bcma: gpio: add own IRQ domain

Input GPIO changes can generate interrupts, but we need kind of ACK for
them by changing IRQ polarity. This is required to stop hardware from
keep generating interrupts and generate another one on the next GPIO
state change.
This code allows using GPIOs with standard interrupts and add for
example GPIO buttons support.

Signed-off-by: Rafał Miłecki <[e-mail]>
Acked-by: Hauke Mehrtens <[e-mail]>
Signed-off-by: John Crispin <[e-mail]>
Patchwork: http://patchwork.linux-mips.org/patch/6216/

drivers/bcma/Kconfig

···
 config BCMA_DRIVER_GPIO
 	bool "BCMA GPIO driver"
 	depends on BCMA && GPIOLIB
+	select IRQ_DOMAIN if BCMA_HOST_SOC
 	help
 	  Driver to provide access to the GPIO pins of the bcma bus.
 

drivers/bcma/driver_gpio.c

···
  */
 
 #include <linux/gpio.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/irqdomain.h>
 #include <linux/export.h>
 #include <linux/bcma/bcma.h>
 
···
 	bcma_chipco_gpio_pullup(cc, 1 << gpio, 0);
 }
 
+#if IS_BUILTIN(CONFIG_BCMA_HOST_SOC)
 static int bcma_gpio_to_irq(struct gpio_chip *chip, unsigned gpio)
 {
 	struct bcma_drv_cc *cc = bcma_gpio_get_cc(chip);
 
 	if (cc->core->bus->hosttype == BCMA_HOSTTYPE_SOC)
-		return bcma_core_irq(cc->core);
+		return irq_find_mapping(cc->irq_domain, gpio);
 	else
 		return -EINVAL;
 }
 
