On Sat, Jul 25, 2009 at 03:25:25PM +0200, ext Hans Verkuil wrote:
> On Friday 24 July 2009 18:37:28 Eduardo Valentin wrote:
> > This patch adds a document file for si4713 device driver.
> > It describes the driver interfaces and organization.
> >
> > Signed-off-by: Eduardo Valentin <eduardo.valentin@xxxxxxxxx>
> > ---
> > linux/Documentation/video4linux/si4713.txt | 175 ++++++++++++++++++++++++++++
> > 1 files changed, 175 insertions(+), 0 deletions(-)
> > create mode 100644 linux/Documentation/video4linux/si4713.txt
> >
> > diff --git a/linux/Documentation/video4linux/si4713.txt b/linux/Documentation/video4linux/si4713.txt
> > new file mode 100644
> > index 0000000..3843af5
> > --- /dev/null
> > +++ b/linux/Documentation/video4linux/si4713.txt
> > @@ -0,0 +1,175 @@
> > +Driver for I2C radios for the Silicon Labs Si4713 FM Radio Transmitters
> > +
> > +Copyright (c) 2009 Nokia Corporation
> > +Contact: Eduardo Valentin <eduardo.valentin@xxxxxxxxx>
> > +
> > +
> > +Information about the Device
> > +============================
> > +This chip is a Silicon Labs product. It is a I2C device, currently on 0Ã?63 address.
> > +Basically, it has transmission and signal noise level measurement features.
> > +
> > +The Si4713 integrates transmit functions for FM broadcast stereo transmission.
> > +The chip also allows integrated receive power scanning to identify low signal
> > +power FM channels.
> > +
> > +The chip is programmed using commands and responses. There are also several
> > +properties which can change the behavior of this chip.
> > +
> > +Users must comply with local regulations on radio frequency (RF) transmission.
> > +
> > +Device driver description
> > +=========================
> > +There are two modules to handle this device. One is a I2C device driver
> > +and the other is a platform driver.
> > +
> > +The I2C device driver exports a v4l2-subdev interface to the kernel.
> > +All properties can also be accessed by v4l2 extended controls interface, by
> > +using the v4l2-subdev calls (g_ext_ctrls, s_ext_ctrls).
> > +
> > +The platform device driver exports a v4l2 radio device interface to user land.
> > +So, it uses the I2C device driver as a sub device in order to send the user
> > +commands to the actual device. Basically it is a wrapper to the I2C device driver.
> > +
> > +Applications can use v4l2 radio API to specify frequency of operation, mute state,
> > +etc. But mostly of its properties will be present in the extended controls.
> > +
> > +When the v4l2 mute property is set to 1 (true), the driver will turn the chip off.
> > +
> > +Properties description
> > +======================
> > +
> > +The properties can be accessed using v4l2 extended controls.
> > +Here is an output from v4l2-ctl util:
> > +
> > +# v4l2-ctl -d /dev/radio0 --all -l
> > +Driver Info:
> > + Driver name : radio-si4713
> > + Card type : Silicon Labs Si4713 Modulator
> > + Bus info :
> > + Driver version: 0
> > + Capabilities : 0x00080800
> > + RDS Output
> > + Modulator
> > +Audio output: 0 (FM Modulator Audio Out)
> > +Frequency: 1545600 (96.600000 MHz)
> > +Video Standard = 0x00000000
> > +Modulator:
> > + Name : FM Modulator
> > + Capabilities : 62.5 Hz stereo rds
> > + Frequency range : 76.0 MHz - 108.0 MHz
> > + Available subchannels: mono rds
> > +
> > +User Controls
> > +
> > + mute (bool) : default=1 value=0
> > +
> > +FM Radio Modulator Controls
> > +
> > + rds_program_id (int) : min=0 max=65535 step=1 default=0 value=0
> > + rds_program_type (int) : min=0 max=31 step=1 default=0 value=0
> > + rds_ps_name (str) : value='Si4713 ' len=1024
> > +' len=1024 rds_radio_text (str) : value='Si4713
>
> This doesn't look right. I think this output is from an old v4l2-ctl version.
> I'd like to see this output anyway using the latest v4l2-ctl version as I
> haven't been able to test it myself.
Yeah. My bad, forgot to update here. This is the output from the older version.
>
> Based on this output it also looks as if the rds_radio_text string has a \r
> at the end. If so, is it supposed to be there?
Yeah, the \r it is required for Radio Text.
