[RFC PATCH 2/6] cpufreq: cpufreq-cpu0: use clk rate-change notifiers

Nishanth Menon
2014-02-18T20:32:19Z

From: Mike Turquette <mturquette@linaro.org>

Removes directly handling of OPP tables and voltage regulators by
calling of_clk_cpufreq_notifier_handler, introduced by commit "clk:
cpufreq helper for voltage scaling".

In the future this can help consolidate code found across similar
CPUfreq drivers.

[nm@ti.com: updates to keep the OPP logic still in cpufreq-cpu0 -
optimization to generalize that for cpufreq is to be done in a later
series]
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
---
drivers/cpufreq/Kconfig | 1 +
drivers/cpufreq/cpufreq-cpu0.c | 140 ++++++++++++----------------------------
2 files changed, 42 insertions(+), 99 deletions(-)

diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
index 4b029c0..70b07ab 100644
--- a/drivers/cpufreq/Kconfig
+++ b/drivers/cpufreq/Kconfig
@@ -187,6 +187,7 @@ config GENERIC_CPUFREQ_CPU0
tristate "Generic CPU0 cpufreq driver"
depends on HAVE_CLK && REGULATOR && OF && THERMAL && CPU_THERMAL
select PM_OPP
+ select VOLTAGE_DOMAIN
help
This adds a generic cpufreq driver for CPU0 frequency management.
It supports both uniprocessor (UP) and symmetric multiprocessor (SMP)
diff --git a/drivers/cpufreq/cpufreq-cpu0.c b/drivers/cpufreq/cpufreq-cpu0.c
index 0c12ffc..32719d3 100644
--- a/drivers/cpufreq/cpufreq-cpu0.c
+++ b/drivers/cpufreq/cpufreq-cpu0.c
@@ -21,23 +21,20 @@
#include <linux/of.h>
#include <linux/pm_opp.h>
#include <linux/platform_device.h>
-#include <linux/regulator/consumer.h>
+#include <linux/pm_voltage_domain.h>
#include <linux/slab.h>
#include <linux/thermal.h>

static unsigned int transition_latency;
-static unsigned int voltage_tolerance; /* in percentage */

static struct device *cpu_dev;
static struct clk *cpu_clk;
-static struct regulator *cpu_reg;
static struct cpufreq_frequency_table *freq_table;
static struct thermal_cooling_device *cdev;
+static struct notifier_block *clk_nb;

static int cpu0_set_target(struct cpufreq_policy *policy, unsigned int index)
{
- struct dev_pm_opp *opp;
- unsigned long volt = 0, volt_old = 0, tol = 0;
unsigned int old_freq, new_freq;
long freq_Hz, freq_exact;
int ret;
@@ -50,50 +47,14 @@ static int cpu0_set_target(struct cpufreq_policy *policy, unsigned int index)
new_freq = freq_Hz / 1000;
old_freq = clk_get_rate(cpu_clk) / 1000;

- if (!IS_ERR(cpu_reg)) {
- rcu_read_lock();
- opp = dev_pm_opp_find_freq_ceil(cpu_dev, &freq_Hz);
- if (IS_ERR(opp)) {
- rcu_read_unlock();
- pr_err("failed to find OPP for %ld\n", freq_Hz);
- return PTR_ERR(opp);
- }
- volt = dev_pm_opp_get_voltage(opp);
- rcu_read_unlock();
- tol = volt * voltage_tolerance / 100;
- volt_old = regulator_get_voltage(cpu_reg);
- }
-
- pr_debug("%u MHz, %ld mV --> %u MHz, %ld mV\n",
- old_freq / 1000, volt_old ? volt_old / 1000 : -1,
- new_freq / 1000, volt ? volt / 1000 : -1);
-
- /* scaling up? scale voltage before frequency */
- if (!IS_ERR(cpu_reg) && new_freq > old_freq) {
- ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
- if (ret) {
- pr_err("failed to scale voltage up: %d\n", ret);
- return ret;
- }
- }
+ pr_debug("%u MHz --> %u MHz\n", old_freq / 1000, new_freq / 1000);

ret = clk_set_rate(cpu_clk, freq_exact);
if (ret) {
pr_err("failed to set clock rate: %d\n", ret);
- if (!IS_ERR(cpu_reg))
- regulator_set_voltage_tol(cpu_reg, volt_old, tol);
return ret;
}

- /* scaling down? scale voltage after frequency */
- if (!IS_ERR(cpu_reg) && new_freq < old_freq) {
- ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
- if (ret) {
- pr_err("failed to scale voltage down: %d\n", ret);
- clk_set_rate(cpu_clk, old_freq * 1000);
- }
- }
-
return ret;
}

@@ -117,33 +78,24 @@ static struct cpufreq_driver cpu0_cpufreq_driver = {
static int cpu0_cpufreq_probe(struct platform_device *pdev)
{
struct device_node *np;
+ unsigned int voltage_latency;
int ret;

