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cpufreq: cpu0: Move per-cluster initialization code to ->init()
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Currently this driver only support platforms on which all CPUs share clock &
voltage lines and there is requirement to support platforms which have separate
clock & voltage lines for CPUs, like Qualcomm's Krait and ARM's big LITTLE.

Each group of CPUs sharing clock/voltage lines are represented by 'struct
cpufreq_policy' in cpufreq framework. And core calls ->init() once for each
policy.

Currently we do all initialization/allocation from probe() which wouldn't work
for above scenario. To make it work for these platforms, the first step is to
move all initialization/allocation to ->init() and add ->exit() to do the
reverse of it.

Also, remove all global variables and allocate space for them at runtime.

This patch creates 'struct private_data' for keeping all such information and
a pointer to that would be stored in policy->driver_data.

The changed probe() routine now tries to see if regulator/clocks are available
or we need to defer probe. In case they are available, it registers cpufreq
driver. Otherwise, returns with -EPROBE_DEFER.

We still *don't* support platforms with separate clock/voltage lines for CPUs.
This would be done in a separate patch later.

Tested-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Viresh Kumar authored and Rafael J. Wysocki committed Sep 8, 2014
1 parent fbd48ca commit d2f31f1
Showing 1 changed file with 136 additions and 53 deletions.
189 changes: 136 additions & 53 deletions drivers/cpufreq/cpufreq-cpu0.c
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Original file line number Diff line number Diff line change
Expand Up @@ -28,18 +28,21 @@
#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;
struct private_data {
struct device *cpu_dev;
struct regulator *cpu_reg;
struct thermal_cooling_device *cdev;
unsigned int voltage_tolerance; /* in percentage */
};

static int cpu0_set_target(struct cpufreq_policy *policy, unsigned int index)
{
struct dev_pm_opp *opp;
struct cpufreq_frequency_table *freq_table = policy->freq_table;
struct clk *cpu_clk = policy->clk;
struct private_data *priv = policy->driver_data;
struct device *cpu_dev = priv->cpu_dev;
struct regulator *cpu_reg = priv->cpu_reg;
unsigned long volt = 0, volt_old = 0, tol = 0;
unsigned int old_freq, new_freq;
long freq_Hz, freq_exact;
Expand All @@ -64,7 +67,7 @@ static int cpu0_set_target(struct cpufreq_policy *policy, unsigned int index)
}
volt = dev_pm_opp_get_voltage(opp);
rcu_read_unlock();
tol = volt * voltage_tolerance / 100;
tol = volt * priv->voltage_tolerance / 100;
volt_old = regulator_get_voltage(cpu_reg);
}

Expand Down Expand Up @@ -103,39 +106,20 @@ static int cpu0_set_target(struct cpufreq_policy *policy, unsigned int index)
return ret;
}

static int cpu0_cpufreq_init(struct cpufreq_policy *policy)
{
policy->clk = cpu_clk;
return cpufreq_generic_init(policy, freq_table, transition_latency);
}

static struct cpufreq_driver cpu0_cpufreq_driver = {
.flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
.verify = cpufreq_generic_frequency_table_verify,
.target_index = cpu0_set_target,
.get = cpufreq_generic_get,
.init = cpu0_cpufreq_init,
.name = "generic_cpu0",
.attr = cpufreq_generic_attr,
};

static int cpu0_cpufreq_probe(struct platform_device *pdev)
static int allocate_resources(struct device **cdev,
struct regulator **creg, struct clk **cclk)
{
struct device_node *np;
int ret;
struct device *cpu_dev;
struct regulator *cpu_reg;
struct clk *cpu_clk;
int ret = 0;

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) {
dev_err(cpu_dev, "failed to find cpu0 node\n");
return -ENOENT;
}

cpu_reg = regulator_get_optional(cpu_dev, "cpu0");
if (IS_ERR(cpu_reg)) {
/*
Expand All @@ -144,15 +128,18 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev)
*/
if (PTR_ERR(cpu_reg) == -EPROBE_DEFER) {
dev_dbg(cpu_dev, "cpu0 regulator not ready, retry\n");
ret = -EPROBE_DEFER;
goto out_put_node;
return -EPROBE_DEFER;
}
dev_warn(cpu_dev, "failed to get cpu0 regulator: %ld\n",
PTR_ERR(cpu_reg));
}

cpu_clk = clk_get(cpu_dev, NULL);
if (IS_ERR(cpu_clk)) {
/* put regulator */
if (!IS_ERR(cpu_reg))
regulator_put(cpu_reg);

ret = PTR_ERR(cpu_clk);

