basic_mmio_gpio: support direction registers

Most controllers require the direction of a GPIO to be set by writing to
a direction register.  Add support for either an input direction
register or an output direction register.

Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Acked-by: Anton Vorontsov <cbouatmailru@gmail.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

drivers/gpio/basic_mmio_gpio.c

@@ -70,6 +70,7 @@ struct bgpio_chip {
 	void __iomem *reg_dat;
 	void __iomem *reg_set;
 	void __iomem *reg_clr;
+	void __iomem *reg_dir;
 
 	/* Number of bits (GPIOs): <register width> * 8. */
 	int bits;
@@ -88,6 +89,9 @@ struct bgpio_chip {
 
 	/* Shadowed data register to clear/set bits safely. */
 	unsigned long data;
+
+	/* Shadowed direction registers to clear/set direction safely. */
+	unsigned long dir;
 };
 
 static struct bgpio_chip *to_bgpio_chip(struct gpio_chip *gc)
@@ -203,15 +207,80 @@ static void bgpio_set_set(struct gpio_chip *gc, unsigned int gpio, int val)
 	spin_unlock_irqrestore(&bgc->lock, flags);
 }
 
+static int bgpio_simple_dir_in(struct gpio_chip *gc, unsigned int gpio)
+{
+	return 0;
+}
+
+static int bgpio_simple_dir_out(struct gpio_chip *gc, unsigned int gpio,
+				int val)
+{
+	gc->set(gc, gpio, val);
+
+	return 0;
+}
+
 static int bgpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
 {
+	struct bgpio_chip *bgc = to_bgpio_chip(gc);
+	unsigned long flags;
+
+	spin_lock_irqsave(&bgc->lock, flags);
+
+	bgc->dir &= ~bgc->pin2mask(bgc, gpio);
+	bgc->write_reg(bgc->reg_dir, bgc->dir);
+
+	spin_unlock_irqrestore(&bgc->lock, flags);
+
 	return 0;
 }
 
 static int bgpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
 {
+	struct bgpio_chip *bgc = to_bgpio_chip(gc);
+	unsigned long flags;
+
 	gc->set(gc, gpio, val);
 
+	spin_lock_irqsave(&bgc->lock, flags);
+
+	bgc->dir |= bgc->pin2mask(bgc, gpio);
+	bgc->write_reg(bgc->reg_dir, bgc->dir);
+
+	spin_unlock_irqrestore(&bgc->lock, flags);
+
+	return 0;
+}
+
+static int bgpio_dir_in_inv(struct gpio_chip *gc, unsigned int gpio)
+{
+	struct bgpio_chip *bgc = to_bgpio_chip(gc);
+	unsigned long flags;
+
+	spin_lock_irqsave(&bgc->lock, flags);
+
+	bgc->dir |= bgc->pin2mask(bgc, gpio);
+	bgc->write_reg(bgc->reg_dir, bgc->dir);
+
+	spin_unlock_irqrestore(&bgc->lock, flags);
+
+	return 0;
+}
+
+static int bgpio_dir_out_inv(struct gpio_chip *gc, unsigned int gpio, int val)
+{
+	struct bgpio_chip *bgc = to_bgpio_chip(gc);
+	unsigned long flags;
+
+	gc->set(gc, gpio, val);
+
+	spin_lock_irqsave(&bgc->lock, flags);
+
+	bgc->dir &= ~bgc->pin2mask(bgc, gpio);
+	bgc->write_reg(bgc->reg_dir, bgc->dir);
+
+	spin_unlock_irqrestore(&bgc->lock, flags);
+
 	return 0;
 }
 
@@ -274,6 +343,14 @@ static int bgpio_setup_accessors(struct platform_device *pdev,
  * by clearing a bit.  For the set clr pair, this drives a 1 by setting a bit
  * in the set register and clears it by setting a bit in the clear register.
  * The configuration is detected by which resources are present.
+ *
+ * For setting the GPIO direction, there are three supported configurations:
+ *
+ *	- simple bidirection GPIO that requires no configuration.
+ *	- an output direction register (named "dirout") where a 1 bit
+ *	indicates the GPIO is an output.
+ *	- an input direction register (named "dirin") where a 1 bit indicates
+ *	the GPIO is an input.
  */
 static int bgpio_setup_io(struct platform_device *pdev,
 			  struct bgpio_chip *bgc)
@@ -330,6 +407,37 @@ static int bgpio_setup_io(struct platform_device *pdev,
 	return 0;
 }
 
+static int bgpio_setup_direction(struct platform_device *pdev,
+				 struct bgpio_chip *bgc)
+{
+	struct resource *res_dirout;
+	struct resource *res_dirin;
+
+	res_dirout = platform_get_resource_byname(pdev, IORESOURCE_MEM,
+						  "dirout");
+	res_dirin = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dirin");
+	if (res_dirout && res_dirin) {
+		return -EINVAL;
+	} else if (res_dirout) {
+		bgc->reg_dir = bgpio_request_and_map(&pdev->dev, res_dirout);
+		if (!bgc->reg_dir)
+			return -ENOMEM;
+		bgc->gc.direction_output = bgpio_dir_out;
+		bgc->gc.direction_input = bgpio_dir_in;
+	} else if (res_dirin) {
+		bgc->reg_dir = bgpio_request_and_map(&pdev->dev, res_dirin);
+		if (!bgc->reg_dir)
+			return -ENOMEM;
+		bgc->gc.direction_output = bgpio_dir_out_inv;
+		bgc->gc.direction_input = bgpio_dir_in_inv;
+	} else {
+		bgc->gc.direction_output = bgpio_simple_dir_out;
+		bgc->gc.direction_input = bgpio_simple_dir_in;
+	}
+
+	return 0;
+}
+
 static int __devinit bgpio_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -360,11 +468,13 @@ static int __devinit bgpio_probe(struct platform_device *pdev)
 		return ret;
 
 	spin_lock_init(&bgc->lock);
+	ret = bgpio_setup_direction(pdev, bgc);
+	if (ret)
+		return ret;
+
 	bgc->data = bgc->read_reg(bgc->reg_dat);
 
 	bgc->gc.ngpio = ngpio;
-	bgc->gc.direction_input = bgpio_dir_in;
-	bgc->gc.direction_output = bgpio_dir_out;
 	bgc->gc.dev = dev;
 	bgc->gc.label = dev_name(dev);