[ARM] 3584/1: AT91RM9200 GPIO suspend/resume support

Patch from Andrew Victor

This patch adds suspend/resume/set_wake support for the AT91RM9200's
GPIO interrupts.

Original patch from David Brownell.

Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 84 insertions, 3 deletions

diff --git a/arch/arm/mach-at91rm9200/gpio.c b/arch/arm/mach-at91rm9200/gpio.c
index 5ab46274e1a3..3430ea054662 100644
--- a/arch/arm/mach-at91rm9200/gpio.c
+++ b/arch/arm/mach-at91rm9200/gpio.c
@@ -213,6 +213,84 @@ EXPORT_SYMBOL(at91_get_gpio_value);
 
 /*--------------------------------------------------------------------------*/
 
+#ifdef CONFIG_PM
+
+static u32 wakeups[BGA_GPIO_BANKS];
+static u32 backups[BGA_GPIO_BANKS];
+
+static int gpio_irq_set_wake(unsigned pin, unsigned state)
+{
+        unsigned        mask = pin_to_mask(pin);
+
+        pin -= PIN_BASE;
+        pin /= 32;
+
+        if (unlikely(pin >= BGA_GPIO_BANKS))
+                return -EINVAL;
+
+        if (state)
+                wakeups[pin] |= mask;
+        else
+                wakeups[pin] &= ~mask;
+
+        return 0;
+}
+
+void at91_gpio_suspend(void)
+{
+        int i;
+
+        for (i = 0; i < BGA_GPIO_BANKS; i++) {
+                u32 pio = pio_controller_offset[i];
+
+                /*
+                 * Note: drivers should have disabled GPIO interrupts that
+                 * aren't supposed to be wakeup sources.
+                 * But that is not much good on ARM.....  disable_irq() does
+                 * not update the hardware immediately, so the hardware mask
+                 * (IMR) has the wrong value (not current, too much is
+                 * permitted).
+                 *
+                 * Our workaround is to disable all non-wakeup IRQs ...
+                 * which is exactly what correct drivers asked for in the
+                 * first place!
+                 */
+                backups[i] = at91_sys_read(pio + PIO_IMR);
+                at91_sys_write(pio_controller_offset[i] + PIO_IDR, backups[i]);
+                at91_sys_write(pio_controller_offset[i] + PIO_IER, wakeups[i]);
+
+                if (!wakeups[i]) {
+                        disable_irq_wake(AT91_ID_PIOA + i);
+                        at91_sys_write(AT91_PMC_PCDR, 1 << (AT91_ID_PIOA + i));
+                } else {
+                        enable_irq_wake(AT91_ID_PIOA + i);
+#ifdef CONFIG_PM_DEBUG
+                        printk(KERN_DEBUG "GPIO-%c may wake for %08x\n", "ABCD"[i], wakeups[i]);
+#endif
+                }
+        }
+}
+
+void at91_gpio_resume(void)
+{
+        int i;
+
+        for (i = 0; i < BGA_GPIO_BANKS; i++) {
+                at91_sys_write(pio_controller_offset[i] + PIO_IDR, wakeups[i]);
+                at91_sys_write(pio_controller_offset[i] + PIO_IER, backups[i]);
+        }
+
+        at91_sys_write(AT91_PMC_PCER,
+                          (1 << AT91_ID_PIOA)
+                        | (1 << AT91_ID_PIOB)
+                        | (1 << AT91_ID_PIOC)
+                        | (1 << AT91_ID_PIOD));
+}
+
+#else
+#define gpio_irq_set_wake       NULL
+#endif
+
 
 /* Several AIC controller irqs are dispatched through this GPIO handler.
  * To use any AT91_PIN_* as an externally triggered IRQ, first call
@@ -252,6 +330,7 @@ static struct irqchip gpio_irqchip = {
         .mask           = gpio_irq_mask,
         .unmask         = gpio_irq_unmask,
         .set_type       = gpio_irq_type,
+        .set_wake       = gpio_irq_set_wake,
 };
 
 static void gpio_irq_handler(unsigned irq, struct irqdesc *desc, struct pt_regs *regs)
@@ -266,6 +345,7 @@ static void gpio_irq_handler(unsigned irq, struct irqdesc *desc, struct pt_regs
         /* temporarily mask (level sensitive) parent IRQ */
         desc->chip->ack(irq);
         for (;;) {
+                /* reading ISR acks the pending (edge triggered) GPIO interrupt */
                 isr = __raw_readl(pio + PIO_ISR) & __raw_readl(pio + PIO_IMR);
                 if (!isr)
                         break;
@@ -315,15 +395,16 @@ void __init at91_gpio_irq_setup(unsigned banks)
                 set_irq_chipdata(id, controller);
 
                 for (i = 0; i < 32; i++, pin++) {
+                        /*
+                         * Can use the "simple" and not "edge" handler since it's
+                         * shorter, and the AIC handles interupts sanely.
+                         */
                         set_irq_chip(pin, &gpio_irqchip);
                         set_irq_handler(pin, do_simple_IRQ);
                         set_irq_flags(pin, IRQF_VALID);
                 }
 
                 set_irq_chained_handler(id, gpio_irq_handler);
-
-                /* enable the PIO peripheral clock */
-                at91_sys_write(AT91_PMC_PCER, 1 << id);
         }
         pr_info("AT91: %d gpio irqs in %d banks\n", pin - PIN_BASE, banks);
 }