ASoC: fix documentation in CS4270 codec driver (ff7bf02f) · Commits · git / linux-nf

sound/soc/codecs/cs4270.c

+105 −58

Original line number	Diff line number	Diff line
		@@ -3,10 +3,10 @@
		*
		* Author: Timur Tabi <timur@freescale.com>
		*
		* Copyright 2007 Freescale Semiconductor, Inc. This file is licensed under
		* the terms of the GNU General Public License version 2. This program
		* is licensed "as is" without any warranty of any kind, whether express
		* or implied.
		* Copyright 2007-2009 Freescale Semiconductor, Inc. This file is licensed
		* under the terms of the GNU General Public License version 2. This
		* program is licensed "as is" without any warranty of any kind, whether
		* express or implied.
		*
		* This is an ASoC device driver for the Cirrus Logic CS4270 codec.
		*
		@@ -111,8 +111,13 @@ struct cs4270_private {
		unsigned int mode; /* The mode (I2S or left-justified) */
		};

		/*
		* Clock Ratio Selection for Master Mode with I2C enabled
		/**
		* struct cs4270_mode_ratios - clock ratio tables
		* @ratio: the ratio of MCLK to the sample rate
		* @speed_mode: the Speed Mode bits to set in the Mode Control register for
		* this ratio
		* @mclk: the Ratio Select bits to set in the Mode Control register for this
		* ratio
		*
		* The data for this chart is taken from Table 5 of the CS4270 reference
		* manual.
		@@ -121,31 +126,30 @@ struct cs4270_private {
		* It is also used by cs4270_set_dai_sysclk() to tell ALSA which sampling
		* rates the CS4270 currently supports.
		*
		* Each element in this array corresponds to the ratios in mclk_ratios[].
		* These two arrays need to be in sync.
		*
		* 'speed_mode' is the corresponding bit pattern to be written to the
		* @speed_mode is the corresponding bit pattern to be written to the
		* MODE bits of the Mode Control Register
		*
		* 'mclk' is the corresponding bit pattern to be wirten to the MCLK bits of
		* @mclk is the corresponding bit pattern to be wirten to the MCLK bits of
		* the Mode Control Register.
		*
		* In situations where a single ratio is represented by multiple speed
		* modes, we favor the slowest speed. E.g, for a ratio of 128, we pick
		* double-speed instead of quad-speed. However, the CS4270 errata states
		* that Divide-By-1.5 can cause failures, so we avoid that mode where
		* that divide-By-1.5 can cause failures, so we avoid that mode where
		* possible.
		*
		* ERRATA: There is an errata for the CS4270 where divide-by-1.5 does not
		* work if VD = 3.3V. If this effects you, select the
		* Errata: There is an errata for the CS4270 where divide-by-1.5 does not
		* work if Vd is 3.3V. If this effects you, select the
		* CONFIG_SND_SOC_CS4270_VD33_ERRATA Kconfig option, and the driver will
		* never select any sample rates that require divide-by-1.5.
		*/
		static struct {
		struct cs4270_mode_ratios {
		unsigned int ratio;
		u8 speed_mode;
		u8 mclk;
		} cs4270_mode_ratios[] = {
		};

		static struct cs4270_mode_ratios[] = {
		{64, CS4270_MODE_4X, CS4270_MODE_DIV1},
		#ifndef CONFIG_SND_SOC_CS4270_VD33_ERRATA
		{96, CS4270_MODE_4X, CS4270_MODE_DIV15},
		@@ -162,34 +166,27 @@ static struct {
		/* The number of MCLK/LRCK ratios supported by the CS4270 */
		#define NUM_MCLK_RATIOS ARRAY_SIZE(cs4270_mode_ratios)

