[PATCH v2 4/7] acpi/cppc: Rework cppc_set_perf() to use cppc_regs index

[Natarajan, Janakarajan]

From: Yazen Ghannam <Yazen.Ghannam@xxxxxxx>

The cppc_set_perf() currently only works for DESIRED_PERF. To make it
generic, pass in the index of the register being accessed.

Also, rename cppc_set_perf() to cppc_set_reg(). This is in preparation
for it to be used for more than just the DESIRED_PERF register.

Signed-off-by: Yazen Ghannam <Yazen.Ghannam@xxxxxxx>
[ carved out into a patch, cleaned up, productized ]
Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan@xxxxxxx>
---
 drivers/acpi/cppc_acpi.c       | 36 ++++++++++++++++++++++------------
 drivers/cpufreq/cppc_cpufreq.c |  6 +++---
 include/acpi/cppc_acpi.h       |  2 +-
 3 files changed, 28 insertions(+), 16 deletions(-)

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 10ae5a5818e6..1cce231b8501 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -60,7 +60,7 @@ struct cppc_pcc_data {
 	/*
 	 * Lock to provide controlled access to the PCC channel.
 	 *
-	 * For performance critical usecases(currently cppc_set_perf)
+	 * For performance-critical usecases(currently cppc_set_reg)
 	 *	We need to take read_lock and check if channel belongs to OSPM
 	 * before reading or writing to PCC subspace
 	 *	We need to take write_lock before transferring the channel
@@ -1346,26 +1346,38 @@ int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs)
 EXPORT_SYMBOL_GPL(cppc_get_perf_ctrs);
 
 /**
- * cppc_set_perf - Set a CPUs performance controls.
- * @cpu: CPU for which to set performance controls.
+ * cppc_set_reg - Set the CPUs control register.
+ * @cpu: CPU for which to set the register.
  * @perf_ctrls: ptr to cppc_perf_ctrls. See cppc_acpi.h
+ * @reg_idx: Index of the register being accessed
  *
  * Return: 0 for success, -ERRNO otherwise.
  */
-int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
+int cppc_set_reg(int cpu, struct cppc_perf_ctrls *perf_ctrls,
+		 enum cppc_regs reg_idx)
 {
 	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
-	struct cpc_register_resource *desired_reg;
 	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
 	struct cppc_pcc_data *pcc_ss_data = NULL;
+	struct cpc_register_resource *reg;
 	int ret = 0;
+	u32 value;
 
 	if (!cpc_desc) {
 		pr_debug("No CPC descriptor for CPU:%d\n", cpu);
 		return -ENODEV;
 	}
 
-	desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
+	switch (reg_idx) {
+	case DESIRED_PERF:
+		value = perf_ctrls->desired_perf;
+		break;
+	default:
+		pr_debug("CPC register index #%d not writeable\n", reg_idx);
+		return -EINVAL;
+	}
+
+	reg = &cpc_desc->cpc_regs[reg_idx];
 
 	/*
 	 * This is Phase-I where we want to write to CPC registers
@@ -1374,7 +1386,7 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
 	 * Since read_lock can be acquired by multiple CPUs simultaneously we
 	 * achieve that goal here
 	 */
-	if (CPC_IN_PCC(desired_reg)) {
+	if (CPC_IN_PCC(reg)) {
 		if (pcc_ss_id < 0) {
 			pr_debug("Invalid pcc_ss_id\n");
 			return -ENODEV;
@@ -1401,14 +1413,14 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
 	 * Skip writing MIN/MAX until Linux knows how to come up with
 	 * useful values.
 	 */
-	cpc_write(cpu, desired_reg, perf_ctrls->desired_perf);
+	cpc_write(cpu, reg, value);
 
-	if (CPC_IN_PCC(desired_reg))
+	if (CPC_IN_PCC(reg))
 		up_read(&pcc_ss_data->pcc_lock);	/* END Phase-I */
 	/*
 	 * This is Phase-II where we transfer the ownership of PCC to Platform
 	 *
-	 * Short Summary: Basically if we think of a group of cppc_set_perf
+	 * Short Summary: Basically if we think of a group of cppc_set_reg
 	 * requests that happened in short overlapping interval. The last CPU to
 	 * come out of Phase-I will enter Phase-II and ring the doorbell.
 	 *
@@ -1451,7 +1463,7 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
 	 * case during a CMD_READ and if there are pending writes it delivers
 	 * the write command before servicing the read command
 	 */
-	if (CPC_IN_PCC(desired_reg)) {
+	if (CPC_IN_PCC(reg)) {
 		if (down_write_trylock(&pcc_ss_data->pcc_lock)) {/* BEGIN Phase-II */
 			/* Update only if there are pending write commands */
 			if (pcc_ss_data->pending_pcc_write_cmd)
@@ -1467,7 +1479,7 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
 	}
 	return ret;
 }
-EXPORT_SYMBOL_GPL(cppc_set_perf);
+EXPORT_SYMBOL_GPL(cppc_set_reg);
 
 /**
  * cppc_get_transition_latency - returns frequency transition latency in ns
diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index 2ae978d27e61..420bd44f6958 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -211,7 +211,7 @@ static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
 	freqs.new = target_freq;
 
 	cpufreq_freq_transition_begin(policy, &freqs);
-	ret = cppc_set_perf(cpu->cpu, &cpu->perf_ctrls);
+	ret = cppc_set_reg(cpu->cpu, &cpu->perf_ctrls, DESIRED_PERF);
 	cpufreq_freq_transition_end(policy, &freqs, ret != 0);
 
 	if (ret)
@@ -235,7 +235,7 @@ static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy)
 
 	cpu->perf_ctrls.desired_perf = cpu->perf_caps.lowest_perf;
 
-	ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
+	ret = cppc_set_reg(cpu_num, &cpu->perf_ctrls, DESIRED_PERF);
 	if (ret)
 		pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
 				cpu->perf_caps.lowest_perf, cpu_num, ret);
@@ -348,7 +348,7 @@ static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
 					cpu->perf_caps.highest_perf);
 	cpu->perf_ctrls.desired_perf = cpu->perf_caps.highest_perf;
 
-	ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
+	ret = cppc_set_reg(cpu_num, &cpu->perf_ctrls, DESIRED_PERF);
 	if (ret)
 		pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
 				cpu->perf_caps.highest_perf, cpu_num, ret);
diff --git a/include/acpi/cppc_acpi.h b/include/acpi/cppc_acpi.h
index ba6fd7202775..ba3b3fb64572 100644
--- a/include/acpi/cppc_acpi.h
+++ b/include/acpi/cppc_acpi.h
@@ -139,7 +139,7 @@ struct cppc_cpudata {
 
 extern int cppc_get_desired_perf(int cpunum, u64 *desired_perf);
 extern int cppc_get_perf_ctrs(int cpu, struct cppc_perf_fb_ctrs *perf_fb_ctrs);
-extern int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls);
+extern int cppc_set_reg(int cpu, struct cppc_perf_ctrls *perf_ctrls, enum cppc_regs reg_idx);
 extern int cppc_get_perf_caps(int cpu, struct cppc_perf_caps *caps);
 extern int acpi_get_psd_map(struct cppc_cpudata **);
 extern unsigned int cppc_get_transition_latency(int cpu);
-- 
2.17.1