PM / OPP: Add dev_pm_opp_set_rate()

This adds a routine, dev_pm_opp_set_rate(), responsible for configuring
power-supply and clock source for an OPP.

The OPP is found by matching against the target_freq passed to the
routine. This shall replace similar code present in most of the OPP
users and help simplify them a lot.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

2 files changed, 182 insertions, 0 deletions

diff --git a/drivers/base/power/opp/core.c b/drivers/base/power/opp/core.c
index 7d7749ce1ce4..ab711c2c3e00 100644
--- a/drivers/base/power/opp/core.c
+++ b/drivers/base/power/opp/core.c
@@ -529,6 +529,182 @@ struct dev_pm_opp *dev_pm_opp_find_freq_floor(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_floor);
 
+/*
+ * The caller needs to ensure that device_opp (and hence the clk) isn't freed,
+ * while clk returned here is used.
+ */
+static struct clk *_get_opp_clk(struct device *dev)
+{
+        struct device_opp *dev_opp;
+        struct clk *clk;
+
+        rcu_read_lock();
+
+        dev_opp = _find_device_opp(dev);
+        if (IS_ERR(dev_opp)) {
+                dev_err(dev, "%s: device opp doesn't exist\n", __func__);
+                clk = ERR_CAST(dev_opp);
+                goto unlock;
+        }
+
+        clk = dev_opp->clk;
+        if (IS_ERR(clk))
+                dev_err(dev, "%s: No clock available for the device\n",
+                        __func__);
+
+unlock:
+        rcu_read_unlock();
+        return clk;
+}
+
+static int _set_opp_voltage(struct device *dev, struct regulator *reg,
+                            unsigned long u_volt, unsigned long u_volt_min,
+                            unsigned long u_volt_max)
+{
+        int ret;
+
+        /* Regulator not available for device */
+        if (IS_ERR(reg)) {
+                dev_dbg(dev, "%s: regulator not available: %ld\n", __func__,
+                        PTR_ERR(reg));
+                return 0;
+        }
+
+        dev_dbg(dev, "%s: voltages (mV): %lu %lu %lu\n", __func__, u_volt_min,
+                u_volt, u_volt_max);
+
+        ret = regulator_set_voltage_triplet(reg, u_volt_min, u_volt,
+                                            u_volt_max);
+        if (ret)
+                dev_err(dev, "%s: failed to set voltage (%lu %lu %lu mV): %d\n",
+                        __func__, u_volt_min, u_volt, u_volt_max, ret);
+
+        return ret;
+}
+
+/**
+ * dev_pm_opp_set_rate() - Configure new OPP based on frequency
+ * @dev:         device for which we do this operation
+ * @target_freq: frequency to achieve
+ *
+ * This configures the power-supplies and clock source to the levels specified
+ * by the OPP corresponding to the target_freq.
+ *
+ * Locking: This function takes rcu_read_lock().
+ */
+int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
+{
+        struct device_opp *dev_opp;
+        struct dev_pm_opp *old_opp, *opp;
+        struct regulator *reg;
+        struct clk *clk;
+        unsigned long freq, old_freq;
+        unsigned long u_volt, u_volt_min, u_volt_max;
+        unsigned long ou_volt, ou_volt_min, ou_volt_max;
+        int ret;
+
+        if (unlikely(!target_freq)) {
+                dev_err(dev, "%s: Invalid target frequency %lu\n", __func__,
+                        target_freq);
+                return -EINVAL;
+        }
+
+        clk = _get_opp_clk(dev);
+        if (IS_ERR(clk))
+                return PTR_ERR(clk);
+
+        freq = clk_round_rate(clk, target_freq);
+        if ((long)freq <= 0)
+                freq = target_freq;
+
+        old_freq = clk_get_rate(clk);
+
+        /* Return early if nothing to do */
+        if (old_freq == freq) {
+                dev_dbg(dev, "%s: old/new frequencies (%lu Hz) are same, nothing to do\n",
