Introduction
This is a sharing of my experience about porting the audio codec WM8960 in Linux BSP. I know this driver is not the perfect one. If you find any place is not good in the driver, please let me know.
This driver is modified base on the wm8960.c in L3.0.35 Linux BSP. This document is talking about how to modify the codec driver. The Audio Codec driver is located in linux/sound/soc/codec/wm8960.c.
ALSA
The Audio Codec driver is based on ALSA to setup up all the things. For details, please see :
Advanced Linux Sound Architecture - Wikipedia, the free encyclopedia.
kcontrols are defined in linux/include/sound/soc.h and soc-dapm.h.
Audio controls and path in WM8960
Left and Right Input signal path
Output signal path
Base on the input and output signal diagrams, we can setup all the controls that we want in the driver. Such as switches, volume controls, PGA controls and so on. All the controls below can be used in the alsamixer.
static const struct snd_kcontrol_new wm8960_snd_controls[] = {
SOC_DOUBLE_R_TLV("PCM DAC Playback Volume", WM8960_LDAC, WM8960_RDAC, 0, 255, 0, dac_tlv), //LDACVOL , RDACVOL
SOC_DOUBLE_R_TLV("PCM ADC Capture Volume", WM8960_LADC, WM8960_RADC, 0, 255, 0, adc_tlv), //LADCVOL, RADCVOL
SOC_DOUBLE_R_TLV("Headphone Volume", WM8960_LOUT1, WM8960_ROUT1, 0, 127, 0, out_tlv),
SOC_DOUBLE_R("Headphone ZC Switch", WM8960_LOUT1, WM8960_ROUT1, 7, 1, 0),
SOC_DOUBLE_R_TLV("Speaker Volume", WM8960_LOUT2, WM8960_ROUT2, 0, 127, 0, out_tlv),
SOC_DOUBLE_R("Speaker ZC Switch", WM8960_LOUT2, WM8960_ROUT2, 7, 1, 0),
SOC_DOUBLE_R("Capture Volume ZC Switch", WM8960_LINVOL, WM8960_RINVOL, 6, 1, 0),
SOC_SINGLE_TLV("Input Volume of LINPUT1", WM8960_LINVOL, 0, 63, 0, in_tlv), //LINVOL
SOC_SINGLE_TLV("Input Volume of RINPUT1", WM8960_RINVOL, 0, 63, 0, in_tlv), //RINVOL
SOC_SINGLE_TLV("Input Boost Volume LINPUT3", WM8960_INBMIX1, 4, 7, 0, boost_tlv), //RIN3BOOST
SOC_SINGLE_TLV("Input Boost Volume LINPUT2", WM8960_INBMIX1, 1, 7, 0, boost_tlv), //RIN2BOOST
SOC_SINGLE_TLV("Input Boost Volume RINPUT3", WM8960_INBMIX2, 4, 7, 0, boost_tlv), //LIN3BOOST
SOC_SINGLE_TLV("Input Boost Volume RINPUT2", WM8960_INBMIX2, 1, 7, 0, boost_tlv), //LIN2BOOST
SOC_SINGLE_TLV("PGA LB2LOVOL-Bypass from Left Boost", WM8960_BYPASS1, 4, 7, 1, bypass_tlv), //LB2LOVOL
SOC_SINGLE_TLV("PGA LI2LOVOL-Bypass from LINPUT3", WM8960_LOUTMIX, 4, 7, 1, bypass_tlv), //LI2LOVOL
SOC_SINGLE_TLV("PGA RB2ROVOL-Bypass from Right Boost", WM8960_BYPASS2, 4, 7, 1, bypass_tlv), //RB2ROVOL
SOC_SINGLE_TLV("PGA RI2ROVOL-Bypass from RINPUT3", WM8960_ROUTMIX, 4, 7, 1, bypass_tlv), //RI2ROVOL
SOC_SINGLE("Capture Mute (Left)", WM8960_LINVOL, 7, 1, 0), // LINMUTE
SOC_SINGLE("Capture Mute (Right)", WM8960_RINVOL, 7, 1, 0), // RINMUTE
SOC_SINGLE("PCM Playback -6dB Switch", WM8960_DACCTL1, 7, 1, 0),
