gpu/drm/drm_mipi_dsi.c

/*
 * MIPI DSI Bus
 *
 * Copyright (C) 2012-2013, Samsung Electronics, Co., Ltd.
 * Andrzej Hajda <a.hajda@samsung.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sub license, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include <drm/drm_mipi_dsi.h>

#include <linux/device.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>

#include <drm/drm_dsc.h>
#include <drm/drm_print.h>
#include <video/mipi_display.h>

/**
 * DOC: dsi helpers
 *
 * These functions contain some common logic and helpers to deal with MIPI DSI
 * peripherals.
 *
 * Helpers are provided for a number of standard MIPI DSI command as well as a
 * subset of the MIPI DCS command set.
 */

static int mipi_dsi_device_match(struct device *dev, struct device_driver *drv)
{
    struct mipi_dsi_device *dsi = to_mipi_dsi_device(dev);

    /* attempt OF style match */
    if (of_driver_match_device(dev, drv)) {
        return 1;
    }

    /* compare DSI device and driver names */
    if (!strcmp(dsi->name, drv->name)) {
        return 1;
    }

    return 0;
}

static int mipi_dsi_uevent(struct device *dev, struct kobj_uevent_env *env)
{
    struct mipi_dsi_device *dsi = to_mipi_dsi_device(dev);
    int err;

    err = of_device_uevent_modalias(dev, env);
    if (err != -ENODEV) {
        return err;
    }

    add_uevent_var(env, "MODALIAS=%s%s", MIPI_DSI_MODULE_PREFIX, dsi->name);

    return 0;
}

static const struct dev_pm_ops mipi_dsi_device_pm_ops = {
    .runtime_suspend = pm_generic_runtime_suspend,
    .runtime_resume = pm_generic_runtime_resume,
    .suspend = pm_generic_suspend,
    .resume = pm_generic_resume,
    .freeze = pm_generic_freeze,
    .thaw = pm_generic_thaw,
    .poweroff = pm_generic_poweroff,
    .restore = pm_generic_restore,
};

static struct bus_type mipi_dsi_bus_type = {
    .name = "mipi-dsi",
    .match = mipi_dsi_device_match,
    .uevent = mipi_dsi_uevent,
    .pm = &mipi_dsi_device_pm_ops,
};

/**
 * of_find_mipi_dsi_device_by_node() - find the MIPI DSI device matching a
 *    device tree node
 * @np: device tree node
 *
 * Return: A pointer to the MIPI DSI device corresponding to @np or NULL if no
 *    such device exists (or has not been registered yet).
 */
struct mipi_dsi_device *of_find_mipi_dsi_device_by_node(struct device_node *np)
{
    struct device *dev;

    dev = bus_find_device_by_of_node(&mipi_dsi_bus_type, np);

    return dev ? to_mipi_dsi_device(dev) : NULL;
}
EXPORT_SYMBOL(of_find_mipi_dsi_device_by_node);

static void mipi_dsi_dev_release(struct device *dev)
{
    struct mipi_dsi_device *dsi = to_mipi_dsi_device(dev);

    of_node_put(dev->of_node);
    kfree(dsi);
}

static const struct device_type mipi_dsi_device_type = {
    .release = mipi_dsi_dev_release,
};

static struct mipi_dsi_device *mipi_dsi_device_alloc(struct mipi_dsi_host *host)
{
    struct mipi_dsi_device *dsi;

    dsi = kzalloc(sizeof(*dsi), GFP_KERNEL);
    if (!dsi) {
        return ERR_PTR(-ENOMEM);
    }

    dsi->host = host;
    dsi->dev.bus = &mipi_dsi_bus_type;
    dsi->dev.parent = host->dev;
    dsi->dev.type = &mipi_dsi_device_type;

    device_initialize(&dsi->dev);

    return dsi;
}

static int mipi_dsi_device_add(struct mipi_dsi_device *dsi)
{
    struct mipi_dsi_host *host = dsi->host;

    dev_set_name(&dsi->dev, "%s.%d", dev_name(host->dev), dsi->channel);

    return device_add(&dsi->dev);
}

#if IS_ENABLED(CONFIG_OF)
static struct mipi_dsi_device *of_mipi_dsi_device_add(struct mipi_dsi_host *host, struct device_node *node)
{
    struct mipi_dsi_device_info info = {};
    int ret;
    u32 reg;

    if (of_modalias_node(node, info.type, sizeof(info.type)) < 0) {
        drm_err(host, "modalias failure on %pOF\n", node);
        return ERR_PTR(-EINVAL);
    }

    ret = of_property_read_u32(node, "reg", &reg);
    if (ret) {
        drm_err(host, "device node %pOF has no valid reg property: %d\n", node, ret);
        return ERR_PTR(-EINVAL);
    }

    info.channel = reg;
    info.node = of_node_get(node);

    return mipi_dsi_device_register_full(host, &info);
}
#else
static struct mipi_dsi_device *of_mipi_dsi_device_add(struct mipi_dsi_host *host, struct device_node *node)
{
    return ERR_PTR(-ENODEV);
}
#endif