		/*
		* Determine the CS4270 samples rates.
		/**
		* cs4270_set_dai_sysclk - determine the CS4270 samples rates.
		* @codec_dai: the codec DAI
		* @clk_id: the clock ID (ignored)
		* @freq: the MCLK input frequency
		* @dir: the clock direction (ignored)
		*
		* 'freq' is the input frequency to MCLK. The other parameters are ignored.
		* This function is used to tell the codec driver what the input MCLK
		* frequency is.
		*
		* The value of MCLK is used to determine which sample rates are supported
		* by the CS4270. The ratio of MCLK / Fs must be equal to one of nine
		* support values: 64, 96, 128, 192, 256, 384, 512, 768, and 1024.
		* supported values - 64, 96, 128, 192, 256, 384, 512, 768, and 1024.
		*
		* This function calculates the nine ratios and determines which ones match
		* a standard sample rate. If there's a match, then it is added to the list
		* of support sample rates.
		* of supported sample rates.
		*
		* This function must be called by the machine driver's 'startup' function,
		* otherwise the list of supported sample rates will not be available in
		* time for ALSA.
		*
		* Note that in stand-alone mode, the sample rate is determined by input
		* pins M0, M1, MDIV1, and MDIV2. Also in stand-alone mode, divide-by-3
		* is not a programmable option. However, divide-by-3 is not an available
		* option in stand-alone mode. This cases two problems: a ratio of 768 is
		* not available (it requires divide-by-3) and B) ratios 192 and 384 can
		* only be selected with divide-by-1.5, but there is an errate that make
		* this selection difficult.
		*
		* In addition, there is no mechanism for communicating with the machine
		* driver what the input settings can be. This would need to be implemented
		* for stand-alone mode to work.
		*/
		static int cs4270_set_dai_sysclk(struct snd_soc_dai *codec_dai,
		int clk_id, unsigned int freq, int dir)
		@@ -230,8 +227,10 @@ static int cs4270_set_dai_sysclk(struct snd_soc_dai *codec_dai,
		return 0;
		}

		/*
		* Configure the codec for the selected audio format
		/**
		* cs4270_set_dai_fmt - configure the codec for the selected audio format
		* @codec_dai: the codec DAI
		* @format: a SND_SOC_DAIFMT_x value indicating the data format
		*
		* This function takes a bitmask of SND_SOC_DAIFMT_x bits and programs the
		* codec accordingly.
		@@ -261,8 +260,16 @@ static int cs4270_set_dai_fmt(struct snd_soc_dai *codec_dai,
		return ret;
		}

		/*
		* Pre-fill the CS4270 register cache.
		/**
		* cs4270_fill_cache - pre-fill the CS4270 register cache.
		* @codec: the codec for this CS4270
		*
		* This function fills in the CS4270 register cache by reading the register
		* values from the hardware.
		*
		* This CS4270 registers are cached to avoid excessive I2C I/O operations.
		* After the initial read to pre-fill the cache, the CS4270 never updates
		* the register values, so we won't have a cache coherency problem.
		*
		* We use the auto-increment feature of the CS4270 to read all registers in
		* one shot.
		@@ -285,12 +292,17 @@ static int cs4270_fill_cache(struct snd_soc_codec *codec)
		return 0;
		}

		/*
		* Read from the CS4270 register cache.
		/**
		* cs4270_read_reg_cache - read from the CS4270 register cache.
		* @codec: the codec for this CS4270
		* @reg: the register to read
		*
		* This function returns the value for a given register. It reads only from
		* the register cache, not the hardware itself.
		*
		* This CS4270 registers are cached to avoid excessive I2C I/O operations.
		* After the initial read to pre-fill the cache, the CS4270 never updates
		* the register values, so we won't have a cache coherncy problem.
		* the register values, so we won't have a cache coherency problem.
		*/
		static unsigned int cs4270_read_reg_cache(struct snd_soc_codec *codec,
		unsigned int reg)
		@@ -303,8 +315,11 @@ static unsigned int cs4270_read_reg_cache(struct snd_soc_codec *codec,
		return cache[reg - CS4270_FIRSTREG];
		}

		/*
		* Write to a CS4270 register via the I2C bus.
		/**
		* cs4270_i2c_write - write to a CS4270 register via the I2C bus.
		* @codec: the codec for this CS4270
		* @reg: the register to write
		* @value: the value to write to the register
		*
		* This function writes the given value to the given CS4270 register, and
		* also updates the register cache.
		@@ -336,11 +351,17 @@ static int cs4270_i2c_write(struct snd_soc_codec *codec, unsigned int reg,
		return 0;
		}

