diff options
Diffstat (limited to 'sound/soc')
| -rw-r--r-- | sound/soc/codecs/cs4270.c | 163 |
1 files changed, 105 insertions, 58 deletions
diff --git a/sound/soc/codecs/cs4270.c b/sound/soc/codecs/cs4270.c index adc1150..e5f5afd 100644 --- a/sound/soc/codecs/cs4270.c +++ b/sound/soc/codecs/cs4270.c @@ -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 @@ error_free_pcms: 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 @@ error_free_codec: 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", |