/**
 * mipi_dsi_device_register_full - create a MIPI DSI device
 * @host: DSI host to which this device is connected
 * @info: pointer to template containing DSI device information
 *
 * Create a MIPI DSI device by using the device information provided by
 * mipi_dsi_device_info template
 *
 * Returns:
 * A pointer to the newly created MIPI DSI device, or, a pointer encoded
 * with an error
 */
struct mipi_dsi_device *mipi_dsi_device_register_full(struct mipi_dsi_host *host,
                                                      const struct mipi_dsi_device_info *info)
{
    struct mipi_dsi_device *dsi;
    int ret;

    if (!info) {
        drm_err(host, "invalid mipi_dsi_device_info pointer\n");
        return ERR_PTR(-EINVAL);
    }

    if (info->channel > 0x3) {
        drm_err(host, "invalid virtual channel: %u\n", info->channel);
        return ERR_PTR(-EINVAL);
    }

    dsi = mipi_dsi_device_alloc(host);
    if (IS_ERR(dsi)) {
        drm_err(host, "failed to allocate DSI device %ld\n", PTR_ERR(dsi));
        return dsi;
    }

    dsi->dev.of_node = info->node;
    dsi->channel = info->channel;
    strlcpy(dsi->name, info->type, sizeof(dsi->name));

    ret = mipi_dsi_device_add(dsi);
    if (ret) {
        drm_err(host, "failed to add DSI device %d\n", ret);
        kfree(dsi);
        return ERR_PTR(ret);
    }

    return dsi;
}
EXPORT_SYMBOL(mipi_dsi_device_register_full);

/**
 * mipi_dsi_device_unregister - unregister MIPI DSI device
 * @dsi: DSI peripheral device
 */
void mipi_dsi_device_unregister(struct mipi_dsi_device *dsi)
{
    device_unregister(&dsi->dev);
}
EXPORT_SYMBOL(mipi_dsi_device_unregister);

static DEFINE_MUTEX(host_lock);
static LIST_HEAD(host_list);

/**
 * of_find_mipi_dsi_host_by_node() - find the MIPI DSI host matching a
 *                     device tree node
 * @node: device tree node
 *
 * Returns:
 * A pointer to the MIPI DSI host corresponding to @node or NULL if no
 * such device exists (or has not been registered yet).
 */
struct mipi_dsi_host *of_find_mipi_dsi_host_by_node(struct device_node *node)
{
    struct mipi_dsi_host *host;

    mutex_lock(&host_lock);

    list_for_each_entry(host, &host_list, list)
    {
        if (host->dev->of_node == node) {
            mutex_unlock(&host_lock);
            return host;
        }
    }

    mutex_unlock(&host_lock);

    return NULL;
}
EXPORT_SYMBOL(of_find_mipi_dsi_host_by_node);

int mipi_dsi_host_register(struct mipi_dsi_host *host)
{
    struct device_node *node;

    for_each_available_child_of_node(host->dev->of_node, node)
    {
        /* skip nodes without reg property */
        if (!of_find_property(node, "reg", NULL)) {
            continue;
        }
        of_mipi_dsi_device_add(host, node);
    }

    mutex_lock(&host_lock);
    list_add_tail(&host->list, &host_list);
    mutex_unlock(&host_lock);

    return 0;
}
EXPORT_SYMBOL(mipi_dsi_host_register);

static int mipi_dsi_remove_device_fn(struct device *dev, void *priv)
{
    struct mipi_dsi_device *dsi = to_mipi_dsi_device(dev);

    mipi_dsi_device_unregister(dsi);

    return 0;
}

void mipi_dsi_host_unregister(struct mipi_dsi_host *host)
{
    device_for_each_child(host->dev, NULL, mipi_dsi_remove_device_fn);

    mutex_lock(&host_lock);
    list_del_init(&host->list);
    mutex_unlock(&host_lock);
}
EXPORT_SYMBOL(mipi_dsi_host_unregister);

/**
 * mipi_dsi_attach - attach a DSI device to its DSI host
 * @dsi: DSI peripheral
 */
int mipi_dsi_attach(struct mipi_dsi_device *dsi)
{
    const struct mipi_dsi_host_ops *ops = dsi->host->ops;

    if (!ops || !ops->attach) {
        return -ENOSYS;
    }

    return ops->attach(dsi->host, dsi);
}
EXPORT_SYMBOL(mipi_dsi_attach);

