@@ -15,6 +15,8 @@ Optional properties:
- clock-latency: Specify the possible maximum transition latency for clock,
in unit of nanoseconds.
- voltage-tolerance: Specify the CPU voltage tolerance in percentage.
+- needs-cooling: The generic cpu cooling (freq clipping) is loaded by the
+generic cpufreq-cpu0 driver in case the device tree node has this boolean.
Examples:
@@ -33,6 +35,7 @@ cpus {
198000 850000
>;
clock-latency = <61036>; /* two CLK32 periods */
+ needs-cooling;
};
cpu@1 {
@@ -97,3 +97,37 @@ thermal_zone {
};
};
};
+
+***************
+cpufreq-cooling
+***************
+
+The generic cpu cooling (freq clipping) can be loaded by the
+generic cpufreq-cpu0 driver in case the device tree node informs
+this need.
+
+In order to load the cpufreq cooling device, it is possible to
+inform that the cpu needs cooling by adding the boolean flag
+'needs-cooling' at the cpu0 phandle.
+
+Example:
+ cpus {
+ cpu@0 {
+ operating-points = <
+ /* kHz uV */
+ 800000 1313000
+ 1008000 1375000
+ >;
+ needs-cooling; /* make sure we have cpufreq-cooling */
+ };
+ ...
+ };
+
+The above will cause the cpufreq-cpu0 driver to understand that
+the cpu will need passive cooling and while probing that node it will
+also load the cpufreq cpu cooling device in that system.
+
+However, be advised that this flag will not describe what needs to
+be done or how the cpufreq cooling device will be used. In order to
+accomplish this, one needs to write a phandle for a thermal zone, as
+described in the section 'thermal_zone'.
@@ -20,6 +20,9 @@
#include <linux/platform_device.h>
#include <linux/regulator/consumer.h>
#include <linux/slab.h>
+#include <linux/thermal.h>
+#include <linux/cpu_cooling.h>
+#include <linux/cpumask.h>
static unsigned int transition_latency;
static unsigned int voltage_tolerance; /* in percentage */
@@ -28,6 +31,7 @@ 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 int cpu0_verify_speed(struct cpufreq_policy *policy)
{
@@ -268,6 +272,9 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev)
goto out_free_table;
}
+ if (of_property_read_bool(np, "needs-cooling"))
+ cdev = cpufreq_cooling_register(cpu_present_mask);
+
of_node_put(np);
of_node_put(parent);
return 0;
@@ -283,6 +290,7 @@ out_put_parent:
static int cpu0_cpufreq_remove(struct platform_device *pdev)
{
+ cpufreq_cooling_unregister(cdev);
cpufreq_unregister_driver(&cpu0_cpufreq_driver);
opp_free_cpufreq_table(cpu_dev, &freq_table);
This patch changes the cpufreq-cpu0 driver to consider if a cpu needs cooling (with cpufreq). In case the cooling is needed, it can be flagged at the cpu0 device tree node, with the boolean property 'needs-cooling'. In case this boolean is present, the driver will load a cpufreq cooling device in the system. The cpufreq-cpu0 driver is not capable of determining how the system should be using the cooling device. This can be described using device tree, to determine what needs to be done with the loaded cpufreq cooling device, in case the system temperature is detected to be high, with help of temperature sensors (check Documentation/devicetree/bindings/thermal/thermal.txt). Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Grant Likely <grant.likely@linaro.org> Cc: Rob Herring <rob.herring@calxeda.com> Cc: cpufreq@vger.kernel.org Cc: linux-pm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: devicetree-discuss@lists.ozlabs.org Signed-off-by: Eduardo Valentin <eduardo.valentin@ti.com> --- .../devicetree/bindings/cpufreq/cpufreq-cpu0.txt | 3 ++ .../devicetree/bindings/thermal/thermal.txt | 34 ++++++++++++++++++++++ drivers/cpufreq/cpufreq-cpu0.c | 8 +++++ 3 files changed, 45 insertions(+)