SOC_SINGLE("Speaker DC gain", WM8960_CLASSD3, 3, 5, 0),
SOC_SINGLE("Speaker AC gain", WM8960_CLASSD3, 0, 5, 0),
SOC_ENUM("ADC Polarity", wm8960_enum[0]),
SOC_SINGLE("ADC High Pass Filter Switch", WM8960_DACCTL1, 0, 1, 0),
SOC_ENUM("DAC Polarity", wm8960_enum[2]),
SOC_SINGLE_BOOL_EXT("DAC Deemphasis Switch", 0, wm8960_get_deemph, wm8960_put_deemph),
SOC_ENUM("3D Filter Upper Cut-Off", wm8960_enum[2]),
SOC_ENUM("3D Filter Lower Cut-Off", wm8960_enum[3]),
SOC_SINGLE("3D Depth", WM8960_3D, 1, 15, 0),
SOC_SINGLE("3D", WM8960_3D, 0, 1, 0),
SOC_ENUM("ALC Function", wm8960_enum[4]),
SOC_SINGLE("ALC Max Gain", WM8960_ALC1, 4, 7, 0),
SOC_SINGLE("ALC Target", WM8960_ALC1, 0, 15, 1),
SOC_SINGLE("ALC Min Gain", WM8960_ALC2, 4, 7, 0),
SOC_SINGLE("ALC Hold Time", WM8960_ALC2, 0, 15, 0),
SOC_ENUM("ALC Mode", wm8960_enum[5]),
SOC_SINGLE("ALC Decay", WM8960_ALC3, 4, 15, 0),
SOC_SINGLE("ALC Attack", WM8960_ALC3, 0, 15, 0),
SOC_SINGLE("Noise Gate Threshold", WM8960_NOISEG, 3, 31, 0),
SOC_SINGLE("Noise Gate Switch", WM8960_NOISEG, 0, 1, 0),
SOC_ENUM("Capture Left Boost", wm8960_enum[6]), //LMICBOOST
SOC_ENUM("Capture Right Boost", wm8960_enum[7]), //RMICBOOT
};
1. SOC_SINGLE(xname, reg, shift, max, invert)
To setup a simple switch, we can use SOC_SINGLE.
e.g
SOC_SINGLE("PCM Playback -6dB Switch", WM8960_DACCTL1, 7, 1, 0),
- The name of this control is “PCM Playback -6dB Switch”.
- The register in WM8960 is WM8960_DACCTL1 . (the register address is 0x5, defined in wm8960.h)
- ‘7’ : The 7th bit in DACCTL1 register is used to enable/disable the DAC 6dB Attenuate.
- ‘1’ : Only one enable or disable option.
- ‘0’ : the value you set is not inverted.
2. SOC_SINGLE_TLV(xname, reg, shift, max, invert, tlv_array)
To setup a switch with levels, we can use SOC_SINGLE_TLV.
e.g.
In this example, the left input volume control is from 000000(-17.25dB) to 111111(+30dB). Each step is 0.75dB. Total is 63 steps.
SOC_SINGLE_TLV("Input Volume of LINPUT1", WM8960_LINVOL, 0, 63, 0, in_tlv),
The scale of in_tlv declare like this:
static const DECLARE_TLV_DB_SCALE(in_tlv, -1725, 75, 0);
in_tlv : the name of the scale.
-1725 : start from -17.25dB
75: each step is 0.75dB
0: the step is start from 0. For some volume control case the first step is "mute", then the step is start from 1 so change this number to 1.
for example: The 0000 0000 of the DAC volume control is digital mute.
static const DECLARE_TLV_DB_SCALE(dac_tlv, -12700, 50, 1);
3. SOC_DOUBLE_R(xname, reg_left, reg_right, xshift, xmax, xinvert)
SOC_DOUBLE_R is a stereo version of SOC_SINGLE. You can control the left and right channel at the same time.
e.g.
SOC_DOUBLE_R("Headphone ZC Switch", WM8960_LOUT1, WM8960_ROUT1, 7, 1, 0),
4. SOC_DOUBLE_R_TLV(xname, reg_left, reg_right, xshift, xmax, xinvert, tlv_array)
SOC_DOUBLE_R_TLV is the stereo version of SOC_SINGLE_TLV.
e.g.
