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linux/arch/arm/mach-imx/gpc.c
Shawn Guo d48866fefd 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>
2013-10-21 09:39:26 +08:00

141 lines
3.1 KiB
C

/*
* Copyright 2011-2013 Freescale Semiconductor, Inc.
* Copyright 2011 Linaro Ltd.
*
* The code contained herein is licensed under the GNU General Public
* License. You may obtain a copy of the GNU General Public License
* Version 2 or later at the following locations:
*
* http://www.opensource.org/licenses/gpl-license.html
* http://www.gnu.org/copyleft/gpl.html
*/
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/irqchip/arm-gic.h>
#include "common.h"
#define GPC_IMR1 0x008
#define GPC_PGC_CPU_PDN 0x2a0
#define IMR_NUM 4
static void __iomem *gpc_base;
static u32 gpc_wake_irqs[IMR_NUM];
static u32 gpc_saved_imrs[IMR_NUM];
void imx_gpc_pre_suspend(void)
{
void __iomem *reg_imr1 = gpc_base + GPC_IMR1;
int i;
/* Tell GPC to power off ARM core when suspend */
writel_relaxed(0x1, gpc_base + GPC_PGC_CPU_PDN);
for (i = 0; i < IMR_NUM; i++) {
gpc_saved_imrs[i] = readl_relaxed(reg_imr1 + i * 4);
writel_relaxed(~gpc_wake_irqs[i], reg_imr1 + i * 4);
}
}
void imx_gpc_post_resume(void)
{
void __iomem *reg_imr1 = gpc_base + GPC_IMR1;
int i;
/* Keep ARM core powered on for other low-power modes */
writel_relaxed(0x0, gpc_base + GPC_PGC_CPU_PDN);
for (i = 0; i < IMR_NUM; i++)
writel_relaxed(gpc_saved_imrs[i], reg_imr1 + i * 4);
}
static int imx_gpc_irq_set_wake(struct irq_data *d, unsigned int on)
{
unsigned int idx = d->irq / 32 - 1;
u32 mask;
/* Sanity check for SPI irq */
if (d->irq < 32)
return -EINVAL;
mask = 1 << d->irq % 32;
gpc_wake_irqs[idx] = on ? gpc_wake_irqs[idx] | mask :
gpc_wake_irqs[idx] & ~mask;
return 0;
}
void imx_gpc_mask_all(void)
{
void __iomem *reg_imr1 = gpc_base + GPC_IMR1;
int i;
for (i = 0; i < IMR_NUM; i++) {
gpc_saved_imrs[i] = readl_relaxed(reg_imr1 + i * 4);
writel_relaxed(~0, reg_imr1 + i * 4);
}
}
void imx_gpc_restore_all(void)
{
void __iomem *reg_imr1 = gpc_base + GPC_IMR1;
int i;
for (i = 0; i < IMR_NUM; i++)
writel_relaxed(gpc_saved_imrs[i], reg_imr1 + i * 4);
}
void imx_gpc_irq_unmask(struct irq_data *d)
{
void __iomem *reg;
u32 val;
/* Sanity check for SPI irq */
if (d->irq < 32)
return;
reg = gpc_base + GPC_IMR1 + (d->irq / 32 - 1) * 4;
val = readl_relaxed(reg);
val &= ~(1 << d->irq % 32);
writel_relaxed(val, reg);
}
void imx_gpc_irq_mask(struct irq_data *d)
{
void __iomem *reg;
u32 val;
/* Sanity check for SPI irq */
if (d->irq < 32)
return;
reg = gpc_base + GPC_IMR1 + (d->irq / 32 - 1) * 4;
val = readl_relaxed(reg);
val |= 1 << (d->irq % 32);
writel_relaxed(val, reg);
}
void __init imx_gpc_init(void)
{
struct device_node *np;
int i;
np = of_find_compatible_node(NULL, NULL, "fsl,imx6q-gpc");
gpc_base = of_iomap(np, 0);
WARN_ON(!gpc_base);
/* Initially mask all interrupts */
for (i = 0; i < IMR_NUM; i++)
writel_relaxed(~0, gpc_base + GPC_IMR1 + i * 4);
/* Register GPC as the secondary interrupt controller behind GIC */
gic_arch_extn.irq_mask = imx_gpc_irq_mask;
gic_arch_extn.irq_unmask = imx_gpc_irq_unmask;
gic_arch_extn.irq_set_wake = imx_gpc_irq_set_wake;
}