[RFC v2] ASoC: core: add a helper for extended byte controls using TLV

[RFC v2] ASoC: core: add a helper for extended byte controls using TLV

[Vinod Koul]

From: Omair Mohammed Abdullah <omair.m.abdullah@intel.com>

ALSA supports arbitrary length TLVs for each kcontrol that can be used
to pass metadata about the control (e.g. volumes, enum information). The
same transport mechanism is now used for arbitrary length data by
defining a new helper.

Signed-off-by: Omair Mohammed Abdullah <omair.m.abdullah@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
---
As discussed in [1] we are adding a new approach to solve the byte control
extensions by using existing TLVs and combining them with byte controls.  The
usermode on seeing byte control + TLV can treat it differently as it does for
control + TLV combination today. This way we don't change kernel API and
existing users will be happy, while providing embedded folks facility to pass
large bytes data to kcontrols
[1]:
http://mailman.alsa-project.org/pipermail/alsa-devel/2013-November/069483.html

 include/sound/soc.h  |   14 +++++++++++++-
 sound/soc/soc-core.c |   22 ++++++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletions(-)

diff --git a/include/sound/soc.h b/include/sound/soc.h
index ed9e2d7..7522221 100644
--- a/include/sound/soc.h
+++ b/include/sound/soc.h
@@ -270,7 +270,14 @@
 	.get = xhandler_get, .put = xhandler_put, \
 	.private_value = (unsigned long)&(struct soc_bytes_ext) \
 		{.max = xcount} }
-
+#define SND_SOC_BYTES_TLV(xname, xcount, xhandler_get, xhandler_put) \
+{	.iface = SNDRV_CTL_ELEM_IFACE_MIXER, .name = xname, \
+	.access = SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE | \
+		  SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK, \
+	.tlv.c = (snd_soc_bytes_tlv_callback), \
+	.info = snd_soc_info_bytes_ext, \
+	.private_value = (unsigned long)&(struct soc_bytes_ext) \
+		{.max = xcount, .get = xhandler_get, .put = xhandler_put, }}
 #define SOC_SINGLE_XR_SX(xname, xregbase, xregcount, xnbits, \
 		xmin, xmax, xinvert) \
 {	.iface = SNDRV_CTL_ELEM_IFACE_MIXER, .name = (xname), \
@@ -552,6 +559,8 @@ int snd_soc_bytes_put(struct snd_kcontrol *kcontrol,
 		      struct snd_ctl_elem_value *ucontrol);
 int snd_soc_bytes_info_ext(struct snd_kcontrol *kcontrol,
 	struct snd_ctl_elem_info *ucontrol);
+int snd_soc_bytes_tlv_callback(struct snd_kcontrol *kcontrol, int op_flag,
+	unsigned int size, unsigned int __user *tlv);
 int snd_soc_info_xr_sx(struct snd_kcontrol *kcontrol,
 	struct snd_ctl_elem_info *uinfo);
 int snd_soc_get_xr_sx(struct snd_kcontrol *kcontrol,
@@ -1119,6 +1128,9 @@ struct soc_bytes {
 
 struct soc_bytes_ext {
 	int max;
+	/* used for TLV byte control */
+	int (*get)(unsigned int __user *bytes, unsigned int size);
+	int (*put)(const unsigned int __user *bytes, unsigned int size);
 };
 
 /* multi register control */
diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index b87d7d8..e6ad95b 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -3267,6 +3267,28 @@ int snd_soc_bytes_info_ext(struct snd_kcontrol *kcontrol,
 }
 EXPORT_SYMBOL_GPL(snd_soc_bytes_info_ext);
 
+int snd_soc_bytes_tlv_callback(struct snd_kcontrol *kcontrol, int op_flag,
+				unsigned int size, unsigned int __user *tlv)
+{
+	struct soc_bytes_ext *params = (void *)kcontrol->private_value;
+	unsigned int count = size < params->max ? size : params->max;
+
+	switch (op_flag) {
+	case 0:
+		if (params->get)
+			params->get(tlv, count);
+		break;
+	case 1:
+		if (params->put)
+			params->put(tlv, count);
+		break;
+	default:
+		return -ENXIO;
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(snd_soc_bytes_tlv_callback);
+
 /**
  * snd_soc_info_xr_sx - signed multi register info callback
  * @kcontrol: mreg control
-- 
1.7.0.4

Re: [RFC v2] ASoC: core: add a helper for extended byte controls using TLV

[Takashi Iwai]

