/*
 * Copyright (c) 2011-2016 Synaptics Incorporated
 * Copyright (c) 2011 Unixphere
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/rmi.h>
#include <linux/slab.h>
#include <linux/spi/spi.h>
#include <linux/of.h>
#include "rmi_driver.h"

#define RMI_SPI_DEFAULT_XFER_BUF_SIZE   64

#define RMI_PAGE_SELECT_REGISTER        0x00FF
#define RMI_SPI_PAGE(addr)              (((addr) >> 8) & 0x80)
#define RMI_SPI_XFER_SIZE_LIMIT         255

#define BUFFER_SIZE_INCREMENT 32

enum rmi_spi_op {
        RMI_SPI_WRITE = 0,
        RMI_SPI_READ,
        RMI_SPI_V2_READ_UNIFIED,
        RMI_SPI_V2_READ_SPLIT,
        RMI_SPI_V2_WRITE,
};

struct rmi_spi_cmd {
        enum rmi_spi_op op;
        u16 addr;
};

struct rmi_spi_xport {
        struct rmi_transport_dev xport;
        struct spi_device *spi;

        struct mutex page_mutex;
        int page;

        u8 *rx_buf;
        u8 *tx_buf;
        int xfer_buf_size;

        struct spi_transfer *rx_xfers;
        struct spi_transfer *tx_xfers;
        int rx_xfer_count;
        int tx_xfer_count;
};

static int rmi_spi_manage_pools(struct rmi_spi_xport *rmi_spi, int len)
{
        struct spi_device *spi = rmi_spi->spi;
        int buf_size = rmi_spi->xfer_buf_size
                ? rmi_spi->xfer_buf_size : RMI_SPI_DEFAULT_XFER_BUF_SIZE;
        struct spi_transfer *xfer_buf;
        void *buf;
        void *tmp;

        while (buf_size < len)
                buf_size *= 2;

        if (buf_size > RMI_SPI_XFER_SIZE_LIMIT)
                buf_size = RMI_SPI_XFER_SIZE_LIMIT;

        tmp = rmi_spi->rx_buf;
        buf = devm_kzalloc(&spi->dev, buf_size * 2,
                                GFP_KERNEL | GFP_DMA);
        if (!buf)
                return -ENOMEM;

        rmi_spi->rx_buf = buf;
        rmi_spi->tx_buf = &rmi_spi->rx_buf[buf_size];
        rmi_spi->xfer_buf_size = buf_size;

        if (tmp)
                devm_kfree(&spi->dev, tmp);

        if (rmi_spi->xport.pdata.spi_data.read_delay_us)
                rmi_spi->rx_xfer_count = buf_size;
        else
                rmi_spi->rx_xfer_count = 1;

        if (rmi_spi->xport.pdata.spi_data.write_delay_us)
                rmi_spi->tx_xfer_count = buf_size;
        else
                rmi_spi->tx_xfer_count = 1;

        /*
         * Allocate a pool of spi_transfer buffers for devices which need
         * per byte delays.
         */
        tmp = rmi_spi->rx_xfers;
        xfer_buf = devm_kzalloc(&spi->dev,
                (rmi_spi->rx_xfer_count + rmi_spi->tx_xfer_count)
                * sizeof(struct spi_transfer), GFP_KERNEL);
        if (!xfer_buf)
                return -ENOMEM;

        rmi_spi->rx_xfers = xfer_buf;
        rmi_spi->tx_xfers = &xfer_buf[rmi_spi->rx_xfer_count];

        if (tmp)
                devm_kfree(&spi->dev, tmp);

        return 0;
}

static int rmi_spi_xfer(struct rmi_spi_xport *rmi_spi,
                        const struct rmi_spi_cmd *cmd, const u8 *tx_buf,
                        int tx_len, u8 *rx_buf, int rx_len)
{
        struct spi_device *spi = rmi_spi->spi;
        struct rmi_device_platform_data_spi *spi_data =
                                        &rmi_spi->xport.pdata.spi_data;
        struct spi_message msg;
        struct spi_transfer *xfer;
        int ret = 0;
        int len;
        int cmd_len = 0;
        int total_tx_len;
        int i;
        u16 addr = cmd->addr;

        spi_message_init(&msg);

        switch (cmd->op) {
        case RMI_SPI_WRITE:
        case RMI_SPI_READ:
                cmd_len += 2;
                break;
        case RMI_SPI_V2_READ_UNIFIED:
        case RMI_SPI_V2_READ_SPLIT:
        case RMI_SPI_V2_WRITE:
                cmd_len += 4;
                break;
        }

