[PATCH] cpufreq: imx6q: add CPU as cooling device

[Bastian Stender <bst@pengutronix.de>]

The cooling device should be part of the i.MX cpufreq driver. So move
it there.

Use of_cpufreq_power_cooling_register to link the cooling device to the
device tree node provided.

This makes it possible to bind the cpufreq cooling device to a custom
thermal zone via a cooling-maps entry like:

	cooling-maps {
		map0 {
			trip = <&board_alert>;
			cooling-device = <&cpu0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
		};
	};

Assuming a cpu node exists with label "cpu0" and #cooling-cells
property.

Signed-off-by: Bastian Stender <bst@pengutronix.de>
---
This is part of a rework of "thermal: imx: use cpufreq cooling of
registration method" (id:20171103164203.5805-1-bst@pengutronix.de).

The cooling device gets removed from imx_thermal code by "thermal: imx:
remove cooling device" (id:20171114134829.1354-1-bst@pengutronix.de)
---
 drivers/cpufreq/imx6q-cpufreq.c | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/cpufreq/imx6q-cpufreq.c b/drivers/cpufreq/imx6q-cpufreq.c
index 14466a9b01c0..66833840236e 100644
--- a/drivers/cpufreq/imx6q-cpufreq.c
+++ b/drivers/cpufreq/imx6q-cpufreq.c
@@ -9,6 +9,7 @@
 #include <linux/clk.h>
 #include <linux/cpu.h>
 #include <linux/cpufreq.h>
+#include <linux/cpu_cooling.h>
 #include <linux/err.h>
 #include <linux/module.h>
 #include <linux/of.h>
@@ -35,6 +36,7 @@ static struct clk *pll2_bus_clk;
 static struct clk *secondary_sel_clk;
 
 static struct device *cpu_dev;
+static struct thermal_cooling_device *cdev;
 static bool free_opp;
 static struct cpufreq_frequency_table *freq_table;
 static unsigned int transition_latency;
@@ -169,6 +171,32 @@ static int imx6q_set_target(struct cpufreq_policy *policy, unsigned int index)
 	return 0;
 }
 
+static void imx6q_cpufreq_ready(struct cpufreq_policy *policy)
+{
+	struct device_node *np = of_node_get(cpu_dev->of_node);
+	u32 capacitance = 0;
+
+	if (WARN_ON(!np))
+		return;
+
+	if (of_find_property(np, "#cooling-cells", NULL)) {
+		of_property_read_u32(np, "dynamic-power-coefficient", &capacitance);
+
+		cdev = of_cpufreq_power_cooling_register(np,
+						policy, capacitance, NULL);
+
+		if (IS_ERR(cdev)) {
+			dev_err(cpu_dev,
+				"running cpufreq without cooling device: %ld\n",
+				PTR_ERR(cdev));
+
+			cdev = NULL;
+		}
+	}
+
+	of_node_put(np);
+}
+
 static int imx6q_cpufreq_init(struct cpufreq_policy *policy)
 {
 	int ret;
@@ -180,13 +208,23 @@ static int imx6q_cpufreq_init(struct cpufreq_policy *policy)
 	return ret;
 }
 
+static int imx6q_cpufreq_exit(struct cpufreq_policy *policy)
+{
+	cpufreq_cooling_unregister(cdev);
+	dev_pm_opp_free_cpufreq_table(cpu_dev, &policy->freq_table);
+
+	return 0;
+}
+
 static struct cpufreq_driver imx6q_cpufreq_driver = {
 	.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 	.verify = cpufreq_generic_frequency_table_verify,
 	.target_index = imx6q_set_target,
 	.get = cpufreq_generic_get,
 	.init = imx6q_cpufreq_init,
+	.exit = imx6q_cpufreq_exit,
 	.name = "imx6q-cpufreq",
+	.ready = imx6q_cpufreq_ready,
 	.attr = cpufreq_generic_attr,
 	.suspend = cpufreq_generic_suspend,
 };
-- 
2.11.0