Re: [PATCH 03/11] firmware: arm_scmi: Simplify clock rates exposed interface

[Peng Fan <peng.fan@oss.nxp.com>]

On Fri, Feb 27, 2026 at 03:32:17PM +0000, Cristian Marussi wrote:
>Move needlessly exposed fields away from scmi_clock_info into the new
>internal struct scmi_clock_desc while keeping exposed only the two new
>min_rate and max_rate fields for each clock.
>
>No functional change.
>
>Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
>---
> drivers/firmware/arm_scmi/clock.c | 145 +++++++++++++++---------------
> include/linux/scmi_protocol.h     |   2 +
> 2 files changed, 74 insertions(+), 73 deletions(-)
>
>diff --git a/drivers/firmware/arm_scmi/clock.c b/drivers/firmware/arm_scmi/clock.c
>index 54e8b59c3941..f5d1c608f85a 100644
>--- a/drivers/firmware/arm_scmi/clock.c
>+++ b/drivers/firmware/arm_scmi/clock.c
>@@ -157,13 +157,27 @@ struct scmi_clock_rate_notify_payld {
> 	__le32 rate_high;
> };
> 
>+struct scmi_clock_desc {
>+	u32 id;
>+	bool rate_discrete;
>+	unsigned int num_rates;
>+	u64 rates[SCMI_MAX_NUM_RATES];
>+#define	RATE_MIN	0
>+#define	RATE_MAX	1
>+#define	RATE_STEP	2
>+	struct scmi_clock_info info;
>+};
>+
>+#define to_desc(p)	(container_of((p), struct scmi_clock_desc, info))

Nit:
no need parentheses

>+
> struct clock_info {
> 	int num_clocks;
> 	int max_async_req;
> 	bool notify_rate_changed_cmd;
> 	bool notify_rate_change_requested_cmd;
> 	atomic_t cur_async_req;
>-	struct scmi_clock_info *clk;
>+	struct scmi_clock_desc *clkds;
>+#define CLOCK_INFO(c, i)	(&(((c)->clkds + (i))->info))

Ditto.