+                        __func__, freq);
+                return 0;
+        }
+
+        rcu_read_lock();
+
+        dev_opp = _find_device_opp(dev);
+        if (IS_ERR(dev_opp)) {
+                dev_err(dev, "%s: device opp doesn't exist\n", __func__);
+                rcu_read_unlock();
+                return PTR_ERR(dev_opp);
+        }
+
+        old_opp = dev_pm_opp_find_freq_ceil(dev, &old_freq);
+        if (!IS_ERR(old_opp)) {
+                ou_volt = old_opp->u_volt;
+                ou_volt_min = old_opp->u_volt_min;
+                ou_volt_max = old_opp->u_volt_max;
+        } else {
+                dev_err(dev, "%s: failed to find current OPP for freq %lu (%ld)\n",
+                        __func__, old_freq, PTR_ERR(old_opp));
+        }
+
+        opp = dev_pm_opp_find_freq_ceil(dev, &freq);
+        if (IS_ERR(opp)) {
+                ret = PTR_ERR(opp);
+                dev_err(dev, "%s: failed to find OPP for freq %lu (%d)\n",
+                        __func__, freq, ret);
+                rcu_read_unlock();
+                return ret;
+        }
+
+        u_volt = opp->u_volt;
+        u_volt_min = opp->u_volt_min;
+        u_volt_max = opp->u_volt_max;
+
+        reg = dev_opp->regulator;
+
+        rcu_read_unlock();
+
+        /* Scaling up? Scale voltage before frequency */
+        if (freq > old_freq) {
+                ret = _set_opp_voltage(dev, reg, u_volt, u_volt_min,
+                                       u_volt_max);
+                if (ret)
+                        goto restore_voltage;
+        }
+
+        /* Change frequency */
+
+        dev_dbg(dev, "%s: switching OPP: %lu Hz --> %lu Hz\n",
+                __func__, old_freq, freq);
+
+        ret = clk_set_rate(clk, freq);
+        if (ret) {
+                dev_err(dev, "%s: failed to set clock rate: %d\n", __func__,
+                        ret);
+                goto restore_voltage;
+        }
+
+        /* Scaling down? Scale voltage after frequency */
+        if (freq < old_freq) {
+                ret = _set_opp_voltage(dev, reg, u_volt, u_volt_min,
+                                       u_volt_max);
+                if (ret)
+                        goto restore_freq;
+        }
+
+        return 0;
+
+restore_freq:
+        if (clk_set_rate(clk, old_freq))
+                dev_err(dev, "%s: failed to restore old-freq (%lu Hz)\n",
+                        __func__, old_freq);
+restore_voltage:
+        /* This shouldn't harm even if the voltages weren't updated earlier */
+        if (!IS_ERR(old_opp))
+                _set_opp_voltage(dev, reg, ou_volt, ou_volt_min, ou_volt_max);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(dev_pm_opp_set_rate);
+
 /* List-dev Helpers */
 static void _kfree_list_dev_rcu(struct rcu_head *head)
 {
diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
index 59da3d9e11ea..cccaf4a29e9f 100644
--- a/include/linux/pm_opp.h
+++ b/include/linux/pm_opp.h
@@ -64,6 +64,7 @@ int dev_pm_opp_set_prop_name(struct device *dev, const char *name);
 void dev_pm_opp_put_prop_name(struct device *dev);
 int dev_pm_opp_set_regulator(struct device *dev, const char *name);
 void dev_pm_opp_put_regulator(struct device *dev);
+int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq);
 #else
 static inline unsigned long dev_pm_opp_get_voltage(struct dev_pm_opp *opp)
 {
@@ -172,6 +173,11 @@ static inline int dev_pm_opp_set_regulator(struct device *dev, const char *name)
 
 static inline void dev_pm_opp_put_regulator(struct device *dev) {}
 
+static inline int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
+{
+        return -EINVAL;
+}
+
 #endif          /* CONFIG_PM_OPP */
 
 #if defined(CONFIG_PM_OPP) && defined(CONFIG_OF)