At Tue, 15 Jul 2014 12:17:45 +0530,
Vinod Koul wrote:
> 
> From: Omair Mohammed Abdullah <omair.m.abdullah@intel.com>
> 
> ALSA supports arbitrary length TLVs for each kcontrol that can be used
> to pass metadata about the control (e.g. volumes, enum information). The
> same transport mechanism is now used for arbitrary length data by
> defining a new helper.
> 
> Signed-off-by: Omair Mohammed Abdullah <omair.m.abdullah@intel.com>
> Signed-off-by: Vinod Koul <vinod.koul@intel.com>
> ---
> As discussed in [1] we are adding a new approach to solve the byte control
> extensions by using existing TLVs and combining them with byte controls.  The
> usermode on seeing byte control + TLV can treat it differently as it does for
> control + TLV combination today. This way we don't change kernel API and
> existing users will be happy, while providing embedded folks facility to pass
> large bytes data to kcontrols
> [1]:
> http://mailman.alsa-project.org/pipermail/alsa-devel/2013-November/069483.html

Yeah, this would bypass the limitation nicely.
Small nitpicking:

> 
>  include/sound/soc.h  |   14 +++++++++++++-
>  sound/soc/soc-core.c |   22 ++++++++++++++++++++++
>  2 files changed, 35 insertions(+), 1 deletions(-)
> 
> diff --git a/include/sound/soc.h b/include/sound/soc.h
> index ed9e2d7..7522221 100644
> --- a/include/sound/soc.h
> +++ b/include/sound/soc.h
> @@ -270,7 +270,14 @@
>  	.get = xhandler_get, .put = xhandler_put, \
>  	.private_value = (unsigned long)&(struct soc_bytes_ext) \
>  		{.max = xcount} }
> -
> +#define SND_SOC_BYTES_TLV(xname, xcount, xhandler_get, xhandler_put) \
> +{	.iface = SNDRV_CTL_ELEM_IFACE_MIXER, .name = xname, \
> +	.access = SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE | \
> +		  SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK, \
> +	.tlv.c = (snd_soc_bytes_tlv_callback), \
> +	.info = snd_soc_info_bytes_ext, \
> +	.private_value = (unsigned long)&(struct soc_bytes_ext) \
> +		{.max = xcount, .get = xhandler_get, .put = xhandler_put, }}
>  #define SOC_SINGLE_XR_SX(xname, xregbase, xregcount, xnbits, \
>  		xmin, xmax, xinvert) \
>  {	.iface = SNDRV_CTL_ELEM_IFACE_MIXER, .name = (xname), \
> @@ -552,6 +559,8 @@ int snd_soc_bytes_put(struct snd_kcontrol *kcontrol,
>  		      struct snd_ctl_elem_value *ucontrol);
>  int snd_soc_bytes_info_ext(struct snd_kcontrol *kcontrol,
>  	struct snd_ctl_elem_info *ucontrol);
> +int snd_soc_bytes_tlv_callback(struct snd_kcontrol *kcontrol, int op_flag,
> +	unsigned int size, unsigned int __user *tlv);
>  int snd_soc_info_xr_sx(struct snd_kcontrol *kcontrol,
>  	struct snd_ctl_elem_info *uinfo);
>  int snd_soc_get_xr_sx(struct snd_kcontrol *kcontrol,
> @@ -1119,6 +1128,9 @@ struct soc_bytes {
>  
>  struct soc_bytes_ext {
>  	int max;
> +	/* used for TLV byte control */
> +	int (*get)(unsigned int __user *bytes, unsigned int size);
> +	int (*put)(const unsigned int __user *bytes, unsigned int size);
>  };
>  
>  /* multi register control */
> diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
> index b87d7d8..e6ad95b 100644
> --- a/sound/soc/soc-core.c
> +++ b/sound/soc/soc-core.c
> @@ -3267,6 +3267,28 @@ int snd_soc_bytes_info_ext(struct snd_kcontrol *kcontrol,
>  }
>  EXPORT_SYMBOL_GPL(snd_soc_bytes_info_ext);
>  
> +int snd_soc_bytes_tlv_callback(struct snd_kcontrol *kcontrol, int op_flag,
> +				unsigned int size, unsigned int __user *tlv)
> +{
> +	struct soc_bytes_ext *params = (void *)kcontrol->private_value;
> +	unsigned int count = size < params->max ? size : params->max;
> +
> +	switch (op_flag) {
> +	case 0:
> +		if (params->get)
> +			params->get(tlv, count);
> +		break;
> +	case 1:
> +		if (params->put)
> +			params->put(tlv, count);
> +		break;

No error propagation from the callback?
Also, if a driver doesn't provide get or put, it gets no error?

BTW, about the value of op_flag: I have a patch to define the
constants (attached below), which I forgot until now.  Now I put it
into topic/tlv-opflag branch of sound git tree.  If you'd like to use
the new constants, merge (or base on) this branch.