/**
 * mipi_dsi_detach - detach a DSI device from its DSI host
 * @dsi: DSI peripheral
 */
int mipi_dsi_detach(struct mipi_dsi_device *dsi)
{
    const struct mipi_dsi_host_ops *ops = dsi->host->ops;

    if (!ops || !ops->detach) {
        return -ENOSYS;
    }

    return ops->detach(dsi->host, dsi);
}
EXPORT_SYMBOL(mipi_dsi_detach);

static ssize_t mipi_dsi_device_transfer(struct mipi_dsi_device *dsi, struct mipi_dsi_msg *msg)
{
    const struct mipi_dsi_host_ops *ops = dsi->host->ops;

    if (!ops || !ops->transfer) {
        return -ENOSYS;
    }

    if (dsi->mode_flags & MIPI_DSI_MODE_LPM) {
        msg->flags |= MIPI_DSI_MSG_USE_LPM;
    }
    msg->flags |= MIPI_DSI_MSG_LASTCOMMAND;

    return ops->transfer(dsi->host, msg);
}

/**
 * mipi_dsi_packet_format_is_short - check if a packet is of the short format
 * @type: MIPI DSI data type of the packet
 *
 * Return: true if the packet for the given data type is a short packet, false
 * otherwise.
 */
bool mipi_dsi_packet_format_is_short(u8 type)
{
    if ((type == MIPI_DSI_V_SYNC_START) || (type == MIPI_DSI_V_SYNC_END) || (type == MIPI_DSI_H_SYNC_START) ||
        (type == MIPI_DSI_H_SYNC_END) || (type == MIPI_DSI_COMPRESSION_MODE) ||
        (type == MIPI_DSI_END_OF_TRANSMISSION) || (type == MIPI_DSI_COLOR_MODE_OFF) ||
        (type == MIPI_DSI_COLOR_MODE_ON) || (type == MIPI_DSI_SHUTDOWN_PERIPHERAL) ||
        (type == MIPI_DSI_TURN_ON_PERIPHERAL) || (type == MIPI_DSI_GENERIC_SHORT_WRITE_0_PARAM) ||
        (type == MIPI_DSI_GENERIC_SHORT_WRITE_1_PARAM) || (type == MIPI_DSI_GENERIC_SHORT_WRITE_2_PARAM) ||
        (type == MIPI_DSI_GENERIC_READ_REQUEST_0_PARAM) || (type == MIPI_DSI_GENERIC_READ_REQUEST_1_PARAM) ||
        (type == MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM) || (type == MIPI_DSI_DCS_SHORT_WRITE) ||
        (type == MIPI_DSI_DCS_SHORT_WRITE_PARAM) || (type == MIPI_DSI_DCS_READ) || (type == MIPI_DSI_EXECUTE_QUEUE) ||
        (type == MIPI_DSI_SET_MAXIMUM_RETURN_PACKET_SIZE)) {
        return true;
    }
    return false;
}
EXPORT_SYMBOL(mipi_dsi_packet_format_is_short);

/**
 * mipi_dsi_packet_format_is_long - check if a packet is of the long format
 * @type: MIPI DSI data type of the packet
 *
 * Return: true if the packet for the given data type is a long packet, false
 * otherwise.
 */
bool mipi_dsi_packet_format_is_long(u8 type)
{
    if ((type == MIPI_DSI_NULL_PACKET) || (type == MIPI_DSI_BLANKING_PACKET) || (type == MIPI_DSI_GENERIC_LONG_WRITE) ||
        (type == MIPI_DSI_DCS_LONG_WRITE) || (type == MIPI_DSI_PICTURE_PARAMETER_SET) ||
        (type == MIPI_DSI_COMPRESSED_PIXEL_STREAM) || (type == MIPI_DSI_LOOSELY_PACKED_PIXEL_STREAM_YCBCR20) ||
        (type == MIPI_DSI_PACKED_PIXEL_STREAM_YCBCR24) || (type == MIPI_DSI_PACKED_PIXEL_STREAM_YCBCR16) ||
        (type == MIPI_DSI_PACKED_PIXEL_STREAM_30) || (type == MIPI_DSI_PACKED_PIXEL_STREAM_36) ||
        (type == MIPI_DSI_PACKED_PIXEL_STREAM_YCBCR12) || (type == MIPI_DSI_PACKED_PIXEL_STREAM_16) ||
        (type == MIPI_DSI_PACKED_PIXEL_STREAM_18) || (type == MIPI_DSI_PIXEL_STREAM_3BYTE_18) ||
        (type == MIPI_DSI_PACKED_PIXEL_STREAM_24)) {
        return true;
    }
    return false;
}
EXPORT_SYMBOL(mipi_dsi_packet_format_is_long);

/**
 * mipi_dsi_create_packet - create a packet from a message according to the
 *     DSI protocol
 * @packet: pointer to a DSI packet structure
 * @msg: message to translate into a packet
 *
 * Return: 0 on success or a negative error code on failure.
 */
int mipi_dsi_create_packet(struct mipi_dsi_packet *packet, const struct mipi_dsi_msg *msg)
{
    if (!packet || !msg) {
        return -EINVAL;
    }