        total_tx_len = cmd_len + tx_len;
        len = max(total_tx_len, rx_len);

        if (len > RMI_SPI_XFER_SIZE_LIMIT)
                return -EINVAL;

        if (rmi_spi->xfer_buf_size < len)
                rmi_spi_manage_pools(rmi_spi, len);

        if (addr == 0)
                /*
                 * SPI needs an address. Use 0x7FF if we want to keep
                 * reading from the last position of the register pointer.
                 */
                addr = 0x7FF;

        switch (cmd->op) {
        case RMI_SPI_WRITE:
                rmi_spi->tx_buf[0] = (addr >> 8);
                rmi_spi->tx_buf[1] = addr & 0xFF;
                break;
        case RMI_SPI_READ:
                rmi_spi->tx_buf[0] = (addr >> 8) | 0x80;
                rmi_spi->tx_buf[1] = addr & 0xFF;
                break;
        case RMI_SPI_V2_READ_UNIFIED:
                break;
        case RMI_SPI_V2_READ_SPLIT:
                break;
        case RMI_SPI_V2_WRITE:
                rmi_spi->tx_buf[0] = 0x40;
                rmi_spi->tx_buf[1] = (addr >> 8) & 0xFF;
                rmi_spi->tx_buf[2] = addr & 0xFF;
                rmi_spi->tx_buf[3] = tx_len;
                break;
        }

        if (tx_buf)
                memcpy(&rmi_spi->tx_buf[cmd_len], tx_buf, tx_len);

        if (rmi_spi->tx_xfer_count > 1) {
                for (i = 0; i < total_tx_len; i++) {
                        xfer = &rmi_spi->tx_xfers[i];
                        memset(xfer, 0, sizeof(struct spi_transfer));
                        xfer->tx_buf = &rmi_spi->tx_buf[i];
                        xfer->len = 1;
                        xfer->delay_usecs = spi_data->write_delay_us;
                        spi_message_add_tail(xfer, &msg);
                }
        } else {
                xfer = rmi_spi->tx_xfers;
                memset(xfer, 0, sizeof(struct spi_transfer));
                xfer->tx_buf = rmi_spi->tx_buf;
                xfer->len = total_tx_len;
                spi_message_add_tail(xfer, &msg);
        }

        rmi_dbg(RMI_DEBUG_XPORT, &spi->dev, "%s: cmd: %s tx_buf len: %d tx_buf: %*ph\n",
                __func__, cmd->op == RMI_SPI_WRITE ? "WRITE" : "READ",
                total_tx_len, total_tx_len, rmi_spi->tx_buf);

        if (rx_buf) {
                if (rmi_spi->rx_xfer_count > 1) {
                        for (i = 0; i < rx_len; i++) {
                                xfer = &rmi_spi->rx_xfers[i];
                                memset(xfer, 0, sizeof(struct spi_transfer));
                                xfer->rx_buf = &rmi_spi->rx_buf[i];
                                xfer->len = 1;
                                xfer->delay_usecs = spi_data->read_delay_us;
                                spi_message_add_tail(xfer, &msg);
                        }
                } else {
                        xfer = rmi_spi->rx_xfers;
                        memset(xfer, 0, sizeof(struct spi_transfer));
                        xfer->rx_buf = rmi_spi->rx_buf;
                        xfer->len = rx_len;
                        spi_message_add_tail(xfer, &msg);
                }
        }

        ret = spi_sync(spi, &msg);
        if (ret < 0) {
                dev_err(&spi->dev, "spi xfer failed: %d\n", ret);
                return ret;
        }

        if (rx_buf) {
                memcpy(rx_buf, rmi_spi->rx_buf, rx_len);
                rmi_dbg(RMI_DEBUG_XPORT, &spi->dev, "%s: (%d) %*ph\n",
                        __func__, rx_len, rx_len, rx_buf);
        }

        return 0;
}

/*
 * rmi_set_page - Set RMI page
 * @xport: The pointer to the rmi_transport_dev struct
 * @page: The new page address.
 *
 * RMI devices have 16-bit addressing, but some of the transport
 * implementations (like SMBus) only have 8-bit addressing. So RMI implements
 * a page address at 0xff of every page so we can reliable page addresses
 * every 256 registers.
 *
 * The page_mutex lock must be held when this function is entered.
 *
 * Returns zero on success, non-zero on failure.
 */
static int rmi_set_page(struct rmi_spi_xport *rmi_spi, u8 page)
{
        struct rmi_spi_cmd cmd;
        int ret;

