ACPI: CPPC: Add cppc_set_reg_val()

Add cppc_set_reg_val() as a generic function for setting CPPC register
values, with this features:

 1. Check register. If a register is writeable, it must be a buffer and
    can not be null.

 2. Extract the operations if register is in PCC out as
    cppc_set_reg_val_in_pcc().

This function can be used to reduce some existing code duplication.

Reviewed-by: Pierre Gondois <[email protected]>
Signed-off-by: Lifeng Zheng <[email protected]>
Reviewed-by: Mario Limonciello <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Rafael J. Wysocki <[email protected]>

Author: Lifeng Zheng

drivers/acpi/cppc_acpi.c

@@ -1232,6 +1232,55 @@ static int cppc_get_reg_val(int cpu, enum cppc_regs reg_idx, u64 *val)
 	return cpc_read(cpu, reg, val);
 }
 
+static int cppc_set_reg_val_in_pcc(int cpu, struct cpc_register_resource *reg, u64 val)
+{
+	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
+	struct cppc_pcc_data *pcc_ss_data = NULL;
+	int ret;
+
+	if (pcc_ss_id < 0) {
+		pr_debug("Invalid pcc_ss_id\n");
+		return -ENODEV;
+	}
+
+	ret = cpc_write(cpu, reg, val);
+	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);
+
+	return ret;
+}
+
+static int cppc_set_reg_val(int cpu, enum cppc_regs reg_idx, u64 val)
+{
+	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
+	struct cpc_register_resource *reg;
+
+	if (!cpc_desc) {
+		pr_debug("No CPC descriptor for CPU:%d\n", cpu);
+		return -ENODEV;
+	}
+
+	reg = &cpc_desc->cpc_regs[reg_idx];
+
+	/* if a register is writeable, it must be a buffer and not null */
+	if ((reg->type != ACPI_TYPE_BUFFER) || IS_NULL_REG(&reg->cpc_entry.reg)) {
+		pr_debug("CPC register is not supported\n");
+		return -EOPNOTSUPP;
+	}
+
+	if (CPC_IN_PCC(reg))
+		return cppc_set_reg_val_in_pcc(cpu, reg, val);
+
+	return cpc_write(cpu, reg, val);
+}
+
 /**
  * cppc_get_desired_perf - Get the desired performance register value.
  * @cpunum: CPU from which to get desired performance.