    /* do some minimum sanity checking */
    if (!mipi_dsi_packet_format_is_short(msg->type) && !mipi_dsi_packet_format_is_long(msg->type)) {
        return -EINVAL;
    }

    if (msg->channel > 0x3) {
        return -EINVAL;
    }

    memset(packet, 0, sizeof(*packet));
    packet->header[0] = ((msg->channel & 0x3) << 0x6) | (msg->type & 0x3f);

    /* compute ECC if hardware support is not available */

    /*
     * Long write packets contain the word count in header bytes 1 and 2.
     * The payload follows the header and is word count bytes long.
     *
     * Short write packets encode up to two parameters in header bytes 1
     * and 2.
     */
    if (mipi_dsi_packet_format_is_long(msg->type)) {
        packet->header[0x1] = (msg->tx_len >> 0) & 0xff;
        packet->header[0x2] = (msg->tx_len >> 0x8) & 0xff;

        packet->payload_length = msg->tx_len;
        packet->payload = msg->tx_buf;
    } else {
        const u8 *tx = msg->tx_buf;

        packet->header[0x1] = (msg->tx_len > 0) ? tx[0] : 0;
        packet->header[0x2] = (msg->tx_len > 1) ? tx[1] : 0;
    }

    packet->size = sizeof(packet->header) + packet->payload_length;

    return 0;
}
EXPORT_SYMBOL(mipi_dsi_create_packet);

/**
 * mipi_dsi_shutdown_peripheral() - sends a Shutdown Peripheral command
 * @dsi: DSI peripheral device
 *
 * Return: 0 on success or a negative error code on failure.
 */
int mipi_dsi_shutdown_peripheral(struct mipi_dsi_device *dsi)
{
    struct mipi_dsi_msg msg = {
        .channel = dsi->channel,
        .type = MIPI_DSI_SHUTDOWN_PERIPHERAL,
        .tx_buf = (u8[2]) {0, 0},
        .tx_len = 2,
    };
    int ret = mipi_dsi_device_transfer(dsi, &msg);

    return (ret < 0) ? ret : 0;
}
EXPORT_SYMBOL(mipi_dsi_shutdown_peripheral);

/**
 * mipi_dsi_turn_on_peripheral() - sends a Turn On Peripheral command
 * @dsi: DSI peripheral device
 *
 * Return: 0 on success or a negative error code on failure.
 */
int mipi_dsi_turn_on_peripheral(struct mipi_dsi_device *dsi)
{
    struct mipi_dsi_msg msg = {
        .channel = dsi->channel,
        .type = MIPI_DSI_TURN_ON_PERIPHERAL,
        .tx_buf = (u8[2]) {0, 0},
        .tx_len = 2,
    };
    int ret = mipi_dsi_device_transfer(dsi, &msg);

    return (ret < 0) ? ret : 0;
}
EXPORT_SYMBOL(mipi_dsi_turn_on_peripheral);

/*
 * mipi_dsi_set_maximum_return_packet_size() - specify the maximum size of the
 *    the payload in a long packet transmitted from the peripheral back to the
 *    host processor
 * @dsi: DSI peripheral device
 * @value: the maximum size of the payload
 *
 * Return: 0 on success or a negative error code on failure.
 */
int mipi_dsi_set_maximum_return_packet_size(struct mipi_dsi_device *dsi, u16 value)
{
    u8 tx[2] = {value & 0xff, value >> 8};
    struct mipi_dsi_msg msg = {
        .channel = dsi->channel,
        .type = MIPI_DSI_SET_MAXIMUM_RETURN_PACKET_SIZE,
        .tx_len = sizeof(tx),
        .tx_buf = tx,
    };
    int ret = mipi_dsi_device_transfer(dsi, &msg);

    return (ret < 0) ? ret : 0;
}
EXPORT_SYMBOL(mipi_dsi_set_maximum_return_packet_size);

/**
 * mipi_dsi_compression_mode() - enable/disable DSC on the peripheral
 * @dsi: DSI peripheral device
 * @enable: Whether to enable or disable the DSC
 *
 * Enable or disable Display Stream Compression on the peripheral using the
 * default Picture Parameter Set and VESA DSC 1.1 algorithm.
 *
 * Return: 0 on success or a negative error code on failure.
 */
ssize_t mipi_dsi_compression_mode(struct mipi_dsi_device *dsi, bool enable)
{
    /* Note: Needs updating for non-default PPS or algorithm */
    u8 tx[2] = {enable << 0, 0};
    struct mipi_dsi_msg msg = {
        .channel = dsi->channel,
        .type = MIPI_DSI_COMPRESSION_MODE,
        .tx_len = sizeof(tx),
        .tx_buf = tx,
    };
    int ret = mipi_dsi_device_transfer(dsi, &msg);

    return (ret < 0) ? ret : 0;
}
EXPORT_SYMBOL(mipi_dsi_compression_mode);

