4412 audio 分析
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文章目录
1. 音频基本概念
1.1 原理图
SOC与codec之间通信分为控制接口I2C和数据接口I2S，I2S有三个时钟信号，MCLK，BCLK，LRCLK，这三个时钟尤为重要。
1.2 IIS通信时序
1.3 了解几个概念
- 采样频率(FS)：一秒采集多少个声音“像素”，每采集一个点，左右声道切换一次，等于左右声道切换的频率，对应LRCLK
- 采样深度：一个声音点的数据宽度，一般一个声道16bit（ADC DAC精度），一个声音点32bit
- IISCLK(BCLK)：bit clk，音频采集的最小粒度，IISCLK=FS声道采样深度
- CODECLK(MCLK)：master clk，这个比较特殊，在主模式 mclk 由 soc 产生，一般为BCLK和LRCLK的整数倍，这个是soc强制要求的，别无它选。
其实soc是冤枉的，它之所以要求这个的目的，是为了满足codec的要求，比如44.1khz采样频率，采样深度16，bclk为1.4112M，codec要求MCLK=11.2896M，正好是8倍的BCLK，256倍的FS
从模式时，MCLK往往都是一颗固定频率的晶振比如24M的晶振，codec拿这个时钟通过内部的pll算出一个sysclk，频率也得是256fs等等，就是不用你soc提供了，我自己算一个。一般来说，用从模式比较好，codec内部的pll算的时钟比较精确，soc单纯靠分频来弄一个类似于11.289600MHz太难了。
2. 主从模式分析
首先来分析一下 tiny4412 网卡的硬件设计支不支持从模式，从模式时，CDCLK 也就是 codec clk 还叫 IISCLK 是什么都不接的，使用外部晶振作为mclk，
但是 tiny4412 使用的是 cdclk作为master，因为 tiny4412 不支持从模式。
3. 时钟分析
4412 音频的时钟分为三部分，第一部分系统时钟，第二部分音频子系统的时钟，第三部分IIS控制器的时钟。
3.1 Audio sub system
音频子系统的时钟输入有多个，EPLL、XXTI、SCLK_AUDIO0、还有外部输入的 cdclock，建议使用EPLL作为时钟输入，因为EPLL可以输出的时钟精度比较高，其它时钟源通过简单的分频都无法满足要求。至于输出给IIS控制器的时钟选择 audio bus clk 还是 i2sclk都可以，我在代码中使用的是 audio bus clk
代码中关于父时钟的设置，I2SCLK的父时钟可以不设置，反正我们用BUSCLK
&clock_audss
assigned-clocks = <&clock_audss EXYNOS_MOUT_AUDSS>,
<&clock_audss EXYNOS_MOUT_I2S>,
<&clock_audss EXYNOS_DOUT_SRP>,
<&clock_audss EXYNOS_DOUT_AUD_BUS>;
assigned-clock-parents = <&clock CLK_FOUT_EPLL>,
<&clock_audss EXYNOS_MOUT_AUDSS>;
;
3.2 epll
由于不同采样率的音频文件需要的mclk不同，比如44.1khz的需要11.2896M的时钟，48khz的需要12.288M的时钟，因此我们需要在代码中根据采样率，动态的调整EPLL的频率，达到最佳的播放效果，如果硬件上设计成从模式，就不用费这么大劲了。
--- a/sound/soc/samsung/i2s.c
+++ b/sound/soc/samsung/i2s.c
@@ -701,7 +701,8 @@ static int i2s_hw_params(struct snd_pcm_substream *substream,
struct i2s_dai *i2s = to_info(dai);
u32 mod, mask = 0, val = 0;
unsigned long flags;
-
+ unsigned long epll_out_rate;
+ struct clk *fout_epll;
WARN_ON(!pm_runtime_active(dai->dev));
if (!is_secondary(i2s))
@@ -780,6 +781,42 @@ static int i2s_hw_params(struct snd_pcm_substream *substream,
snd_soc_dai_init_dma_data(dai, &i2s->dma_playback, &i2s->dma_capture);
i2s->frmclk = params_rate(params);
+
+ switch (i2s->frmclk)
+ case 8000:
+ case 12000:
+ case 16000:
+ case 24000:
+ case 32000:
+ case 48000:
+ case 64000:
+ case 96000:
+ epll_out_rate = 49151992;
+ break;
+ case 11025:
+ case 22050:
+ case 44100:
+ case 88200:
+ epll_out_rate = 67737602;
