[media] v4l2: Add a V4L2 driver for SI476X MFD

This commit adds a driver that exposes all the radio related
functionality of the Si476x series of chips via the V4L2 subsystem.
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

Documentation/video4linux/si476x.txt

+SI476x Driver Readme
+------------------------------------------------
+	Copyright (C) 2013 Andrey Smirnov <andrew.smirnov@gmail.com>
+
+TODO for the driver
+------------------------------
+
+- According to the SiLabs' datasheet it is possible to update the
+  firmware of the radio chip in the run-time, thus bringing it to the
+  most recent version. Unfortunately I couldn't find any mentioning of
+  the said firmware update for the old chips that I tested the driver
+  against, so for chips like that the driver only exposes the old
+  functionality.
+
+
+Parameters exposed over debugfs
+-------------------------------
+SI476x allow user to get multiple characteristics that can be very
+useful for EoL testing/RF performance estimation, parameters that have
+very little to do with V4L2 subsystem. Such parameters are exposed via
+debugfs and can be accessed via regular file I/O operations.
+
+The drivers exposes following files:
+
+* /sys/kernel/debug/<device-name>/acf
+  This file contains ACF(Automatically Controlled Features) status
+  information. The contents of the file is binary data of the
+  following layout:
+
+  Offset	| Name		| Description
+  ====================================================================
+  0x00		| blend_int	| Flag, set when stereo separation has
+  		|  		| crossed below the blend threshold
+  --------------------------------------------------------------------
+  0x01		| hblend_int	| Flag, set when HiBlend cutoff
+  		| 		| frequency is lower than threshold
+  --------------------------------------------------------------------
+  0x02		| hicut_int	| Flag, set when HiCut cutoff
+  		| 		| frequency is lower than threshold
+  --------------------------------------------------------------------
+  0x03		| chbw_int	| Flag, set when channel filter
+  		| 		| bandwidth is less than threshold
+  --------------------------------------------------------------------
+  0x04		| softmute_int	| Flag indicating that softmute
+  		| 		| attenuation has increased above
+		|		| softmute threshold
+  --------------------------------------------------------------------
+  0x05		| smute		| 0 - Audio is not soft muted
+  		| 		| 1 - Audio is soft muted
+  --------------------------------------------------------------------
+  0x06		| smattn	| Soft mute attenuation level in dB
+  --------------------------------------------------------------------
+  0x07		| chbw		| Channel filter bandwidth in kHz
+  --------------------------------------------------------------------
+  0x08		| hicut		| HiCut cutoff frequency in units of
+  		| 		| 100Hz
+  --------------------------------------------------------------------
+  0x09		| hiblend	| HiBlend cutoff frequency in units
+  		| 		| of 100 Hz
+  --------------------------------------------------------------------
+  0x10		| pilot		| 0 - Stereo pilot is not present
+  		| 		| 1 - Stereo pilot is present
+  --------------------------------------------------------------------
+  0x11		| stblend	| Stereo blend in %
+  --------------------------------------------------------------------
+
+
+* /sys/kernel/debug/<device-name>/rds_blckcnt
+  This file contains statistics about RDS receptions. It's binary data
+  has the following layout:
+
+  Offset	| Name		| Description
+  ====================================================================
+  0x00		| expected	| Number of expected RDS blocks
+  --------------------------------------------------------------------
+  0x02		| received	| Number of received RDS blocks
+  --------------------------------------------------------------------
+  0x04		| uncorrectable	| Number of uncorrectable RDS blocks
+  --------------------------------------------------------------------
+
+* /sys/kernel/debug/<device-name>/agc
+  This file contains information about parameters pertaining to
+  AGC(Automatic Gain Control)
+
+  The layout is:
+  Offset	| Name		| Description
+  ====================================================================
+  0x00		| mxhi		| 0 - FM Mixer PD high threshold is
+  		| 		| not tripped
+		|		| 1 - FM Mixer PD high threshold is
+		|		| tripped
+  --------------------------------------------------------------------
+  0x01		| mxlo		| ditto for FM Mixer PD low
+  --------------------------------------------------------------------
+  0x02		| lnahi		| ditto for FM LNA PD high
+  --------------------------------------------------------------------
+  0x03		| lnalo		| ditto for FM LNA PD low
+  --------------------------------------------------------------------
+  0x04		| fmagc1	| FMAGC1 attenuator resistance
+  		| 		| (see datasheet for more detail)
+  --------------------------------------------------------------------
+  0x05		| fmagc2	| ditto for FMAGC2
+  --------------------------------------------------------------------
+  0x06		| pgagain	| PGA gain in dB
+  --------------------------------------------------------------------
+  0x07		| fmwblang	| FM/WB LNA Gain in dB
+  --------------------------------------------------------------------
+
+* /sys/kernel/debug/<device-name>/rsq
+  This file contains information about parameters pertaining to
+  RSQ(Received Signal Quality)
+
+  The layout is:
+  Offset	| Name		| Description
+  ====================================================================
+  0x00		| multhint	| 0 - multipath value has not crossed
+  		| 		| the Multipath high threshold
+		|		| 1 - multipath value has crossed
+  		| 		| the Multipath high threshold
+  --------------------------------------------------------------------
+  0x01		| multlint	| ditto for Multipath low threshold
+  --------------------------------------------------------------------
+  0x02		| snrhint	| 0 - received signal's SNR has not
+  		| 		| crossed high threshold
+		|		| 1 - received signal's SNR has
+  		| 		| crossed high threshold
+  --------------------------------------------------------------------
+  0x03		| snrlint	| ditto for low threshold
+  --------------------------------------------------------------------
+  0x04		| rssihint	| ditto for RSSI high threshold
+  --------------------------------------------------------------------
+  0x05		| rssilint	| ditto for RSSI low threshold
+  --------------------------------------------------------------------
+  0x06		| bltf		| Flag indicating if seek command
+  		| 		| reached/wrapped seek band limit
+  --------------------------------------------------------------------
+  0x07		| snr_ready	| Indicates that SNR metrics is ready
+  --------------------------------------------------------------------
+  0x08		| rssiready	| ditto for RSSI metrics
+  --------------------------------------------------------------------
+  0x09		| injside	| 0 - Low-side injection is being used
+  		| 		| 1 - High-side injection is used
+  --------------------------------------------------------------------
+  0x10		| afcrl		| Flag indicating if AFC rails
+  --------------------------------------------------------------------
+  0x11		| valid		| Flag indicating if channel is valid
+  --------------------------------------------------------------------
+  0x12		| readfreq	| Current tuned frequency
+  --------------------------------------------------------------------
+  0x14		| freqoff	| Singed frequency offset in units of
+  		| 		| 2ppm
+  --------------------------------------------------------------------
+  0x15		| rssi		| Signed value of RSSI in dBuV
+  --------------------------------------------------------------------
+  0x16		| snr		| Signed RF SNR in dB
+  --------------------------------------------------------------------
+  0x17		| issi		| Signed Image Strength Signal
+  		| 		| indicator
+  --------------------------------------------------------------------
+  0x18		| lassi		| Signed Low side adjacent Channel
+  		| 		| Strength indicator
+  --------------------------------------------------------------------
+  0x19		| hassi		| ditto fpr High side
+  --------------------------------------------------------------------
+  0x20		| mult		| Multipath indicator
+  --------------------------------------------------------------------
+  0x21		| dev		| Frequency deviation
+  --------------------------------------------------------------------
+  0x24		| assi		| Adjascent channel SSI
+  --------------------------------------------------------------------
+  0x25		| usn		| Ultrasonic noise indicator
+  --------------------------------------------------------------------
+  0x26		| pilotdev	| Pilot deviation in units of 100 Hz
+  --------------------------------------------------------------------
+  0x27		| rdsdev	| ditto for RDS
+  --------------------------------------------------------------------
+  0x28		| assidev	| ditto for ASSI
+  --------------------------------------------------------------------
+  0x29		| strongdev	| Frequency deviation
+  --------------------------------------------------------------------
+  0x30		| rdspi		| RDS PI code
+  --------------------------------------------------------------------
+
+* /sys/kernel/debug/<device-name>/rsq_primary
+  This file contains information about parameters pertaining to
+  RSQ(Received Signal Quality) for primary tuner only. Layout is as
+  the one above.

