It's often the case that we would write or read a particular field in register. With the current soc_component apis, reading a particular field in register would involve first read the register and then perform shift operations.
Ex: to read from a field mask of 0xf0
val = snd_soc_component_read(component, reg); field = ((val & 0xf0) >> 0x4);
This is sometimes prone to errors and code become less readable!
With this new api we could just do field = snd_soc_component_read_field(component, reg, 0xf0);
this makes it bit simple, easy to write and less error prone!
This also applies to writing!
There are various places in kernel which provides such field interfaces however soc_component seems to be missing this.
This patch is inspired by FIELD_GET/FIELD_PREP macros in include/linux/bitfield.h
Signed-off-by: Srinivas Kandagatla srinivas.kandagatla@linaro.org --- include/sound/soc-component.h | 6 ++++ sound/soc/soc-component.c | 62 +++++++++++++++++++++++++++++++++++ 2 files changed, 68 insertions(+)
diff --git a/include/sound/soc-component.h b/include/sound/soc-component.h index 0bce41fefd30..5b47768222b7 100644 --- a/include/sound/soc-component.h +++ b/include/sound/soc-component.h @@ -353,6 +353,12 @@ int snd_soc_component_test_bits(struct snd_soc_component *component, unsigned int reg, unsigned int mask, unsigned int value);
+unsigned int snd_soc_component_read_field(struct snd_soc_component *component, + unsigned int reg, unsigned int mask); +int snd_soc_component_write_field(struct snd_soc_component *component, + unsigned int reg, unsigned int mask, + unsigned int val); + /* component wide operations */ int snd_soc_component_set_sysclk(struct snd_soc_component *component, int clk_id, int source, diff --git a/sound/soc/soc-component.c b/sound/soc/soc-component.c index 760523382f3c..6bdfc6f61ed6 100644 --- a/sound/soc/soc-component.c +++ b/sound/soc/soc-component.c @@ -12,6 +12,7 @@ #include <linux/pm_runtime.h> #include <sound/soc.h>
+#define __soc_component_field_shift(x) (__builtin_ffs(x) - 1) #define soc_component_ret(dai, ret) _soc_component_ret(dai, __func__, ret) static inline int _soc_component_ret(struct snd_soc_component *component, const char *func, int ret) @@ -839,6 +840,67 @@ int snd_soc_component_update_bits_async(struct snd_soc_component *component, } EXPORT_SYMBOL_GPL(snd_soc_component_update_bits_async);
+/** + * snd_soc_component_read_field() - Read register field value + * @component: Component to read from + * @reg: Register to read + * @mask: mask of the register field + * + * Return: read value of register field. + */ +unsigned int snd_soc_component_read_field(struct snd_soc_component *component, + unsigned int reg, unsigned int mask) +{ + unsigned int val; + + mutex_lock(&component->io_mutex); + val = soc_component_read_no_lock(component, reg); + if (mask) + val = (val & mask) >> __soc_component_field_shift(mask); + mutex_unlock(&component->io_mutex); + + return val; +} +EXPORT_SYMBOL_GPL(snd_soc_component_read_field); + +/** + * snd_soc_component_write_field() - write to register field + * @component: Component to write to + * @reg: Register to write + * @mask: mask of the register field to update + * @val: value of the field to write + * + * Return: 1 for change, otherwise 0. + */ +int snd_soc_component_write_field(struct snd_soc_component *component, + unsigned int reg, unsigned int mask, + unsigned int val) +{ + unsigned int old, new; + int ret = 0; + bool change; + + if (!mask) + return false; + + mutex_lock(&component->io_mutex); + + old = soc_component_read_no_lock(component, reg); + + val = val << __soc_component_field_shift(mask); + + new = (old & ~mask) | (val & mask); + + change = old != new; + if (change) + ret = soc_component_write_no_lock(component, reg, new); + + mutex_unlock(&component->io_mutex); + + return change; +} +EXPORT_SYMBOL_GPL(snd_soc_component_write_field); + /** * snd_soc_component_async_complete() - Ensure asynchronous I/O has completed * @component: Component for which to wait