> 	int (*clock_config_set)(const struct scmi_protocol_handle *ph,
> 				u32 clk_id, enum clk_state state,
> 				enum scmi_clock_oem_config oem_type,
>@@ -185,7 +199,7 @@ scmi_clock_domain_lookup(struct clock_info *ci, u32 clk_id)
> 	if (clk_id >= ci->num_clocks)
> 		return ERR_PTR(-EINVAL);
> 
>-	return ci->clk + clk_id;
>+	return CLOCK_INFO(ci, clk_id);
> }
> 
> static int
>@@ -226,8 +240,7 @@ scmi_clock_protocol_attributes_get(const struct scmi_protocol_handle *ph,
> 
> struct scmi_clk_ipriv {
> 	struct device *dev;
>-	u32 clk_id;
>-	struct scmi_clock_info *clk;
>+	struct scmi_clock_desc *clkd;
> };
> 
> static void iter_clk_possible_parents_prepare_message(void *message, unsigned int desc_index,
>@@ -236,7 +249,7 @@ static void iter_clk_possible_parents_prepare_message(void *message, unsigned in
> 	struct scmi_msg_clock_possible_parents *msg = message;
> 	const struct scmi_clk_ipriv *p = priv;
> 
>-	msg->id = cpu_to_le32(p->clk_id);
>+	msg->id = cpu_to_le32(p->clkd->id);
> 	/* Set the number of OPPs to be skipped/already read */
> 	msg->skip_parents = cpu_to_le32(desc_index);
> }
>@@ -246,7 +259,6 @@ static int iter_clk_possible_parents_update_state(struct scmi_iterator_state *st
> {
> 	const struct scmi_msg_resp_clock_possible_parents *r = response;
> 	struct scmi_clk_ipriv *p = priv;
>-	struct device *dev = ((struct scmi_clk_ipriv *)p)->dev;
> 	u32 flags;
> 
> 	flags = le32_to_cpu(r->num_parent_flags);
>@@ -258,12 +270,13 @@ static int iter_clk_possible_parents_update_state(struct scmi_iterator_state *st
> 	 * assume it's returned+remaining on first call.
> 	 */
> 	if (!st->max_resources) {
>-		p->clk->num_parents = st->num_returned + st->num_remaining;
>-		p->clk->parents = devm_kcalloc(dev, p->clk->num_parents,
>-					       sizeof(*p->clk->parents),
>-					       GFP_KERNEL);
>-		if (!p->clk->parents) {
>-			p->clk->num_parents = 0;
>+		p->clkd->info.num_parents = st->num_returned + st->num_remaining;
>+		p->clkd->info.parents = devm_kcalloc(p->dev,
>+						     p->clkd->info.num_parents,
>+						     sizeof(*p->clkd->info.parents),
>+						     GFP_KERNEL);
>+		if (!p->clkd->info.parents) {
>+			p->clkd->info.num_parents = 0;
> 			return -ENOMEM;
> 		}
> 		st->max_resources = st->num_returned + st->num_remaining;
>@@ -280,29 +293,27 @@ static int iter_clk_possible_parents_process_response(const struct scmi_protocol
> 	const struct scmi_msg_resp_clock_possible_parents *r = response;
> 	struct scmi_clk_ipriv *p = priv;
> 
>-	u32 *parent = &p->clk->parents[st->desc_index + st->loop_idx];
>+	u32 *parent = &p->clkd->info.parents[st->desc_index + st->loop_idx];
> 
> 	*parent = le32_to_cpu(r->possible_parents[st->loop_idx]);
> 
> 	return 0;
> }
> 
>-static int scmi_clock_possible_parents(const struct scmi_protocol_handle *ph, u32 clk_id,
>-				       struct scmi_clock_info *clk)
>+static int scmi_clock_possible_parents(const struct scmi_protocol_handle *ph,
>+				       u32 clk_id, struct clock_info *cinfo)
> {
> 	struct scmi_iterator_ops ops = {
> 		.prepare_message = iter_clk_possible_parents_prepare_message,
> 		.update_state = iter_clk_possible_parents_update_state,
> 		.process_response = iter_clk_possible_parents_process_response,
> 	};
>-
>+	struct scmi_clock_desc *clkd = &cinfo->clkds[clk_id];
> 	struct scmi_clk_ipriv ppriv = {
>-		.clk_id = clk_id,
>-		.clk = clk,
>+		.clkd = clkd,
> 		.dev = ph->dev,
> 	};
> 	void *iter;
>-	int ret;
> 
> 	iter = ph->hops->iter_response_init(ph, &ops, 0,
> 					    CLOCK_POSSIBLE_PARENTS_GET,
>@@ -311,9 +322,7 @@ static int scmi_clock_possible_parents(const struct scmi_protocol_handle *ph, u3
> 	if (IS_ERR(iter))
> 		return PTR_ERR(iter);
> 
>-	ret = ph->hops->iter_response_run(iter);
>-
>-	return ret;
>+	return ph->hops->iter_response_run(iter);
> }
> 
> static int
>@@ -352,7 +361,7 @@ static int scmi_clock_attributes_get(const struct scmi_protocol_handle *ph,
> 	u32 attributes;
> 	struct scmi_xfer *t;
> 	struct scmi_msg_resp_clock_attributes *attr;
