memory: omap-gpmc: Support general purpose input for WAITPINs

OMAPs can have 2 to 4 WAITPINs that can be used as general purpose
input if not used for memory wait state insertion.

The first user will be the OMAP NAND chip to get the NAND
read/busy status using gpiolib.
Signed-off-by: Roger Quadros <rogerq@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Tony Lindgren <tony@atomide.com>

Documentation/devicetree/bindings/memory-controllers/omap-gpmc.txt

@@ -38,6 +38,10 @@ Required properties:
 			0 - NAND_fifoevent
 			1 - NAND_termcount
  - interrupt-cells:	Must be set to 2
+ - gpio-controller:	The GPMC driver implements a GPIO controller for the
+			GPMC WAIT pins that can be used as general purpose inputs.
+			0 maps to GPMC_WAIT0 pin.
+ - gpio-cells:		Must be set to 2
 
 Timing properties for child nodes. All are optional and default to 0.
 
@@ -138,6 +142,8 @@ Example for an AM33xx board:
 		ranges = <0 0 0x08000000 0x10000000>; /* CS0 @addr 0x8000000, size 0x10000000 */
 		interrupt-controller;
 		#interrupt-cells = <2>;
+		gpio-controller;
+		#gpio-cells = <2>;
 
 		/* child nodes go here */
 	};

drivers/memory/Kconfig

@@ -51,6 +51,7 @@ config TI_EMIF
 
 config OMAP_GPMC
 	bool
+	select GPIOLIB
 	help
 	  This driver is for the General Purpose Memory Controller (GPMC)
 	  present on Texas Instruments SoCs (e.g. OMAP2+). GPMC allows

drivers/memory/omap-gpmc.c

@@ -21,6 +21,7 @@
 #include <linux/spinlock.h>
 #include <linux/io.h>
 #include <linux/module.h>
+#include <linux/gpio/driver.h>
 #include <linux/interrupt.h>
 #include <linux/irqdomain.h>
 #include <linux/platform_device.h>
@@ -237,6 +238,7 @@ struct gpmc_device {
 	struct device *dev;
 	int irq;
 	struct irq_chip irq_chip;
+	struct gpio_chip gpio_chip;
 };
 
 static struct irq_domain *gpmc_irq_domain;
@@ -2064,10 +2066,71 @@ static int gpmc_probe_generic_child(struct platform_device *pdev,
 	return ret;
 }
 
+static int gpmc_gpio_get_direction(struct gpio_chip *chip, unsigned int offset)
+{
+	return 1;	/* we're input only */
+}
+
+static int gpmc_gpio_direction_input(struct gpio_chip *chip,
+				     unsigned int offset)
+{
+	return 0;	/* we're input only */
+}
+
+static int gpmc_gpio_direction_output(struct gpio_chip *chip,
+				      unsigned int offset, int value)
+{
+	return -EINVAL;	/* we're input only */
+}
+
+static void gpmc_gpio_set(struct gpio_chip *chip, unsigned int offset,
+			  int value)
+{
+}
+
+static int gpmc_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+	u32 reg;
+
+	offset += 8;
+
+	reg = gpmc_read_reg(GPMC_STATUS) & BIT(offset);
+
+	return !!reg;
+}
+
+static int gpmc_gpio_init(struct gpmc_device *gpmc)
+{
+	int ret;
+
+	gpmc->gpio_chip.parent = gpmc->dev;
+	gpmc->gpio_chip.owner = THIS_MODULE;
+	gpmc->gpio_chip.label = DEVICE_NAME;
+	gpmc->gpio_chip.ngpio = gpmc_nr_waitpins;
+	gpmc->gpio_chip.get_direction = gpmc_gpio_get_direction;
+	gpmc->gpio_chip.direction_input = gpmc_gpio_direction_input;
+	gpmc->gpio_chip.direction_output = gpmc_gpio_direction_output;
+	gpmc->gpio_chip.set = gpmc_gpio_set;
+	gpmc->gpio_chip.get = gpmc_gpio_get;
+	gpmc->gpio_chip.base = -1;
+
+	ret = gpiochip_add(&gpmc->gpio_chip);
+	if (ret < 0) {
+		dev_err(gpmc->dev, "could not register gpio chip: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void gpmc_gpio_exit(struct gpmc_device *gpmc)
+{
+	gpiochip_remove(&gpmc->gpio_chip);
+}
+
 static int gpmc_probe_dt(struct platform_device *pdev)
 {
 	int ret;
-	struct device_node *child;
 	const struct of_device_id *of_id =
 		of_match_device(gpmc_dt_ids, &pdev->dev);
 
