[PATCH V2] thermal: ti-soc-thermal: Enable addition power management

[Adam Ford]

The bandgap sensor can be idled when the processor is, but it
isn't currently being done. The power consumption of OMAP3
boards can elevated if the bangap sensor is enabled, because
the bandgap clock blocks deeper idle states the SoC.

We should idle bandgap with cpu_notifier instead of
runtime PM to avoid tagging it with pm_runtime_irq_safe()
that we want to stop using for drivers in general.

This patch uses additional power management to idle the clock
of the bandgap when it is not needed.

Reviewed-by: Tony Lindgren <tony@xxxxxxxxxxx>
Tested-by: Tony Lindgren <tony@xxxxxxxxxxx>
Suggested-by: Tony Lindgren <tony@xxxxxxxxxxx>
Signed-off-by: Adam Ford <aford173@xxxxxxxxx>

diff --git a/drivers/thermal/ti-soc-thermal/ti-bandgap.c b/drivers/thermal/ti-soc-thermal/ti-bandgap.c
index 2fa78f738568..35edac688843 100644
--- a/drivers/thermal/ti-soc-thermal/ti-bandgap.c
+++ b/drivers/thermal/ti-soc-thermal/ti-bandgap.c
@@ -26,10 +26,18 @@
 #include <linux/of_irq.h>
 #include <linux/of_gpio.h>
 #include <linux/io.h>
+#include <linux/cpu_pm.h>
+#include <linux/device.h>
+#include <linux/pm_runtime.h>
+#include <linux/pm.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
 
 #include "ti-bandgap.h"
 
 static int ti_bandgap_force_single_read(struct ti_bandgap *bgp, int id);
+static int bandgap_omap_cpu_notifier(struct notifier_block *nb,
+				  unsigned long cmd, void *v);
 
 /***   Helper functions to access registers and their bitfields   ***/
 
@@ -1025,6 +1033,9 @@ int ti_bandgap_probe(struct platform_device *pdev)
 		}
 	}
 
+	bgp->nb.notifier_call = bandgap_omap_cpu_notifier;
+	cpu_pm_register_notifier(&bgp->nb);
+
 	return 0;
 
 remove_last_cooling:
@@ -1060,7 +1071,9 @@ int ti_bandgap_remove(struct platform_device *pdev)
 	struct ti_bandgap *bgp = platform_get_drvdata(pdev);
 	int i;
 
-	/* First thing is to remove sensor interfaces */
+	cpu_pm_unregister_notifier(&bgp->nb);
+
+	/* Remove sensor interfaces */
 	for (i = 0; i < bgp->conf->sensor_count; i++) {
 		if (bgp->conf->sensors[i].unregister_cooling)
 			bgp->conf->sensors[i].unregister_cooling(bgp, i);
@@ -1174,6 +1187,38 @@ static int ti_bandgap_suspend(struct device *dev)
 	return err;
 }
 
+static int bandgap_omap_cpu_notifier(struct notifier_block *nb,
+				  unsigned long cmd, void *v)
+{
+	struct ti_bandgap *bgp;
+
+	bgp = container_of(nb, struct ti_bandgap, nb);
+
+	spin_lock(&bgp->lock);
+	switch (cmd) {
+	case CPU_CLUSTER_PM_ENTER:
+		if (bgp->is_suspended)
+			break;
+		ti_bandgap_save_ctxt(bgp);
+		ti_bandgap_power(bgp, false);
+		if (TI_BANDGAP_HAS(bgp, CLK_CTRL))
+			clk_disable(bgp->fclock);
+		break;
+	case CPU_CLUSTER_PM_ENTER_FAILED:
+	case CPU_CLUSTER_PM_EXIT:
+		if (bgp->is_suspended)
+			break;
+		if (TI_BANDGAP_HAS(bgp, CLK_CTRL))
+			clk_enable(bgp->fclock);
+		ti_bandgap_power(bgp, true);
+		ti_bandgap_restore_ctxt(bgp);
+		break;
+	}
+	spin_unlock(&bgp->lock);
+
+	return NOTIFY_OK;
+}
+
 static int ti_bandgap_resume(struct device *dev)
 {
 	struct ti_bandgap *bgp = dev_get_drvdata(dev);
diff --git a/drivers/thermal/ti-soc-thermal/ti-bandgap.h b/drivers/thermal/ti-soc-thermal/ti-bandgap.h
index bb9b0f7faf99..a21d07a1a23a 100644
--- a/drivers/thermal/ti-soc-thermal/ti-bandgap.h
+++ b/drivers/thermal/ti-soc-thermal/ti-bandgap.h
@@ -12,6 +12,10 @@
 #include <linux/spinlock.h>
 #include <linux/types.h>
 #include <linux/err.h>
+#include <linux/cpu_pm.h>
+#include <linux/device.h>
+#include <linux/pm_runtime.h>
+#include <linux/pm.h>
 
 /**
  * DOC: bandgap driver data structure
@@ -201,6 +205,8 @@ struct ti_bandgap {
 	int				irq;
 	int				tshut_gpio;
 	u32				clk_rate;
+	struct notifier_block		nb;
+	unsigned int is_suspended:1;
 };
 
 /**
-- 
2.20.1