- cpu_dev = get_cpu_device(0);
if (!cpu_dev) {
- pr_err("failed to get cpu0 device\n");
- return -ENODEV;
- }
-
- np = of_node_get(cpu_dev->of_node);
- if (!np) {
- pr_err("failed to find cpu0 node\n");
- return -ENOENT;
- }
+ cpu_dev = get_cpu_device(0);
+ if (!cpu_dev) {
+ pr_err("failed to get cpu0 device\n");
+ return -ENODEV;
+ }

- cpu_reg = devm_regulator_get_optional(cpu_dev, "cpu0");
- if (IS_ERR(cpu_reg)) {
- /*
- * If cpu0 regulator supply node is present, but regulator is
- * not yet registered, we should try defering probe.
- */
- if (PTR_ERR(cpu_reg) == -EPROBE_DEFER) {
- dev_err(cpu_dev, "cpu0 regulator not ready, retry\n");
- ret = -EPROBE_DEFER;
- goto out_put_node;
+ np = of_node_get(cpu_dev->of_node);
+ ret = of_init_opp_table(cpu_dev);
+ if (ret) {
+ pr_err("failed to init OPP table: %d\n", ret);
+ return ret;
}
- pr_warn("failed to get cpu0 regulator: %ld\n",
- PTR_ERR(cpu_reg));
+ } else {
+ np = of_node_get(cpu_dev->of_node);
}

cpu_clk = devm_clk_get(cpu_dev, NULL);
@@ -153,11 +105,8 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev)
goto out_put_node;
}

- ret = of_init_opp_table(cpu_dev);
- if (ret) {
- pr_err("failed to init OPP table: %d\n", ret);
- goto out_put_node;
- }
+ if (of_property_read_u32(np, "clock-latency", &transition_latency))
+ transition_latency = CPUFREQ_ETERNAL;

ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
if (ret) {
@@ -165,40 +114,30 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev)
goto out_put_node;
}

- of_property_read_u32(np, "voltage-tolerance", &voltage_tolerance);
-
- if (of_property_read_u32(np, "clock-latency", &transition_latency))
- transition_latency = CPUFREQ_ETERNAL;
-
- if (!IS_ERR(cpu_reg)) {
- struct dev_pm_opp *opp;
- unsigned long min_uV, max_uV;
- int i;
-
- /*
- * OPP is maintained in order of increasing frequency, and
- * freq_table initialised from OPP is therefore sorted in the
- * same order.
- */
- for (i = 0; freq_table[i].frequency != CPUFREQ_TABLE_END; i++)
- ;
- rcu_read_lock();
- opp = dev_pm_opp_find_freq_exact(cpu_dev,
- freq_table[0].frequency * 1000, true);
- min_uV = dev_pm_opp_get_voltage(opp);
- opp = dev_pm_opp_find_freq_exact(cpu_dev,
- freq_table[i-1].frequency * 1000, true);
- max_uV = dev_pm_opp_get_voltage(opp);
- rcu_read_unlock();
- ret = regulator_set_voltage_time(cpu_reg, min_uV, max_uV);
- if (ret > 0)
- transition_latency += ret * 1000;
+ clk_nb = of_pm_voltdm_notifier_register(cpu_dev, np, cpu_clk, "cpu0",
+ &voltage_latency);
+
+ if (IS_ERR(clk_nb)) {
+ ret = PTR_ERR(clk_nb);
+ /* defer probe if regulator is not yet registered */
+ if (ret == -EPROBE_DEFER) {
+ dev_err(cpu_dev,
+ "cpu0 clock notifier not ready, retry\n");
+ } else {
+ dev_err(cpu_dev,
+ "Failed to register cpu0 clock notifier: %d\n",
+ ret);
+ }
+ goto out_freq_table_free;
}

+ if (voltage_latency > 0)
+ transition_latency += voltage_latency;
+
ret = cpufreq_register_driver(&cpu0_cpufreq_driver);
if (ret) {
pr_err("failed register driver: %d\n", ret);
- goto out_free_table;
+ goto out_notifier_unregister;
}

/*
@@ -215,7 +154,9 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev)
of_node_put(np);
return 0;

-out_free_table:
+out_notifier_unregister:
+ of_pm_voltdm_notifier_unregister(clk_nb);
+out_freq_table_free:
dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
out_put_node:
of_node_put(np);
@@ -226,6 +167,7 @@ static int cpu0_cpufreq_remove(struct platform_device *pdev)
{
cpufreq_cooling_unregister(cdev);
cpufreq_unregister_driver(&cpu0_cpufreq_driver);
+ of_pm_voltdm_notifier_unregister(clk_nb);
dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);

return 0;
--
1.7.9.5