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Message-ID: <20201124083353.GH8403@vkoul-mobl>
Date: Tue, 24 Nov 2020 14:03:53 +0530
From: Vinod Koul <vkoul@...nel.org>
To: Bard Liao <yung-chuan.liao@...ux.intel.com>
Cc: alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
tiwai@...e.de, broonie@...nel.org, gregkh@...uxfoundation.org,
jank@...ence.com, srinivas.kandagatla@...aro.org,
rander.wang@...ux.intel.com, ranjani.sridharan@...ux.intel.com,
hui.wang@...onical.com, pierre-louis.bossart@...ux.intel.com,
sanyog.r.kale@...el.com, mengdong.lin@...el.com,
bard.liao@...el.com
Subject: Re: [PATCH 1/5] soundwire: SDCA: add helper macro to access controls
On 04-11-20, 01:22, Bard Liao wrote:
> From: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
>
> 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@...ux.intel.com>
> Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@...ux.intel.com>
> Reviewed-by: Kai Vehmanen <kai.vehmanen@...ux.intel.com>
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
> Signed-off-by: Bard Liao <yung-chuan.liao@...ux.intel.com>
> ---
> 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))
Ideally would have liked to use defines with GENMASK etc instead of
numbers, but this is not a strong issue so:
Acked-By: Vinod Koul <vkoul@...nel.org>
--
~Vinod
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