Re: [PATCH V2 1/2] firmware: arm_scmi: clock: implement get permissions

[Peng Fan]

Hi Sudeep, Cristian,

Are you ok with this patchset? It's been pending for 1 month.

Thanks,
Peng.

On 12/7/2023 5:33 PM, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@xxxxxxx>
>
> ARM SCMI Spec 3.2 introduces Clock Get Permission command. This patch
> is to add the support. Add three bool entries to scmi_clock_info to
> indicate the operation is forbidden or not. If the CLOCK_GET_PERMISSIONS
> command is not supported, the three bool variables will default
> set to false, otherwise they will be set according to the return result
> of CLOCK_GET_PERMISSIONS.
>
> Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
> ---
>
> V2:
>   Take Cristian's suggestion, https://lore.kernel.org/all/ZWiqqfQ73tezFmSk@pluto/
>
>   drivers/firmware/arm_scmi/clock.c | 53 +++++++++++++++++++++++++++++++
>   include/linux/scmi_protocol.h     |  4 +++
>   2 files changed, 57 insertions(+)
>
> diff --git a/drivers/firmware/arm_scmi/clock.c b/drivers/firmware/arm_scmi/clock.c
> index 98511a3aa367..0e048530bea2 100644
> --- a/drivers/firmware/arm_scmi/clock.c
> +++ b/drivers/firmware/arm_scmi/clock.c
> @@ -25,8 +25,13 @@ enum scmi_clock_protocol_cmd {
>   	CLOCK_POSSIBLE_PARENTS_GET = 0xC,
>   	CLOCK_PARENT_SET = 0xD,
>   	CLOCK_PARENT_GET = 0xE,
> +	CLOCK_GET_PERMISSIONS = 0xF,
>   };
>   
> +#define CLOCK_STATE_CONTROL_ALLOWED	BIT(31)
> +#define CLOCK_PARENT_CONTROL_ALLOWED	BIT(30)
> +#define CLOCK_RATE_CONTROL_ALLOWED	BIT(29)
> +
>   enum clk_state {
>   	CLK_STATE_DISABLE,
>   	CLK_STATE_ENABLE,
> @@ -46,6 +51,7 @@ struct scmi_msg_resp_clock_attributes {
>   #define SUPPORTS_RATE_CHANGE_REQUESTED_NOTIF(x)	((x) & BIT(30))
>   #define SUPPORTS_EXTENDED_NAMES(x)		((x) & BIT(29))
>   #define SUPPORTS_PARENT_CLOCK(x)		((x) & BIT(28))
> +#define SUPPORTS_GET_PERMISSIONS(x)		((x) & BIT(1))
>   	u8 name[SCMI_SHORT_NAME_MAX_SIZE];
>   	__le32 clock_enable_latency;
>   };
> @@ -281,6 +287,35 @@ static int scmi_clock_possible_parents(const struct scmi_protocol_handle *ph, u3
>   	return ret;
>   }
>   
> +static int
> +scmi_clock_get_permissions(const struct scmi_protocol_handle *ph, u32 clk_id,
> +			   struct scmi_clock_info *clk)
> +{
> +	struct scmi_xfer *t;
> +	u32 perm;
> +	int ret;
> +
> +	ret = ph->xops->xfer_get_init(ph, CLOCK_GET_PERMISSIONS,
> +				      sizeof(clk_id), sizeof(perm), &t);
> +	if (ret)
> +		return ret;
> +
> +	put_unaligned_le32(clk_id, t->tx.buf);
> +
> +	ret = ph->xops->do_xfer(ph, t);
> +	if (!ret) {
> +		perm = get_unaligned_le32(t->rx.buf);
> +
> +		clk->state_ctrl_forbidden = !(perm & CLOCK_STATE_CONTROL_ALLOWED);
> +		clk->rate_ctrl_forbidden = !(perm & CLOCK_RATE_CONTROL_ALLOWED);
> +		clk->parent_ctrl_forbidden = !(perm & CLOCK_PARENT_CONTROL_ALLOWED);
> +	}
> +
> +	ph->xops->xfer_put(ph, t);
> +
> +	return ret;
> +}
> +
>   static int scmi_clock_attributes_get(const struct scmi_protocol_handle *ph,
