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Message-ID: <20251001150104.1275188-3-sumitg@nvidia.com>
Date: Wed, 1 Oct 2025 20:30:58 +0530
From: Sumit Gupta <sumitg@...dia.com>
To: <rafael@...nel.org>, <viresh.kumar@...aro.org>, <lenb@...nel.org>,
<robert.moore@...el.com>, <corbet@....net>, <pierre.gondois@....com>,
<zhenglifeng1@...wei.com>, <rdunlap@...radead.org>, <ray.huang@....com>,
<gautham.shenoy@....com>, <mario.limonciello@....com>, <perry.yuan@....com>,
<linux-pm@...r.kernel.org>, <linux-acpi@...r.kernel.org>,
<linux-doc@...r.kernel.org>, <acpica-devel@...ts.linux.dev>,
<linux-kernel@...r.kernel.org>
CC: <linux-tegra@...r.kernel.org>, <treding@...dia.com>,
<jonathanh@...dia.com>, <vsethi@...dia.com>, <ksitaraman@...dia.com>,
<sanjayc@...dia.com>, <bbasu@...dia.com>, <sumitg@...dia.com>
Subject: [PATCH v3 2/8] 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, and energy_perf.
This provides a read interface to complement the existing cppc_set_perf()
write interface for performance control registers.
Signed-off-by: Sumit Gupta <sumitg@...dia.com>
---
drivers/acpi/cppc_acpi.c | 73 ++++++++++++++++++++++++++++++++++++++++
include/acpi/cppc_acpi.h | 5 +++
2 files changed, 78 insertions(+)
diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 6b649031808f..ab8dd5cdb13b 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -1731,6 +1731,79 @@ int cppc_set_enable(int cpu, bool enable)
return cppc_set_reg_val(cpu, ENABLE, 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;
+ u64 desired_perf = 0, min = 0, max = 0, energy_perf = 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];
+
+ /* 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)) {
+ 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) {
+ pr_debug("Failed to send PCC command for CPU:%d, ret:%d\n", cpu, ret);
+ 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;
+
+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.
diff --git a/include/acpi/cppc_acpi.h b/include/acpi/cppc_acpi.h
index 20f3d62e7a16..213bd389ec57 100644
--- 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);
@@ -192,6 +193,10 @@ 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;
--
2.34.1
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