ACPI / CPPC: Add a helper to get desired performance

This patch add a helper to get the value of desired performance
register.

Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
[ rjw: More white space ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 42 insertions, 0 deletions

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 217a782c3e55..1b207fca1420 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -1051,6 +1051,48 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
 }
 
 /**
+ * cppc_get_desired_perf - Get the value of desired performance register.
+ * @cpunum: CPU from which to get desired performance.
+ * @desired_perf: address of a variable to store the returned desired performance
+ *
+ * Return: 0 for success, -EIO otherwise.
+ */
+int cppc_get_desired_perf(int cpunum, u64 *desired_perf)
+{
+        struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
+        int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
+        struct cpc_register_resource *desired_reg;
+        struct cppc_pcc_data *pcc_ss_data = NULL;
+
+        desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
+
+        if (CPC_IN_PCC(desired_reg)) {
+                int ret = 0;
+
+                if (pcc_ss_id < 0)
+                        return -EIO;
+
+                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, desired_reg, desired_perf);
+                else
+                        ret = -EIO;
+
+                up_write(&pcc_ss_data->pcc_lock);
+
+                return ret;
+        }
+
+        cpc_read(cpunum, desired_reg, desired_perf);
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(cppc_get_desired_perf);
+
+/**
  * cppc_get_perf_caps - Get a CPUs performance capabilities.
  * @cpunum: CPU from which to get capabilities info.
  * @perf_caps: ptr to cppc_perf_caps. See cppc_acpi.h