/**
 * mipi_dsi_picture_parameter_set() - transmit the DSC PPS to the peripheral
 * @dsi: DSI peripheral device
 * @pps: VESA DSC 1.1 Picture Parameter Set
 *
 * Transmit the VESA DSC 1.1 Picture Parameter Set to the peripheral.
 *
 * Return: 0 on success or a negative error code on failure.
 */
ssize_t mipi_dsi_picture_parameter_set(struct mipi_dsi_device *dsi, const struct drm_dsc_picture_parameter_set *pps)
{
    struct mipi_dsi_msg msg = {
        .channel = dsi->channel,
        .type = MIPI_DSI_PICTURE_PARAMETER_SET,
        .tx_len = sizeof(*pps),
        .tx_buf = pps,
    };
    int ret = mipi_dsi_device_transfer(dsi, &msg);

    return (ret < 0) ? ret : 0;
}
EXPORT_SYMBOL(mipi_dsi_picture_parameter_set);

/**
 * mipi_dsi_generic_write() - transmit data using a generic write packet
 * @dsi: DSI peripheral device
 * @payload: buffer containing the payload
 * @size: size of payload buffer
 *
 * This function will automatically choose the right data type depending on
 * the payload length.
 *
 * Return: The number of bytes transmitted on success or a negative error code
 * on failure.
 */
ssize_t mipi_dsi_generic_write(struct mipi_dsi_device *dsi, const void *payload, size_t size)
{
    struct mipi_dsi_msg msg = {.channel = dsi->channel, .tx_buf = payload, .tx_len = size};

    switch (size) {
        case 0x0:
            msg.type = MIPI_DSI_GENERIC_SHORT_WRITE_0_PARAM;
            break;

        case 0x1:
            msg.type = MIPI_DSI_GENERIC_SHORT_WRITE_1_PARAM;
            break;

        case 0x2:
            msg.type = MIPI_DSI_GENERIC_SHORT_WRITE_2_PARAM;
            break;

        default:
            msg.type = MIPI_DSI_GENERIC_LONG_WRITE;
            break;
    }

    return mipi_dsi_device_transfer(dsi, &msg);
}
EXPORT_SYMBOL(mipi_dsi_generic_write);

/**
 * mipi_dsi_generic_read() - receive data using a generic read packet
 * @dsi: DSI peripheral device
 * @params: buffer containing the request parameters
 * @num_params: number of request parameters
 * @data: buffer in which to return the received data
 * @size: size of receive buffer
 *
 * This function will automatically choose the right data type depending on
 * the number of parameters passed in.
 *
 * Return: The number of bytes successfully read or a negative error code on
 * failure.
 */
ssize_t mipi_dsi_generic_read(struct mipi_dsi_device *dsi, const void *params, size_t num_params, void *data,
                              size_t size)
{
    struct mipi_dsi_msg msg = {
        .channel = dsi->channel, .tx_len = num_params, .tx_buf = params, .rx_len = size, .rx_buf = data};

    switch (num_params) {
        case 0x0:
            msg.type = MIPI_DSI_GENERIC_READ_REQUEST_0_PARAM;
            break;

        case 0x1:
            msg.type = MIPI_DSI_GENERIC_READ_REQUEST_1_PARAM;
            break;

        case 0x2:
            msg.type = MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM;
            break;

        default:
            return -EINVAL;
    }

    return mipi_dsi_device_transfer(dsi, &msg);
}
EXPORT_SYMBOL(mipi_dsi_generic_read);

/**
 * mipi_dsi_dcs_write_buffer() - transmit a DCS command with payload
 * @dsi: DSI peripheral device
 * @data: buffer containing data to be transmitted
 * @len: size of transmission buffer
 *
 * This function will automatically choose the right data type depending on
 * the command payload length.
 *
 * Return: The number of bytes successfully transmitted or a negative error
 * code on failure.
 */
ssize_t mipi_dsi_dcs_write_buffer(struct mipi_dsi_device *dsi, const void *data, size_t len)
{
    struct mipi_dsi_msg msg = {.channel = dsi->channel, .tx_buf = data, .tx_len = len};

    switch (len) {
        case 0x0:
            return -EINVAL;

        case 0x1:
            msg.type = MIPI_DSI_DCS_SHORT_WRITE;
            break;

        case 0x2:
            msg.type = MIPI_DSI_DCS_SHORT_WRITE_PARAM;
            break;

        default:
            msg.type = MIPI_DSI_DCS_LONG_WRITE;
            break;
    }

    return mipi_dsi_device_transfer(dsi, &msg);
}
EXPORT_SYMBOL(mipi_dsi_dcs_write_buffer);

