From: Sumit Gupta Date: Fri, 6 Feb 2026 14:26:52 +0000 (+0530) Subject: ACPI: CPPC: Add cppc_get_perf() API to read performance controls X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=658fa7b1c47a857af484c5c5dff8d0164b7c7bfb;p=thirdparty%2Flinux.git 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 Reviewed-by: Pierre Gondois Reviewed-by: Lifeng Zheng Link: https://patch.msgid.link/20260206142658.72583-2-sumitg@nvidia.com Signed-off-by: Rafael J. Wysocki --- diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c index f0e513e9ed5d3..5122e99bddb09 100644 --- 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 011f35cb47b94..a61a24e0dcaed 100644 --- 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 4d644f03098e3..3fc796c0d9022 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); @@ -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;