Re: [PATCH v3 2/5] dt-bindings: ti_sci_pm_domains: Add support for exclusive and shared access

[Tero Kristo <t-kristo@ti.com>]

On 10/04/2019 08:37, Lokesh Vutla wrote:
> TISCI protocol supports for enabling the device either with exclusive
> permissions for the requesting host or with sharing across the hosts.
> There are certain devices which are exclusive to Linux context and
> there are certain devices that are shared across different host contexts.
> So add support for getting this information from DT by increasing
> the power-domain cells to 2.
> 
> Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
> ---
>   .../devicetree/bindings/soc/ti/sci-pm-domain.txt      | 11 +++++++++--
>   MAINTAINERS                                           |  1 +
>   include/dt-bindings/soc/ti,sci_pm_domain.h            |  9 +++++++++
>   3 files changed, 19 insertions(+), 2 deletions(-)
>   create mode 100644 include/dt-bindings/soc/ti,sci_pm_domain.h
> 
> diff --git a/Documentation/devicetree/bindings/soc/ti/sci-pm-domain.txt b/Documentation/devicetree/bindings/soc/ti/sci-pm-domain.txt
> index f7b00a7c0f68..f541d1f776a2 100644
> --- a/Documentation/devicetree/bindings/soc/ti/sci-pm-domain.txt
> +++ b/Documentation/devicetree/bindings/soc/ti/sci-pm-domain.txt
> @@ -19,8 +19,15 @@ child of the pmmc node.
>   Required Properties:
>   --------------------
>   - compatible: should be "ti,sci-pm-domain"
> -- #power-domain-cells: Must be 1 so that an id can be provided in each
> -		       device node.
> +- #power-domain-cells: Can be one of the following:
> +			1: Containing the device id of each node
> +			2: First entry should be device id
> +			   Second entry should be one of the floowing:
> +			   TI_SCI_PD_EXCLUSIVE: To allow device to be
> +						exclusively controlled by
> +						the requesting hosts.
> +			   TI_SCI_PD_SHARED: To allow device to be shared
> +					     by multiple hosts.

One thing should be noted on this, the added flag is purely for software 
configuration, and is not telling us anything about the HW / firmware. 
Software can decide to have the flag either way and it will work. I just 
wonder if DT is the correct location to have something like this... 
Expect to have plenty of churn on this by people swapping the 
permissions around according to their use-case needs.

-Tero


>   
>   Example (K2G):
>   -------------
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 2359e12e4c41..dc7a19cc1831 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -15345,6 +15345,7 @@ F:	drivers/firmware/ti_sci*
>   F:	include/linux/soc/ti/ti_sci_protocol.h
>   F:	Documentation/devicetree/bindings/soc/ti/sci-pm-domain.txt
>   F:	drivers/soc/ti/ti_sci_pm_domains.c
> +F:	include/dt-bindings/soc/ti,sci_pm_domain.h
>   F:	Documentation/devicetree/bindings/reset/ti,sci-reset.txt
>   F:	Documentation/devicetree/bindings/clock/ti,sci-clk.txt
>   F:	drivers/clk/keystone/sci-clk.c
> diff --git a/include/dt-bindings/soc/ti,sci_pm_domain.h b/include/dt-bindings/soc/ti,sci_pm_domain.h
> new file mode 100644
> index 000000000000..8f2a7360b65e
> --- /dev/null
> +++ b/include/dt-bindings/soc/ti,sci_pm_domain.h
> @@ -0,0 +1,9 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#ifndef __DT_BINDINGS_TI_SCI_PM_DOMAIN_H
> +#define __DT_BINDINGS_TI_SCI_PM_DOMAIN_H
> +
> +#define TI_SCI_PD_EXCLUSIVE	1
> +#define TI_SCI_PD_SHARED	0
> +
> +#endif /* __DT_BINDINGS_TI_SCI_PM_DOMAIN_H */
> 

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