Takashi

-- 8< --
From: Takashi Iwai <tiwai@suse.de>
Subject: [PATCH] ALSA: control: Define SNDRV_CTL_TLV_OP_* constants

Instead of hard-coded magic numbers, define constants for op_flag to
tlv callbacks.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 include/sound/control.h | 7 ++++++-
 sound/core/control.c    | 6 +++---
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/include/sound/control.h b/include/sound/control.h
index 5358892b1b39..042613938a1d 100644
--- a/include/sound/control.h
+++ b/include/sound/control.h
@@ -31,10 +31,15 @@ typedef int (snd_kcontrol_info_t) (struct snd_kcontrol * kcontrol, struct snd_ct
 typedef int (snd_kcontrol_get_t) (struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol);
 typedef int (snd_kcontrol_put_t) (struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol);
 typedef int (snd_kcontrol_tlv_rw_t)(struct snd_kcontrol *kcontrol,
-				    int op_flag, /* 0=read,1=write,-1=command */
+				    int op_flag, /* SNDRV_CTL_TLV_OP_XXX */
 				    unsigned int size,
 				    unsigned int __user *tlv);
 
+enum {
+	SNDRV_CTL_TLV_OP_READ = 0,
+	SNDRV_CTL_TLV_OP_WRITE = 1,
+	SNDRV_CTL_TLV_OP_CMD = -1,
+};
 
 struct snd_kcontrol_new {
 	snd_ctl_elem_iface_t iface;	/* interface identifier */
diff --git a/sound/core/control.c b/sound/core/control.c
index f0b0e14497a5..b9611344ff9e 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -1406,11 +1406,11 @@ static long snd_ctl_ioctl(struct file *file, unsigned int cmd, unsigned long arg
 	case SNDRV_CTL_IOCTL_SUBSCRIBE_EVENTS:
 		return snd_ctl_subscribe_events(ctl, ip);
 	case SNDRV_CTL_IOCTL_TLV_READ:
-		return snd_ctl_tlv_ioctl(ctl, argp, 0);
+		return snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_READ);
 	case SNDRV_CTL_IOCTL_TLV_WRITE:
-		return snd_ctl_tlv_ioctl(ctl, argp, 1);
+		return snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_WRITE);
 	case SNDRV_CTL_IOCTL_TLV_COMMAND:
-		return snd_ctl_tlv_ioctl(ctl, argp, -1);
+		return snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_CMD);
 	case SNDRV_CTL_IOCTL_POWER:
 		return -ENOPROTOOPT;
 	case SNDRV_CTL_IOCTL_POWER_STATE:
-- 
2.0.1

Re: [RFC v2] ASoC: core: add a helper for extended byte controls using TLV

[Vinod Koul]

On Tue, Jul 15, 2014 at 04:36:21PM +0200, Takashi Iwai wrote:
> At Tue, 15 Jul 2014 12:17:45 +0530,
> Vinod Koul wrote:
> > 
> > From: Omair Mohammed Abdullah <omair.m.abdullah@intel.com>
> > 
> > ALSA supports arbitrary length TLVs for each kcontrol that can be used
> > to pass metadata about the control (e.g. volumes, enum information). The
> > same transport mechanism is now used for arbitrary length data by
> > defining a new helper.
> > 
> > Signed-off-by: Omair Mohammed Abdullah <omair.m.abdullah@intel.com>
> > Signed-off-by: Vinod Koul <vinod.koul@intel.com>
> > ---
> > As discussed in [1] we are adding a new approach to solve the byte control
> > extensions by using existing TLVs and combining them with byte controls.  The
> > usermode on seeing byte control + TLV can treat it differently as it does for
> > control + TLV combination today. This way we don't change kernel API and
> > existing users will be happy, while providing embedded folks facility to pass
> > large bytes data to kcontrols
> > [1]:
> > http://mailman.alsa-project.org/pipermail/alsa-devel/2013-November/069483.html
> 
> Yeah, this would bypass the limitation nicely.
Yes thats what I realized when Omair pointed this out!

> > +int snd_soc_bytes_tlv_callback(struct snd_kcontrol *kcontrol, int op_flag,
> > +				unsigned int size, unsigned int __user *tlv)
> > +{
> > +	struct soc_bytes_ext *params = (void *)kcontrol->private_value;
> > +	unsigned int count = size < params->max ? size : params->max;
> > +
> > +	switch (op_flag) {
> > +	case 0:
> > +		if (params->get)
> > +			params->get(tlv, count);
> > +		break;
> > +	case 1:
> > +		if (params->put)
> > +			params->put(tlv, count);
> > +		break;
> 
> No error propagation from the callback?
> Also, if a driver doesn't provide get or put, it gets no error?
Will fix that
> 
> BTW, about the value of op_flag: I have a patch to define the
> constants (attached below), which I forgot until now.  Now I put it
> into topic/tlv-opflag branch of sound git tree.  If you'd like to use
> the new constants, merge (or base on) this branch.
yes rebased now..

-- 
~Vinod