/**
 * mipi_dsi_dcs_write() - send DCS write command
 * @dsi: DSI peripheral device
 * @cmd: DCS command
 * @data: buffer containing the command payload
 * @len: command payload length
 *
 * This function will automatically choose the right data type depending on
 * the command payload length.
 *
 * Return: The number of bytes successfully transmitted or a negative error
 * code on failure.
 */
ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, u8 cmd, const void *data, size_t len)
{
    ssize_t err;
    size_t size;
    u8 stack_tx[0x8];
    u8 *tx;

    size = 1 + len;
    if (len > ARRAY_SIZE(stack_tx) - 1) {
        tx = kmalloc(size, GFP_KERNEL);
        if (!tx) {
            return -ENOMEM;
        }
    } else {
        tx = stack_tx;
    }

    /* concatenate the DCS command byte and the payload */
    tx[0] = cmd;
    if (data) {
        memcpy(&tx[1], data, len);
    }

    err = mipi_dsi_dcs_write_buffer(dsi, tx, size);

    if (tx != stack_tx) {
        kfree(tx);
    }

    return err;
}
EXPORT_SYMBOL(mipi_dsi_dcs_write);

/**
 * mipi_dsi_dcs_read() - send DCS read request command
 * @dsi: DSI peripheral device
 * @cmd: DCS command
 * @data: buffer in which to receive data
 * @len: size of receive buffer
 *
 * Return: The number of bytes read or a negative error code on failure.
 */
ssize_t mipi_dsi_dcs_read(struct mipi_dsi_device *dsi, u8 cmd, void *data, size_t len)
{
    struct mipi_dsi_msg msg = {
        .channel = dsi->channel, .type = MIPI_DSI_DCS_READ, .tx_buf = &cmd, .tx_len = 1, .rx_buf = data, .rx_len = len};

    return mipi_dsi_device_transfer(dsi, &msg);
}
EXPORT_SYMBOL(mipi_dsi_dcs_read);

/**
 * mipi_dsi_dcs_nop() - send DCS nop packet
 * @dsi: DSI peripheral device
 *
 * Return: 0 on success or a negative error code on failure.
 */
int mipi_dsi_dcs_nop(struct mipi_dsi_device *dsi)
{
    ssize_t err;

    err = mipi_dsi_dcs_write(dsi, MIPI_DCS_NOP, NULL, 0);
    if (err < 0) {
        return err;
    }

    return 0;
}
EXPORT_SYMBOL(mipi_dsi_dcs_nop);

/**
 * mipi_dsi_dcs_soft_reset() - perform a software reset of the display module
 * @dsi: DSI peripheral device
 *
 * Return: 0 on success or a negative error code on failure.
 */
int mipi_dsi_dcs_soft_reset(struct mipi_dsi_device *dsi)
{
    ssize_t err;

    err = mipi_dsi_dcs_write(dsi, MIPI_DCS_SOFT_RESET, NULL, 0);
    if (err < 0) {
        return err;
    }

    return 0;
}
EXPORT_SYMBOL(mipi_dsi_dcs_soft_reset);

/**
 * mipi_dsi_dcs_get_power_mode() - query the display module's current power
 *    mode
 * @dsi: DSI peripheral device
 * @mode: return location for the current power mode
 *
 * Return: 0 on success or a negative error code on failure.
 */
int mipi_dsi_dcs_get_power_mode(struct mipi_dsi_device *dsi, u8 *mode)
{
    ssize_t err;

    err = mipi_dsi_dcs_read(dsi, MIPI_DCS_GET_POWER_MODE, mode, sizeof(*mode));
    if (err <= 0) {
        if (err == 0) {
            err = -ENODATA;
        }

        return err;
    }

    return 0;
}
EXPORT_SYMBOL(mipi_dsi_dcs_get_power_mode);

/**
 * mipi_dsi_dcs_get_pixel_format() - gets the pixel format for the RGB image
 *    data used by the interface
 * @dsi: DSI peripheral device
 * @format: return location for the pixel format
 *
 * Return: 0 on success or a negative error code on failure.
 */
int mipi_dsi_dcs_get_pixel_format(struct mipi_dsi_device *dsi, u8 *format)
{
    ssize_t err;

    err = mipi_dsi_dcs_read(dsi, MIPI_DCS_GET_PIXEL_FORMAT, format, sizeof(*format));
    if (err <= 0) {
        if (err == 0) {
            err = -ENODATA;
        }

        return err;
    }

    return 0;
}
EXPORT_SYMBOL(mipi_dsi_dcs_get_pixel_format);

/**
 * mipi_dsi_dcs_enter_sleep_mode() - disable all unnecessary blocks inside the
 *    display module except interface communication
 * @dsi: DSI peripheral device
 *
 * Return: 0 on success or a negative error code on failure.
 */
int mipi_dsi_dcs_enter_sleep_mode(struct mipi_dsi_device *dsi)
{
    ssize_t err;

    err = mipi_dsi_dcs_write(dsi, MIPI_DCS_ENTER_SLEEP_MODE, NULL, 0);
    if (err < 0) {
        return err;
    }

    return 0;
}
EXPORT_SYMBOL(mipi_dsi_dcs_enter_sleep_mode);

