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authorShawn Guo <shawn.guo@linaro.org>2013-10-16 19:52:00 +0800
committerShawn Guo <shawn.guo@linaro.org>2013-10-21 09:39:26 +0800
commitd48866fefdac239a4e02777e712aad60db9ee8a8 (patch)
treebe0bb666ba9a8d0c29a262407e885ee91abb85e7
parent1d674a73c59211cc33cb9c2954659033d8458fa9 (diff)
downloadop-kernel-dev-d48866fefdac239a4e02777e712aad60db9ee8a8.zip
op-kernel-dev-d48866fefdac239a4e02777e712aad60db9ee8a8.tar.gz
ARM: imx: ensure dsm_request signal is not asserted when setting LPM
There is a defect in imx6 LPM design. When SW tries to enter low power mode with following sequence, the chip will enter low power mode before A9 CPU execute WFI instruction: 1. Set CCM_CLPCR[1:0] to 2'b00; 2. ARM CPU enters WFI; 3. ARM CPU wakeup from an interrupt event, which is masked by GPC or not visible to GPC, such as interrupt from local timer; 4. Set CCM_CLPCR[1:0] to 2'b01 or 2'b10; 5. ARM CPU execute WFI. Before the last step, the chip will enter WAIT mode if CCM_CLPCR[1:0] is set to 2'b01, or enter STOP mode if CCM_CLPCR[1:0] is set to 2'b10. The patch implements a recommended workaround for this issue. 1. SW triggers irq #32(IOMUX) to be always pending manually by setting IOMUX_GPR1_GINT bit; 2. SW should then unmask it in GPC before setting CCM LPM; 3. SW should mask it right after CCM LPM is set (bit0-1 of CCM_CLPCR). Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
-rw-r--r--arch/arm/mach-imx/common.h3
-rw-r--r--arch/arm/mach-imx/gpc.c4
-rw-r--r--arch/arm/mach-imx/pm-imx6q.c26
3 files changed, 31 insertions, 2 deletions
diff --git a/arch/arm/mach-imx/common.h b/arch/arm/mach-imx/common.h
index fde6661..7cbe22d 100644
--- a/arch/arm/mach-imx/common.h
+++ b/arch/arm/mach-imx/common.h
@@ -13,6 +13,7 @@
#include <linux/reboot.h>
+struct irq_data;
struct platform_device;
struct pt_regs;
struct clk;
@@ -136,6 +137,8 @@ void imx_gpc_pre_suspend(void);
void imx_gpc_post_resume(void);
void imx_gpc_mask_all(void);
void imx_gpc_restore_all(void);
+void imx_gpc_irq_mask(struct irq_data *d);
+void imx_gpc_irq_unmask(struct irq_data *d);
void imx_anatop_init(void);
void imx_anatop_pre_suspend(void);
void imx_anatop_post_resume(void);
diff --git a/arch/arm/mach-imx/gpc.c b/arch/arm/mach-imx/gpc.c
index 44a65e9..586e017 100644
--- a/arch/arm/mach-imx/gpc.c
+++ b/arch/arm/mach-imx/gpc.c
@@ -90,7 +90,7 @@ void imx_gpc_restore_all(void)
writel_relaxed(gpc_saved_imrs[i], reg_imr1 + i * 4);
}
-static void imx_gpc_irq_unmask(struct irq_data *d)
+void imx_gpc_irq_unmask(struct irq_data *d)
{
void __iomem *reg;
u32 val;
@@ -105,7 +105,7 @@ static void imx_gpc_irq_unmask(struct irq_data *d)
writel_relaxed(val, reg);
}
-static void imx_gpc_irq_mask(struct irq_data *d)
+void imx_gpc_irq_mask(struct irq_data *d)
{
void __iomem *reg;
u32 val;
diff --git a/arch/arm/mach-imx/pm-imx6q.c b/arch/arm/mach-imx/pm-imx6q.c
index fb7d90d..f303b56 100644
--- a/arch/arm/mach-imx/pm-imx6q.c
+++ b/arch/arm/mach-imx/pm-imx6q.c
@@ -13,8 +13,12 @@
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/mfd/syscon.h>
+#include <linux/mfd/syscon/imx6q-iomuxc-gpr.h>
#include <linux/of.h>
#include <linux/of_address.h>
+#include <linux/regmap.h>
#include <linux/suspend.h>
#include <asm/cacheflush.h>
#include <asm/proc-fns.h>
@@ -116,6 +120,7 @@ static void imx6q_enable_wb(bool enable)
int imx6q_set_lpm(enum mxc_cpu_pwr_mode mode)
{
+ struct irq_desc *iomuxc_irq_desc;
u32 val = readl_relaxed(ccm_base + CLPCR);
val &= ~BM_CLPCR_LPM;
@@ -144,7 +149,16 @@ int imx6q_set_lpm(enum mxc_cpu_pwr_mode mode)
return -EINVAL;
}
+ /*
+ * Unmask the always pending IOMUXC interrupt #32 as wakeup source to
+ * deassert dsm_request signal, so that we can ensure dsm_request
+ * is not asserted when we're going to write CLPCR register to set LPM.
+ * After setting up LPM bits, we need to mask this wakeup source.
+ */
+ iomuxc_irq_desc = irq_to_desc(32);
+ imx_gpc_irq_unmask(&iomuxc_irq_desc->irq_data);
writel_relaxed(val, ccm_base + CLPCR);
+ imx_gpc_irq_mask(&iomuxc_irq_desc->irq_data);
return 0;
}
@@ -193,8 +207,20 @@ void __init imx6q_pm_set_ccm_base(void __iomem *base)
void __init imx6q_pm_init(void)
{
+ struct regmap *gpr;
+
WARN_ON(!ccm_base);
+ /*
+ * Force IOMUXC irq pending, so that the interrupt to GPC can be
+ * used to deassert dsm_request signal when the signal gets
+ * asserted unexpectedly.
+ */
+ gpr = syscon_regmap_lookup_by_compatible("fsl,imx6q-iomuxc-gpr");
+ if (!IS_ERR(gpr))
+ regmap_update_bits(gpr, IOMUXC_GPR1, IMX6Q_GPR1_GINT,
+ IMX6Q_GPR1_GINT);
+
/* Set initial power mode */
imx6q_set_lpm(WAIT_CLOCKED);
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