>-	struct scmi_clock_info *clk = cinfo->clk + clk_id;
>+	struct scmi_clock_info *clk = CLOCK_INFO(cinfo, clk_id);
> 
> 	ret = ph->xops->xfer_get_init(ph, CLOCK_ATTRIBUTES,
> 				      sizeof(clk_id), sizeof(*attr), &t);
>@@ -394,7 +403,7 @@ static int scmi_clock_attributes_get(const struct scmi_protocol_handle *ph,
> 			clk->rate_change_requested_notifications = true;
> 		if (PROTOCOL_REV_MAJOR(ph->version) >= 0x3) {
> 			if (SUPPORTS_PARENT_CLOCK(attributes))
>-				scmi_clock_possible_parents(ph, clk_id, clk);
>+				scmi_clock_possible_parents(ph, clk_id, cinfo);
> 			if (SUPPORTS_GET_PERMISSIONS(attributes))
> 				scmi_clock_get_permissions(ph, clk_id, clk);
> 			if (SUPPORTS_EXTENDED_CONFIG(attributes))
>@@ -424,7 +433,7 @@ static void iter_clk_describe_prepare_message(void *message,
> 	struct scmi_msg_clock_describe_rates *msg = message;
> 	const struct scmi_clk_ipriv *p = priv;
> 
>-	msg->id = cpu_to_le32(p->clk_id);
>+	msg->id = cpu_to_le32(p->clkd->id);
> 	/* Set the number of rates to be skipped/already read */
> 	msg->rate_index = cpu_to_le32(desc_index);
> }
>@@ -457,14 +466,14 @@ iter_clk_describe_update_state(struct scmi_iterator_state *st,
> 	flags = le32_to_cpu(r->num_rates_flags);
> 	st->num_remaining = NUM_REMAINING(flags);
> 	st->num_returned = NUM_RETURNED(flags);
>-	p->clk->rate_discrete = RATE_DISCRETE(flags);
>+	p->clkd->rate_discrete = RATE_DISCRETE(flags);
> 
> 	/* Warn about out of spec replies ... */
>-	if (!p->clk->rate_discrete &&
>+	if (!p->clkd->rate_discrete &&
> 	    (st->num_returned != 3 || st->num_remaining != 0)) {
> 		dev_warn(p->dev,
> 			 "Out-of-spec CLOCK_DESCRIBE_RATES reply for %s - returned:%d remaining:%d rx_len:%zd\n",
>-			 p->clk->name, st->num_returned, st->num_remaining,
>+			 p->clkd->info.name, st->num_returned, st->num_remaining,
> 			 st->rx_len);
> 
> 		SCMI_QUIRK(clock_rates_triplet_out_of_spec,
>@@ -479,38 +488,19 @@ iter_clk_describe_process_response(const struct scmi_protocol_handle *ph,
> 				   const void *response,
> 				   struct scmi_iterator_state *st, void *priv)
> {
>-	int ret = 0;
> 	struct scmi_clk_ipriv *p = priv;
> 	const struct scmi_msg_resp_clock_describe_rates *r = response;
> 
>-	if (!p->clk->rate_discrete) {
>-		switch (st->desc_index + st->loop_idx) {
>-		case 0:
>-			p->clk->range.min_rate = RATE_TO_U64(r->rate[0]);
>-			break;
>-		case 1:
>-			p->clk->range.max_rate = RATE_TO_U64(r->rate[1]);
>-			break;
>-		case 2:
>-			p->clk->range.step_size = RATE_TO_U64(r->rate[2]);
>-			break;
>-		default:
>-			ret = -EINVAL;
>-			break;
>-		}
>-	} else {
>-		u64 *rate = &p->clk->list.rates[st->desc_index + st->loop_idx];
>+	p->clkd->rates[st->desc_index + st->loop_idx] =
>+		RATE_TO_U64(r->rate[st->loop_idx]);
>+	p->clkd->num_rates++;
> 
>-		*rate = RATE_TO_U64(r->rate[st->loop_idx]);
>-		p->clk->list.num_rates++;
>-	}
>-
>-	return ret;
>+	return 0;
> }
> 
> static int
> scmi_clock_describe_rates_get(const struct scmi_protocol_handle *ph, u32 clk_id,
>-			      struct scmi_clock_info *clk)
>+			      struct clock_info *cinfo)
> {
> 	int ret;
> 	void *iter;
>@@ -519,9 +509,9 @@ scmi_clock_describe_rates_get(const struct scmi_protocol_handle *ph, u32 clk_id,
> 		.update_state = iter_clk_describe_update_state,
> 		.process_response = iter_clk_describe_process_response,
> 	};
>+	struct scmi_clock_desc *clkd = &cinfo->clkds[clk_id];
> 	struct scmi_clk_ipriv cpriv = {
>-		.clk_id = clk_id,
>-		.clk = clk,
>+		.clkd = clkd,
> 		.dev = ph->dev,
> 	};
> 
>@@ -536,16 +526,23 @@ scmi_clock_describe_rates_get(const struct scmi_protocol_handle *ph, u32 clk_id,
> 	if (ret)
> 		return ret;
> 
>-	if (!clk->rate_discrete) {
>+	/* empty set ? */
>+	if (!clkd->num_rates)
>+		return 0;
>+
>+	if (!clkd->rate_discrete) {
>+		clkd->info.max_rate = clkd->rates[RATE_MAX];

Not related to this patch. Just have a question,
if a broken firmware returns RATE_MIN, but no RATE_MAX and RATE_STEP,
should some sanity checking being added?

Regards,
Peng