jiffies + msecs_to_jiffies(MLXSW_I2C_TIMEOUT_MSECS);
        do {
                u32 ctrl;

                err = i2c_transfer(client->adapter, read_sema,
                                   ARRAY_SIZE(read_sema));

                ctrl = be32_to_cpu(*(__be32 *) buf);
                if (err == ARRAY_SIZE(read_sema)) {
                        if (!(ctrl & MLXSW_I2C_GO_BIT)) {
                                wait_done = true;
                                *p_status = ctrl >>
                                            MLXSW_I2C_CIR_CTRL_STATUS_SHIFT;
                                break;
                        }
                }
                cond_resched();
        } while ((time_before(jiffies, end)) || (i++ < MLXSW_I2C_RETRY));

        if (wait_done) {
                if (*p_status)
                        err = -EIO;
        } else {
                return -ETIMEDOUT;
        }

        return err > 0 ? 0 : err;
}

/* Routine posts a command to ASIC though mail box. */
static int mlxsw_i2c_write_cmd(struct i2c_client *client,
                               struct mlxsw_i2c *mlxsw_i2c,
                               int immediate)
{
        __be32 push_cmd_buf[MLXSW_I2C_PUSH_CMD_SIZE / 4] = {
                0, cpu_to_be32(MLXSW_I2C_PUSH_IMM_CMD)
        };
        __be32 prep_cmd_buf[MLXSW_I2C_PREP_SIZE / 4] = {
                0, 0, 0, 0, 0, 0,
                cpu_to_be32(client->adapter->nr & 0xffff),
                cpu_to_be32(MLXSW_I2C_SET_IMM_CMD)
        };
        struct i2c_msg push_cmd =
                MLXSW_I2C_WRITE_MSG(client, push_cmd_buf,
                                    MLXSW_I2C_PUSH_CMD_SIZE);
        struct i2c_msg prep_cmd =
                MLXSW_I2C_WRITE_MSG(client, prep_cmd_buf, MLXSW_I2C_PREP_SIZE);
        int err;

        if (!immediate) {
                push_cmd_buf[1] = cpu_to_be32(MLXSW_I2C_PUSH_CMD);
                prep_cmd_buf[7] = cpu_to_be32(MLXSW_I2C_SET_CMD);
        }
        mlxsw_i2c_set_slave_addr((u8 *)prep_cmd_buf,
                                 MLXSW_I2C_CIR2_BASE);
        mlxsw_i2c_set_slave_addr((u8 *)push_cmd_buf,
                                 MLXSW_I2C_CIR2_OFF_STATUS);

        /* Prepare Command Interface Register for transaction */
        err = i2c_transfer(client->adapter, &prep_cmd, 1);
        if (err < 0)
                return err;
        else if (err != 1)
                return -EIO;

        /* Write out Command Interface Register GO bit to push transaction */
        err = i2c_transfer(client->adapter, &push_cmd, 1);
        if (err < 0)
                return err;
        else if (err != 1)
                return -EIO;

        return 0;
}

/* Routine obtains mail box offsets from ASIC register space. */
static int mlxsw_i2c_get_mbox(struct i2c_client *client,
                              struct mlxsw_i2c *mlxsw_i2c)
{
        u8 addr_buf[MLXSW_I2C_ADDR_BUF_SIZE];
        u8 buf[MLXSW_I2C_MBOX_SIZE];
        struct i2c_msg mbox_cmd[] =
                MLXSW_I2C_READ_MSG(client, addr_buf, buf, MLXSW_I2C_MBOX_SIZE);
        int err;

        /* Read mail boxes offsets. */
        mlxsw_i2c_set_slave_addr(addr_buf, MLXSW_I2C_CIR2_BASE);
        err = i2c_transfer(client->adapter, mbox_cmd, 2);
        if (err != 2) {
                dev_err(&client->dev, "Could not obtain mail boxes\n");
                if (!err)
                        return -EIO;
                else
                        return err;
        }

