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

["Peng Fan (OSS)" <peng.fan@oss.nxp.com>]

From: Peng Fan <peng.fan@nxp.com>

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@nxp.com>
---

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 {
-- 
2.37.1