[PATCH v2 4/6] gpio: brcmstb: Allow GPIOs to be wakeup sources

[Gregory Fong <gregory.0xf0@gmail.com>]

Several drivers (e.g. gpio-keys) allow for GPIOs to be configured as
wakeup sources, and this GPIO controller supports that through a
separate interrupt path.

The de-facto standard DT property "wakeup-source" is checked, since
that indicates whether the GPIO controller hardware can wake.  Uses
the IRQCHIP_MASK_ON_SUSPEND irq_chip flag because UPG GIO doesn't have
any of its own wakeup source configuration.

Signed-off-by: Gregory Fong <gregory.0xf0@gmail.com>
---
New in v2.

 drivers/gpio/gpio-brcmstb.c | 53 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/drivers/gpio/gpio-brcmstb.c b/drivers/gpio/gpio-brcmstb.c
index b9962ff..2598c1e 100644
--- a/drivers/gpio/gpio-brcmstb.c
+++ b/drivers/gpio/gpio-brcmstb.c
@@ -19,6 +19,7 @@
 #include <linux/basic_mmio_gpio.h>
 #include <linux/irqdomain.h>
 #include <linux/irqchip/chained_irq.h>
+#include <linux/interrupt.h>
 
 #define GIO_BANK_SIZE           0x20
 #define GIO_ODEN(bank)          (((bank) * GIO_BANK_SIZE) + 0x00)
@@ -48,6 +49,7 @@ struct brcmstb_gpio_priv {
 	struct irq_domain *irq_domain;
 	int parent_irq;
 	int gpio_base;
+	int parent_wake_irq;
 };
 
 #define MAX_GPIO_PER_BANK           32
@@ -183,6 +185,31 @@ static int brcmstb_gpio_irq_set_type(struct irq_data *d, unsigned int type)
 	return 0;
 }
 
+static int brcmstb_gpio_irq_set_wake(struct irq_data *d, unsigned int enable)
+{
+	struct brcmstb_gpio_bank *bank = irq_data_get_irq_chip_data(d);
+	struct brcmstb_gpio_priv *priv = bank->parent_priv;
+
+	/*
+	 * Only enable wake IRQ once for however many hwirqs can wake
+	 * since they all use the same wake IRQ.  Mask will be set
+	 * up appropriately thanks to IRQCHIP_MASK_ON_SUSPEND flag.
+	 */
+	if (enable)
+		enable_irq_wake(priv->parent_wake_irq);
+	else
+		disable_irq_wake(priv->parent_wake_irq);
+	return 0;
+}
+
+static irqreturn_t brcmstb_gpio_wake_irq_handler(int irq, void *data)
+{
+	struct brcmstb_gpio_priv *priv = data;
+
+	pm_wakeup_event(&priv->pdev->dev, 0);
+	return IRQ_HANDLED;
+}
+
 static void brcmstb_gpio_irq_bank_handler(int irq,
 		struct brcmstb_gpio_bank *bank)
 {
@@ -369,6 +396,32 @@ static int brcmstb_gpio_irq_setup(struct platform_device *pdev,
 	priv->irq_chip.irq_mask = brcmstb_gpio_irq_mask;
 	priv->irq_chip.irq_unmask = brcmstb_gpio_irq_unmask;
 	priv->irq_chip.irq_set_type = brcmstb_gpio_irq_set_type;
+
+	/* Ensures that all non-wakeup IRQs are disabled at suspend */
+	priv->irq_chip.flags = IRQCHIP_MASK_ON_SUSPEND;
+
+	if (IS_ENABLED(CONFIG_PM_SLEEP) &&
+			of_get_property(np, "wakeup-source", NULL)) {
+		priv->parent_wake_irq = platform_get_irq(pdev, 1);
+		if (priv->parent_wake_irq < 0)  {
+			dev_warn(dev,
+				"Couldn't get wake IRQ - GPIOs will not be able to wake from sleep");
+		} else {
+			int err = devm_request_irq(dev, priv->parent_wake_irq,
+					brcmstb_gpio_wake_irq_handler, 0,
+					"brcmstb-gpio-wake", priv);
+
+			if (err < 0) {
+				dev_err(dev, "Couldn't request wake IRQ");
+				return err;
+			}
+
+			device_set_wakeup_capable(dev, true);
+			device_wakeup_enable(dev);
+			priv->irq_chip.irq_set_wake = brcmstb_gpio_irq_set_wake;
+		}
+	}
+
 	priv->irq_domain =
 		irq_domain_add_linear(np, priv->num_gpios,
 				      &brcmstb_gpio_irq_domain_ops,
-- 
1.9.1