SOC_DOUBLE_R_TLV("PCM DAC Playback Volume", WM8960_LDAC, WM8960_RDAC, 0, 255, 0, dac_tlv),
5. SOC_ENUM_SINGLE(xreg, xshift, xmax, xtexts)
When the control option are some texts, we can use SOC_ENUM to enum the options.
e.g. MIC boost
5.1. setup the array for the texts.
static const char *wm8960_micboost[] = {"0dB","+13dB","+20dB","+29dB"};
5.2. use the SOC_ENUM_SINGLE.
static const struct soc_enum wm8960_enum[] = {
SOC_ENUM_SINGLE(WM8960_DACCTL1, 5, 4, wm8960_polarity),
SOC_ENUM_SINGLE(WM8960_DACCTL2, 5, 4, wm8960_polarity),
SOC_ENUM_SINGLE(WM8960_3D, 6, 2, wm8960_3d_upper_cutoff),
SOC_ENUM_SINGLE(WM8960_3D, 5, 2, wm8960_3d_lower_cutoff),
SOC_ENUM_SINGLE(WM8960_ALC1, 7, 4, wm8960_alcfunc),
SOC_ENUM_SINGLE(WM8960_ALC3, 8, 2, wm8960_alcmode),
SOC_ENUM_SINGLE(WM8960_LINPATH, 4, 4, wm8960_micboost),
SOC_ENUM_SINGLE(WM8960_RINPATH, 4, 4, wm8960_micboost),
};
5.3. use SOC_ENUM to add the controls for MIC boost.
SOC_ENUM("Capture Left Boost", wm8960_enum[6]),
SOC_ENUM("Capture Right Boost", wm8960_enum[7]),
After created all the controls, we can start to create the switches.
The following switches created base on the input and output diagrams. I used the same name from datasheet of each switch. It will more easy to find out the proper switch in alsamixer.
static const struct snd_kcontrol_new wm8960_lin[] = {
SOC_DAPM_SINGLE("<- LMP2", WM8960_LINPATH, 6, 1, 0), //LMP2
SOC_DAPM_SINGLE("<- LMP3", WM8960_LINPATH, 7, 1, 0), //LMP3
SOC_DAPM_SINGLE("<- LMN1", WM8960_LINPATH, 8, 1, 0), //LMN1
};
static const struct snd_kcontrol_new wm8960_lin_boost[] = {
SOC_DAPM_SINGLE("<- LMIC2B", WM8960_LINPATH, 3, 1, 0), //LMIC2B
};
static const struct snd_kcontrol_new wm8960_rin[] = {
SOC_DAPM_SINGLE("<- RMP2", WM8960_RINPATH, 6, 1, 0), //RMP2
SOC_DAPM_SINGLE("<- RMP3", WM8960_RINPATH, 7, 1, 0), //RMP3
SOC_DAPM_SINGLE("<- RMN1", WM8960_RINPATH, 8, 1, 0), //RMN1
};
static const struct snd_kcontrol_new wm8960_rin_boost[] = {
SOC_DAPM_SINGLE("<- RMIC2B", WM8960_RINPATH, 3, 1, 0), //RMIC2B
};
static const struct snd_kcontrol_new wm8960_loutput_mixer[] = {
SOC_DAPM_SINGLE("<- LD2LO", WM8960_LOUTMIX, 8, 1, 0), //LD2LO
SOC_DAPM_SINGLE("<- LI2LO", WM8960_LOUTMIX, 7, 1, 0), //LI2LO
SOC_DAPM_SINGLE("<- LB2LO", WM8960_BYPASS1, 7, 1, 0), //LB2LO
};
static const struct snd_kcontrol_new wm8960_routput_mixer[] = {
SOC_DAPM_SINGLE("<- RD2RO", WM8960_ROUTMIX, 8, 1, 0), //RD2RO
SOC_DAPM_SINGLE("<- RI2RO", WM8960_ROUTMIX, 7, 1, 0), //RI2RO
SOC_DAPM_SINGLE("<- RB2RO", WM8960_BYPASS2, 7, 1, 0), //RB2RO
};
static const struct snd_kcontrol_new wm8960_mono_out[] = {
SOC_DAPM_SINGLE("<- L2MO", WM8960_MONOMIX1, 7, 1, 0), //L2MO
SOC_DAPM_SINGLE("<- R2MO", WM8960_MONOMIX2, 7, 1, 0), //R2MO
};
Then, create the inputs, ADC, DAC, mixers, PGA and outputs.