        cmd.op = RMI_SPI_WRITE;
        cmd.addr = RMI_PAGE_SELECT_REGISTER;

        ret = rmi_spi_xfer(rmi_spi, &cmd, &page, 1, NULL, 0);

        if (ret)
                rmi_spi->page = page;

        return ret;
}

static int rmi_spi_write_block(struct rmi_transport_dev *xport, u16 addr,
                               const void *buf, size_t len)
{
        struct rmi_spi_xport *rmi_spi =
                container_of(xport, struct rmi_spi_xport, xport);
        struct rmi_spi_cmd cmd;
        int ret;

        mutex_lock(&rmi_spi->page_mutex);

        if (RMI_SPI_PAGE(addr) != rmi_spi->page) {
                ret = rmi_set_page(rmi_spi, RMI_SPI_PAGE(addr));
                if (ret)
                        goto exit;
        }

        cmd.op = RMI_SPI_WRITE;
        cmd.addr = addr;

        ret = rmi_spi_xfer(rmi_spi, &cmd, buf, len, NULL, 0);

exit:
        mutex_unlock(&rmi_spi->page_mutex);
        return ret;
}

static int rmi_spi_read_block(struct rmi_transport_dev *xport, u16 addr,
                              void *buf, size_t len)
{
        struct rmi_spi_xport *rmi_spi =
                container_of(xport, struct rmi_spi_xport, xport);
        struct rmi_spi_cmd cmd;
        int ret;

        mutex_lock(&rmi_spi->page_mutex);

        if (RMI_SPI_PAGE(addr) != rmi_spi->page) {
                ret = rmi_set_page(rmi_spi, RMI_SPI_PAGE(addr));
                if (ret)
                        goto exit;
        }

        cmd.op = RMI_SPI_READ;
        cmd.addr = addr;

        ret = rmi_spi_xfer(rmi_spi, &cmd, NULL, 0, buf, len);

exit:
        mutex_unlock(&rmi_spi->page_mutex);
        return ret;
}

static const struct rmi_transport_ops rmi_spi_ops = {
        .write_block    = rmi_spi_write_block,
        .read_block     = rmi_spi_read_block,
};

#ifdef CONFIG_OF
static int rmi_spi_of_probe(struct spi_device *spi,
                        struct rmi_device_platform_data *pdata)
{
        struct device *dev = &spi->dev;
        int retval;

        retval = rmi_of_property_read_u32(dev,
                        &pdata->spi_data.read_delay_us,
                        "spi-rx-delay-us", 1);
        if (retval)
                return retval;

        retval = rmi_of_property_read_u32(dev,
                        &pdata->spi_data.write_delay_us,
                        "spi-tx-delay-us", 1);
        if (retval)
                return retval;

        return 0;
}

static const struct of_device_id rmi_spi_of_match[] = {
        { .compatible = "syna,rmi4-spi" },
        {},
};
MODULE_DEVICE_TABLE(of, rmi_spi_of_match);
#else
static inline int rmi_spi_of_probe(struct spi_device *spi,
                                struct rmi_device_platform_data *pdata)
{
        return -ENODEV;
}
#endif

static void rmi_spi_unregister_transport(void *data)
{
        struct rmi_spi_xport *rmi_spi = data;

        rmi_unregister_transport_device(&rmi_spi->xport);
}

static int rmi_spi_probe(struct spi_device *spi)
{
        struct rmi_spi_xport *rmi_spi;
        struct rmi_device_platform_data *pdata;
        struct rmi_device_platform_data *spi_pdata = spi->dev.platform_data;
        int error;

        if (spi->master->flags & SPI_MASTER_HALF_DUPLEX)
                return -EINVAL;

        rmi_spi = devm_kzalloc(&spi->dev, sizeof(struct rmi_spi_xport),
                        GFP_KERNEL);
        if (!rmi_spi)
                return -ENOMEM;

        pdata = &rmi_spi->xport.pdata;

        if (spi->dev.of_node) {
                error = rmi_spi_of_probe(spi, pdata);
                if (error)
                        return error;
        } else if (spi_pdata) {
                *pdata = *spi_pdata;
        }

