cpufreq: cpu0: Move per-cluster initialization code to ->init()

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>

1 files changed, 136 insertions, 53 deletions

diff --git a/drivers/cpufreq/cpufreq-cpu0.c b/drivers/cpufreq/cpufreq-cpu0.c
index 741ff220f9bf..03e352b627dd 100644
--- a/drivers/cpufreq/cpufreq-cpu0.c
+++ b/drivers/cpufreq/cpufreq-cpu0.c
@@ -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;
@@ -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);
         }
 
@@ -103,26 +106,13 @@ 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) {
@@ -130,12 +120,6 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev)
                 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)) {
                 /*
@@ -144,8 +128,7 @@ 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));
@@ -153,6 +136,10 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev)
 
         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);
 
                 /*
@@ -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 */
@@ -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;
@@ -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.
@@ -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;
 }