// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2011-2016 Synaptics Incorporated
 * Copyright (c) 2011 Unixphere
 */

#include <linux/i2c.h>
#include <linux/rmi.h>
#include <linux/of.h>
#include <linux/delay.h>
#include <linux/regulator/consumer.h>
#include "rmi_driver.h"

#define BUFFER_SIZE_INCREMENT 32

/**
 * struct rmi_i2c_xport - stores information for i2c communication
 *
 * @xport: The transport interface structure
 * @client: The I2C client device structure
 *
 * @page_mutex: Locks current page to avoid changing pages in unexpected ways.
 * @page: Keeps track of the current virtual page
 *
 * @tx_buf: Buffer used for transmitting data to the sensor over i2c.
 * @tx_buf_size: Size of the buffer
 *
 * @supplies: Array of voltage regulators
 * @startup_delay: Milliseconds to pause after powering up the regulators
 */
struct rmi_i2c_xport {
        struct rmi_transport_dev xport;
        struct i2c_client *client;

        struct mutex page_mutex;
        int page;

        u8 *tx_buf;
        size_t tx_buf_size;

        struct regulator_bulk_data supplies[2];
        u32 startup_delay;
};

#define RMI_PAGE_SELECT_REGISTER 0xff
#define RMI_I2C_PAGE(addr) (((addr) >> 8) & 0xff)

/*
 * 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_i2c_xport *rmi_i2c, u8 page)
{
        struct i2c_client *client = rmi_i2c->client;
        u8 txbuf[2] = {RMI_PAGE_SELECT_REGISTER, page};
        int retval;

        retval = i2c_master_send(client, txbuf, sizeof(txbuf));
        if (retval != sizeof(txbuf)) {
                dev_err(&client->dev,
                        "%s: set page failed: %d.", __func__, retval);
                return (retval < 0) ? retval : -EIO;
        }

        rmi_i2c->page = page;
        return 0;
}

static int rmi_i2c_write_block(struct rmi_transport_dev *xport, u16 addr,
                               const void *buf, size_t len)
{
        struct rmi_i2c_xport *rmi_i2c =
                container_of(xport, struct rmi_i2c_xport, xport);
        struct i2c_client *client = rmi_i2c->client;
        size_t tx_size = len + 1;
        int retval;

        mutex_lock(&rmi_i2c->page_mutex);

        if (!rmi_i2c->tx_buf || rmi_i2c->tx_buf_size < tx_size) {
                if (rmi_i2c->tx_buf)
                        devm_kfree(&client->dev, rmi_i2c->tx_buf);
                rmi_i2c->tx_buf_size = tx_size + BUFFER_SIZE_INCREMENT;
                rmi_i2c->tx_buf = devm_kzalloc(&client->dev,
                                               rmi_i2c->tx_buf_size,
                                               GFP_KERNEL);
                if (!rmi_i2c->tx_buf) {
                        rmi_i2c->tx_buf_size = 0;
                        retval = -ENOMEM;
                        goto exit;
                }
        }

        rmi_i2c->tx_buf[0] = addr & 0xff;
        memcpy(rmi_i2c->tx_buf + 1, buf, len);

        if (RMI_I2C_PAGE(addr) != rmi_i2c->page) {
                retval = rmi_set_page(rmi_i2c, RMI_I2C_PAGE(addr));
                if (retval)
                        goto exit;
        }

        retval = i2c_master_send(client, rmi_i2c->tx_buf, tx_size);
        if (retval == tx_size)
                retval = 0;
        else if (retval >= 0)
                retval = -EIO;

exit:
        rmi_dbg(RMI_DEBUG_XPORT, &client->dev,
                "write %zd bytes at %#06x: %d (%*ph)\n",
                len, addr, retval, (int)len, buf);