+ break;
+ default:
+ printk(KERN_ERR "%s:%d Sampling Rate %u not supported!\\n",
+ __func__, __LINE__, i2s->frmclk);
+ return -EINVAL;
+
+
+ fout_epll = devm_clk_get(dai->dev, "fout_epll");
+ if(IS_ERR(fout_epll))
+ printk("get fout_epll err\\n");
+
+
+ if (clk_get_rate(fout_epll) != epll_out_rate)
+ if(clk_set_rate(fout_epll, epll_out_rate) != 0)
+ printk("set epll rate err\\n");
+
+
+ i2s_set_sysclk(dai, SAMSUNG_I2S_CDCLK, 0, SND_SOC_CLOCK_OUT);
+ i2s->rclk_srcrate = clk_get_rate(i2s->op_clk);
return 0;
49151992 和 67737602 是所需频率的整数倍的近似值，为什么只是近似值呢？因为EPLL能输出的范围也是有限的，EPLL在内核里是以一个Table的形式注册的
static const struct samsung_pll_rate_table exynos4210_epll_rates[] __initconst =
PLL_4600_RATE(192000000, 48, 3, 1, 0, 0),
PLL_4600_RATE(180633605, 45, 3, 1, 10381, 0),
PLL_4600_RATE(180000000, 45, 3, 1, 0, 0),
PLL_4600_RATE( 73727996, 73, 3, 3, 47710, 1),
PLL_4600_RATE( 67737602, 90, 4, 3, 20762, 1),
PLL_4600_RATE( 49151992, 49, 3, 3, 9961, 0),
PLL_4600_RATE( 45158401, 45, 3, 3, 10381, 0),
/* sentinel */
;
如果你clk_set_rate设置的值不在Table里，那么就会被设置成相邻的值，差距很大！！
3.3 IIS
IIS 这里有一个父时钟的选择，以及分频系数的计算，audio sub system 里边的分频器值都是默认值不分频，所以这里的输入时钟就等于EPLL的时钟
当然，为了保险起见，还是i2s->rclk_srcrate = clk_get_rate(i2s->op_clk);获取时钟频率
设置父时钟是在set_sysclk函数中，根据clk_id进行设置
case SAMSUNG_I2S_RCLKSRC_0: /* clock corrsponding to IISMOD[10] := 0 */
case SAMSUNG_I2S_RCLKSRC_1: /* clock corrsponding to IISMOD[10] := 1 */
mask = 1 << i2s_regs->rclksrc_off;
if ((i2s->quirks & QUIRK_NO_MUXPSR)
|| (clk_id == SAMSUNG_I2S_RCLKSRC_0))
clk_id = 0;
else
clk_id = 1;
if (!any_active(i2s))
if (i2s->op_clk && !IS_ERR(i2s->op_clk))
if ((clk_id && !(mod & rsrc_mask)) ||
(!clk_id && (mod & rsrc_mask)))
clk_disable_unprepare(i2s->op_clk);
clk_put(i2s->op_clk);
else
i2s->rclk_srcrate =
clk_get_rate(i2s->op_clk);
goto done;
if (clk_id)
i2s->op_clk = clk_get(&i2s->pdev->dev,
"i2s_opclk1");
else
i2s->op_clk = clk_get(&i2s->pdev->dev,
"i2s_opclk0");
SAMSUNG_I2S_RCLKSRC_0 的值为0，在 simple_card 中误打误撞设置了父时钟为BUSCLK
int asoc_simple_card_init_dai(struct snd_soc_dai *dai,
struct asoc_simple_dai *simple_dai)
int ret;
if (simple_dai->sysclk)
ret = snd_soc_dai_set_sysclk(dai, 0, simple_dai->sysclk,
simple_dai->clk_direction);
if (ret && ret != -ENOTSUPP)
dev_err(dai->dev, "simple-card: set_sysclk error\\n");
return ret;
关于分频系数的设置默认是在i2s.c config_setup中，这里没有改动，整个音频部分的改动如下
