ARM: imx: support arm power off in cpuidle for i.mx6sx

This patch introduces an independent cpuidle driver for
i.MX6SX, and supports arm power off in idle, totally
3 levels of cpuidle are supported as below:

1. ARM WFI;
2. SOC in WAIT mode;
3. SOC in WAIT mode + ARM power off.

ARM power off can save at least 5mW power.

This patch also replaces imx6q_enable_rbc with imx6_enable_rbc.

Signed-off-by: Anson Huang <b20788@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

1 files changed, 107 insertions, 0 deletions

diff --git a/arch/arm/mach-imx/cpuidle-imx6sx.c b/arch/arm/mach-imx/cpuidle-imx6sx.c
new file mode 100644
index 000000000000..d8a9f219e028
--- /dev/null
+++ b/arch/arm/mach-imx/cpuidle-imx6sx.c
@@ -0,0 +1,107 @@
+/*
+ * Copyright (C) 2014 Freescale Semiconductor, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/cpuidle.h>
+#include <linux/cpu_pm.h>
+#include <linux/module.h>
+#include <asm/cpuidle.h>
+#include <asm/proc-fns.h>
+#include <asm/suspend.h>
+
+#include "common.h"
+#include "cpuidle.h"
+
+static int imx6sx_idle_finish(unsigned long val)
+{
+	cpu_do_idle();
+
+	return 0;
+}
+
+static int imx6sx_enter_wait(struct cpuidle_device *dev,
+			    struct cpuidle_driver *drv, int index)
+{
+	imx6q_set_lpm(WAIT_UNCLOCKED);
+
+	switch (index) {
+	case 1:
+		cpu_do_idle();
+		break;
+	case 2:
+		imx6_enable_rbc(true);
+		imx_gpc_set_arm_power_in_lpm(true);
+		imx_set_cpu_jump(0, v7_cpu_resume);
+		/* Need to notify there is a cpu pm operation. */
+		cpu_pm_enter();
+		cpu_cluster_pm_enter();
+
+		cpu_suspend(0, imx6sx_idle_finish);
+
+		cpu_cluster_pm_exit();
+		cpu_pm_exit();
+		imx_gpc_set_arm_power_in_lpm(false);
+		imx6_enable_rbc(false);
+		break;
+	default:
+		break;
+	}
+
+	imx6q_set_lpm(WAIT_CLOCKED);
+
+	return index;
+}
+
+static struct cpuidle_driver imx6sx_cpuidle_driver = {
+	.name = "imx6sx_cpuidle",
+	.owner = THIS_MODULE,
+	.states = {
+		/* WFI */
+		ARM_CPUIDLE_WFI_STATE,
+		/* WAIT */
+		{
+			.exit_latency = 50,
+			.target_residency = 75,
+			.flags = CPUIDLE_FLAG_TIME_VALID |
+				CPUIDLE_FLAG_TIMER_STOP,
+			.enter = imx6sx_enter_wait,
+			.name = "WAIT",
+			.desc = "Clock off",
+		},
+		/* WAIT + ARM power off  */
+		{
+			/*
+			 * ARM gating 31us * 5 + RBC clear 65us
+			 * and some margin for SW execution, here set it
+			 * to 300us.
+			 */
+			.exit_latency = 300,
+			.target_residency = 500,
+			.flags = CPUIDLE_FLAG_TIME_VALID,
+			.enter = imx6sx_enter_wait,
+			.name = "LOW-POWER-IDLE",
+			.desc = "ARM power off",
+		},
+	},
+	.state_count = 3,
+	.safe_state_index = 0,
+};
+
+int __init imx6sx_cpuidle_init(void)
+{
+	imx6_enable_rbc(false);
+	/*
+	 * set ARM power up/down timing to the fastest,
+	 * sw2iso and sw can be set to one 32K cycle = 31us
+	 * except for power up sw2iso which need to be
+	 * larger than LDO ramp up time.
+	 */
+	imx_gpc_set_arm_power_up_timing(2, 1);
+	imx_gpc_set_arm_power_down_timing(1, 1);
+
+	return cpuidle_register(&imx6sx_cpuidle_driver, NULL);
+}