        /* Convert mail boxes. */
        mlxsw_i2c_convert_mbox(mlxsw_i2c, &buf[MLXSW_I2C_MBOX_OUT_PARAM_OFF]);

        return err;
}

/* Routine sends I2C write transaction to ASIC device. */
static int
mlxsw_i2c_write(struct device *dev, size_t in_mbox_size, u8 *in_mbox, int num,
                u8 *p_status)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct mlxsw_i2c *mlxsw_i2c = i2c_get_clientdata(client);
        unsigned long timeout = msecs_to_jiffies(MLXSW_I2C_TIMEOUT_MSECS);
        u8 tran_buf[MLXSW_I2C_MAX_BUFF_SIZE + MLXSW_I2C_ADDR_BUF_SIZE];
        int off = mlxsw_i2c->cmd.mb_off_in, chunk_size, i, j;
        unsigned long end;
        struct i2c_msg write_tran =
                MLXSW_I2C_WRITE_MSG(client, tran_buf, MLXSW_I2C_PUSH_CMD_SIZE);
        int err;

        for (i = 0; i < num; i++) {
                chunk_size = (in_mbox_size > MLXSW_I2C_BLK_MAX) ?
                             MLXSW_I2C_BLK_MAX : in_mbox_size;
                write_tran.len = MLXSW_I2C_ADDR_WIDTH + chunk_size;
                mlxsw_i2c_set_slave_addr(tran_buf, off);
                memcpy(&tran_buf[MLXSW_I2C_ADDR_BUF_SIZE], in_mbox +
                       MLXSW_I2C_BLK_MAX * i, chunk_size);

                j = 0;
                end = jiffies + timeout;
                do {
                        err = i2c_transfer(client->adapter, &write_tran, 1);
                        if (err == 1)
                                break;

                        cond_resched();
                } while ((time_before(jiffies, end)) ||
                         (j++ < MLXSW_I2C_RETRY));

                if (err != 1) {
                        if (!err)
                                err = -EIO;
                        return err;
                }

                off += chunk_size;
                in_mbox_size -= chunk_size;
        }

        /* Prepare and write out Command Interface Register for transaction. */
        err = mlxsw_i2c_write_cmd(client, mlxsw_i2c, 0);
        if (err) {
                dev_err(&client->dev, "Could not start transaction");
                return -EIO;
        }

        /* Wait until go bit is cleared. */
        err = mlxsw_i2c_wait_go_bit(client, mlxsw_i2c, p_status);
        if (err) {
                dev_err(&client->dev, "HW semaphore is not released");
                return err;
        }

        /* Validate transaction completion status. */
        if (*p_status) {
                dev_err(&client->dev, "Bad transaction completion status %x\n",
                        *p_status);
                return -EIO;
        }

        return 0;
}

/* Routine executes I2C command. */
static int
mlxsw_i2c_cmd(struct device *dev, size_t in_mbox_size, u8 *in_mbox,
              size_t out_mbox_size, u8 *out_mbox, u8 *status)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct mlxsw_i2c *mlxsw_i2c = i2c_get_clientdata(client);
        unsigned long timeout = msecs_to_jiffies(MLXSW_I2C_TIMEOUT_MSECS);
        u8 tran_buf[MLXSW_I2C_ADDR_BUF_SIZE];
        int num, chunk_size, reg_size, i, j;
        int off = mlxsw_i2c->cmd.mb_off_out;
        unsigned long end;
        struct i2c_msg read_tran[] =
                MLXSW_I2C_READ_MSG(client, tran_buf, NULL, 0);
        int err;