4. 修改记录
From 579b374467fe9085777ffd1cc0fb70f32376efbf Mon Sep 17 00:00:00 2001
From: lizuobin <271526143@qq.com>
Date: Tue, 7 Aug 2018 22:51:47 +0800
Subject: [PATCH] 4412:wm8960
---
arch/arm/boot/dts/exynos4.dtsi | 5 +-
arch/arm/boot/dts/exynos4412-tiny4412.dts | 95 +++++++++++++++++++++++++++----
arch/arm/configs/exynos_defconfig | 10 +++-
sound/soc/codecs/wm8960.c | 18 ++++--
sound/soc/samsung/i2s.c | 39 ++++++++++++-
5 files changed, 144 insertions(+), 23 deletions(-)
diff --git a/arch/arm/boot/dts/exynos4.dtsi b/arch/arm/boot/dts/exynos4.dtsi
index 6d59cc8..d740d1d 100644
--- a/arch/arm/boot/dts/exynos4.dtsi
+++ b/arch/arm/boot/dts/exynos4.dtsi
@@ -66,8 +66,9 @@
reg = <0x03830000 0x100>;
clocks = <&clock_audss EXYNOS_I2S_BUS>,
<&clock_audss EXYNOS_DOUT_AUD_BUS>,
- <&clock_audss EXYNOS_SCLK_I2S>;
- clock-names = "iis", "i2s_opclk0", "i2s_opclk1";
+ <&clock_audss EXYNOS_SCLK_I2S>,
+ <&clock CLK_FOUT_EPLL>;
+ clock-names = "iis", "i2s_opclk0", "i2s_opclk1", "fout_epll";
#clock-cells = <1>;
clock-output-names = "i2s_cdclk0";
dmas = <&pdma0 12>, <&pdma0 11>, <&pdma0 10>;
diff --git a/arch/arm/boot/dts/exynos4412-tiny4412.dts b/arch/arm/boot/dts/exynos4412-tiny4412.dts
index bc0862f..587095f 100644
--- a/arch/arm/boot/dts/exynos4412-tiny4412.dts
+++ b/arch/arm/boot/dts/exynos4412-tiny4412.dts
@@ -14,6 +14,7 @@
/dts-v1/;
#include "exynos4412.dtsi"
#include <dt-bindings/gpio/gpio.h>
+#include <dt-bindings/sound/samsung-i2s.h>
/
model = "FriendlyARM TINY4412 board based on Exynos4412";
@@ -99,6 +100,88 @@
;
;
;
+
+ sound
+ compatible = "simple-audio-card";
+ simple-audio-card,name = "wm-sound";
+
+ simple-audio-card,format = "i2s";
+ simple-audio-card,bitclock-master = <&cpu>;
+ simple-audio-card,frame-master = <&cpu>;
+
+ simple-audio-card,widgets =
+ "Microphone", "Mic Jack",
+ "Line", "Line In",
+ "Line", "Line Out",
+ "Speaker", "Speaker",
+ "Headphone", "Headphone Jack";
+ simple-audio-card,routing =
+ "Headphone Jack", "HP_L",
+ "Headphone Jack", "HP_R",
+ "Speaker", "SPK_LP",
+ "Speaker", "SPK_LN",
+ "Speaker", "SPK_RP",
+ "Speaker", "SPK_RN",
+ "LINPUT1", "Mic Jack",
+ "LINPUT3", "Mic Jack",
+ "RINPUT1", "Mic Jack",
+ "RINPUT2", "Mic Jack";
+
+ cpu: simple-audio-card,cpu
+ sound-dai = <&i2s0 0>;
+ ;
+
+ link0_codec: simple-audio-card,codec
+ sound-dai = <&codec>;
