[PATCH v3] cpufreq: cppc: Add update_limits support for Highest Performance changes

[Xueqin Luo]

ACPI CPPC specification requires OSPM to re-evaluate the Highest
Performance register when Notify(0x85) is received for a processor
device.

Implement cppc_cpufreq_update_limits() to refresh the cached
highest_perf capability through cppc_get_highest_perf() and update
policy->cpuinfo.max_freq accordingly.

When autonomous selection mode is enabled, reprogram the runtime
MIN_PERF/MAX_PERF envelope against the updated Highest Performance
capability through cppc_cpufreq_set_autonomous_perf().

--
change v2->v3:
- Fix build issues reported by kernel test robot
- Fold cppc_cpufreq_set_autonomous_perf() refactoring into
  this patch to keep it self-contained

Reported-by: kernel test robot <lkp@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-kbuild-all/202605101404.fqz0MXIe-lkp@xxxxxxxxx/
Signed-off-by: Xueqin Luo <luoxueqin@xxxxxxxxxx>
---
 drivers/cpufreq/cppc_cpufreq.c | 89 +++++++++++++++++++++++++++++-----
 1 file changed, 76 insertions(+), 13 deletions(-)

diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index 7e7f9dfb7a24..9184d5570de8 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -843,6 +843,80 @@ static int cppc_cpufreq_set_boost(struct cpufreq_policy *policy, int state)
 	return 0;
 }
 
+/**
+ * cppc_cpufreq_set_autonomous_perf - Configure performance bounds for
+ *                                     autonomous mode
+ * @policy: cpufreq policy structure
+ *
+ * When enabling autonomous selection, program MIN_PERF and MAX_PERF from
+ * current policy limits so that the platform uses the correct performance
+ * bounds immediately.
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+static int cppc_cpufreq_set_autonomous_perf(struct cpufreq_policy *policy)
+{
+	struct cppc_cpudata *cpu_data = policy->driver_data;
+	u32 old_min_perf = cpu_data->perf_ctrls.min_perf;
+	u32 old_max_perf = cpu_data->perf_ctrls.max_perf;
+	int ret;
+
+	cppc_cpufreq_update_perf_limits(cpu_data, policy);
+
+	ret = cppc_set_perf(policy->cpu, &cpu_data->perf_ctrls);
+	if (ret) {
+		cpu_data->perf_ctrls.min_perf = old_min_perf;
+		cpu_data->perf_ctrls.max_perf = old_max_perf;
+		return ret;
+	}
+
+	return 0;
+}
+
+static void cppc_cpufreq_update_limits(struct cpufreq_policy *policy)
+{
+	struct cppc_cpudata *cpu_data = policy->driver_data;
+	u64 prev_highest_perf;
+	u64 highest_perf;
+	u64 nominal_perf;
+	int ret;
+
+	guard(cpufreq_policy_write)(policy);
+
+	prev_highest_perf = cpu_data->perf_caps.highest_perf;
+
+	ret = cppc_get_highest_perf(policy->cpu, &highest_perf);
+	if (ret)
+		return;
+
+	if (highest_perf == prev_highest_perf)
+		return;
+
+	cpu_data->perf_caps.highest_perf = highest_perf;
+	nominal_perf = min_t(u64, highest_perf,
+			     cpu_data->perf_caps.nominal_perf);
+
+	policy->max = cppc_perf_to_khz(&cpu_data->perf_caps,
+			policy->boost_enabled ?
+			highest_perf : nominal_perf);
+
+	policy->cpuinfo.max_freq = policy->max;
+
+	/*
+	 * Autonomous selection mode uses MIN/MAX performance as runtime
+	 * hardware control bounds.
+	 *
+	 * Re-program them when highest_perf changes.
+	 */
+	if (cpu_data->perf_ctrls.auto_sel)
+		cppc_cpufreq_set_autonomous_perf(policy);
+
+	pr_debug("CPU%d: highest_perf updated %llu -> %llu\n",
+		 policy->cpu,
+		 prev_highest_perf,
+		 highest_perf);
+}
+
 static ssize_t show_freqdomain_cpus(struct cpufreq_policy *policy, char *buf)
 {
 	struct cppc_cpudata *cpu_data = policy->driver_data;
@@ -885,20 +959,8 @@ static ssize_t store_auto_select(struct cpufreq_policy *policy,
 	cpu_data->perf_ctrls.auto_sel = val;
 
 	if (val) {
-		u32 old_min_perf = cpu_data->perf_ctrls.min_perf;
-		u32 old_max_perf = cpu_data->perf_ctrls.max_perf;
-
-		/*
-		 * When enabling autonomous selection, program MIN_PERF and
-		 * MAX_PERF from current policy limits so that the platform
-		 * uses the correct performance bounds immediately.
-		 */
-		cppc_cpufreq_update_perf_limits(cpu_data, policy);
-
-		ret = cppc_set_perf(policy->cpu, &cpu_data->perf_ctrls);
+		ret = cppc_cpufreq_set_autonomous_perf(policy);
 		if (ret) {
-			cpu_data->perf_ctrls.min_perf = old_min_perf;
-			cpu_data->perf_ctrls.max_perf = old_max_perf;
 			cppc_set_auto_sel(policy->cpu, false);
 			cpu_data->perf_ctrls.auto_sel = false;
 			return ret;
@@ -1009,6 +1071,7 @@ static struct cpufreq_driver cppc_cpufreq_driver = {
 	.init = cppc_cpufreq_cpu_init,
 	.exit = cppc_cpufreq_cpu_exit,
 	.set_boost = cppc_cpufreq_set_boost,
+	.update_limits = cppc_cpufreq_update_limits,
 	.attr = cppc_cpufreq_attr,
 	.name = "cppc_cpufreq",
 };
-- 
2.43.0