V4L/DVB (5306): Add support for VIDIOC_G_CHIP_IDENT

VIDIOC_G_CHIP_IDENT improves debugging of card problems: it can be
used to detect which chips are on the board and based on that information
selected register dumps can be made, making it easy to debug complicated
media chips containing tens or hundreds of registers.
This ioctl replaces the internal VIDIOC_INT_G_CHIP_IDENT ioctl.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
diff --git a/drivers/media/video/v4l2-common.c b/drivers/media/video/v4l2-common.c
index 4a3635c..49f1df7 100644
--- a/drivers/media/video/v4l2-common.c
+++ b/drivers/media/video/v4l2-common.c
@@ -60,6 +60,7 @@
 #include <linux/video_decoder.h>
 #define __OLD_VIDIOC_ /* To allow fixing old calls*/
 #include <media/v4l2-common.h>
+#include <media/v4l2-chip-ident.h>
 
 #ifdef CONFIG_KMOD
 #include <linux/kmod.h>
@@ -383,6 +384,8 @@
 
 	[_IOC_NR(VIDIOC_DBG_S_REGISTER)]   = "VIDIOC_DBG_S_REGISTER",
 	[_IOC_NR(VIDIOC_DBG_G_REGISTER)]   = "VIDIOC_DBG_G_REGISTER",
+
+	[_IOC_NR(VIDIOC_G_CHIP_IDENT)]     = "VIDIOC_G_CHIP_IDENT",
 #endif
 };
 #define V4L2_IOCTLS ARRAY_SIZE(v4l2_ioctls)
@@ -413,7 +416,6 @@
 	[_IOC_NR(VIDIOC_INT_DECODE_VBI_LINE)]  = "VIDIOC_INT_DECODE_VBI_LINE",
 	[_IOC_NR(VIDIOC_INT_S_VBI_DATA)]       = "VIDIOC_INT_S_VBI_DATA",
 	[_IOC_NR(VIDIOC_INT_G_VBI_DATA)]       = "VIDIOC_INT_G_VBI_DATA",
-	[_IOC_NR(VIDIOC_INT_G_CHIP_IDENT)]     = "VIDIOC_INT_G_CHIP_IDENT",
 	[_IOC_NR(VIDIOC_INT_I2S_CLOCK_FREQ)]   = "VIDIOC_INT_I2S_CLOCK_FREQ",
 	[_IOC_NR(VIDIOC_INT_S_STANDBY)]        = "VIDIOC_INT_S_STANDBY",
 	[_IOC_NR(VIDIOC_INT_S_AUDIO_ROUTING)]  = "VIDIOC_INT_S_AUDIO_ROUTING",
@@ -981,6 +983,22 @@
 	}
 }
 
+int v4l2_chip_ident_i2c_client(struct i2c_client *c, struct v4l2_chip_ident *chip,
+		u32 ident, u32 revision)
+{
+	if (!v4l2_chip_match_i2c_client(c, chip->match_type, chip->match_chip))
+		return 0;
+	if (chip->ident == V4L2_IDENT_NONE) {
+		chip->ident = ident;
+		chip->revision = revision;
+	}
+	else {
+		chip->ident = V4L2_IDENT_AMBIGUOUS;
+		chip->revision = 0;
+	}
+	return 0;
+}
+
 int v4l2_chip_match_host(u32 match_type, u32 match_chip)
 {
 	switch (match_type) {
@@ -1015,6 +1033,7 @@
 EXPORT_SYMBOL(v4l2_ctrl_query_fill_std);
 
 EXPORT_SYMBOL(v4l2_chip_match_i2c_client);
+EXPORT_SYMBOL(v4l2_chip_ident_i2c_client);
 EXPORT_SYMBOL(v4l2_chip_match_host);
 
 /*