+ clocks = <&i2s0 CLK_I2S_CDCLK>;
+ ;
+ ;
+
+ xrtcxti: xrtcxti
+ compatible = "fixed-clock";
+ clock-frequency = <32768>;
+ clock-output-names = "xrtcxti";
+ #clock-cells = <0>;
+ ;
+
+;
+
+&clock_audss
+ assigned-clocks = <&clock_audss EXYNOS_MOUT_AUDSS>,
+ <&clock_audss EXYNOS_MOUT_I2S>,
+ <&clock_audss EXYNOS_DOUT_SRP>,
+ <&clock_audss EXYNOS_DOUT_AUD_BUS>;
+ assigned-clock-parents = <&clock CLK_FOUT_EPLL>,
+ <&clock_audss EXYNOS_MOUT_AUDSS>;
+;
+
+&i2s0
+ pinctrl-0 = <&i2s0_bus>;
+ pinctrl-names = "default";
+ status = "okay";
+;
+
+&rtc
+ clocks = <&clock CLK_RTC>, <&xrtcxti>;
+ clock-names = "rtc","rtc_src";
+ status = "okay";
+;
+
+&i2c_0
+ #address-cells = <1>;
+ #size-cells = <0>;
+ samsung,i2c-sda-delay = <100>;
+ samsung,i2c-max-bus-freq = <100000>;
+ pinctrl-0 = <&i2c0_bus>;
+ pinctrl-names = "default";
+ status = "okay";
+
+ codec: wm8960@1a
+ compatible = "wlf,wm8960";
+ reg = <0x1a>;
+ #sound-dai-cells = <0>;
+ ;
;
&i2c_1
@@ -139,10 +222,6 @@
;
;
-&rtc
- status = "okay";
-;
-
&mshc_0
status = "okay";
non-removable;
;
diff --git a/arch/arm/configs/exynos_defconfig b/arch/arm/configs/exynos_defconfig
index 7f10b66..ef37909 100644
--- a/arch/arm/configs/exynos_defconfig
+++ b/arch/arm/configs/exynos_defconfig
@@ -2711,7 +2711,8 @@ CONFIG_LOGO_LINUX_MONO=y
CONFIG_LOGO_LINUX_VGA16=y
CONFIG_LOGO_LINUX_CLUT224=y
CONFIG_SOUND=y
-# CONFIG_SOUND_OSS_CORE is not set
+CONFIG_SOUND_OSS_CORE=y
+CONFIG_SOUND_OSS_CORE_PRECLAIM=y
CONFIG_SND=y
CONFIG_SND_TIMER=y
CONFIG_SND_PCM=y
@@ -2720,7 +2721,10 @@ CONFIG_SND_PCM_IEC958=y
CONFIG_SND_DMAENGINE_PCM=y
CONFIG_SND_JACK=y
CONFIG_SND_JACK_INPUT_DEV=y
-# CONFIG_SND_OSSEMUL is not set
+CONFIG_SND_OSSEMUL=y
+CONFIG_SND_MIXER_OSS=y
+CONFIG_SND_PCM_OSS=y
+CONFIG_SND_PCM_OSS_PLUGINS=y
CONFIG_SND_PCM_TIMER=y
# CONFIG_SND_HRTIMER is not set
# CONFIG_SND_DYNAMIC_MINORS is not set
@@ -2896,7 +2900,7 @@ CONFIG_SND_SOC_MAX98095=y
# CONFIG_SND_SOC_WM8804_I2C is not set
# CONFIG_SND_SOC_WM8804_SPI is not set
# CONFIG_SND_SOC_WM8903 is not set
-# CONFIG_SND_SOC_WM8960 is not set
+CONFIG_SND_SOC_WM8960=y
# CONFIG_SND_SOC_WM8962 is not set
# CONFIG_SND_SOC_WM8974 is not set
# CONFIG_SND_SOC_WM8978 is not set
diff --git a/sound/soc/codecs/wm8960.c b/sound/soc/codecs/wm8960.c
index 9ed4557..6fa1a6f 100644
--- a/sound/soc/codecs/wm8960.c
