ACPI: CPPC: Add cppc_get_perf() API to read performance controls

Add cppc_get_perf() function to read values of performance control
registers including desired_perf, min_perf, max_perf, energy_perf,
and auto_sel.

This provides a read interface to complement the existing
cppc_set_perf() write interface for performance control registers.

Note that auto_sel is read by cppc_get_perf() but not written by
cppc_set_perf() to avoid unintended mode changes during performance
updates. It can be updated with existing dedicated cppc_set_auto_sel()
API.

Use cppc_get_perf() in cppc_cpufreq_get_cpu_data() to initialize
perf_ctrls with current hardware register values during cpufreq
policy initialization.

Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
Reviewed-by: Pierre Gondois <pierre.gondois@arm.com>
Reviewed-by: Lifeng Zheng <zhenglifeng1@huawei.com>
Link: https://patch.msgid.link/20260206142658.72583-2-sumitg@nvidia.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index f0e513e9ed5d3bc6d107c586f8266afa19660105..5122e99bddb09f6c35bc2b56963d1232299460ab 100644 (file)
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -1738,6 +1738,86 @@ int cppc_set_enable(int cpu, bool enable)
 }
 EXPORT_SYMBOL_GPL(cppc_set_enable);
 
+/**
+ * cppc_get_perf - Get a CPU's performance controls.
+ * @cpu: CPU for which to get performance controls.
+ * @perf_ctrls: ptr to cppc_perf_ctrls. See cppc_acpi.h
+ *
+ * Return: 0 for success with perf_ctrls, -ERRNO otherwise.
+ */
+int cppc_get_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
+{
+       struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
+       struct cpc_register_resource *desired_perf_reg,
+                                    *min_perf_reg, *max_perf_reg,
+                                    *energy_perf_reg, *auto_sel_reg;
+       u64 desired_perf = 0, min = 0, max = 0, energy_perf = 0, auto_sel = 0;
+       int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
+       struct cppc_pcc_data *pcc_ss_data = NULL;
+       int ret = 0, regs_in_pcc = 0;
+
+       if (!cpc_desc) {
+               pr_debug("No CPC descriptor for CPU:%d\n", cpu);
+               return -ENODEV;
+       }
+
+       if (!perf_ctrls) {
+               pr_debug("Invalid perf_ctrls pointer\n");
+               return -EINVAL;
+       }
+
+       desired_perf_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
+       min_perf_reg = &cpc_desc->cpc_regs[MIN_PERF];
+       max_perf_reg = &cpc_desc->cpc_regs[MAX_PERF];
+       energy_perf_reg = &cpc_desc->cpc_regs[ENERGY_PERF];
+       auto_sel_reg = &cpc_desc->cpc_regs[AUTO_SEL_ENABLE];
+
+       /* Are any of the regs PCC ?*/
+       if (CPC_IN_PCC(desired_perf_reg) || CPC_IN_PCC(min_perf_reg) ||
+           CPC_IN_PCC(max_perf_reg) || CPC_IN_PCC(energy_perf_reg) ||
+           CPC_IN_PCC(auto_sel_reg)) {
+               if (pcc_ss_id < 0) {
+                       pr_debug("Invalid pcc_ss_id for CPU:%d\n", cpu);
+                       return -ENODEV;
+               }
+               pcc_ss_data = pcc_data[pcc_ss_id];
+               regs_in_pcc = 1;
+               down_write(&pcc_ss_data->pcc_lock);
+               /* Ring doorbell once to update PCC subspace */
+               if (send_pcc_cmd(pcc_ss_id, CMD_READ) < 0) {
+                       ret = -EIO;
+                       goto out_err;
+               }
+       }
+
+       /* Read optional elements if present */
+       if (CPC_SUPPORTED(max_perf_reg))
+               cpc_read(cpu, max_perf_reg, &max);
+       perf_ctrls->max_perf = max;
+
+       if (CPC_SUPPORTED(min_perf_reg))
+               cpc_read(cpu, min_perf_reg, &min);
+       perf_ctrls->min_perf = min;
+
+       if (CPC_SUPPORTED(desired_perf_reg))
+               cpc_read(cpu, desired_perf_reg, &desired_perf);
+       perf_ctrls->desired_perf = desired_perf;
+
+       if (CPC_SUPPORTED(energy_perf_reg))
+               cpc_read(cpu, energy_perf_reg, &energy_perf);
+       perf_ctrls->energy_perf = energy_perf;
+
+       if (CPC_SUPPORTED(auto_sel_reg))
+               cpc_read(cpu, auto_sel_reg, &auto_sel);
+       perf_ctrls->auto_sel = (bool)auto_sel;
+
+out_err:
+       if (regs_in_pcc)
+               up_write(&pcc_ss_data->pcc_lock);
+       return ret;
+}
+EXPORT_SYMBOL_GPL(cppc_get_perf);
+
 /**
  * cppc_set_perf - Set a CPU's performance controls.
  * @cpu: CPU for which to set performance controls.

diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index 011f35cb47b942f5ca4d287074f5dc7e567fc8a4..a61a24e0dcaedcfb418246ce1f4e10b6560c1c20 100644 (file)
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -594,6 +594,12 @@ static struct cppc_cpudata *cppc_cpufreq_get_cpu_data(unsigned int cpu)
                goto free_mask;
        }
 
+       ret = cppc_get_perf(cpu, &cpu_data->perf_ctrls);
+       if (ret) {
+               pr_debug("Err reading CPU%d perf ctrls: ret:%d\n", cpu, ret);
+               goto free_mask;
+       }
+
        return cpu_data;
 
 free_mask:

diff --git a/include/acpi/cppc_acpi.h b/include/acpi/cppc_acpi.h
index 4d644f03098e318230797f785d3b2420181b04e4..3fc796c0d9022b7938545e6048e2a5bf6cc3273d 100644 (file)
--- a/include/acpi/cppc_acpi.h
+++ b/include/acpi/cppc_acpi.h
@@ -151,6 +151,7 @@ extern int cppc_get_desired_perf(int cpunum, u64 *desired_perf);
 extern int cppc_get_nominal_perf(int cpunum, u64 *nominal_perf);
 extern int cppc_get_highest_perf(int cpunum, u64 *highest_perf);
 extern int cppc_get_perf_ctrs(int cpu, struct cppc_perf_fb_ctrs *perf_fb_ctrs);
+extern int cppc_get_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls);
 extern int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls);
 extern int cppc_set_enable(int cpu, bool enable);
 extern int cppc_get_perf_caps(int cpu, struct cppc_perf_caps *caps);
@@ -193,6 +194,10 @@ static inline int cppc_get_perf_ctrs(int cpu, struct cppc_perf_fb_ctrs *perf_fb_
 {
        return -EOPNOTSUPP;
 }
+static inline int cppc_get_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
+{
+       return -EOPNOTSUPP;
+}
 static inline int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
 {
        return -EOPNOTSUPP;