        if (pdata->spi_data.bits_per_word)
                spi->bits_per_word = pdata->spi_data.bits_per_word;

        if (pdata->spi_data.mode)
                spi->mode = pdata->spi_data.mode;

        error = spi_setup(spi);
        if (error < 0) {
                dev_err(&spi->dev, "spi_setup failed!\n");
                return error;
        }

        pdata->irq = spi->irq;

        rmi_spi->spi = spi;
        mutex_init(&rmi_spi->page_mutex);

        rmi_spi->xport.dev = &spi->dev;
        rmi_spi->xport.proto_name = "spi";
        rmi_spi->xport.ops = &rmi_spi_ops;

        spi_set_drvdata(spi, rmi_spi);

        error = rmi_spi_manage_pools(rmi_spi, RMI_SPI_DEFAULT_XFER_BUF_SIZE);
        if (error)
                return error;

        /*
         * Setting the page to zero will (a) make sure the PSR is in a
         * known state, and (b) make sure we can talk to the device.
         */
        error = rmi_set_page(rmi_spi, 0);
        if (error) {
                dev_err(&spi->dev, "Failed to set page select to 0.\n");
                return error;
        }

        dev_info(&spi->dev, "registering SPI-connected sensor\n");

        error = rmi_register_transport_device(&rmi_spi->xport);
        if (error) {
                dev_err(&spi->dev, "failed to register sensor: %d\n", error);
                return error;
        }

        error = devm_add_action_or_reset(&spi->dev,
                                          rmi_spi_unregister_transport,
                                          rmi_spi);
        if (error)
                return error;

        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int rmi_spi_suspend(struct device *dev)
{
        struct spi_device *spi = to_spi_device(dev);
        struct rmi_spi_xport *rmi_spi = spi_get_drvdata(spi);
        int ret;

        ret = rmi_driver_suspend(rmi_spi->xport.rmi_dev, true);
        if (ret)
                dev_warn(dev, "Failed to resume device: %d\n", ret);

        return ret;
}

static int rmi_spi_resume(struct device *dev)
{
        struct spi_device *spi = to_spi_device(dev);
        struct rmi_spi_xport *rmi_spi = spi_get_drvdata(spi);
        int ret;

        ret = rmi_driver_resume(rmi_spi->xport.rmi_dev, true);
        if (ret)
                dev_warn(dev, "Failed to resume device: %d\n", ret);

        return ret;
}
#endif

#ifdef CONFIG_PM
static int rmi_spi_runtime_suspend(struct device *dev)
{
        struct spi_device *spi = to_spi_device(dev);
        struct rmi_spi_xport *rmi_spi = spi_get_drvdata(spi);
        int ret;

        ret = rmi_driver_suspend(rmi_spi->xport.rmi_dev, false);
        if (ret)
                dev_warn(dev, "Failed to resume device: %d\n", ret);

        return 0;
}

static int rmi_spi_runtime_resume(struct device *dev)
{
        struct spi_device *spi = to_spi_device(dev);
        struct rmi_spi_xport *rmi_spi = spi_get_drvdata(spi);
        int ret;

        ret = rmi_driver_resume(rmi_spi->xport.rmi_dev, false);
        if (ret)
                dev_warn(dev, "Failed to resume device: %d\n", ret);

        return 0;
}
#endif

static const struct dev_pm_ops rmi_spi_pm = {
        SET_SYSTEM_SLEEP_PM_OPS(rmi_spi_suspend, rmi_spi_resume)
        SET_RUNTIME_PM_OPS(rmi_spi_runtime_suspend, rmi_spi_runtime_resume,
                           NULL)
};

static const struct spi_device_id rmi_id[] = {
        { "rmi4_spi", 0 },
        { }
};
MODULE_DEVICE_TABLE(spi, rmi_id);

static struct spi_driver rmi_spi_driver = {
        .driver = {
                .name   = "rmi4_spi",
                .pm     = &rmi_spi_pm,
                .of_match_table = of_match_ptr(rmi_spi_of_match),
        },
        .id_table       = rmi_id,
        .probe          = rmi_spi_probe,
};

module_spi_driver(rmi_spi_driver);

MODULE_AUTHOR("Christopher Heiny <cheiny@synaptics.com>");
MODULE_AUTHOR("Andrew Duggan <aduggan@synaptics.com>");
MODULE_DESCRIPTION("RMI SPI driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(RMI_DRIVER_VERSION);