Add a clock operation to get the whole set of rates available to a specific
clock: when needed this request could transparently trigger a full rate
discovery enumeration if this specific clock-rates were previously only
lazily enumerated.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
---
drivers/firmware/arm_scmi/clock.c | 85 +++++++++++++++++++++----------
include/linux/scmi_protocol.h     |  9 ++++
2 files changed, 67 insertions(+), 27 deletions(-)

diff --git a/drivers/firmware/arm_scmi/clock.c b/drivers/firmware/arm_scmi/clock.c
index a0de10652abe..c2fd9a1c3316 100644
--- a/drivers/firmware/arm_scmi/clock.c
+++ b/drivers/firmware/arm_scmi/clock.c

@@ -159,10 +159,8 @@ struct scmi_clock_rate_notify_payld {

struct scmi_clock_desc {
	u32 id;
-	bool rate_discrete;
	unsigned int tot_rates;
-	unsigned int num_rates;
-	u64 *rates;
+	struct scmi_clock_rates r;
#define	RATE_MIN	0
#define	RATE_MAX	1
#define	RATE_STEP	2

@@ -469,10 +467,10 @@ 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->clkd->rate_discrete = RATE_DISCRETE(flags);
+	p->clkd->r.rate_discrete = RATE_DISCRETE(flags);

	/* Warn about out of spec replies ... */
-	if (!p->clkd->rate_discrete &&
+	if (!p->clkd->r.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",

@@ -486,9 +484,9 @@ iter_clk_describe_update_state(struct scmi_iterator_state *st,

	if (!st->max_resources) {
		unsigned int tot_rates = st->num_returned + st->num_remaining;

-		p->clkd->rates = devm_kcalloc(p->dev, tot_rates,
-					      sizeof(*p->clkd->rates), GFP_KERNEL);
-		if (!p->clkd->rates)
+		p->clkd->r.rates = devm_kcalloc(p->dev, tot_rates,
+						sizeof(*p->clkd->r.rates), GFP_KERNEL);
+		if (!p->clkd->r.rates)
			return -ENOMEM;

		/* max_resources is used by the iterators to control bounds */

@@ -507,10 +505,10 @@ iter_clk_describe_process_response(const struct scmi_protocol_handle *ph,

	struct scmi_clk_ipriv *p = priv;
	const struct scmi_msg_resp_clock_describe_rates *r = response;

-	p->clkd->rates[p->clkd->num_rates] = RATE_TO_U64(r->rate[st->loop_idx]);
+	p->clkd->r.rates[p->clkd->r.num_rates] = RATE_TO_U64(r->rate[st->loop_idx]);

	/* Count only effectively discovered rates */
-	p->clkd->num_rates++;
+	p->clkd->r.num_rates++;

	return 0;
}

@@ -531,7 +529,13 @@ scmi_clock_describe_rates_get_full(const struct scmi_protocol_handle *ph,

		.dev = ph->dev,
	};

-	iter = ph->hops->iter_response_init(ph, &ops, 0, CLOCK_DESCRIBE_RATES,
+	/*
+	 * Using tot_rates as max_resources parameter here so as to trigger
+	 * the dynamic allocation only when strictly needed: when trying a
+	 * full enumeration after a lazy one tot_rates will be non-zero.
+	 */
+	iter = ph->hops->iter_response_init(ph, &ops, clkd->tot_rates,
+					    CLOCK_DESCRIBE_RATES,
					    sizeof(struct scmi_msg_clock_describe_rates),
					    &cpriv);
	if (IS_ERR(iter))

@@ -542,12 +546,12 @@ scmi_clock_describe_rates_get_full(const struct scmi_protocol_handle *ph,

		return ret;

	/* empty set ? */
-	if (!clkd->num_rates)
+	if (!clkd->r.num_rates)
		return 0;

-	if (clkd->rate_discrete)
-		sort(clkd->rates, clkd->num_rates,
-		     sizeof(clkd->rates[0]), rate_cmp_func, NULL);
+	if (clkd->r.rate_discrete && PROTOCOL_REV_MAJOR(ph->version) == 0x1)