OSCL-LXR linux-6.0.1/​drivers/​gpu/​drm/​drm_mipi_dsi.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 /*
  * 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 <linux/device.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/slab.h>
 
 #include <drm/display/drm_dsc.h>
 #include <drm/drm_mipi_dsi.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 > 3) {
         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 void devm_mipi_dsi_device_unregister(void *arg)
 {
     struct mipi_dsi_device *dsi = arg;
 
     mipi_dsi_device_unregister(dsi);
 }
 
 /**
  * devm_mipi_dsi_device_register_full - create a managed MIPI DSI device
  * @dev: device to tie the MIPI-DSI device lifetime to
  * @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
  *
  * This is the managed version of mipi_dsi_device_register_full() which
  * automatically calls mipi_dsi_device_unregister() when @dev is
  * unbound.
  *
  * Returns:
  * A pointer to the newly created MIPI DSI device, or, a pointer encoded
  * with an error
  */
 struct mipi_dsi_device *
 devm_mipi_dsi_device_register_full(struct device *dev,
                    struct mipi_dsi_host *host,
                    const struct mipi_dsi_device_info *info)
 {
     struct mipi_dsi_device *dsi;
     int ret;
 
     dsi = mipi_dsi_device_register_full(host, info);
     if (IS_ERR(dsi))
         return dsi;
 
     ret = devm_add_action_or_reset(dev,
                        devm_mipi_dsi_device_unregister,
                        dsi);
     if (ret)
         return ERR_PTR(ret);
 
     return dsi;
 }
 EXPORT_SYMBOL_GPL(devm_mipi_dsi_device_register_full);
 
 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 void devm_mipi_dsi_detach(void *arg)
 {
     struct mipi_dsi_device *dsi = arg;
 
     mipi_dsi_detach(dsi);
 }
 
 /**
  * devm_mipi_dsi_attach - Attach a MIPI-DSI device to its DSI Host
  * @dev: device to tie the MIPI-DSI device attachment lifetime to
  * @dsi: DSI peripheral
  *
  * This is the managed version of mipi_dsi_attach() which automatically
  * calls mipi_dsi_detach() when @dev is unbound.
  *
  * Returns:
  * 0 on success, a negative error code on failure.
  */
 int devm_mipi_dsi_attach(struct device *dev,
              struct mipi_dsi_device *dsi)
 {
     int ret;
 
     ret = mipi_dsi_attach(dsi);
     if (ret)
         return ret;
 
     ret = devm_add_action_or_reset(dev, devm_mipi_dsi_detach, dsi);
     if (ret)
         return ret;
 
     return 0;
 }
 EXPORT_SYMBOL_GPL(devm_mipi_dsi_attach);
 
 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;
 
     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)
 {
     switch (type) {
     case MIPI_DSI_V_SYNC_START:
     case MIPI_DSI_V_SYNC_END:
     case MIPI_DSI_H_SYNC_START:
     case MIPI_DSI_H_SYNC_END:
     case MIPI_DSI_COMPRESSION_MODE:
     case MIPI_DSI_END_OF_TRANSMISSION:
     case MIPI_DSI_COLOR_MODE_OFF:
     case MIPI_DSI_COLOR_MODE_ON:
     case MIPI_DSI_SHUTDOWN_PERIPHERAL:
     case MIPI_DSI_TURN_ON_PERIPHERAL:
     case MIPI_DSI_GENERIC_SHORT_WRITE_0_PARAM:
     case MIPI_DSI_GENERIC_SHORT_WRITE_1_PARAM:
     case MIPI_DSI_GENERIC_SHORT_WRITE_2_PARAM:
     case MIPI_DSI_GENERIC_READ_REQUEST_0_PARAM:
     case MIPI_DSI_GENERIC_READ_REQUEST_1_PARAM:
     case MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM:
     case MIPI_DSI_DCS_SHORT_WRITE:
     case MIPI_DSI_DCS_SHORT_WRITE_PARAM:
     case MIPI_DSI_DCS_READ:
     case MIPI_DSI_EXECUTE_QUEUE:
     case 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)
 {
     switch (type) {
     case MIPI_DSI_NULL_PACKET:
     case MIPI_DSI_BLANKING_PACKET:
     case MIPI_DSI_GENERIC_LONG_WRITE:
     case MIPI_DSI_DCS_LONG_WRITE:
     case MIPI_DSI_PICTURE_PARAMETER_SET:
     case MIPI_DSI_COMPRESSED_PIXEL_STREAM:
     case MIPI_DSI_LOOSELY_PACKED_PIXEL_STREAM_YCBCR20:
     case MIPI_DSI_PACKED_PIXEL_STREAM_YCBCR24:
     case MIPI_DSI_PACKED_PIXEL_STREAM_YCBCR16:
     case MIPI_DSI_PACKED_PIXEL_STREAM_30:
     case MIPI_DSI_PACKED_PIXEL_STREAM_36:
     case MIPI_DSI_PACKED_PIXEL_STREAM_YCBCR12:
     case MIPI_DSI_PACKED_PIXEL_STREAM_16:
     case MIPI_DSI_PACKED_PIXEL_STREAM_18:
     case MIPI_DSI_PIXEL_STREAM_3BYTE_18:
     case 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 > 3)
         return -EINVAL;
 
     memset(packet, 0, sizeof(*packet));
     packet->header[0] = ((msg->channel & 0x3) << 6) | (msg->type & 0x3f);
 
     /* TODO: 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[1] = (msg->tx_len >> 0) & 0xff;
         packet->header[2] = (msg->tx_len >> 8) & 0xff;
 
         packet->payload_length = msg->tx_len;
         packet->payload = msg->tx_buf;
     } else {
         const u8 *tx = msg->tx_buf;
 
         packet->header[1] = (msg->tx_len > 0) ? tx[0] : 0;
         packet->header[2] = (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 0:
         msg.type = MIPI_DSI_GENERIC_SHORT_WRITE_0_PARAM;
         break;
 
     case 1:
         msg.type = MIPI_DSI_GENERIC_SHORT_WRITE_1_PARAM;
         break;
 
     case 2:
         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 0:
         msg.type = MIPI_DSI_GENERIC_READ_REQUEST_0_PARAM;
         break;
 
     case 1:
         msg.type = MIPI_DSI_GENERIC_READ_REQUEST_1_PARAM;
         break;
 
     case 2:
         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 0:
         return -EINVAL;
 
     case 1:
         msg.type = MIPI_DSI_DCS_SHORT_WRITE;
         break;
 
     case 2:
         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[8];
     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[4] = { start >> 8, start & 0xff, end >> 8, 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[2] = { scanline >> 8, 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[2] = { brightness & 0xff, brightness >> 8 };
     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");

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