        WARN_ON(in_mbox_size % sizeof(u32) || out_mbox_size % sizeof(u32));

        reg_size = mlxsw_i2c_get_reg_size(in_mbox);
        num = reg_size / MLXSW_I2C_BLK_MAX;
        if (reg_size % MLXSW_I2C_BLK_MAX)
                num++;

        if (mutex_lock_interruptible(&mlxsw_i2c->cmd.lock) < 0) {
                dev_err(&client->dev, "Could not acquire lock");
                return -EINVAL;
        }

        err = mlxsw_i2c_write(dev, reg_size, in_mbox, num, status);
        if (err)
                goto cmd_fail;

        /* No out mailbox is case of write transaction. */
        if (!out_mbox) {
                mutex_unlock(&mlxsw_i2c->cmd.lock);
                return 0;
        }

        /* Send read transaction to get output mailbox content. */
        read_tran[1].buf = out_mbox;
        for (i = 0; i < num; i++) {
                chunk_size = (reg_size > MLXSW_I2C_BLK_MAX) ?
                             MLXSW_I2C_BLK_MAX : reg_size;
                read_tran[1].len = chunk_size;
                mlxsw_i2c_set_slave_addr(tran_buf, off);

                j = 0;
                end = jiffies + timeout;
                do {
                        err = i2c_transfer(client->adapter, read_tran,
                                           ARRAY_SIZE(read_tran));
                        if (err == ARRAY_SIZE(read_tran))
                                break;

                        cond_resched();
                } while ((time_before(jiffies, end)) ||
                         (j++ < MLXSW_I2C_RETRY));

                if (err != ARRAY_SIZE(read_tran)) {
                        if (!err)
                                err = -EIO;

                        goto cmd_fail;
                }

                off += chunk_size;
                reg_size -= chunk_size;
                read_tran[1].buf += chunk_size;
        }

        mutex_unlock(&mlxsw_i2c->cmd.lock);

        return 0;

cmd_fail:
        mutex_unlock(&mlxsw_i2c->cmd.lock);
        return err;
}

static int mlxsw_i2c_cmd_exec(void *bus_priv, u16 opcode, u8 opcode_mod,
                              u32 in_mod, bool out_mbox_direct,
                              char *in_mbox, size_t in_mbox_size,
                              char *out_mbox, size_t out_mbox_size,
                              u8 *status)
{
        struct mlxsw_i2c *mlxsw_i2c = bus_priv;

        return mlxsw_i2c_cmd(mlxsw_i2c->dev, in_mbox_size, in_mbox,
                             out_mbox_size, out_mbox, status);
}

static bool mlxsw_i2c_skb_transmit_busy(void *bus_priv,
                                        const struct mlxsw_tx_info *tx_info)
{
        return false;
}

static int mlxsw_i2c_skb_transmit(void *bus_priv, struct sk_buff *skb,
                                  const struct mlxsw_tx_info *tx_info)
{
        return 0;
}

static int
mlxsw_i2c_init(void *bus_priv, struct mlxsw_core *mlxsw_core,
               const struct mlxsw_config_profile *profile,
               struct mlxsw_res *resources)
{
        struct mlxsw_i2c *mlxsw_i2c = bus_priv;

        mlxsw_i2c->core = mlxsw_core;

        return 0;
}

static void mlxsw_i2c_fini(void *bus_priv)
{
        struct mlxsw_i2c *mlxsw_i2c = bus_priv;

        mlxsw_i2c->core = NULL;
}

static const struct mlxsw_bus mlxsw_i2c_bus = {
        .kind                   = "i2c",
        .init                   = mlxsw_i2c_init,
        .fini                   = mlxsw_i2c_fini,
        .skb_transmit_busy      = mlxsw_i2c_skb_transmit_busy,
        .skb_transmit           = mlxsw_i2c_skb_transmit,
        .cmd_exec               = mlxsw_i2c_cmd_exec,
};

static int mlxsw_i2c_probe(struct i2c_client *client,
                           const struct i2c_device_id *id)
{
        struct mlxsw_i2c *mlxsw_i2c;
        u8 status;
        int err;

        mlxsw_i2c = devm_kzalloc(&client->dev, sizeof(*mlxsw_i2c), GFP_KERNEL);
        if (!mlxsw_i2c)
                return -ENOMEM;

        i2c_set_clientdata(client, mlxsw_i2c);
        mutex_init(&mlxsw_i2c->cmd.lock);

