[PATCH V3] ARM: imx: add cpuidle support for i.mx6sl
Anson Huang
b20788 at freescale.com
Thu Jan 9 03:03:16 EST 2014
Add cpuidle support for i.MX6SL, currently only support
two cpuidle levels(ARM wfi and WAIT mode), and add software
workaround for WAIT mode errata as below:
ERR005311 CCM: After exit from WAIT mode, unwanted interrupt(s) taken
during WAIT mode entry process could cause cache memory
corruption.
Software workaround:
To prevent this issue from occurring, software should ensure that
the ARM to IPG clock ratio is less than 12:5 (that is < 2.4x), before
entering WAIT mode.
Signed-off-by: Anson Huang <b20788 at freescale.com>
---
Changes since V2:
Fix conflict when applying patch to shawnguo/for-next, as I
generated it from linux-next before.
arch/arm/mach-imx/Makefile | 1 +
arch/arm/mach-imx/clk-imx6sl.c | 26 ++++++++++++++++
arch/arm/mach-imx/common.h | 1 +
arch/arm/mach-imx/cpuidle-imx6sl.c | 57 ++++++++++++++++++++++++++++++++++++
arch/arm/mach-imx/cpuidle.h | 5 ++++
arch/arm/mach-imx/mach-imx6sl.c | 3 ++
6 files changed, 93 insertions(+)
create mode 100644 arch/arm/mach-imx/cpuidle-imx6sl.c
diff --git a/arch/arm/mach-imx/Makefile b/arch/arm/mach-imx/Makefile
index befcaf5..8589032 100644
--- a/arch/arm/mach-imx/Makefile
+++ b/arch/arm/mach-imx/Makefile
@@ -30,6 +30,7 @@ obj-$(CONFIG_MXC_DEBUG_BOARD) += 3ds_debugboard.o
ifeq ($(CONFIG_CPU_IDLE),y)
obj-$(CONFIG_SOC_IMX5) += cpuidle-imx5.o
obj-$(CONFIG_SOC_IMX6Q) += cpuidle-imx6q.o
+obj-$(CONFIG_SOC_IMX6SL) += cpuidle-imx6sl.o
endif
ifdef CONFIG_SND_IMX_SOC
diff --git a/arch/arm/mach-imx/clk-imx6sl.c b/arch/arm/mach-imx/clk-imx6sl.c
index 5877eea..f6c3b4f 100644
--- a/arch/arm/mach-imx/clk-imx6sl.c
+++ b/arch/arm/mach-imx/clk-imx6sl.c
@@ -66,6 +66,32 @@ static struct clk_div_table video_div_table[] = {
static struct clk *clks[IMX6SL_CLK_END];
static struct clk_onecell_data clk_data;
+/*
+ * ERR005311 CCM: After exit from WAIT mode, unwanted interrupt(s) taken
+ * during WAIT mode entry process could cause cache memory
+ * corruption.
+ *
+ * Software workaround:
+ * To prevent this issue from occurring, software should ensure that the
+ * ARM to IPG clock ratio is less than 12:5 (that is < 2.4x), before
+ * entering WAIT mode.
+ *
+ * This function will set the ARM clk to max value within the 12:5 limit.