>   				     u32 clk_id, struct scmi_clock_info *clk,
>   				     u32 version)
> @@ -307,6 +342,7 @@ static int scmi_clock_attributes_get(const struct scmi_protocol_handle *ph,
>   		if (PROTOCOL_REV_MAJOR(version) >= 0x2)
>   			latency = le32_to_cpu(attr->clock_enable_latency);
>   		clk->enable_latency = latency ? : U32_MAX;
> +		clk->attributes = attributes;
>   	}
>   
>   	ph->xops->xfer_put(ph, t);
> @@ -327,6 +363,8 @@ static int scmi_clock_attributes_get(const struct scmi_protocol_handle *ph,
>   			clk->rate_change_requested_notifications = true;
>   		if (SUPPORTS_PARENT_CLOCK(attributes))
>   			scmi_clock_possible_parents(ph, clk_id, clk);
> +		if (SUPPORTS_GET_PERMISSIONS(attributes))
> +			scmi_clock_get_permissions(ph, clk_id, clk);
>   	}
>   
>   	return ret;
> @@ -499,6 +537,10 @@ static int scmi_clock_rate_set(const struct scmi_protocol_handle *ph,
>   	struct scmi_xfer *t;
>   	struct scmi_clock_set_rate *cfg;
>   	struct clock_info *ci = ph->get_priv(ph);
> +	struct scmi_clock_info *clk = ci->clk + clk_id;
> +
> +	if (clk->rate_ctrl_forbidden)
> +		return -EACCES;
>   
>   	ret = ph->xops->xfer_get_init(ph, CLOCK_RATE_SET, sizeof(*cfg), 0, &t);
>   	if (ret)
> @@ -585,6 +627,9 @@ scmi_clock_set_parent(const struct scmi_protocol_handle *ph, u32 clk_id,
>   	if (parent_id >= clk->num_parents)
>   		return -EINVAL;
>   
> +	if (clk->parent_ctrl_forbidden)
> +		return -EACCES;
> +
>   	ret = ph->xops->xfer_get_init(ph, CLOCK_PARENT_SET,
>   				      sizeof(*cfg), 0, &t);
>   	if (ret)
> @@ -668,6 +713,10 @@ static int scmi_clock_enable(const struct scmi_protocol_handle *ph, u32 clk_id,
>   			     bool atomic)
>   {
>   	struct clock_info *ci = ph->get_priv(ph);
> +	struct scmi_clock_info *clk = ci->clk + clk_id;
> +
> +	if (clk->state_ctrl_forbidden)
> +		return -EACCES;
>   
>   	return ci->clock_config_set(ph, clk_id, CLK_STATE_ENABLE,
>   				    NULL_OEM_TYPE, 0, atomic);
> @@ -677,6 +726,10 @@ static int scmi_clock_disable(const struct scmi_protocol_handle *ph, u32 clk_id,
>   			      bool atomic)
>   {
>   	struct clock_info *ci = ph->get_priv(ph);
> +	struct scmi_clock_info *clk = ci->clk + clk_id;
> +
> +	if (clk->state_ctrl_forbidden)
> +		return -EACCES;
>   
>   	return ci->clock_config_set(ph, clk_id, CLK_STATE_DISABLE,
>   				    NULL_OEM_TYPE, 0, atomic);
> diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
> index f2f05fb42d28..ad75784b567b 100644
> --- a/include/linux/scmi_protocol.h
> +++ b/include/linux/scmi_protocol.h
> @@ -47,6 +47,9 @@ struct scmi_clock_info {
>   	bool rate_discrete;
>   	bool rate_changed_notifications;
>   	bool rate_change_requested_notifications;
> +	bool state_ctrl_forbidden;
> +	bool rate_ctrl_forbidden;
> +	bool parent_ctrl_forbidden;
>   	union {
>   		struct {
>   			int num_rates;
> @@ -60,6 +63,7 @@ struct scmi_clock_info {
>   	};
>   	int num_parents;
>   	u32 *parents;
> +	u32 attributes;
>   };
>   
>   enum scmi_power_scale {