From: Allen Chen <allen.c...@ite.com.tw>

This add can let us find it6505 char device in the /dev file and use read/write 
function to let the driver be hold.

Signed-off-by: Allen Chen <allen.c...@ite.com.tw>

---
 drivers/gpu/drm/bridge/ite-it6505.c | 131 ++++++++++++++++++++++++++++++++++++
 1 file changed, 131 insertions(+)

diff --git a/drivers/gpu/drm/bridge/ite-it6505.c 
b/drivers/gpu/drm/bridge/ite-it6505.c
index 13079a8..1529e61 100644
--- a/drivers/gpu/drm/bridge/ite-it6505.c
+++ b/drivers/gpu/drm/bridge/ite-it6505.c
@@ -70,6 +70,13 @@
 /* if use this define will enable SHA debug */
 /* #define SHA_DEBUG */
 
+/* register char device for it6505 */
+#define IT6505_CLASS_NAME "it6505_class"
+#define IT6505_DEVICE_NAME "it6505_device"
+#define IT6505_MAX_DEV 128
+/* The device major number */
+static int it6505_major_num;
+
 enum sys_status {
        SYS_UNPLUG = 0,
        SYS_HPD,
@@ -144,6 +151,8 @@ struct it6505 {
        struct it6505_platform_data pdata;
        struct mutex lock;
        struct regmap *regmap;
+       struct cdev cdev;
+       struct device class_dev;
        struct it6505_dp_port *port;
        /* thread sequence control */
        struct semaphore sem_notifier;
@@ -2502,6 +2511,80 @@ static int it6505_init_pdata(struct it6505 *it6505)
        return PTR_ERR_OR_ZERO(pdata->gpiod_reset);
 }
 
+static int it6505_open(struct inode *inode, struct file *file)
+{
+       struct it6505 *ctx = container_of(inode->i_cdev, struct it6505, cdev);
+
+       DRM_DEBUG_DRIVER("[%s]: successful", __func__);
+       if (!ctx)
+               DRM_DEBUG_DRIVER("[%s]:get it6505 struct fail!", __func__);
+       file->private_data = ctx;
+       get_device(&ctx->class_dev);
+       return 0;
+}
+
+static int it6505_release(struct inode *inode, struct file *file)
+{
+       struct it6505 *ctx = file->private_data;
+
+       DRM_DEBUG_DRIVER("[%s]: successful", __func__);
+       put_device(&ctx->class_dev);
+       return 0;
+}
+
+static ssize_t it6505_read(struct file *file, char *buf,
+                          size_t count, loff_t *ptr)
+{
+       struct it6505 *ctx = file->private_data;
+       char kbuff[16];
+       size_t len;
+
+       DRM_DEBUG_DRIVER("[%s]start count=%zu", __func__, count);
+       DRM_DEBUG_DRIVER("it6505_drv_hold:%d", ctx->it6505_drv_hold);
+       len = snprintf(kbuff, sizeof(kbuff), "%d", ctx->it6505_drv_hold);
+       len = min3(count, len, sizeof(kbuff));
+       return copy_to_user(buf, kbuff, len) ? -EFAULT : len;
+}
+
+static ssize_t it6505_write(struct file *file, const char *buff,
+                           size_t count, loff_t *ptr)
+{
+       struct it6505 *ctx = file->private_data;
+       char kbuff[16];
+       int num;
+
+       DRM_DEBUG_DRIVER("[%s]start count=%zu", __func__, count);
+       count = min(count, sizeof(kbuff) - 1);
+       if (copy_from_user(kbuff, buff, count))
+               return -EFAULT;
+       kbuff[count] = '\0';
+       if (kstrtoint(kbuff, 10, &num) < 0)
+               return -EINVAL;
+       ctx->it6505_drv_hold = num;
+       DRM_DEBUG_DRIVER("set it6505_drv_hold:%d", ctx->it6505_drv_hold);
+       return count;
+}
+
+static struct class it6505_class_file = {
+       .owner          = THIS_MODULE,
+       .name           = IT6505_CLASS_NAME,
+};
+
+static const struct file_operations it6505_fops = {
+       .owner = THIS_MODULE,
+       .read  = it6505_read,
+       .write = it6505_write,
+       .open  = it6505_open,
+       .release = it6505_release
+};
+
+static void it6505_release_device(struct device *dev)
+{
+       struct it6505 *ctx = container_of(dev, struct it6505, class_dev);
+
+       kfree(ctx);
+}
+
 static int it6505_i2c_probe(struct i2c_client *client,
                        const struct i2c_device_id *id)
 {
@@ -2575,8 +2658,38 @@ static int it6505_i2c_probe(struct i2c_client *client,
        ctx->bridge.funcs = &it6505_bridge_funcs;
 
        drm_bridge_add(&ctx->bridge);
+       device_initialize(&ctx->class_dev);
+       ctx->class_dev.parent = &client->dev;
+       ctx->class_dev.release = it6505_release_device;
+       cdev_init(&ctx->cdev, &it6505_fops);
+       err = dev_set_name(&ctx->class_dev, "%s", IT6505_DEVICE_NAME);
+       DRM_DEBUG_DRIVER("[%s] dev_set_name:%s",
+                        __func__, err ? "failed" : "success");
+       if (err) {
+               DRM_DEBUG_DRIVER("dev_set_name failed => %d", err);
+               goto put_class_dev;
+       }
+       /*
+        * Add the class device
+        * Link to the character device for creating the /dev entry
+        * in devtmpfs.
+        */
+       ctx->class_dev.devt = MKDEV(it6505_major_num, 0);
+       ctx->class_dev.class = &it6505_class_file;
+
+       /* We can now add the sysfs class, we know which parameter to show */
+       err = cdev_device_add(&ctx->cdev, &ctx->class_dev);
+       if (err) {
+               DRM_DEBUG_DRIVER("cdev_device_add failed => %d",
+                                err);
+               goto put_class_dev;
+       }
        DRM_DEBUG_DRIVER("[%s]end", __func__);
        return 0;
+
+put_class_dev:
+       put_device(&ctx->class_dev);
+       return err;
 }
 
 static int it6505_remove(struct i2c_client *client)
@@ -2616,16 +2729,34 @@ struct i2c_driver it6505_i2c_driver = {
 
 static int __init it6505_init(void)
 {
+       int err;
+       dev_t dev = 0;
+
        DRM_DEBUG_DRIVER("[%s]start", __func__);
+       /* Register the device class */
+       err = class_register(&it6505_class_file);
+       err = alloc_chrdev_region(&dev, 0, IT6505_MAX_DEV,
+                       IT6505_DEVICE_NAME);
+       it6505_major_num = MAJOR(dev);
+       if (err < 0) {
+               DRM_DEBUG_DRIVER("alloc_chrdev_region() fail!");
+               goto failed_chrdevreg;
+       }
        i2c_add_driver(&it6505_i2c_driver);
        DRM_DEBUG_DRIVER("[%s]end", __func__);
        return 0;
+
+failed_chrdevreg:
+       class_unregister(&it6505_class_file);
+       return err;
 }
 
 static void __exit it6505_exit(void)
 {
        DRM_DEBUG_DRIVER("[%s]start", __func__);
        i2c_del_driver(&it6505_i2c_driver);
+       unregister_chrdev(it6505_major_num, IT6505_DEVICE_NAME);
+       class_unregister(&it6505_class_file);
        DRM_DEBUG_DRIVER("[%s]end", __func__);
 }
 
-- 
1.9.1

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