+ */
+void imx6sl_set_wait_clk(bool enter)
+{
+ static unsigned long saved_arm_rate;
+
+ if (enter) {
+ unsigned long ipg_rate = clk_get_rate(clks[IMX6SL_CLK_IPG]);
+ unsigned long max_arm_wait_rate = (12 * ipg_rate) / 5;
+ saved_arm_rate = clk_get_rate(clks[IMX6SL_CLK_ARM]);
+ clk_set_rate(clks[IMX6SL_CLK_ARM], max_arm_wait_rate);
+ } else {
+ clk_set_rate(clks[IMX6SL_CLK_ARM], saved_arm_rate);
+ }
+}
+
static void __init imx6sl_clocks_init(struct device_node *ccm_node)
{
struct device_node *np;
diff --git a/arch/arm/mach-imx/common.h b/arch/arm/mach-imx/common.h
index 4f4a95c..1048248 100644
--- a/arch/arm/mach-imx/common.h
+++ b/arch/arm/mach-imx/common.h
@@ -140,6 +140,7 @@ void imx_anatop_pre_suspend(void);
void imx_anatop_post_resume(void);
int imx6q_set_lpm(enum mxc_cpu_pwr_mode mode);
void imx6q_set_int_mem_clk_lpm(void);
+void imx6sl_set_wait_clk(bool enter);
void imx_cpu_die(unsigned int cpu);
int imx_cpu_kill(unsigned int cpu);
diff --git a/arch/arm/mach-imx/cpuidle-imx6sl.c b/arch/arm/mach-imx/cpuidle-imx6sl.c
new file mode 100644
index 0000000..d4b6b81
--- /dev/null
+++ b/arch/arm/mach-imx/cpuidle-imx6sl.c
@@ -0,0 +1,57 @@
+/*
+ * 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/module.h>
+#include <asm/cpuidle.h>
+#include <asm/proc-fns.h>
+
+#include "common.h"
+#include "cpuidle.h"
+
+static int imx6sl_enter_wait(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int index)
+{
+ imx6q_set_lpm(WAIT_UNCLOCKED);
+ /*
+ * Software workaround for ERR005311, see function
+ * description for details.
+ */
+ imx6sl_set_wait_clk(true);
+ cpu_do_idle();
+ imx6sl_set_wait_clk(false);
+ imx6q_set_lpm(WAIT_CLOCKED);
+
+ return index;
+}
+
+static struct cpuidle_driver imx6sl_cpuidle_driver = {
+ .name = "imx6sl_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 = imx6sl_enter_wait,
+ .name = "WAIT",
+ .desc = "Clock off",
+ },
+ },
+ .state_count = 2,
+ .safe_state_index = 0,
+};
+
+int __init imx6sl_cpuidle_init(void)
+{
+ return cpuidle_register(&imx6sl_cpuidle_driver, NULL);
+}
diff --git a/arch/arm/mach-imx/cpuidle.h b/arch/arm/mach-imx/cpuidle.h
index 786f98e..24e3367 100644
--- a/arch/arm/mach-imx/cpuidle.h
+++ b/arch/arm/mach-imx/cpuidle.h
@@ -13,6 +13,7 @@
#ifdef CONFIG_CPU_IDLE
extern int imx5_cpuidle_init(void);
extern int imx6q_cpuidle_init(void);
+extern int imx6sl_cpuidle_init(void);
#else
static inline int imx5_cpuidle_init(void)
{
@@ -22,4 +23,8 @@ static inline int imx6q_cpuidle_init(void)
{
return 0;
}
+static inline int imx6sl_cpuidle_init(void)
+{
+ return 0;
+}
#endif
diff --git a/arch/arm/mach-imx/mach-imx6sl.c b/arch/arm/mach-imx/mach-imx6sl.c
index 0f4fd4c..a26fdb2 100644
--- a/arch/arm/mach-imx/mach-imx6sl.c
+++ b/arch/arm/mach-imx/mach-imx6sl.c
@@ -17,6 +17,7 @@
#include <asm/mach/map.h>
#include "common.h"
+#include "cpuidle.h"
static void __init imx6sl_fec_init(void)
{
@@ -39,6 +40,8 @@ static void __init imx6sl_init_late(void)
/* imx6sl reuses imx6q cpufreq driver */
if (IS_ENABLED(CONFIG_ARM_IMX6Q_CPUFREQ))
platform_device_register_simple("imx6q-cpufreq", -1, NULL, 0);
+
+ imx6sl_cpuidle_init();
}
static void __init imx6sl_init_machine(void)
--
1.7.9.5
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