RE: [PATCH v3] soundwire: SDCA: add helper macro to access controls

[Liao, Bard]

> -----Original Message-----
> From: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
> Sent: Friday, October 30, 2020 5:37 PM
> To: Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx>
> Cc: alsa-devel@xxxxxxxxxxxxxxxx; vkoul@xxxxxxxxxx; vinod.koul@xxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx; jank@xxxxxxxxxxx;
> srinivas.kandagatla@xxxxxxxxxx; rander.wang@xxxxxxxxxxxxxxx;
> ranjani.sridharan@xxxxxxxxxxxxxxx; hui.wang@xxxxxxxxxxxxx; pierre-
> louis.bossart@xxxxxxxxxxxxxxx; Kale, Sanyog R <sanyog.r.kale@xxxxxxxxx>; Lin,
> Mengdong <mengdong.lin@xxxxxxxxx>; Liao, Bard <bard.liao@xxxxxxxxx>
> Subject: Re: [PATCH v3] soundwire: SDCA: add helper macro to access
> controls
> 
> On Fri, Oct 30, 2020 at 04:49:55AM +0800, Bard Liao wrote:
> > From: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
> >
> > The upcoming SDCA (SoundWire Device Class Audio) specification defines
> > a hierarchical encoding to interface with Class-defined capabilities.
> >
> > The specification is not yet accessible to the general public but this
> > information is released with explicit permission from the MIPI Board
> > to avoid delays with SDCA support on Linux platforms.
> >
> > A block of 64 MBytes of register addresses are allocated to SDCA
> > controls, starting at address 0x40000000. The 26 LSBs which identify
> > individual controls are set based on the following variables:
> >
> > - Function Number. An SCDA device can be split in up to 8 independent
> >   Functions. Each of these Functions is described in the SDCA
> >   specification, e.g. Smart Amplifier, Smart Microphone, Simple
> >   Microphone, Jack codec, HID, etc.
> >
> > - Entity Number.  Within each Function,  an Entity is  an identifiable
> >   block.  Up   to  127  Entities   are  connected  in   a  pre-defined
> >   graph  (similar to  USB), with  Entity0 reserved  for Function-level
> >   configurations.  In  contrast  to  USB, the  SDCA  spec  pre-defines
> >   Function Types, topologies, and allowed  options, i.e. the degree of
> >   freedom  is not  unlimited to  limit  the possibility  of errors  in
> >   descriptors leading to software quirks.
> >
> > - Control Selector. Within each Entity, the SDCA specification defines
> >   48 controls such as Mute, Gain, AGC, etc, and 16 implementation
> >   defined ones. Some Control Selectors might be used for low-level
> >   platform setup, and other exposed to applications and users. Note
> >   that the same Control Selector capability, e.g. Latency control,
> >   might be located at different offsets in different entities, the
> >   Control Selector mapping is Entity-specific.
> >
> > - Control Number. Some Control Selectors allow channel-specific values
> >   to be set, with up to 64 channels allowed. This is mostly used for
> >   volume control.
> >
> > - Current/Next values. Some Control Selectors are
> >   'Dual-Ranked'. Software may either update the Current value directly
> >   for immediate effect. Alternatively, software may write into the
> >   'Next' values and update the SoundWire 1.2 'Commit Groups' register
> >   to copy 'Next' values into 'Current' ones in a synchronized
> >   manner. This is different from bank switching which is typically
> >   used to change the bus configuration only.
> >
> > - MBQ. the Multi-Byte Quantity bit is used to provide atomic updates
> >   when accessing more that one byte, for example a 16-bit volume
> >   control would be updated consistently, the intermediate values
> >   mixing old MSB with new LSB are not applied.
> >
> > These 6 parameters are used to build a 32-bit address to access the
> > desired Controls. Because of address range, paging is required, but
> > the most often used parameter values are placed in the lower 16 bits
> > of the address. This helps to keep the paging registers constant while
> > updating Controls for a specific Device/Function.
> >
> > Reviewed-by: Rander Wang <rander.wang@xxxxxxxxxxxxxxx>
> > Reviewed-by: Guennadi Liakhovetski
> > <guennadi.liakhovetski@xxxxxxxxxxxxxxx>
> > Reviewed-by: Kai Vehmanen <kai.vehmanen@xxxxxxxxxxxxxxx>
> > Signed-off-by: Pierre-Louis Bossart
> > <pierre-louis.bossart@xxxxxxxxxxxxxxx>
> > Signed-off-by: Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx>
> > ---
> > Changelog:
> >
> > v2:
> >  - add SDW_SDCA_MBQ_CTL
> >
> > v3:
> >  - add SDW_SDCA_NEXT_CTL
> >
> > ---
> >  include/linux/soundwire/sdw_registers.h | 32
> > +++++++++++++++++++++++++
> >  1 file changed, 32 insertions(+)
> >
> > diff --git a/include/linux/soundwire/sdw_registers.h
> > b/include/linux/soundwire/sdw_registers.h
> > index f420e8059779..e14dff9a9c7f 100644
> > --- a/include/linux/soundwire/sdw_registers.h
> > +++ b/include/linux/soundwire/sdw_registers.h
> > @@ -298,4 +298,36 @@
> >  #define SDW_CASC_PORT_MASK_INTSTAT3		1
> >  #define SDW_CASC_PORT_REG_OFFSET_INTSTAT3	2
> >
> > +/*
> > + * v1.2 device - SDCA address mapping
> > + *
> > + * Spec definition
> > + *	Bits		Contents
> > + *	31		0 (required by addressing range)
> > + *	30:26		0b10000 (Control Prefix)
> > + *	25		0 (Reserved)
> > + *	24:22		Function Number [2:0]
> > + *	21		Entity[6]
> > + *	20:19		Control Selector[5:4]
> > + *	18		0 (Reserved)
> > + *	17:15		Control Number[5:3]
> > + *	14		Next
> > + *	13		MBQ
> > + *	12:7		Entity[5:0]
> > + *	6:3		Control Selector[3:0]
> > + *	2:0		Control Number[2:0]
> > + */
> > +
> > +#define SDW_SDCA_CTL(fun, ent, ctl, ch)		(BIT(30) |
> 		\
> > +						 (((fun) & 0x7) << 22) |	\
> > +						 (((ent) & 0x40) << 15) |	\
> > +						 (((ent) & 0x3f) << 7) |	\
> > +						 (((ctl) & 0x30) << 15) |	\
> > +						 (((ctl) & 0x0f) << 3) |	\
> > +						 (((ch) & 0x38) << 12) |	\
> > +						 ((ch) & 0x07))
> > +
> > +#define SDW_SDCA_MBQ_CTL(reg)			((reg) | BIT(13))
> > +#define SDW_SDCA_NEXT_CTL(reg)			((reg) | BIT(14))
> > +
> >  #endif /* __SDW_REGISTERS_H */
> 
> 
> No users of these macros?

SDW_SDCA_CTL is used in sdca codec drivers which are not upstream yet.
SDW_SDCA_MBQ_CTL will be used in a new regmap method.
SDW_SDCA_NEXT_CTL can be used in sdca codec drivers, too.