/*
Expand All @@ -163,8 +150,39 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev)
dev_dbg(cpu_dev, "cpu0 clock not ready, retry\n");
else
dev_err(cpu_dev, "failed to get cpu0 clock: %d\n", ret);
} else {
*cdev = cpu_dev;
*creg = cpu_reg;
*cclk = cpu_clk;
}

return ret;
}

static int cpu0_cpufreq_init(struct cpufreq_policy *policy)
{
struct cpufreq_frequency_table *freq_table;
struct thermal_cooling_device *cdev;
struct device_node *np;
struct private_data *priv;
struct device *cpu_dev;
struct regulator *cpu_reg;
struct clk *cpu_clk;
unsigned int transition_latency;
int ret;

/* We only support cpu0 currently */
ret = allocate_resources(&cpu_dev, &cpu_reg, &cpu_clk);
if (ret) {
pr_err("%s: Failed to allocate resources\n: %d", __func__, ret);
return ret;
}

goto out_put_reg;
np = of_node_get(cpu_dev->of_node);
if (!np) {
dev_err(cpu_dev, "failed to find cpu%d node\n", policy->cpu);
ret = -ENOENT;
goto out_put_reg_clk;
}

/* OPPs might be populated at runtime, don't check for error here */
Expand All @@ -173,10 +191,16 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev)
ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
if (ret) {
dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
goto out_put_clk;
goto out_put_node;
}

priv = kzalloc(sizeof(*priv), GFP_KERNEL);
if (!priv) {
ret = -ENOMEM;
goto out_free_table;
}

of_property_read_u32(np, "voltage-tolerance", &voltage_tolerance);
of_property_read_u32(np, "voltage-tolerance", &priv->voltage_tolerance);

if (of_property_read_u32(np, "clock-latency", &transition_latency))
transition_latency = CPUFREQ_ETERNAL;
Expand Down Expand Up @@ -206,12 +230,6 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev)
transition_latency += ret * 1000;
}

ret = cpufreq_register_driver(&cpu0_cpufreq_driver);
if (ret) {
dev_err(cpu_dev, "failed to register driver: %d\n", ret);
goto out_free_table;
}

/*
* For now, just loading the cooling device;
* thermal DT code takes care of matching them.
Expand All @@ -222,29 +240,94 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev)
dev_err(cpu_dev,
"running cpufreq without cooling device: %ld\n",
PTR_ERR(cdev));
else
priv->cdev = cdev;
}

of_node_put(np);

priv->cpu_dev = cpu_dev;
priv->cpu_reg = cpu_reg;
policy->driver_data = priv;

policy->clk = cpu_clk;
ret = cpufreq_generic_init(policy, freq_table, transition_latency);
if (ret)
goto out_cooling_unregister;

return 0;

out_cooling_unregister:
cpufreq_cooling_unregister(priv->cdev);
kfree(priv);
out_free_table:
dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
out_put_clk:
out_put_node:
of_node_put(np);
out_put_reg_clk:
clk_put(cpu_clk);
out_put_reg:
if (!IS_ERR(cpu_reg))
regulator_put(cpu_reg);
out_put_node:
of_node_put(np);

return ret;
}

static int cpu0_cpufreq_exit(struct cpufreq_policy *policy)
{
struct private_data *priv = policy->driver_data;

cpufreq_cooling_unregister(priv->cdev);
dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
clk_put(policy->clk);
if (!IS_ERR(priv->cpu_reg))
regulator_put(priv->cpu_reg);
kfree(priv);

return 0;
}

static struct cpufreq_driver cpu0_cpufreq_driver = {
.flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
.verify = cpufreq_generic_frequency_table_verify,
.target_index = cpu0_set_target,
.get = cpufreq_generic_get,
.init = cpu0_cpufreq_init,
.exit = cpu0_cpufreq_exit,
.name = "generic_cpu0",
.attr = cpufreq_generic_attr,
};

static int cpu0_cpufreq_probe(struct platform_device *pdev)
{
struct device *cpu_dev;
struct regulator *cpu_reg;
struct clk *cpu_clk;
int ret;

/*
* All per-cluster (CPUs sharing clock/voltages) initialization is done
* from ->init(). In probe(), we just need to make sure that clk and
* regulators are available. Else defer probe and retry.
*
* FIXME: Is checking this only for CPU0 sufficient ?
*/
ret = allocate_resources(&cpu_dev, &cpu_reg, &cpu_clk);
if (ret)
return ret;

clk_put(cpu_clk);
if (!IS_ERR(cpu_reg))
regulator_put(cpu_reg);

ret = cpufreq_register_driver(&cpu0_cpufreq_driver);
if (ret)
dev_err(cpu_dev, "failed register driver: %d\n", ret);

return ret;
}

static int cpu0_cpufreq_remove(struct platform_device *pdev)
{
cpufreq_cooling_unregister(cdev);
cpufreq_unregister_driver(&cpu0_cpufreq_driver);
dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);

return 0;
}

Expand Down

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