        /* In order to use mailboxes through the i2c, special area is reserved
         * on the i2c address space that can be used for input and output
         * mailboxes. Such mailboxes are called local mailboxes. When using a
         * local mailbox, software should specify 0 as the Input/Output
         * parameters. The location of the Local Mailbox addresses on the i2c
         * space can be retrieved through the QUERY_FW command.
         * For this purpose QUERY_FW is to be issued with opcode modifier equal
         * 0x01. For such command the output parameter is an immediate value.
         * Here QUERY_FW command is invoked for ASIC probing and for getting
         * local mailboxes addresses from immedate output parameters.
         */

        /* Prepare and write out Command Interface Register for transaction */
        err = mlxsw_i2c_write_cmd(client, mlxsw_i2c, 1);
        if (err) {
                dev_err(&client->dev, "Could not start transaction");
                goto errout;
        }

        /* Wait until go bit is cleared. */
        err = mlxsw_i2c_wait_go_bit(client, mlxsw_i2c, &status);
        if (err) {
                dev_err(&client->dev, "HW semaphore is not released");
                goto errout;
        }

        /* Validate transaction completion status. */
        if (status) {
                dev_err(&client->dev, "Bad transaction completion status %x\n",
                        status);
                err = -EIO;
                goto errout;
        }

        /* Get mailbox offsets. */
        err = mlxsw_i2c_get_mbox(client, mlxsw_i2c);
        if (err < 0) {
                dev_err(&client->dev, "Fail to get mailboxes\n");
                goto errout;
        }

        dev_info(&client->dev, "%s mb size=%x off=0x%08x out mb size=%x off=0x%08x\n",
                 id->name, mlxsw_i2c->cmd.mb_size_in,
                 mlxsw_i2c->cmd.mb_off_in, mlxsw_i2c->cmd.mb_size_out,
                 mlxsw_i2c->cmd.mb_off_out);

        /* Register device bus. */
        mlxsw_i2c->bus_info.device_kind = id->name;
        mlxsw_i2c->bus_info.device_name = client->name;
        mlxsw_i2c->bus_info.dev = &client->dev;
        mlxsw_i2c->dev = &client->dev;

        err = mlxsw_core_bus_device_register(&mlxsw_i2c->bus_info,
                                             &mlxsw_i2c_bus, mlxsw_i2c, false,
                                             NULL);
        if (err) {
                dev_err(&client->dev, "Fail to register core bus\n");
                return err;
        }

        return 0;

errout:
        i2c_set_clientdata(client, NULL);

        return err;
}

static int mlxsw_i2c_remove(struct i2c_client *client)
{
        struct mlxsw_i2c *mlxsw_i2c = i2c_get_clientdata(client);

        mlxsw_core_bus_device_unregister(mlxsw_i2c->core, false);
        mutex_destroy(&mlxsw_i2c->cmd.lock);

        return 0;
}

int mlxsw_i2c_driver_register(struct i2c_driver *i2c_driver)
{
        i2c_driver->probe = mlxsw_i2c_probe;
        i2c_driver->remove = mlxsw_i2c_remove;
        return i2c_add_driver(i2c_driver);
}
EXPORT_SYMBOL(mlxsw_i2c_driver_register);

void mlxsw_i2c_driver_unregister(struct i2c_driver *i2c_driver)
{
        i2c_del_driver(i2c_driver);
}
EXPORT_SYMBOL(mlxsw_i2c_driver_unregister);

MODULE_AUTHOR("Vadim Pasternak <vadimp@mellanox.com>");
MODULE_DESCRIPTION("Mellanox switch I2C interface driver");
MODULE_LICENSE("Dual BSD/GPL");