[Linux Audio Driver] 移植外部CODEC常见编译报错解决（持续更新）

0. 背景

最近一直在调试codec芯片，好多代码FAE给的和平台不适配，比如结构体改了之类的，一些编译问题老是忘记，就想着顺手写下总结。

1. function definition is not allowed here

error: function definition is not allowed here

好家伙，它说函数不能够在这里定义。网上看了一下，这个报错的原因是在函数原型里面又定义了一个函数，这个地方不一样啊。

回头看下函数报错的位置，这里for循环的括号丢了一个，添上即可。

（其他还有类似报错，但是 发生在报错函数的前一个函数少一个括号-_-）。

这玩意会带来一系列报错，改一个就改好好多报错。

2. extraneous ‘)’ before ‘;’

627:109: error: extraneous ')' before ';'

这个报错说有个括号很突兀，不晓得哪里来的，extraneous是外来的意思。

然后看了下，发现多了一个括号。

3. no member named ‘codec’ in 'struct snd_soc_dai

这个报错是说，snd_soc_dai结构体里面缺少成员变量codec，

好家伙，我发现这个snd_soc_codec结构体在android 11直接被干没了。 之前在msm-3.18 、 android 7是有的，如下：

grep -nr "struct snd_soc_codec {"  ./kernel/msm-3.18/

  /* SoC Audio Codec device */
  struct snd_soc_codec {
      struct device *dev;
      const struct snd_soc_codec_driver *driver;
 
      struct mutex mutex;
      struct list_head list;
      struct list_head card_list;
      int (*volatile_register)(struct snd_soc_codec *, unsigned int);
      int (*readable_register)(struct snd_soc_codec *, unsigned int);
      int (*writable_register)(struct snd_soc_codec *, unsigned int);
 
      /* runtime */
      struct snd_ac97 *ac97;  /* for ad-hoc ac97 devices */
      unsigned int cache_bypass:1; /* Suppress access to the cache */
      unsigned int suspended:1; /* Codec is in suspend PM state */
      unsigned int ac97_registered:1; /* Codec has been AC97 registered */
      unsigned int ac97_created:1; /* Codec has been created by SoC */
      unsigned int cache_init:1; /* codec cache has been initialized */
      u32 cache_sync; /* Cache needs to be synced to hardware */
 
      /* codec IO */
      void *control_data; /* codec control (i2c/3wire) data */
      hw_write_t hw_write;
      void *reg_cache;
      struct mutex cache_rw_mutex;
 
      /* component */
      struct snd_soc_component component;
 
      /* dapm */
      struct snd_soc_dapm_context dapm;
 
  #ifdef CONFIG_DEBUG_FS
      struct dentry *debugfs_reg;
  #endif
  };

仔细看了下代码，发现这个报错的地方就是根据dai（传进来的参数），找到codec，然后根据codec找到es7210结构体，目的是根据es7210->pcm_pop_work1的地址传参给schedule_delayed_work这个延迟队列，看了下pcm_pop_work1函数是处理POP音的，目前代码还在移植阶段，干脆简单粗暴把这个几个都注释掉：

4. warning: ISO C90 forbids mixing declarations and code [-Wdeclaration-after-statement] error

995:6: warning: ISO C90 forbids mixing declarations and code

这个错误真的无力吐槽，也不知道哪个兄弟写的代码…这个要把int i放在前面。

5. implicit declaration of function ‘snd_soc_codec_get_drvdata’ [-Werror,-Wimplicit-function-declaration]

error: implicit declaration of function 'snd_soc_codec_get_drvdata' [-Werror,-Wimplicit-function-declaration]

这里又用到了snd_soc_codec结构体，这里看起来绕不掉了，因为es7210_tdm_init_codec这个函数看起来比较重要。

于是想着看看平台默认的codec驱动是咋搞的，看了下snd_soc_component结构体与snd_soc_codec类似，于是决定全面改写代码，把传参struct snd_soc_codec *codec全部干掉，换成struct snd_soc_component *component。

6. implicit declaration of function 'snd_soc_unregister_codec

.c:2187:2: error: implicit declaration of function 'snd_soc_unregister_codec' 
[-Werror,-Wimplicit-function-declaration]

snd_soc_unregister_codec这个函数也木得，（后面直接用SI看了，不grep了)，还是看了下平台的codec芯片代码，
发现应该是用snd_soc_unregister_component函数。