@@ -2095,6 +2158,14 @@ static int gpmc_probe_dt(struct platform_device *pdev)
 		return ret;
 	}
 
+	return 0;
+}
+
+static int gpmc_probe_dt_children(struct platform_device *pdev)
+{
+	int ret;
+	struct device_node *child;
+
 	for_each_available_child_of_node(pdev->dev.of_node, child) {
 
 		if (!child->name)
@@ -2104,6 +2175,9 @@ static int gpmc_probe_dt(struct platform_device *pdev)
 			ret = gpmc_probe_onenand_child(pdev, child);
 		else
 			ret = gpmc_probe_generic_child(pdev, child);
+
+		if (ret)
+			return ret;
 	}
 
 	return 0;
@@ -2113,6 +2187,11 @@ static int gpmc_probe_dt(struct platform_device *pdev)
 {
 	return 0;
 }
+
+static int gpmc_probe_dt_children(struct platform_device *pdev)
+{
+	return 0;
+}
 #endif
 
 static int gpmc_probe(struct platform_device *pdev)
@@ -2159,6 +2238,15 @@ static int gpmc_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
+	if (pdev->dev.of_node) {
+		rc = gpmc_probe_dt(pdev);
+		if (rc)
+			return rc;
+	} else {
+		gpmc_cs_num = GPMC_CS_NUM;
+		gpmc_nr_waitpins = GPMC_NR_WAITPINS;
+	}
+
 	pm_runtime_enable(&pdev->dev);
 	pm_runtime_get_sync(&pdev->dev);
 
@@ -2184,29 +2272,33 @@ static int gpmc_probe(struct platform_device *pdev)
 		 GPMC_REVISION_MINOR(l));
 
 	gpmc_mem_init();
+	rc = gpmc_gpio_init(gpmc);
+	if (rc)
+		goto gpio_init_failed;
 
 	rc = gpmc_setup_irq(gpmc);
 	if (rc) {
 		dev_err(gpmc->dev, "gpmc_setup_irq failed\n");
-		goto fail;
+		goto setup_irq_failed;
 	}
 
-	if (!pdev->dev.of_node) {
-		gpmc_cs_num	 = GPMC_CS_NUM;
-		gpmc_nr_waitpins = GPMC_NR_WAITPINS;
-	}
-
-	rc = gpmc_probe_dt(pdev);
+	rc = gpmc_probe_dt_children(pdev);
 	if (rc < 0) {
-		dev_err(gpmc->dev, "failed to probe DT parameters\n");
-		gpmc_free_irq(gpmc);
-		goto fail;
+		dev_err(gpmc->dev, "failed to probe DT children\n");
+		goto dt_children_failed;
 	}
 
 	return 0;
 
-fail:
+dt_children_failed:
+	gpmc_free_irq(gpmc);
+setup_irq_failed:
+	gpmc_gpio_exit(gpmc);
+gpio_init_failed:
+	gpmc_mem_exit();
 	pm_runtime_put_sync(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+
 	return rc;
 }
 
@@ -2215,6 +2307,7 @@ static int gpmc_remove(struct platform_device *pdev)
 	struct gpmc_device *gpmc = platform_get_drvdata(pdev);
 
 	gpmc_free_irq(gpmc);
+	gpmc_gpio_exit(gpmc);
 	gpmc_mem_exit();
 	pm_runtime_put_sync(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);