/**
 * mipi_dsi_dcs_exit_sleep_mode() - enable all blocks inside the display
 *    module
 * @dsi: DSI peripheral device
 *
 * Return: 0 on success or a negative error code on failure.
 */
int mipi_dsi_dcs_exit_sleep_mode(struct mipi_dsi_device *dsi)
{
    ssize_t err;

    err = mipi_dsi_dcs_write(dsi, MIPI_DCS_EXIT_SLEEP_MODE, NULL, 0);
    if (err < 0) {
        return err;
    }

    return 0;
}
EXPORT_SYMBOL(mipi_dsi_dcs_exit_sleep_mode);

/**
 * mipi_dsi_dcs_set_display_off() - stop displaying the image data on the
 *    display device
 * @dsi: DSI peripheral device
 *
 * Return: 0 on success or a negative error code on failure.
 */
int mipi_dsi_dcs_set_display_off(struct mipi_dsi_device *dsi)
{
    ssize_t err;

    err = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_OFF, NULL, 0);
    if (err < 0) {
        return err;
    }

    return 0;
}
EXPORT_SYMBOL(mipi_dsi_dcs_set_display_off);

/**
 * mipi_dsi_dcs_set_display_on() - start displaying the image data on the
 *    display device
 * @dsi: DSI peripheral device
 *
 * Return: 0 on success or a negative error code on failure
 */
int mipi_dsi_dcs_set_display_on(struct mipi_dsi_device *dsi)
{
    ssize_t err;

    err = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_ON, NULL, 0);
    if (err < 0) {
        return err;
    }

    return 0;
}
EXPORT_SYMBOL(mipi_dsi_dcs_set_display_on);

/**
 * mipi_dsi_dcs_set_column_address() - define the column extent of the frame
 *    memory accessed by the host processor
 * @dsi: DSI peripheral device
 * @start: first column of frame memory
 * @end: last column of frame memory
 *
 * Return: 0 on success or a negative error code on failure.
 */
int mipi_dsi_dcs_set_column_address(struct mipi_dsi_device *dsi, u16 start, u16 end)
{
    u8 payload[4] = {start >> 8, start & 0xff, end >> 8, end & 0xff};
    ssize_t err;

    err = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_COLUMN_ADDRESS, payload, sizeof(payload));
    if (err < 0) {
        return err;
    }

    return 0;
}
EXPORT_SYMBOL(mipi_dsi_dcs_set_column_address);

/**
 * mipi_dsi_dcs_set_page_address() - define the page extent of the frame
 *    memory accessed by the host processor
 * @dsi: DSI peripheral device
 * @start: first page of frame memory
 * @end: last page of frame memory
 *
 * Return: 0 on success or a negative error code on failure.
 */
int mipi_dsi_dcs_set_page_address(struct mipi_dsi_device *dsi, u16 start, u16 end)
{
    u8 payload[0x4] = {start >> 0x8, start & 0xff, end >> 0x8, end & 0xff};
    ssize_t err;

    err = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_PAGE_ADDRESS, payload, sizeof(payload));
    if (err < 0) {
        return err;
    }

    return 0;
}
EXPORT_SYMBOL(mipi_dsi_dcs_set_page_address);

/**
 * mipi_dsi_dcs_set_tear_off() - turn off the display module's Tearing Effect
 *    output signal on the TE signal line
 * @dsi: DSI peripheral device
 *
 * Return: 0 on success or a negative error code on failure
 */
int mipi_dsi_dcs_set_tear_off(struct mipi_dsi_device *dsi)
{
    ssize_t err;

    err = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_TEAR_OFF, NULL, 0);
    if (err < 0) {
        return err;
    }

    return 0;
}
EXPORT_SYMBOL(mipi_dsi_dcs_set_tear_off);

/**
 * mipi_dsi_dcs_set_tear_on() - turn on the display module's Tearing Effect
 *    output signal on the TE signal line.
 * @dsi: DSI peripheral device
 * @mode: the Tearing Effect Output Line mode
 *
 * Return: 0 on success or a negative error code on failure
 */
int mipi_dsi_dcs_set_tear_on(struct mipi_dsi_device *dsi, enum mipi_dsi_dcs_tear_mode mode)
{
    u8 value = mode;
    ssize_t err;

    err = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_TEAR_ON, &value, sizeof(value));
    if (err < 0) {
        return err;
    }

    return 0;
}
EXPORT_SYMBOL(mipi_dsi_dcs_set_tear_on);

/**
 * mipi_dsi_dcs_set_pixel_format() - sets the pixel format for the RGB image
 *    data used by the interface
 * @dsi: DSI peripheral device
 * @format: pixel format
 *
 * Return: 0 on success or a negative error code on failure.
 */
int mipi_dsi_dcs_set_pixel_format(struct mipi_dsi_device *dsi, u8 format)
{
    ssize_t err;

    err = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_PIXEL_FORMAT, &format, sizeof(format));
    if (err < 0) {
        return err;
    }

    return 0;
}
EXPORT_SYMBOL(mipi_dsi_dcs_set_pixel_format);