drivers/media/radio/Kconfig

@@ -18,6 +18,23 @@ config RADIO_SI470X
 
 source "drivers/media/radio/si470x/Kconfig"
 
+config RADIO_SI476X
+	tristate "Silicon Laboratories Si476x I2C FM Radio"
+	depends on I2C && VIDEO_V4L2
+	select MFD_CORE
+	select MFD_SI476X_CORE
+	select SND_SOC_SI476X
+	---help---
+	  Choose Y here if you have this FM radio chip.
+
+	  In order to control your radio card, you will need to use programs
+	  that are compatible with the Video For Linux 2 API.  Information on
+	  this API and pointers to "v4l2" programs may be found at
+	  <file:Documentation/video4linux/API.html>.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called radio-si476x.
+
 config USB_MR800
 	tristate "AverMedia MR 800 USB FM radio support"
 	depends on USB && VIDEO_V4L2

drivers/media/radio/Makefile

@@ -19,6 +19,7 @@ obj-$(CONFIG_RADIO_GEMTEK) += radio-gemtek.o
 obj-$(CONFIG_RADIO_TRUST) += radio-trust.o
 obj-$(CONFIG_I2C_SI4713) += si4713-i2c.o
 obj-$(CONFIG_RADIO_SI4713) += radio-si4713.o
+obj-$(CONFIG_RADIO_SI476X) += radio-si476x.o
 obj-$(CONFIG_RADIO_MIROPCM20) += radio-miropcm20.o
 obj-$(CONFIG_USB_DSBR) += dsbr100.o
 obj-$(CONFIG_RADIO_SI470X) += si470x/