+static void bcma_gpio_irq_unmask(struct irq_data *d)
+{
+	struct bcma_drv_cc *cc = irq_data_get_irq_chip_data(d);
+	int gpio = irqd_to_hwirq(d);
+
+	bcma_chipco_gpio_intmask(cc, BIT(gpio), BIT(gpio));
+}
+
+static void bcma_gpio_irq_mask(struct irq_data *d)
+{
+	struct bcma_drv_cc *cc = irq_data_get_irq_chip_data(d);
+	int gpio = irqd_to_hwirq(d);
+
+	bcma_chipco_gpio_intmask(cc, BIT(gpio), 0);
+}
+
+static struct irq_chip bcma_gpio_irq_chip = {
+	.name		= "BCMA-GPIO",
+	.irq_mask	= bcma_gpio_irq_mask,
+	.irq_unmask	= bcma_gpio_irq_unmask,
+};
+
+static irqreturn_t bcma_gpio_irq_handler(int irq, void *dev_id)
+{
+	struct bcma_drv_cc *cc = dev_id;
+	u32 val = bcma_cc_read32(cc, BCMA_CC_GPIOIN);
+	u32 mask = bcma_cc_read32(cc, BCMA_CC_GPIOIRQ);
+	u32 pol = bcma_cc_read32(cc, BCMA_CC_GPIOPOL);
+	u32 irqs = (val ^ pol) & mask;
+	int gpio;
+
+	if (!irqs)
+		return IRQ_NONE;
+
+	for_each_set_bit(gpio, (unsigned long *)&irqs, cc->gpio.ngpio)
+		generic_handle_irq(bcma_gpio_to_irq(&cc->gpio, gpio));
+	bcma_chipco_gpio_polarity(cc, irqs, val & irqs);
+
+	return IRQ_HANDLED;
+}
+
+static int bcma_gpio_irq_domain_init(struct bcma_drv_cc *cc)
+{
+	struct gpio_chip *chip = &cc->gpio;
+	int gpio, hwirq, err;
+
+	if (cc->core->bus->hosttype != BCMA_HOSTTYPE_SOC)
+		return 0;
+
+	cc->irq_domain = irq_domain_add_linear(NULL, chip->ngpio,
+					       &irq_domain_simple_ops, cc);
+	if (!cc->irq_domain) {
+		err = -ENODEV;
+		goto err_irq_domain;
+	}
+	for (gpio = 0; gpio < chip->ngpio; gpio++) {
+		int irq = irq_create_mapping(cc->irq_domain, gpio);
+
+		irq_set_chip_data(irq, cc);
+		irq_set_chip_and_handler(irq, &bcma_gpio_irq_chip,
+					 handle_simple_irq);
+	}
+
+	hwirq = bcma_core_irq(cc->core);
+	err = request_irq(hwirq, bcma_gpio_irq_handler, IRQF_SHARED, "gpio",
+			  cc);
+	if (err)
+		goto err_req_irq;
+
+	bcma_cc_set32(cc, BCMA_CC_IRQMASK, BCMA_CC_IRQ_GPIO);
+
+	return 0;
+
+err_req_irq:
+	for (gpio = 0; gpio < chip->ngpio; gpio++) {
+		int irq = irq_find_mapping(cc->irq_domain, gpio);
+
+		irq_dispose_mapping(irq);
+	}
+	irq_domain_remove(cc->irq_domain);
+err_irq_domain:
+	return err;
+}
+
+static void bcma_gpio_irq_domain_exit(struct bcma_drv_cc *cc)
+{
+	struct gpio_chip *chip = &cc->gpio;
+	int gpio;
+
+	if (cc->core->bus->hosttype != BCMA_HOSTTYPE_SOC)
+		return;
+
+	bcma_cc_mask32(cc, BCMA_CC_IRQMASK, ~BCMA_CC_IRQ_GPIO);
+	free_irq(bcma_core_irq(cc->core), cc);
+	for (gpio = 0; gpio < chip->ngpio; gpio++) {
+		int irq = irq_find_mapping(cc->irq_domain, gpio);
+
+		irq_dispose_mapping(irq);
+	}
+	irq_domain_remove(cc->irq_domain);
+}
+#else
+static int bcma_gpio_irq_domain_init(struct bcma_drv_cc *cc)
+{
+	return 0;
+}
+
+static void bcma_gpio_irq_domain_exit(struct bcma_drv_cc *cc)
+{
+}
+#endif
+
 int bcma_gpio_init(struct bcma_drv_cc *cc)
 {
 	struct gpio_chip *chip = &cc->gpio;
+	int err;
 
 	chip->label		= "bcma_gpio";
 	chip->owner		= THIS_MODULE;
···
 	chip->set		= bcma_gpio_set_value;
 	chip->direction_input	= bcma_gpio_direction_input;
 	chip->direction_output	= bcma_gpio_direction_output;
+#if IS_BUILTIN(CONFIG_BCMA_HOST_SOC)
 	chip->to_irq		= bcma_gpio_to_irq;
+#endif
 	chip->ngpio		= 16;
 	/* There is just one SoC in one device and its GPIO addresses should be
 	 * deterministic to address them more easily. The other buses could get
···
 	else
 		chip->base		= -1;
 
-	return gpiochip_add(chip);
+	err = bcma_gpio_irq_domain_init(cc);
+	if (err)
+		return err;
+
+	err = gpiochip_add(chip);
+	if (err) {
+		bcma_gpio_irq_domain_exit(cc);
+		return err;
+	}
+
+	return 0;
 }
 
 int bcma_gpio_unregister(struct bcma_drv_cc *cc)
 {
+	bcma_gpio_irq_domain_exit(cc);
 	return gpiochip_remove(&cc->gpio);
 }

include/linux/bcma/bcma_driver_chipcommon.h

···
 	spinlock_t gpio_lock;
 #ifdef CONFIG_BCMA_DRIVER_GPIO
 	struct gpio_chip gpio;
+	struct irq_domain *irq_domain;
 #endif
 };