ACPI: CPPC: Add auto select register read/write support

For some AMD shared memory based systems, the autonomous selection bit
needed to be set explicitly. Add autonomous selection register related
APIs to acpi driver, which amd_pstate driver uses later.
Acked-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Wyes Karny <wyes.karny@amd.com>
[ rjw: Fixed up kerneldoc comments, white space adjustment, subject edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/cppc_acpi.c

@@ -1433,6 +1433,102 @@ int cppc_set_epp_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls, bool enable)
 }
 EXPORT_SYMBOL_GPL(cppc_set_epp_perf);
 
+/**
+ * cppc_get_auto_sel_caps - Read autonomous selection register.
+ * @cpunum : CPU from which to read register.
+ * @perf_caps : struct where autonomous selection register value is updated.
+ */
+int cppc_get_auto_sel_caps(int cpunum, struct cppc_perf_caps *perf_caps)
+{
+	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
+	struct cpc_register_resource *auto_sel_reg;
+	u64  auto_sel;
+
+	if (!cpc_desc) {
+		pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
+		return -ENODEV;
+	}
+
+	auto_sel_reg = &cpc_desc->cpc_regs[AUTO_SEL_ENABLE];
+
+	if (!CPC_SUPPORTED(auto_sel_reg))
+		pr_warn_once("Autonomous mode is not unsupported!\n");
+
+	if (CPC_IN_PCC(auto_sel_reg)) {
+		int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
+		struct cppc_pcc_data *pcc_ss_data = NULL;
+		int ret = 0;
+
+		if (pcc_ss_id < 0)
+			return -ENODEV;
+
+		pcc_ss_data = pcc_data[pcc_ss_id];
+
+		down_write(&pcc_ss_data->pcc_lock);
+
+		if (send_pcc_cmd(pcc_ss_id, CMD_READ) >= 0) {
+			cpc_read(cpunum, auto_sel_reg, &auto_sel);
+			perf_caps->auto_sel = (bool)auto_sel;
+		} else {
+			ret = -EIO;
+		}
+
+		up_write(&pcc_ss_data->pcc_lock);
+
+		return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(cppc_get_auto_sel_caps);
+
+/**
+ * cppc_set_auto_sel - Write autonomous selection register.
+ * @cpu    : CPU to which to write register.
+ * @enable : the desired value of autonomous selection resiter to be updated.
+ */
+int cppc_set_auto_sel(int cpu, bool enable)
+{
+	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
+	struct cpc_register_resource *auto_sel_reg;
+	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
+	struct cppc_pcc_data *pcc_ss_data = NULL;
+	int ret = -EINVAL;
+
+	if (!cpc_desc) {
+		pr_debug("No CPC descriptor for CPU:%d\n", cpu);
+		return -ENODEV;
+	}
+
+	auto_sel_reg = &cpc_desc->cpc_regs[AUTO_SEL_ENABLE];
+
+	if (CPC_IN_PCC(auto_sel_reg)) {
+		if (pcc_ss_id < 0) {
+			pr_debug("Invalid pcc_ss_id\n");
+			return -ENODEV;
+		}
+
+		if (CPC_SUPPORTED(auto_sel_reg)) {
+			ret = cpc_write(cpu, auto_sel_reg, enable);
+			if (ret)
+				return ret;
+		}
+
+		pcc_ss_data = pcc_data[pcc_ss_id];
+
+		down_write(&pcc_ss_data->pcc_lock);
+		/* after writing CPC, transfer the ownership of PCC to platform */
+		ret = send_pcc_cmd(pcc_ss_id, CMD_WRITE);
+		up_write(&pcc_ss_data->pcc_lock);
+	} else {
+		ret = -ENOTSUPP;
+		pr_debug("_CPC in PCC is not supported\n");
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(cppc_set_auto_sel);
+
 /**
  * cppc_set_enable - Set to enable CPPC on the processor by writing the
  * Continuous Performance Control package EnableRegister field.

include/acpi/cppc_acpi.h

@@ -109,6 +109,7 @@ struct cppc_perf_caps {
 	u32 lowest_freq;
 	u32 nominal_freq;
 	u32 energy_perf;
+	bool auto_sel;
 };
 
 struct cppc_perf_ctrls {
@@ -153,6 +154,8 @@ extern int cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val);
 extern int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val);
 extern int cppc_get_epp_perf(int cpunum, u64 *epp_perf);
 extern int cppc_set_epp_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls, bool enable);
+extern int cppc_get_auto_sel_caps(int cpunum, struct cppc_perf_caps *perf_caps);
+extern int cppc_set_auto_sel(int cpu, bool enable);
 #else /* !CONFIG_ACPI_CPPC_LIB */
 static inline int cppc_get_desired_perf(int cpunum, u64 *desired_perf)
 {
@@ -214,6 +217,14 @@ static inline int cppc_get_epp_perf(int cpunum, u64 *epp_perf)
 {
 	return -ENOTSUPP;
 }
+static inline int cppc_set_auto_sel(int cpu, bool enable)
+{
+	return -ENOTSUPP;
+}
+static inline int cppc_get_auto_sel_caps(int cpunum, struct cppc_perf_caps *perf_caps)
+{
+	return -ENOTSUPP;
+}
 #endif /* !CONFIG_ACPI_CPPC_LIB */
 
 #endif /* _CPPC_ACPI_H*/