ASoC: soc-cache: Add support for default readable()/volatile() functions

For common scenarios, device drivers can provide a table of all the
registers that are at least either readable/writable/volatile.  The idea
is that if a register lookup fails, all of its read/write/vol members
will be zero and will be treated as default.  This also reduces the
size of the register access array.

Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

2 files changed, 71 insertions, 0 deletions

diff --git a/include/sound/soc.h b/include/sound/soc.h
index d609232da82a..b8acf99ac89d 100644
--- a/include/sound/soc.h
+++ b/include/sound/soc.h
@@ -276,6 +276,10 @@ int snd_soc_cache_write(struct snd_soc_codec *codec,
                         unsigned int reg, unsigned int value);
 int snd_soc_cache_read(struct snd_soc_codec *codec,
                        unsigned int reg, unsigned int *value);
+int snd_soc_default_volatile_register(struct snd_soc_codec *codec,
+                                      unsigned int reg);
+int snd_soc_default_readable_register(struct snd_soc_codec *codec,
+                                      unsigned int reg);
 
 /* Utility functions to get clock rates from various things */
 int snd_soc_calc_frame_size(int sample_size, int channels, int tdm_slots);
@@ -367,6 +371,22 @@ int snd_soc_put_volsw_2r_sx(struct snd_kcontrol *kcontrol,
         struct snd_ctl_elem_value *ucontrol);
 
 /**
+ * struct snd_soc_reg_access - Describes whether a given register is
+ * readable, writable or volatile.
+ *
+ * @reg: the register number
+ * @read: whether this register is readable
+ * @write: whether this register is writable
+ * @vol: whether this register is volatile
+ */
+struct snd_soc_reg_access {
+        u16 reg;
+        u16 read;
+        u16 write;
+        u16 vol;
+};
+
+/**
  * struct snd_soc_jack_pin - Describes a pin to update based on jack detection
  *
  * @pin:    name of the pin to update
@@ -515,6 +535,8 @@ struct snd_soc_codec_driver {
         short reg_cache_step;
         short reg_word_size;
         const void *reg_cache_default;
+        short reg_access_size;
+        const struct snd_soc_reg_access *reg_access_default;
         enum snd_soc_compress_type compress_type;
 
         /* codec bias level */
diff --git a/sound/soc/soc-cache.c b/sound/soc/soc-cache.c
index 1a36b36c5baa..d97a59f6a249 100644
--- a/sound/soc/soc-cache.c
+++ b/sound/soc/soc-cache.c
@@ -1603,3 +1603,52 @@ int snd_soc_cache_sync(struct snd_soc_codec *codec)
         return -EINVAL;
 }
 EXPORT_SYMBOL_GPL(snd_soc_cache_sync);
+
+static int snd_soc_get_reg_access_index(struct snd_soc_codec *codec,
+                                        unsigned int reg)
+{
+        const struct snd_soc_codec_driver *codec_drv;
+        unsigned int min, max, index;
+
+        codec_drv = codec->driver;
+        min = 0;
+        max = codec_drv->reg_access_size - 1;
+        do {
+                index = (min + max) / 2;
+                if (codec_drv->reg_access_default[index].reg == reg)
+                        return index;
+                if (codec_drv->reg_access_default[index].reg < reg)
+                        min = index + 1;
+                else
+                        max = index;
+        } while (min <= max);
+        return -1;
+}
+
+int snd_soc_default_volatile_register(struct snd_soc_codec *codec,
+                                      unsigned int reg)
+{
+        int index;
+
+        if (reg >= codec->driver->reg_cache_size)
+                return 1;
+        index = snd_soc_get_reg_access_index(codec, reg);
+        if (index < 0)
+                return 0;
+        return codec->driver->reg_access_default[index].vol;
+}
+EXPORT_SYMBOL_GPL(snd_soc_default_volatile_register);
+
+int snd_soc_default_readable_register(struct snd_soc_codec *codec,
+                                      unsigned int reg)
+{
+        int index;
+
+        if (reg >= codec->driver->reg_cache_size)
+                return 1;
+        index = snd_soc_get_reg_access_index(codec, reg);
+        if (index < 0)
+                return 0;
+        return codec->driver->reg_access_default[index].read;
+}
+EXPORT_SYMBOL_GPL(snd_soc_default_readable_register);