drm/panel/raspberrypi-touchscreen: Use independent I2C actions with delay.

[platform/kernel/linux-rpi.git] / drivers / gpu / drm / panel / panel-raspberrypi-touchscreen.c

diff --git a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
index 4618c89..b2395e7 100644 (file)
--- a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
+++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
@@ -218,7 +218,35 @@ static struct rpi_touchscreen *panel_to_ts(struct drm_panel *panel)
 
 static int rpi_touchscreen_i2c_read(struct rpi_touchscreen *ts, u8 reg)
 {
-       return i2c_smbus_read_byte_data(ts->i2c, reg);
+       struct i2c_client *client = ts->i2c;
+       struct i2c_msg msgs[1];
+       u8 addr_buf[1] = { reg };
+       u8 data_buf[1] = { 0, };
+       int ret;
+
+       /* Write register address */
+       msgs[0].addr = client->addr;
+       msgs[0].flags = 0;
+       msgs[0].len = ARRAY_SIZE(addr_buf);
+       msgs[0].buf = addr_buf;
+
+       ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+       if (ret != ARRAY_SIZE(msgs))
+               return -EIO;
+
+       usleep_range(100, 300);
+
+       /* Read data from register */
+       msgs[0].addr = client->addr;
+       msgs[0].flags = I2C_M_RD;
+       msgs[0].len = 1;
+       msgs[0].buf = data_buf;
+
+       ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+       if (ret != ARRAY_SIZE(msgs))
+               return -EIO;
+
+       return data_buf[0];
 }
 
 static void rpi_touchscreen_i2c_write(struct rpi_touchscreen *ts,