同样，snd_soc_register_codec这个函数也木有了，我们替换成snd_soc_register_component。

7. use of undeclared identifier ‘GPIO_HIGH’

 error: use of undeclared identifier 'GPIO_HIGH'

这个都不用看，直接把宏定义放在代码前面即可。

#define GPIO_LOW 0
#define GPIO_HIGH 1

8. no member named ‘power_enable_gpio’ in ‘struct es7210_priv’

error: no member named 'power_enable_gpio' in 'struct es7210_priv'

struct es7210_priv {
	struct regmap *regmap;
	struct device *dev;
	struct i2c_client *i2c;
	unsigned int sysclk;
	struct clk *mclk;
	struct snd_pcm_hw_constraint_list *sysclk_constraints;
	unsigned int tdm_mode;
	struct delayed_work pcm_pop_work;
	struct delayed_work pcm_pop_work1;
	//struct delayed_work es7243_init_work;
	struct voltage_supply vol_supply;
	int power_enable_gpio;
};

这个没啥说的，成员变量power_enable_gpio没有，那就加上。

9. use of undeclared identifier ‘np’

error: implicit declaration of function 'gpio_is_valid' 
[-Werror,-Wimplicit-function-declaration]
        if (!gpio_is_valid(es7210->power_enable_gpio)){

看下 of_get_named_gpio的函数原型：

static inline int of_get_named_gpio(struct device_node *np,
                                   const char *propname, int index)
{
	return of_get_named_gpio_flags(np, propname, index, NULL);
}

kernel\msm-4.19\include\linux\of_gpio.h

于是给它加上文件头。

#include <linux/of_gpio.h>

10. variable has incomplete type ‘struct snd_soc_codec_driver’

snd_soc_codec_driver这个结构体没有，看看对比的codec驱动咋搞的。。

把他换成snd_soc_component_driver。

11. implicit declaration of function ‘gpio_direction_output’ [-Werror,-Wimplicit-function-declaration]

error: implicit declaration of function 'gpio_free' 
[-Werror,-Wimplicit-function-declaration] ，gpio_free(es7210->power_enable_gpio);

这个报错前后看了下没啥异常的，原因是没有包含文件头，gpio.h，这个在代码开头添上即可：

#include <linux/gpio.h>

12. incompatible pointer types initializing ‘void (*)(struct snd_soc_component *)’ with an expression of type ‘int (struct snd_soc_component *)’ [-Werror,-Wincompatible-pointer-types]

error: incompatible pointer types initializing 'void (*)(struct snd_soc_component *)' 
with an expression of type 'int (struct snd_soc_component *)' [-Werror,-Wincompatible-pointer-types]
        .remove = es7210_remove,

这个地方报错得看下snd_soc_component_driver结构体，从报错来看应该是定义的结构体成员变量类型不匹配，

所以我们要调整下函数：es7210_remove

static int es7210_remove(struct snd_soc_component *component)
{
	return 0;
}

修改为：

static void es7210_remove(struct snd_soc_component *component)
{
	return ;
}

13. field designator ‘reg_word_size’ does not refer to any field in type ‘struct snd_soc_component_driver’

error: field designator 'reg_word_size' does not refer to any field in type 
'struct snd_soc_component_driver'
.reg_word_size = sizeof(u8),

/* component interface */

struct snd_soc_component_driver {
	const char *name;

	/* Default control and setup, added after probe() is run */
	const struct snd_kcontrol_new *controls;
	unsigned int num_controls;
	const struct snd_soc_dapm_widget *dapm_widgets;
	unsigned int num_dapm_widgets;
	const struct snd_soc_dapm_route *dapm_routes;
	unsigned int num_dapm_routes;

	int (*probe)(struct snd_soc_component *);
	void (*remove)(struct snd_soc_component *);
	int (*suspend)(struct snd_soc_component *);
	int (*resume)(struct snd_soc_component *);

	unsigned int (*read)(struct snd_soc_component *, unsigned int);
	int (*write)(struct snd_soc_component *, unsigned int, unsigned int);

	/* pcm creation and destruction */
	int (*pcm_new)(struct snd_soc_pcm_runtime *);
	void (*pcm_free)(struct snd_pcm *);