+++ b/sound/soc/codecs/wm8960.c
@@ -1396,6 +1396,7 @@ static int wm8960_i2c_probe(struct i2c_client *i2c,
struct wm8960_data *pdata = dev_get_platdata(&i2c->dev);
struct wm8960_priv *wm8960;
int ret;
+ int retry;
wm8960 = devm_kzalloc(&i2c->dev, sizeof(struct wm8960_priv),
GFP_KERNEL);
@@ -1417,12 +1418,19 @@ static int wm8960_i2c_probe(struct i2c_client *i2c,
else if (i2c->dev.of_node)
wm8960_set_pdata_from_of(i2c, &wm8960->pdata);
- ret = wm8960_reset(wm8960->regmap);
- if (ret != 0)
- dev_err(&i2c->dev, "Failed to issue reset\\n");
- return ret;
+ for (retry = 0; retry < 5; retry++)
+ ret = wm8960_reset(wm8960->regmap);
+ if (ret != 0)
+ if (retry == 5)
+ dev_err(&i2c->dev, "Failed to issue reset\\n");
+ return ret;
+
+
+ else
+ break;
+
-
+
if (wm8960->pdata.shared_lrclk)
ret = regmap_update_bits(wm8960->regmap, WM8960_ADDCTL2,
0x4, 0x4);
diff --git a/sound/soc/samsung/i2s.c b/sound/soc/samsung/i2s.c
index aeba0ae..9d6ee86 100644
--- a/sound/soc/samsung/i2s.c
+++ b/sound/soc/samsung/i2s.c
@@ -701,7 +701,8 @@ static int i2s_hw_params(struct snd_pcm_substream *substream,
struct i2s_dai *i2s = to_info(dai);
u32 mod, mask = 0, val = 0;
unsigned long flags;
-
+ unsigned long epll_out_rate;
+ struct clk *fout_epll;
WARN_ON(!pm_runtime_active(dai->dev));
if (!is_secondary(i2s))
@@ -780,6 +781,42 @@ static int i2s_hw_params(struct snd_pcm_substream *substream,
snd_soc_dai_init_dma_data(dai, &i2s->dma_playback, &i2s->dma_capture);
i2s->frmclk = params_rate(params);
+
+ switch (i2s->frmclk)
+ case 8000:
+ case 12000:
+ case 16000:
+ case 24000:
+ case 32000:
+ case 48000:
+ case 64000:
+ case 96000:
+ epll_out_rate = 49151992;
+ break;
+ case 11025:
+ case 22050:
+ case 44100:
+ case 88200:
+ epll_out_rate = 67737602;
+ break;
+ default:
+ printk(KERN_ERR "%s:%d Sampling Rate %u not supported!\\n",
+ __func__, __LINE__, i2s->frmclk);
+ return -EINVAL;
+
+
+ fout_epll = devm_clk_get(dai->dev, "fout_epll");
+ if(IS_ERR(fout_epll))
+ printk("get fout_epll err\\n");
+
+
+ if (clk_get_rate(fout_epll) != epll_out_rate)
+ if(clk_set_rate(fout_epll, epll_out_rate) != 0)
+ printk("set epll rate err\\n");
+
+
+ i2s_set_sysclk(dai, SAMSUNG_I2S_CDCLK, 0, SND_SOC_CLOCK_OUT);
+ i2s->rclk_srcrate = clk_get_rate(i2s->op_clk);
return 0;
--
1.9.1
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