        mutex_unlock(&rmi_i2c->page_mutex);
        return retval;
}

static int rmi_i2c_read_block(struct rmi_transport_dev *xport, u16 addr,
                              void *buf, size_t len)
{
        struct rmi_i2c_xport *rmi_i2c =
                container_of(xport, struct rmi_i2c_xport, xport);
        struct i2c_client *client = rmi_i2c->client;
        u8 addr_offset = addr & 0xff;
        int retval;
        struct i2c_msg msgs[] = {
                {
                        .addr   = client->addr,
                        .len    = sizeof(addr_offset),
                        .buf    = &addr_offset,
                },
                {
                        .addr   = client->addr,
                        .flags  = I2C_M_RD,
                        .len    = len,
                        .buf    = buf,
                },
        };

        mutex_lock(&rmi_i2c->page_mutex);

        if (RMI_I2C_PAGE(addr) != rmi_i2c->page) {
                retval = rmi_set_page(rmi_i2c, RMI_I2C_PAGE(addr));
                if (retval)
                        goto exit;
        }

        retval = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
        if (retval == ARRAY_SIZE(msgs))
                retval = 0; /* success */
        else if (retval >= 0)
                retval = -EIO;

exit:
        rmi_dbg(RMI_DEBUG_XPORT, &client->dev,
                "read %zd bytes at %#06x: %d (%*ph)\n",
                len, addr, retval, (int)len, buf);

        mutex_unlock(&rmi_i2c->page_mutex);
        return retval;
}

static const struct rmi_transport_ops rmi_i2c_ops = {
        .write_block    = rmi_i2c_write_block,
        .read_block     = rmi_i2c_read_block,
};

#ifdef CONFIG_OF
static const struct of_device_id rmi_i2c_of_match[] = {
        { .compatible = "syna,rmi4-i2c" },
        {},
};
MODULE_DEVICE_TABLE(of, rmi_i2c_of_match);
#endif

static void rmi_i2c_regulator_bulk_disable(void *data)
{
        struct rmi_i2c_xport *rmi_i2c = data;

        regulator_bulk_disable(ARRAY_SIZE(rmi_i2c->supplies),
                               rmi_i2c->supplies);
}

static void rmi_i2c_unregister_transport(void *data)
{
        struct rmi_i2c_xport *rmi_i2c = data;

        rmi_unregister_transport_device(&rmi_i2c->xport);
}

static int rmi_i2c_probe(struct i2c_client *client)
{
        struct rmi_device_platform_data *pdata;
        struct rmi_device_platform_data *client_pdata =
                                        dev_get_platdata(&client->dev);
        struct rmi_i2c_xport *rmi_i2c;
        int error;

        rmi_i2c = devm_kzalloc(&client->dev, sizeof(struct rmi_i2c_xport),
                                GFP_KERNEL);
        if (!rmi_i2c)
                return -ENOMEM;

        pdata = &rmi_i2c->xport.pdata;

        if (!client->dev.of_node && client_pdata)
                *pdata = *client_pdata;

        pdata->irq = client->irq;

        rmi_dbg(RMI_DEBUG_XPORT, &client->dev, "Probing %s.\n",
                        dev_name(&client->dev));

        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
                dev_err(&client->dev,
                        "adapter does not support required functionality\n");
                return -ENODEV;
        }

        rmi_i2c->supplies[0].supply = "vdd";
        rmi_i2c->supplies[1].supply = "vio";
        error = devm_regulator_bulk_get(&client->dev,
                                         ARRAY_SIZE(rmi_i2c->supplies),
                                         rmi_i2c->supplies);
        if (error < 0)
                return error;

        error = regulator_bulk_enable(ARRAY_SIZE(rmi_i2c->supplies),
                                       rmi_i2c->supplies);
        if (error < 0)
                return error;

        error = devm_add_action_or_reset(&client->dev,
                                          rmi_i2c_regulator_bulk_disable,
                                          rmi_i2c);
        if (error)
                return error;

        of_property_read_u32(client->dev.of_node, "syna,startup-delay-ms",
                             &rmi_i2c->startup_delay);

        msleep(rmi_i2c->startup_delay);

        rmi_i2c->client = client;
        mutex_init(&rmi_i2c->page_mutex);

        rmi_i2c->xport.dev = &client->dev;
        rmi_i2c->xport.proto_name = "i2c";
        rmi_i2c->xport.ops = &rmi_i2c_ops;

        i2c_set_clientdata(client, rmi_i2c);