static const struct snd_soc_dapm_widget wm8960_dapm_widgets[] = {
SND_SOC_DAPM_INPUT("LINPUT1"),
SND_SOC_DAPM_INPUT("RINPUT1"),
SND_SOC_DAPM_INPUT("LINPUT2"),
SND_SOC_DAPM_INPUT("RINPUT2"),
SND_SOC_DAPM_INPUT("LINPUT3"),
SND_SOC_DAPM_INPUT("RINPUT3"),
SND_SOC_DAPM_MICBIAS("MICB", WM8960_POWER1, 1, 0),
SND_SOC_DAPM_MIXER("Left Boost Mixer", WM8960_POWER1, 5, 0, wm8960_lin_boost, ARRAY_SIZE(wm8960_lin_boost)),
SND_SOC_DAPM_MIXER("Right Boost Mixer", WM8960_POWER1, 4, 0, wm8960_rin_boost, ARRAY_SIZE(wm8960_rin_boost)),
SND_SOC_DAPM_MIXER("Left Input PGA", WM8960_POWER3, 5, 0, wm8960_lin, ARRAY_SIZE(wm8960_lin)),
SND_SOC_DAPM_MIXER("Right Input PGA", WM8960_POWER3, 4, 0, wm8960_rin, ARRAY_SIZE(wm8960_rin)),
SND_SOC_DAPM_ADC("Left ADC", "Capture", WM8960_POWER1, 3, 0),
SND_SOC_DAPM_ADC("Right ADC", "Capture", WM8960_POWER1, 2, 0),
SND_SOC_DAPM_DAC("Left DAC", "Playback", WM8960_POWER2, 8, 0),
SND_SOC_DAPM_DAC("Right DAC", "Playback", WM8960_POWER2, 7, 0),
SND_SOC_DAPM_MIXER("Left Output Mixer", WM8960_POWER3, 3, 0, wm8960_loutput_mixer, ARRAY_SIZE(wm8960_loutput_mixer)),
SND_SOC_DAPM_MIXER("Right Output Mixer", WM8960_POWER3, 2, 0, wm8960_routput_mixer, ARRAY_SIZE(wm8960_routput_mixer)),
SND_SOC_DAPM_PGA("Left HP PGA", WM8960_POWER2, 6, 0, NULL, 0),
SND_SOC_DAPM_PGA("Right HP PGA", WM8960_POWER2, 5, 0, NULL, 0),
SND_SOC_DAPM_PGA("Left Speaker PGA", WM8960_POWER2, 4, 0, NULL, 0),
SND_SOC_DAPM_PGA("Right Speaker PGA", WM8960_POWER2, 3, 0, NULL, 0),
SND_SOC_DAPM_PGA("Right Speaker Output", WM8960_CLASSD1, 7, 0, NULL, 0), //SPK_OP_EN
SND_SOC_DAPM_PGA("Left Speaker Output", WM8960_CLASSD1, 6, 0, NULL, 0),
SND_SOC_DAPM_OUTPUT("SPK_LP"),
SND_SOC_DAPM_OUTPUT("SPK_LN"),
SND_SOC_DAPM_OUTPUT("HP_L"),
SND_SOC_DAPM_OUTPUT("HP_R"),
SND_SOC_DAPM_OUTPUT("SPK_RP"),
SND_SOC_DAPM_OUTPUT("SPK_RN"),
SND_SOC_DAPM_OUTPUT("OUT3"),
};
Now, we can start to route the audio path.
The path is from right to left , like : { “destination”, “switch”, “source” }
So, lets take the LINPUT1 to ADC as an example:
{ "Left Input PGA", "<- LMN1", "LINPUT1" },
{ "Left Boost Mixer", "<- LMIC2B", "Left Input PGA" },
{ "Left ADC", NULL, "Left Boost Mixer" },
Another example is DAC to Headphone.
{ "Left Output Mixer", "<- LD2LO", "Left DAC" },
{ "Right Output Mixer", "<- RD2RO", "Right DAC" },
{ "Left HP PGA", NULL, "Left Output Mixer" },
{ "Right HP PGA", NULL, "Right Output Mixer" },
{ "HP_L", NULL, "Left HP PGA" },
{ "HP_R", NULL, "Right HP PGA" },
In linux, you can run "alsamixer" to turn on/off the switches and adjust the volumes.
