GPIO: gpio-dwapb: Support Debounce

This patch enables 'debounce' for the designware GPIO, and
it is based on Josef Ahmad's previous work.

Reviewed-by: Hock Leong Kweh <hock.leong.kweh@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Weike Chen <alvin.chen@intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 34 insertions, 2 deletions

diff --git a/drivers/gpio/gpio-dwapb.c b/drivers/gpio/gpio-dwapb.c
index 551eaf7208f4..db059bb8edc3 100644
--- a/drivers/gpio/gpio-dwapb.c
+++ b/drivers/gpio/gpio-dwapb.c
@@ -37,6 +37,7 @@
 #define GPIO_INTTYPE_LEVEL      0x38
 #define GPIO_INT_POLARITY       0x3c
 #define GPIO_INTSTATUS          0x40
+#define GPIO_PORTA_DEBOUNCE     0x48
 #define GPIO_PORTA_EOI          0x4c
 #define GPIO_EXT_PORTA          0x50
 #define GPIO_EXT_PORTB          0x54
@@ -64,6 +65,12 @@ struct dwapb_gpio {
         struct irq_domain       *domain;
 };
 
+static inline struct dwapb_gpio_port *
+to_dwapb_gpio_port(struct bgpio_chip *bgc)
+{
+        return container_of(bgc, struct dwapb_gpio_port, bgc);
+}
+
 static inline u32 dwapb_read(struct dwapb_gpio *gpio, unsigned int offset)
 {
         struct bgpio_chip *bgc  = &gpio->ports[0].bgc;
@@ -84,8 +91,7 @@ static inline void dwapb_write(struct dwapb_gpio *gpio, unsigned int offset,
 static int dwapb_gpio_to_irq(struct gpio_chip *gc, unsigned offset)
 {
         struct bgpio_chip *bgc = to_bgpio_chip(gc);
-        struct dwapb_gpio_port *port = container_of(bgc, struct
-                                                    dwapb_gpio_port, bgc);
+        struct dwapb_gpio_port *port = to_dwapb_gpio_port(bgc);
         struct dwapb_gpio *gpio = port->gpio;
 
         return irq_find_mapping(gpio->domain, offset);
@@ -235,6 +241,28 @@ static int dwapb_irq_set_type(struct irq_data *d, u32 type)
         return 0;
 }
 
+static int dwapb_gpio_set_debounce(struct gpio_chip *gc,
+                                   unsigned offset, unsigned debounce)
+{
+        struct bgpio_chip *bgc = to_bgpio_chip(gc);
+        struct dwapb_gpio_port *port = to_dwapb_gpio_port(bgc);
+        struct dwapb_gpio *gpio = port->gpio;
+        unsigned long flags, val_deb;
+        unsigned long mask = bgc->pin2mask(bgc, offset);
+
+        spin_lock_irqsave(&bgc->lock, flags);
+
+        val_deb = dwapb_read(gpio, GPIO_PORTA_DEBOUNCE);
+        if (debounce)
+                dwapb_write(gpio, GPIO_PORTA_DEBOUNCE, val_deb | mask);
+        else
+                dwapb_write(gpio, GPIO_PORTA_DEBOUNCE, val_deb & ~mask);
+
+        spin_unlock_irqrestore(&bgc->lock, flags);
+
+        return 0;
+}
+
 static irqreturn_t dwapb_irq_handler_mfd(int irq, void *dev_id)
 {
         u32 worked;
@@ -373,6 +401,10 @@ static int dwapb_gpio_add_port(struct dwapb_gpio *gpio,
         port->bgc.gc.ngpio = pp->ngpio;
         port->bgc.gc.base = pp->gpio_base;
 
+        /* Only port A support debounce */
+        if (pp->idx == 0)
+                port->bgc.gc.set_debounce = dwapb_gpio_set_debounce;
+
         if (pp->irq)
                 dwapb_configure_irqs(gpio, port, pp);