        /*
         * 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_i2c, 0);
        if (error) {
                dev_err(&client->dev, "Failed to set page select to 0\n");
                return error;
        }

        dev_info(&client->dev, "registering I2C-connected sensor\n");

        error = rmi_register_transport_device(&rmi_i2c->xport);
        if (error) {
                dev_err(&client->dev, "failed to register sensor: %d\n", error);
                return error;
        }

        error = devm_add_action_or_reset(&client->dev,
                                          rmi_i2c_unregister_transport,
                                          rmi_i2c);
        if (error)
                return error;

        return 0;
}

static int rmi_i2c_suspend(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct rmi_i2c_xport *rmi_i2c = i2c_get_clientdata(client);
        int ret;

        ret = rmi_driver_suspend(rmi_i2c->xport.rmi_dev, true);
        if (ret)
                dev_warn(dev, "Failed to resume device: %d\n", ret);

        regulator_bulk_disable(ARRAY_SIZE(rmi_i2c->supplies),
                               rmi_i2c->supplies);

        return ret;
}

static int rmi_i2c_resume(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct rmi_i2c_xport *rmi_i2c = i2c_get_clientdata(client);
        int ret;

        ret = regulator_bulk_enable(ARRAY_SIZE(rmi_i2c->supplies),
                                    rmi_i2c->supplies);
        if (ret)
                return ret;

        msleep(rmi_i2c->startup_delay);

        ret = rmi_driver_resume(rmi_i2c->xport.rmi_dev, true);
        if (ret)
                dev_warn(dev, "Failed to resume device: %d\n", ret);

        return ret;
}

static int rmi_i2c_runtime_suspend(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct rmi_i2c_xport *rmi_i2c = i2c_get_clientdata(client);
        int ret;

        ret = rmi_driver_suspend(rmi_i2c->xport.rmi_dev, false);
        if (ret)
                dev_warn(dev, "Failed to resume device: %d\n", ret);

        regulator_bulk_disable(ARRAY_SIZE(rmi_i2c->supplies),
                               rmi_i2c->supplies);

        return 0;
}

static int rmi_i2c_runtime_resume(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct rmi_i2c_xport *rmi_i2c = i2c_get_clientdata(client);
        int ret;

        ret = regulator_bulk_enable(ARRAY_SIZE(rmi_i2c->supplies),
                                    rmi_i2c->supplies);
        if (ret)
                return ret;

        msleep(rmi_i2c->startup_delay);

        ret = rmi_driver_resume(rmi_i2c->xport.rmi_dev, false);
        if (ret)
                dev_warn(dev, "Failed to resume device: %d\n", ret);

        return 0;
}

static const struct dev_pm_ops rmi_i2c_pm = {
        SYSTEM_SLEEP_PM_OPS(rmi_i2c_suspend, rmi_i2c_resume)
        RUNTIME_PM_OPS(rmi_i2c_runtime_suspend, rmi_i2c_runtime_resume, NULL)
};

static const struct i2c_device_id rmi_id[] = {
        { "rmi4_i2c" },
        { }
};
MODULE_DEVICE_TABLE(i2c, rmi_id);

static struct i2c_driver rmi_i2c_driver = {
        .driver = {
                .name   = "rmi4_i2c",
                .pm     = pm_ptr(&rmi_i2c_pm),
                .of_match_table = of_match_ptr(rmi_i2c_of_match),
        },
        .id_table       = rmi_id,
        .probe          = rmi_i2c_probe,
};

module_i2c_driver(rmi_i2c_driver);

MODULE_AUTHOR("Christopher Heiny <cheiny@synaptics.com>");
MODULE_AUTHOR("Andrew Duggan <aduggan@synaptics.com>");
MODULE_DESCRIPTION("RMI I2C driver");
MODULE_LICENSE("GPL");