[PATCH v2 4/4] gpio: mb86s7x: enable ACPI support

[Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>]

Make the mb86s7x GPIO block discoverable via ACPI. In addition, add
support for ACPI GPIO interrupts routed via platform interrupts, by
wiring the two together via the to_irq() gpiochip callback.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
 drivers/gpio/gpio-mb86s7x.c | 57 ++++++++++++++++----
 1 file changed, 48 insertions(+), 9 deletions(-)

diff --git a/drivers/gpio/gpio-mb86s7x.c b/drivers/gpio/gpio-mb86s7x.c
index 3134c0d2bfe4..61ad95c3e3d2 100644
--- a/drivers/gpio/gpio-mb86s7x.c
+++ b/drivers/gpio/gpio-mb86s7x.c
@@ -14,6 +14,7 @@
  *  GNU General Public License for more details.
  */
 
+#include <linux/acpi.h>
 #include <linux/io.h>
 #include <linux/init.h>
 #include <linux/clk.h>
@@ -27,6 +28,8 @@
 #include <linux/spinlock.h>
 #include <linux/slab.h>
 
+#include "gpiolib.h"
+
 /*
  * Only first 8bits of a register correspond to each pin,
  * so there are 4 registers for 32 pins.
@@ -143,6 +146,20 @@ static void mb86s70_gpio_set(struct gpio_chip *gc, unsigned gpio, int value)
 	spin_unlock_irqrestore(&gchip->lock, flags);
 }
 
+static int mb86s70_gpio_to_irq(struct gpio_chip *gc, unsigned int offset)
+{
+	int irq, index;
+
+	for (index = 0;; index++) {
+		irq = platform_get_irq(to_platform_device(gc->parent), index);
+		if (irq <= 0)
+			break;
+		if (irq_get_irq_data(irq)->hwirq == offset)
+			return irq;
+	}
+	return -EINVAL;
+}
+
 static int mb86s70_gpio_probe(struct platform_device *pdev)
 {
 	struct mb86s70_gpio_chip *gchip;
@@ -160,13 +177,15 @@ static int mb86s70_gpio_probe(struct platform_device *pdev)
 	if (IS_ERR(gchip->base))
 		return PTR_ERR(gchip->base);
 
-	gchip->clk = devm_clk_get(&pdev->dev, NULL);
-	if (IS_ERR(gchip->clk))
-		return PTR_ERR(gchip->clk);
+	if (!ACPI_COMPANION(&pdev->dev)) {
+		gchip->clk = devm_clk_get(&pdev->dev, NULL);
+		if (IS_ERR(gchip->clk))
+			return PTR_ERR(gchip->clk);
 
-	ret = clk_prepare_enable(gchip->clk);
-	if (ret)
-		return ret;
+		ret = clk_prepare_enable(gchip->clk);
+		if (ret)
+			return ret;
+	}
 
 	spin_lock_init(&gchip->lock);
 
@@ -182,21 +201,32 @@ static int mb86s70_gpio_probe(struct platform_device *pdev)
 	gchip->gc.parent = &pdev->dev;
 	gchip->gc.base = -1;
 
+	if (ACPI_COMPANION(&pdev->dev))
+		gchip->gc.to_irq = mb86s70_gpio_to_irq;
+
 	ret = gpiochip_add_data(&gchip->gc, gchip);
 	if (ret) {
 		dev_err(&pdev->dev, "couldn't register gpio driver\n");
-		clk_disable_unprepare(gchip->clk);
+		if (gchip->clk)
+			clk_disable_unprepare(gchip->clk);
+		return ret;
 	}
 
-	return ret;
+	if (ACPI_COMPANION(&pdev->dev))
+		acpi_gpiochip_request_interrupts(&gchip->gc);
+
+	return 0;
 }
 
 static int mb86s70_gpio_remove(struct platform_device *pdev)
 {
 	struct mb86s70_gpio_chip *gchip = platform_get_drvdata(pdev);
 
+	if (ACPI_COMPANION(&pdev->dev))
+		acpi_gpiochip_free_interrupts(&gchip->gc);
 	gpiochip_remove(&gchip->gc);
-	clk_disable_unprepare(gchip->clk);
+	if (gchip->clk)
+		clk_disable_unprepare(gchip->clk);
 
 	return 0;
 }
@@ -207,10 +237,19 @@ static const struct of_device_id mb86s70_gpio_dt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, mb86s70_gpio_dt_ids);
 
+#ifdef CONFIG_ACPI
+static const struct acpi_device_id mb86s70_gpio_acpi_ids[] = {
+	{ "SCX0007" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(acpi, mb86s70_gpio_acpi_ids);
+#endif
+
 static struct platform_driver mb86s70_gpio_driver = {
 	.driver = {
 		.name = "mb86s70-gpio",
 		.of_match_table = mb86s70_gpio_dt_ids,
+		.acpi_match_table = ACPI_PTR(mb86s70_gpio_acpi_ids),
 	},
 	.probe = mb86s70_gpio_probe,
 	.remove = mb86s70_gpio_remove,
-- 
2.20.1