[PATCH 06/10] OPP: Add clock-latency-ns support

Viresh Kumar
2015-06-15T11:58:18Z

With "operating-points-v2" bindings, clock-latency is defined per OPP.
Users of this value expect a single value which defines the latency to
switch to any clock rate. Find maximum clock-latency-ns from the OPP
table to service requests from such users.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
drivers/base/power/opp.c | 41 +++++++++++++++++++++++++++++++++++++++--
include/linux/pm_opp.h | 6 ++++++
2 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
index 3198c3e77224..fe79e5146a29 100644
--- a/drivers/base/power/opp.c
+++ b/drivers/base/power/opp.c
@@ -57,6 +57,8 @@
* @u_volt_min: Minimum voltage in microvolts corresponding to this OPP
* @u_volt_max: Maximum voltage in microvolts corresponding to this OPP
* @u_amp: Maximum current drawn by the device in microamperes
+ * @clock_latency_ns: Latency (in nanoseconds) of switching to this OPP's
+ * frequency from any other OPP's frequency.
* @dev_opp: points back to the device_opp struct this opp belongs to
* @rcu_head: RCU callback head used for deferred freeing
* @np: OPP's device node.
@@ -79,6 +81,7 @@ struct dev_pm_opp {
unsigned long u_volt_min;
unsigned long u_volt_max;
unsigned long u_amp;
+ unsigned long clock_latency_ns;

struct device_opp *dev_opp;
struct rcu_head rcu_head;
@@ -113,6 +116,8 @@ struct device_opp {
struct srcu_notifier_head srcu_head;
struct rcu_head rcu_head;
struct list_head opp_list;
+
+ unsigned long clock_latency_ns_max;
};

/*
@@ -230,6 +235,32 @@ unsigned long dev_pm_opp_get_freq(struct dev_pm_opp *opp)
EXPORT_SYMBOL_GPL(dev_pm_opp_get_freq);

/**
+ * dev_pm_opp_get_max_clock_latency() - Get max clock latency in nanoseconds
+ * @dev: device for which we do this operation
+ *
+ * Return: This function returns the max clock latency in nanoseconds.
+ *
+ * Locking: This function takes rcu_read_lock().
+ */
+unsigned long dev_pm_opp_get_max_clock_latency(struct device *dev)
+{
+ struct device_opp *dev_opp;
+ unsigned long clock_latency_ns;
+
+ rcu_read_lock();
+
+ dev_opp = _find_device_opp(dev);
+ if (IS_ERR(dev_opp))
+ clock_latency_ns = 0;
+ else
+ clock_latency_ns = dev_opp->clock_latency_ns_max;
+
+ rcu_read_unlock();
+ return clock_latency_ns;
+}
+EXPORT_SYMBOL_GPL(dev_pm_opp_get_max_clock_latency);
+
+/**
* dev_pm_opp_get_opp_count() - Get number of opps available in the opp list
* @dev: device for which we do this operation
*
@@ -741,6 +772,8 @@ static int _opp_add_static_v2(struct device *dev, struct device_node *np)
new_opp->np = np;
new_opp->dynamic = false;
new_opp->available = true;
+ of_property_read_u32(np, "clock-latency-ns",
+ (u32 *)&new_opp->clock_latency_ns);

/*
* TODO: Support multiple regulators
@@ -765,9 +798,13 @@ static int _opp_add_static_v2(struct device *dev, struct device_node *np)
if (ret)
goto free_opp;

- pr_debug("%s: turbo:%d rate:%lu uv:%lu uvmin:%lu uvmax:%lu\n",
+ if (new_opp->clock_latency_ns > dev_opp->clock_latency_ns_max)
+ dev_opp->clock_latency_ns_max = new_opp->clock_latency_ns;
+
+ pr_debug("%s: turbo:%d rate:%lu uv:%lu uvmin:%lu uvmax:%lu latency:%lu\n",
__func__, new_opp->turbo, new_opp->rate, new_opp->u_volt,
- new_opp->u_volt_min, new_opp->u_volt_max);
+ new_opp->u_volt_min, new_opp->u_volt_max,
+ new_opp->clock_latency_ns);

mutex_unlock(&dev_opp_list_lock);

diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
index cec2d4540914..20324b579adc 100644
--- a/include/linux/pm_opp.h
+++ b/include/linux/pm_opp.h
@@ -31,6 +31,7 @@ unsigned long dev_pm_opp_get_voltage(struct dev_pm_opp *opp);
unsigned long dev_pm_opp_get_freq(struct dev_pm_opp *opp);

int dev_pm_opp_get_opp_count(struct device *dev);
+unsigned long dev_pm_opp_get_max_clock_latency(struct device *dev);

struct dev_pm_opp *dev_pm_opp_find_freq_exact(struct device *dev,
unsigned long freq,
@@ -67,6 +68,11 @@ static inline int dev_pm_opp_get_opp_count(struct device *dev)
return 0;
}

+static inline unsigned long dev_pm_opp_get_max_clock_latency(struct device *dev)
+{
+ return 0;
+}
+
static inline struct dev_pm_opp *dev_pm_opp_find_freq_exact(struct device *dev,
unsigned long freq, bool available)
{
--
2.4.0