V4L/DVB (9953): em28xx: Add suport for debugging AC97 anciliary chips

The em28xx driver can be coupled to an anciliary AC97 chip. This patch
allows read/write AC97 registers directly.
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/em28xx/em28xx-core.c

@@ -259,7 +259,7 @@ static int em28xx_is_ac97_ready(struct em28xx *dev)
  * em28xx_read_ac97()
  * write a 16 bit value to the specified AC97 address (LSB first!)
  */
-static int em28xx_read_ac97(struct em28xx *dev, u8 reg)
+int em28xx_read_ac97(struct em28xx *dev, u8 reg)
 {
 	int ret;
 	u8 addr = (reg & 0x7f) | 0x80;
@@ -285,7 +285,7 @@ static int em28xx_read_ac97(struct em28xx *dev, u8 reg)
  * em28xx_write_ac97()
  * write a 16 bit value to the specified AC97 address (LSB first!)
  */
-static int em28xx_write_ac97(struct em28xx *dev, u8 reg, u16 val)
+int em28xx_write_ac97(struct em28xx *dev, u8 reg, u16 val)
 {
 	int ret;
 	u8 addr = reg & 0x7f;

drivers/media/video/em28xx/em28xx-video.c

@@ -1221,6 +1221,17 @@ static int vidioc_g_register(struct file *file, void *priv,
 	struct em28xx         *dev = fh->dev;
 	int ret;
 
+	if (reg->match_type == V4L2_CHIP_MATCH_AC97) {
+		mutex_lock(&dev->lock);
+		ret = em28xx_read_ac97(dev, reg->reg);
+		mutex_unlock(&dev->lock);
+		if (ret < 0)
+			return ret;
+
+		reg->val = ret;
+		return 0;
+	}
+
 	if (!v4l2_chip_match_host(reg->match_type, reg->match_chip))
 		return -EINVAL;
 
@@ -1256,6 +1267,14 @@ static int vidioc_s_register(struct file *file, void *priv,
 	__le64 buf;
 	int    rc;
 
+	if (reg->match_type == V4L2_CHIP_MATCH_AC97) {
+		mutex_lock(&dev->lock);
+		rc = em28xx_write_ac97(dev, reg->reg, reg->val);
+		mutex_unlock(&dev->lock);
+
+		return rc;
+	}
+
 	buf = cpu_to_le64(reg->val);
 
 	mutex_lock(&dev->lock);

drivers/media/video/em28xx/em28xx.h

@@ -564,6 +564,9 @@ int em28xx_write_regs_req(struct em28xx *dev, u8 req, u16 reg, char *buf,
 int em28xx_write_regs(struct em28xx *dev, u16 reg, char *buf, int len);
 int em28xx_write_reg(struct em28xx *dev, u16 reg, u8 val);
 
+int em28xx_read_ac97(struct em28xx *dev, u8 reg);
+int em28xx_write_ac97(struct em28xx *dev, u8 reg, u16 val);
+
 int em28xx_audio_analog_set(struct em28xx *dev);
 int em28xx_audio_setup(struct em28xx *dev);
 

include/linux/videodev2.h

@@ -1376,6 +1376,7 @@ struct v4l2_streamparm {
 #define V4L2_CHIP_MATCH_HOST       0  /* Match against chip ID on host (0 for the host) */
 #define V4L2_CHIP_MATCH_I2C_DRIVER 1  /* Match against I2C driver ID */
 #define V4L2_CHIP_MATCH_I2C_ADDR   2  /* Match against I2C 7-bit address */
+#define V4L2_CHIP_MATCH_AC97       3  /* Match against anciliary AC97 chip */
 
 struct v4l2_register {
 	__u32 match_type; /* Match type */