ARM: keystone: add PM domain support for clock management

Add runtime PM core support to Keystone SOCs by using the pm_clk
infrastructure of the PM core. Patch is based on Kevin's pm_domain
work on DaVinci SOCs.

Keystone SOC doesn't have depedency to enable clocks in early
in the boot and hence the clock and PM domain initialisation is done
at subsys_init() level.

Cc: Kevin Hilman <khilman@linaro.org>

Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>

arch/arm/mach-keystone/Makefile

@@ -4,3 +4,6 @@ plus_sec := $(call as-instr,.arch_extension sec,+sec)
 AFLAGS_smc.o				:=-Wa,-march=armv7-a$(plus_sec)
 
 obj-$(CONFIG_SMP)			+= platsmp.o
+
+# PM domain driver for Keystone SOCs
+obj-$(CONFIG_ARCH_KEYSTONE)		+= pm_domain.o

arch/arm/mach-keystone/pm_domain.c

@@ -0,0 +1,70 @@
+/*
+ * PM domain driver for Keystone2 devices
+ *
+ * Copyright 2013 Texas Instruments, Inc.
+ *	Santosh Shilimkar <santosh.shillimkar@ti.com>
+ *
+ * Based on Kevins work on DAVINCI SOCs
+ *	Kevin Hilman <khilman@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ */
+
+#include <linux/init.h>
+#include <linux/pm_runtime.h>
+#include <linux/pm_clock.h>
+#include <linux/platform_device.h>
+#include <linux/clk-provider.h>
+
+#ifdef CONFIG_PM_RUNTIME
+static int keystone_pm_runtime_suspend(struct device *dev)
+{
+	int ret;
+
+	dev_dbg(dev, "%s\n", __func__);
+
+	ret = pm_generic_runtime_suspend(dev);
+	if (ret)
+		return ret;
+
+	ret = pm_clk_suspend(dev);
+	if (ret) {
+		pm_generic_runtime_resume(dev);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int keystone_pm_runtime_resume(struct device *dev)
+{
+	dev_dbg(dev, "%s\n", __func__);
+
+	pm_clk_resume(dev);
+
+	return pm_generic_runtime_resume(dev);
+}
+#endif
+
+static struct dev_pm_domain keystone_pm_domain = {
+	.ops = {
+		SET_RUNTIME_PM_OPS(keystone_pm_runtime_suspend,
+				   keystone_pm_runtime_resume, NULL)
+		USE_PLATFORM_PM_SLEEP_OPS
+	},
+};
+
+static struct pm_clk_notifier_block platform_domain_notifier = {
+	.pm_domain = &keystone_pm_domain,
+};
+
+int __init keystone_pm_runtime_init(void)
+{
+	of_clk_init(NULL);
+	pm_clk_add_notifier(&platform_bus_type, &platform_domain_notifier);
+
+	return 0;
+}
+subsys_initcall(keystone_pm_runtime_init);