(this picture is an example of alsamixer of other codec, not for wm8960)
In alsamixer, use 'M' to turn the switch on/off, use arrow keys to control the volumes.
wm8960_dai_ops is another important part in the driver.
Here is the ops of the wm8960_dai.
static struct snd_soc_dai_ops wm8960_dai_ops = {
.hw_params = wm8960_hw_params,
.digital_mute = wm8960_mute,
.set_fmt = wm8960_set_dai_fmt,
.set_clkdiv = wm8960_set_dai_clkdiv,
.set_pll = wm8960_set_dai_pll,
};
wm8960_hw_params : used to set the PCM format (16bit/24bit), set the deemph, alc_rates and etc.
wm8960_mute: used to mute the output
wm8960_set_dai_fmt : used to set the Master/Slave mode, set the interface format (I2S, DSP, Left justified and Right justified) and set the clock inversion.
wm8960_set_dai_clkdiv: used to set the CLK divider such as DACDIV, ADCDIV, BCLKDIV and so on.
wm8960_set_dai_pll: used to calculate the proper PLL values.
In the wm8960_set_dai_pll, we need to calculate the proper PLL values.
Base on the table, if the MCLK >14.4, the sysclk prescale divider is 2. So, set the sysclk pre-divider to 2 before finding pll_factors.
if (freq_in > 15000000 ) {
/* update sysclk div */
reg = snd_soc_read(codec, WM8960_CLOCK1) & 0x1f9;
snd_soc_write(codec, WM8960_CLOCK1, reg | 0x4);
clk_in = clk_in/2;
}
if (freq_in && freq_out) {
ret = pll_factors(clk_in, freq_out, &pll_div);
if (ret != 0)
return ret;
}
In the driver, there are two names are important. One is the name of codec dai. The name is “wm8960”. Make sure this codec dai name is the same codec dai name used in the imx-wm8960.c.
static struct snd_soc_dai_driver wm8960_dai = {
.name = "wm8960",
.playback = {
.stream_name = "Playback",
.channels_min = 1,
.channels_max = 2,
.rates = WM8960_RATES,
.formats = WM8960_FORMATS,},
.capture = {
.stream_name = "Capture",
.channels_min = 1,
.channels_max = 2,
.rates = WM8960_RATES,
.formats = WM8960_FORMATS,},
.ops = &wm8960_dai_ops,
.symmetric_rates = 1,
};
Another name is the I2C device id. Make sure the I2C name is same as the name used in your_board.c file.
static const struct i2c_device_id wm8960_i2c_id[] = {
{ "wm8960", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, wm8960_i2c_id);
static struct i2c_driver wm8960_i2c_driver = {
.driver = {
.name = "wm8960",
.owner = THIS_MODULE,
},
.probe = wm8960_i2c_probe,
.remove = __devexit_p(wm8960_i2c_remove),
.id_table = wm8960_i2c_id,
};
Here is the name used in your_board.c
static struct i2c_board_info mxc_i2c0_board_info[] __initdata = {
{
I2C_BOARD_INFO("wm8960", 0x1a),
},
}
Machine driver imx-wm8960.c
Basically, the machine driver is the connection between wm8960.c and the i.MX.
It is modified base on the imx-wm8962.c. I didn't add the HP and MIC detection in this driver. If you need the HP and MIC detection, please take the imx-wm8962.c for reference.
Here is an example of my_board.c. The following platform data pass to the machine driver from my board.
static struct platform_device audio_wm8960_device = {
.name = "imx-wm8960",
};
static struct mxc_audio_platform_data wm8960_pdata;
static int wm8960_clk_enable(int enable)
{
if (enable)
clk_enable(clko);
else
clk_disable(clko);
return 0;
}
static int mxc_wm8960_init(void)
{
int rate;
clko = clk_get(NULL, "clko_clk");
if (IS_ERR(clko)) {
pr_err("can't get CLKO clock.\n");
return PTR_ERR(clko);
}
/* both audio codec and comera use CLKO clk*/
rate = clk_round_rate(clko, 24000000);
clk_set_rate(clko, rate);
wm8960_pdata.sysclk = rate;
return 0;
}
static struct mxc_audio_platform_data wm8960_pdata = {
.ssi_num = 1,
.src_port = 2,
.ext_port = 3,
.init = mxc_wm8960_init,
.clock_enable = wm8960_clk_enable,
};
I attach the driver and the machine driver here. I hope this document is useful for you.