		/*
		* Program the CS4270 with the given hardware parameters.
		/**
		* cs4270_hw_params - program the CS4270 with the given hardware parameters.
		* @substream: the audio stream
		* @params: the hardware parameters to set
		* @dai: the SOC DAI (ignored)
		*
		* The .ops functions are used to provide board-specific data, like
		* input frequencies, to this driver. This function takes that information,
		* This function programs the hardware with the values provided.
		* Specifically, the sample rate and the data format.
		*
		* The .ops functions are used to provide board-specific data, like input
		* frequencies, to this driver. This function takes that information,
		* combines it with the hardware parameters provided, and programs the
		* hardware accordingly.
		*/
		@@ -455,8 +476,10 @@ static int cs4270_hw_params(struct snd_pcm_substream *substream,
		}

		#ifdef CONFIG_SND_SOC_CS4270_HWMUTE
		/*
		* Set the CS4270 external mute
		/**
		* cs4270_mute - enable/disable the CS4270 external mute
		* @dai: the SOC DAI
		* @mute: 0 = disable mute, 1 = enable mute
		*
		* This function toggles the mute bits in the MUTE register. The CS4270's
		* mute capability is intended for external muting circuitry, so if the
		@@ -490,7 +513,7 @@ static const struct snd_kcontrol_new cs4270_snd_controls[] = {
		};

		/*
		* Global variable to store codec for the ASoC probe function.
		* cs4270_codec - global variable to store codec for the ASoC probe function
		*
		* If struct i2c_driver had a private_data field, we wouldn't need to use
		* cs4270_codec. This is the only way to pass the codec structure from
		@@ -527,8 +550,12 @@ struct snd_soc_dai cs4270_dai = {
		};
		EXPORT_SYMBOL_GPL(cs4270_dai);

		/*
		* ASoC probe function
		/**
		* cs4270_probe - ASoC probe function
		* @pdev: platform device
		*
		* This function is called when ASoC has all the pieces it needs to
		* instantiate a sound driver.
		*/
		static int cs4270_probe(struct platform_device *pdev)
		{
		@@ -582,6 +609,12 @@ static int cs4270_probe(struct platform_device *pdev)
		return ret;
		}

		/**
		* cs4270_remove - ASoC remove function
		* @pdev: platform device
		*
		* This function is the counterpart to cs4270_probe().
		*/
		static int cs4270_remove(struct platform_device *pdev)
		{
		struct snd_soc_device *socdev = platform_get_drvdata(pdev);
		@@ -591,14 +624,13 @@ static int cs4270_remove(struct platform_device *pdev)
		return 0;
		};

		/*
		* Initialize the I2C interface of the CS4270
		*
		* This function is called for whenever the I2C subsystem finds a device
		* at a particular address.
		/**
		* cs4270_i2c_probe - initialize the I2C interface of the CS4270
		* @i2c_client: the I2C client object
		* @id: the I2C device ID (ignored)
		*
		* Note: snd_soc_new_pcms() must be called before this function can be called,
		* because of snd_ctl_add().
		* This function is called whenever the I2C subsystem finds a device that
		* matches the device ID given via a prior call to i2c_add_driver().
		*/
		static int cs4270_i2c_probe(struct i2c_client *i2c_client,
		const struct i2c_device_id *id)
		@@ -690,6 +722,12 @@ static int cs4270_i2c_probe(struct i2c_client *i2c_client,
		return ret;
		}

		/**
		* cs4270_i2c_remove - remove an I2C device
		* @i2c_client: the I2C client object
		*
		* This function is the counterpart to cs4270_i2c_probe().
		*/
		static int cs4270_i2c_remove(struct i2c_client *i2c_client)
		{
		struct cs4270_private *cs4270 = i2c_get_clientdata(i2c_client);
		@@ -699,12 +737,21 @@ static int cs4270_i2c_remove(struct i2c_client *i2c_client)
		return 0;
		}

		/*
		* cs4270_id - I2C device IDs supported by this driver
		*/
		static struct i2c_device_id cs4270_id[] = {
		{"cs4270", 0},
		{}
		};
		MODULE_DEVICE_TABLE(i2c, cs4270_id);

		/*
		* cs4270_i2c_driver - I2C device identification
		*
		* This structure tells the I2C subsystem how to identify and support a
		* given I2C device type.
		*/
		static struct i2c_driver cs4270_i2c_driver = {
		.driver = {
		.name = "cs4270",