ARM: zynq: Add cpuidle support

Add cpuidle support for Xilinx Zynq.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

MAINTAINERS

@@ -1309,6 +1309,7 @@ W:	http://wiki.xilinx.com
 T:	git git://git.xilinx.com/linux-xlnx.git
 S:	Supported
 F:	arch/arm/mach-zynq/
+F:	drivers/cpuidle/cpuidle-zynq.c
 
 ARM64 PORT (AARCH64 ARCHITECTURE)
 M:	Catalin Marinas <catalin.marinas@arm.com>

drivers/cpuidle/Kconfig

@@ -37,4 +37,11 @@ config CPU_IDLE_CALXEDA
 	depends on ARCH_HIGHBANK
 	help
 	  Select this to enable cpuidle on Calxeda processors.
+
+config CPU_IDLE_ZYNQ
+	bool "CPU Idle Driver for Xilinx Zynq processors"
+	depends on ARCH_ZYNQ
+	help
+	  Select this to enable cpuidle on Xilinx Zynq processors.
+
 endif

drivers/cpuidle/Makefile

@@ -7,3 +7,4 @@ obj-$(CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED) += coupled.o
 
 obj-$(CONFIG_CPU_IDLE_CALXEDA) += cpuidle-calxeda.o
 obj-$(CONFIG_ARCH_KIRKWOOD) += cpuidle-kirkwood.o
+obj-$(CONFIG_CPU_IDLE_ZYNQ) += cpuidle-zynq.o

drivers/cpuidle/cpuidle-zynq.c

@@ -0,0 +1,83 @@
+/*
+ * Copyright (C) 2012-2013 Xilinx
+ *
+ * CPU idle support for Xilinx Zynq
+ *
+ * based on arch/arm/mach-at91/cpuidle.c
+ *
+ * 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.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * The cpu idle uses wait-for-interrupt and RAM self refresh in order
+ * to implement two idle states -
+ * #1 wait-for-interrupt
+ * #2 wait-for-interrupt and RAM self refresh
+ *
+ * Maintainer: Michal Simek <michal.simek@xilinx.com>
+ */
+
+#include <linux/init.h>
+#include <linux/cpu_pm.h>
+#include <linux/cpuidle.h>
+#include <linux/of.h>
+#include <asm/proc-fns.h>
+#include <asm/cpuidle.h>
+
+#define ZYNQ_MAX_STATES		2
+
+/* Actual code that puts the SoC in different idle states */
+static int zynq_enter_idle(struct cpuidle_device *dev,
+			   struct cpuidle_driver *drv, int index)
+{
+	/* Devices must be stopped here */
+	cpu_pm_enter();
+
+	/* Add code for DDR self refresh start */
+	cpu_do_idle();
+
+	/* Add code for DDR self refresh stop */
+	cpu_pm_exit();
+
+	return index;
+}
+
+static struct cpuidle_driver zynq_idle_driver = {
+	.name = "zynq_idle",
+	.owner = THIS_MODULE,
+	.states = {
+		ARM_CPUIDLE_WFI_STATE,
+		{
+			.enter			= zynq_enter_idle,
+			.exit_latency		= 10,
+			.target_residency	= 10000,
+			.flags			= CPUIDLE_FLAG_TIME_VALID |
+						  CPUIDLE_FLAG_TIMER_STOP,
+			.name			= "RAM_SR",
+			.desc			= "WFI and RAM Self Refresh",
+		},
+	},
+	.safe_state_index = 0,
+	.state_count = ZYNQ_MAX_STATES,
+};
+
+/* Initialize CPU idle by registering the idle states */
+static int __init zynq_cpuidle_init(void)
+{
+	if (!of_machine_is_compatible("xlnx,zynq-7000"))
+		return -ENODEV;
+
+	pr_info("Xilinx Zynq CpuIdle Driver started\n");
+
+	return cpuidle_register(&zynq_idle_driver, NULL);
+}
+
+device_initcall(zynq_cpuidle_init);