/**
 * mipi_dsi_dcs_set_tear_scanline() - set the scanline to use as trigger for
 *    the Tearing Effect output signal of the display module
 * @dsi: DSI peripheral device
 * @scanline: scanline to use as trigger
 *
 * Return: 0 on success or a negative error code on failure
 */
int mipi_dsi_dcs_set_tear_scanline(struct mipi_dsi_device *dsi, u16 scanline)
{
    u8 payload[0x2] = {scanline >> 0x8, scanline & 0xff};
    ssize_t err;

    err = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_TEAR_SCANLINE, payload, sizeof(payload));
    if (err < 0) {
        return err;
    }

    return 0;
}
EXPORT_SYMBOL(mipi_dsi_dcs_set_tear_scanline);

/**
 * mipi_dsi_dcs_set_display_brightness() - sets the brightness value of the
 *    display
 * @dsi: DSI peripheral device
 * @brightness: brightness value
 *
 * Return: 0 on success or a negative error code on failure.
 */
int mipi_dsi_dcs_set_display_brightness(struct mipi_dsi_device *dsi, u16 brightness)
{
    u8 payload[0x2] = {brightness & 0xff, brightness >> 0x8};
    ssize_t err;

    err = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS, payload, sizeof(payload));
    if (err < 0) {
        return err;
    }

    return 0;
}
EXPORT_SYMBOL(mipi_dsi_dcs_set_display_brightness);

/**
 * mipi_dsi_dcs_get_display_brightness() - gets the current brightness value
 *    of the display
 * @dsi: DSI peripheral device
 * @brightness: brightness value
 *
 * Return: 0 on success or a negative error code on failure.
 */
int mipi_dsi_dcs_get_display_brightness(struct mipi_dsi_device *dsi, u16 *brightness)
{
    ssize_t err;

    err = mipi_dsi_dcs_read(dsi, MIPI_DCS_GET_DISPLAY_BRIGHTNESS, brightness, sizeof(*brightness));
    if (err <= 0) {
        if (err == 0) {
            err = -ENODATA;
        }

        return err;
    }

    return 0;
}
EXPORT_SYMBOL(mipi_dsi_dcs_get_display_brightness);

static int mipi_dsi_drv_probe(struct device *dev)
{
    struct mipi_dsi_driver *drv = to_mipi_dsi_driver(dev->driver);
    struct mipi_dsi_device *dsi = to_mipi_dsi_device(dev);

    return drv->probe(dsi);
}

static int mipi_dsi_drv_remove(struct device *dev)
{
    struct mipi_dsi_driver *drv = to_mipi_dsi_driver(dev->driver);
    struct mipi_dsi_device *dsi = to_mipi_dsi_device(dev);

    return drv->remove(dsi);
}

static void mipi_dsi_drv_shutdown(struct device *dev)
{
    struct mipi_dsi_driver *drv = to_mipi_dsi_driver(dev->driver);
    struct mipi_dsi_device *dsi = to_mipi_dsi_device(dev);

    drv->shutdown(dsi);
}

/**
 * mipi_dsi_driver_register_full() - register a driver for DSI devices
 * @drv: DSI driver structure
 * @owner: owner module
 *
 * Return: 0 on success or a negative error code on failure.
 */
int mipi_dsi_driver_register_full(struct mipi_dsi_driver *drv, struct module *owner)
{
    drv->driver.bus = &mipi_dsi_bus_type;
    drv->driver.owner = owner;

    if (drv->probe) {
        drv->driver.probe = mipi_dsi_drv_probe;
    }
    if (drv->remove) {
        drv->driver.remove = mipi_dsi_drv_remove;
    }
    if (drv->shutdown) {
        drv->driver.shutdown = mipi_dsi_drv_shutdown;
    }

    return driver_register(&drv->driver);
}
EXPORT_SYMBOL(mipi_dsi_driver_register_full);

/**
 * mipi_dsi_driver_unregister() - unregister a driver for DSI devices
 * @drv: DSI driver structure
 *
 * Return: 0 on success or a negative error code on failure.
 */
void mipi_dsi_driver_unregister(struct mipi_dsi_driver *drv)
{
    driver_unregister(&drv->driver);
}
EXPORT_SYMBOL(mipi_dsi_driver_unregister);

static int __init mipi_dsi_bus_init(void)
{
    return bus_register(&mipi_dsi_bus_type);
}
postcore_initcall(mipi_dsi_bus_init);

MODULE_AUTHOR("Andrzej Hajda <a.hajda@samsung.com>");
MODULE_DESCRIPTION("MIPI DSI Bus");
MODULE_LICENSE("GPL and additional rights");