>
> Regards,
>
> Hans
>
> > + audio_limiter_feature_enabled (bool) : default=1 value=1
> > + audio_limiter_release_time (int) : min=250 max=102390 step=50 default=5010 value=5010 flags=slider
> > + audio_limiter_deviation (int) : min=0 max=90000 step=10 default=66250 value=1020 flags=slider
> > +audio_compression_feature_enabl (bool) : default=1 value=1
> > + audio_compression_gain (int) : min=0 max=20 step=1 default=15 value=15 flags=slider
> > + audio_compression_threshold (int) : min=-40 max=0 step=1 default=-40 value=-40 flags=slider
> > + audio_compression_attack_time (int) : min=0 max=5000 step=500 default=0 value=0 flags=slider
> > + audio_compression_release_time (int) : min=100000 max=1000000 step=100000 default=1000000 value=1000000 flags=slider
> > + pilot_tone_feature_enabled (bool) : default=1 value=1
> > + pilot_tone_deviation (int) : min=0 max=90000 step=10 default=6750 value=6750 flags=slider
> > + pilot_tone_frequency (int) : min=0 max=19000 step=1 default=19000 value=19000 flags=slider
> > + pre_emphasis_settings (menu) : min=0 max=2 default=1 value=1
> > + tune_power_level (int) : min=0 max=120 step=1 default=88 value=120 flags=slider
> > + tune_antenna_capacitor (int) : min=0 max=191 step=1 default=0 value=112 flags=slider
> > +
> > +Here is a summary of them:
> > +
> > +* Pilot is an audible tone sent by the device.
> > +
> > +pilot_frequency - Configures the frequency of the stereo pilot tone.
> > +pilot_deviation - Configures pilot tone frequency deviation level.
> > +pilot_enabled - Enables or disables the pilot tone feature.
> > +
> > +* The si4713 device is capable of applying audio compression to the transmitted signal.
> > +
> > +acomp_enabled - Enables or disables the audio dynamic range control feature.
> > +acomp_gain - Sets the gain for audio dynamic range control.
> > +acomp_threshold - Sets the threshold level for audio dynamic range control.
> > +acomp_attack_time - Sets the attack time for audio dynamic range control.
> > +acomp_release_time - Sets the release time for audio dynamic range control.
> > +
> > +* Limiter setups audio deviation limiter feature. Once a over deviation occurs,
> > +it is possible to adjust the front-end gain of the audio input and always
> > +prevent over deviation.
> > +
> > +limiter_enabled - Enables or disables the limiter feature.
> > +limiter_deviation - Configures audio frequency deviation level.
> > +limiter_release_time - Sets the limiter release time.
> > +
> > +* Tuning power
> > +
> > +power_level - Sets the output power level for signal transmission.
> > +antenna_capacitor - This selects the value of antenna tuning capacitor manually
> > +or automatically if set to zero.
> > +
> > +* RDS related
> > +
> > +rds_ps_name - Sets the RDS ps name field for transmission.
> > +rds_radio_text - Sets the RDS radio text for transmission.
> > +rds_pi - Sets the RDS PI field for transmission.
> > +rds_pty - Sets the RDS PTY field for transmission.
> > +
> > +* Region related
> > +
> > +preemphasis - sets the preemphasis to be applied for transmission.
> > +
> > +RNL
> > +===
> > +
> > +This device also has an interface to measure received noise level. To do that, you should
> > +ioctl the device node. Here is an code of example:
> > +
> > +int main (int argc, char *argv[])
> > +{
> > + struct si4713_rnl rnl;
> > + int fd = open("/dev/radio0", O_RDWR);
> > + int rval;
> > +
> > + if (argc < 2)
> > + return -EINVAL;
> > +
> > + if (fd < 0)
> > + return fd;
> > +
> > + sscanf(argv[1], "%d", &rnl.frequency);
> > +
> > + rval = ioctl(fd, SI4713_IOC_MEASURE_RNL, &rnl);
> > + if (rval < 0)
> > + return rval;
> > +
> > + printf("received noise level: %d\n", rnl.rnl);
> > +
> > + close(fd);
> > +}
> > +
> > +The struct si4713_rnl and SI4713_IOC_MEASURE_RNL are defined under
> > +include/media/si4713.h.
> > +
> > +Stereo/Mono and RDS subchannels
> > +===============================
> > +
> > +The device can also be configured using the available sub channels for
> > +transmission. To do that use S/G_MODULATOR ioctl and configure txsubchans properly.
> > +Refer to v4l2-spec for proper use of this ioctl.
> > +
> > +Testing
> > +=======
> > +Testing is usually done with v4l2-ctl utility for managing FM tuner cards.
> > +The tool can be found in v4l-dvb repository under v4l2-apps/util directory.
> > +
> > +Example for setting rds ps name:
> > +# v4l2-ctl -d /dev/radio0 --set-ctrl=rds_ps_name="Dummy"
> > +
>
>
>
> --
> Hans Verkuil - video4linux developer - sponsored by TANDBERG Telecom
--
Eduardo Valentin
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