[PATCH v3] arm: zynq: Add cpuidle support

[Michal Simek]

Add support for cpuidle.

Signed-off-by: Michal Simek <michal.simek at xilinx.com>
---
Changes in v3:
- Move driver to drivers/cpuidle/
- Check zynq compatible string suggested by Arnd
- Use zynq_ function prefix because of multiplatform kernel
- Incorporate comments from Daniel Lezcano
- Rebase on the top of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next

Changes in v2:
- Fix file header

Changes in v1:
- It was the part of Zynq core changes
  https://patchwork.kernel.org/patch/2342511/

 drivers/cpuidle/Kconfig        |   6 +++
 drivers/cpuidle/Makefile       |   1 +
 drivers/cpuidle/cpuidle-zynq.c | 100 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 107 insertions(+)
 create mode 100644 drivers/cpuidle/cpuidle-zynq.c

diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
index c4cc27e..8272a08 100644
--- a/drivers/cpuidle/Kconfig
+++ b/drivers/cpuidle/Kconfig
@@ -39,4 +39,10 @@ config CPU_IDLE_CALXEDA
 	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
diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
index 0d8bd55..8767a7b 100644
--- a/drivers/cpuidle/Makefile
+++ b/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
diff --git a/drivers/cpuidle/cpuidle-zynq.c b/drivers/cpuidle/cpuidle-zynq.c
new file mode 100644
index 0000000..afe6af3
--- /dev/null
+++ b/drivers/cpuidle/cpuidle-zynq.c
@@ -0,0 +1,100 @@
+/*
+ * Copyright (C) 2012-2013 Xilinx
+ *
+ * CPU idle support for Xilinx Zynq
+ *
+ * based on arch/arm/mach-at91/cpuidle.c
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ *
+ * 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
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/cpuidle.h>
+#include <linux/io.h>
+#include <linux/export.h>
+#include <linux/clockchips.h>
+#include <linux/cpu_pm.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <asm/proc-fns.h>
+#include <asm/cpuidle.h>
+
+#define ZYNQ_MAX_STATES		2
+
+static DEFINE_PER_CPU(struct cpuidle_device, zynq_cpuidle_device);
+
+/* 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 zynq_init_cpuidle(void)
+{
+	unsigned int cpu;
+	struct cpuidle_device *device;
+	int ret;
+
+	if (!of_machine_is_compatible("xlnx,zynq-7000"))
+		return -ENODEV;
+
+	ret = cpuidle_register_driver(&zynq_idle_driver);
+	if (ret) {
+		pr_err("%s: Driver registration failed\n", __func__);
+		return ret;
+	}
+
+	for_each_possible_cpu(cpu) {
+		device = &per_cpu(zynq_cpuidle_device, cpu);
+		device->cpu = cpu;
+		ret = cpuidle_register_device(device);
+		if (ret) {
+			pr_err("%s: Device registration failed\n", __func__);
+			return ret;
+		}
+	}
+
+	pr_info("Xilinx Zynq CpuIdle Driver started\n");
+	return 0;
+}
+module_init(zynq_init_cpuidle);
--
1.8.2.3

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