	/* component wide operations */
	int (*set_sysclk)(struct snd_soc_component *component,
			  int clk_id, int source, unsigned int freq, int dir);
	int (*set_pll)(struct snd_soc_component *component, int pll_id,
		       int source, unsigned int freq_in, unsigned int freq_out);
	int (*set_jack)(struct snd_soc_component *component,
			struct snd_soc_jack *jack,  void *data);

	/* DT */
	int (*of_xlate_dai_name)(struct snd_soc_component *component,
				 struct of_phandle_args *args,
				 const char **dai_name);
	int (*of_xlate_dai_id)(struct snd_soc_component *comment,
			       struct device_node *endpoint);
	void (*seq_notifier)(struct snd_soc_component *, enum snd_soc_dapm_type,
		int subseq);
	int (*stream_event)(struct snd_soc_component *, int event);
	int (*set_bias_level)(struct snd_soc_component *component,
			      enum snd_soc_bias_level level);

	/*
	 * For platform-caused delay reporting, where the thread blocks waiting
	 * for the delay amount to be determined.  Defining this will cause the
	 * ASoC core to skip calling the delay callbacks for all components in
	 * the runtime.
	 * Optional.
	 */
	snd_pcm_sframes_t (*delay_blk)(struct snd_pcm_substream *substream,
			struct snd_soc_dai *dai);

	const struct snd_pcm_ops *ops;
	const struct snd_compr_ops *compr_ops;

	/* probe ordering - for components with runtime dependencies */
	int probe_order;
	int remove_order;

	/* bits */
	unsigned int idle_bias_on:1;
	unsigned int suspend_bias_off:1;
	unsigned int use_pmdown_time:1; /* care pmdown_time at stop */
	unsigned int endianness:1;
	unsigned int non_legacy_dai_naming:1;

	/* this component uses topology and ignore machine driver FEs */
	const char *ignore_machine;
	const char *topology_name_prefix;
	int (*be_hw_params_fixup)(struct snd_soc_pcm_runtime *rtd,
				  struct snd_pcm_hw_params *params);
	bool use_dai_pcm_id;	/* use the DAI link PCM ID as PCM device number */
	int be_pcm_base;	/* base device ID for all BE PCMs */
};

看了下结构体的成员变量，这个里面没有reg_word_size，那就给它加上，.reg_word_size = sizeof(u8),这个给它整个short就足够了，

unsigned int (*read)(struct snd_soc_component *, unsigned int);
int (*write)(struct snd_soc_component *, unsigned int, unsigned int);
+ short reg_word_size;
/* pcm creation and destruction */
int (*pcm_new)(struct snd_soc_pcm_runtime *);

14. ‘reg_cache_default’ does not refer to any field in type ‘struct snd_soc_component_driver’

.reg_cache_default = es7210_reg_defaults,

这个也是结构体的成员变量里面没有，它指向的是结构体数组的地址，所以使用unsigned long int，

unsigned long int reg_cache_default;

结果还是类型不匹配-_-，这样改了下就好了：

const struct reg_default *reg_cache_default;

15. field designator ‘reg_cache_size’ does not refer to any field in type ‘struct snd_soc_component_driver’

error: field designator 'reg_cache_size' does not refer to any field in 
type 'struct snd_soc_component_driver'
        .reg_cache_size = ARRAY_SIZE(es7210_reg_defaults),

#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))

从这个宏定义来看，我给它一个整型，

unsigned int reg_cache_size;

16.field designator ‘component_driver’ does not refer to any field in type 'struct snd_soc_component_driver

它这个是结构体里面又嵌入了一个结构体，这个操作很简单，因为默认的结构里里面是有：controls和num_controls
的：

所以修改如下：

17.implicit declaration of function ‘of_get_named_gpio’ [-Werror,-Wimplicit-function-declaration]

implicit declaration of function 'of_get_named_gpio' [-Werror,-Wimplicit-function-declaration]
power_enable_gpio = of_get_named_gpio(np, "es7210,power-enable-gpio", 0);

这个函数原型：of_get_named_gpio，用SI看了下在：

kernel\msm-4.19\include\linux\of_gpio.h

所以加上文件头：

#include <linux/of_gpio.h>

18. unused function ‘es7210_multi_chips_write’

 warning: unused function 'es7210_multi_chips_write' [-Wunused-function]
 error, forbidden warning:

代码被调用的地方，默认全部被注释了，所以直接把这个函数也注释了即可。

好家伙，我解了50-60个编译报错，终于编过去了。