gpio/generic: initialize basic_mmio_gpio shadow variables properly

It fixes the issue in gpio-generic that commit fb14921 (gpio/mxc: add
missing initialization of basic_mmio_gpio shadow variables) manged to
fix in gpio-mxc driver, so that other platform specific drivers do not
suffer from the same problem over and over again.

Changes since v1:
* Turn the last parameter of bgpio_init() "bool big_endian" into
  "unsigned long flags" and give those really quirky hardwares a
  chance to tell that reg_set and reg_dir are unreadable.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
[grant.likely: Fix big-endian usage to explicitly set BBGPIOF_BIG_ENDIAN]
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

drivers/gpio/gpio-ep93xx.c

@@ -325,7 +325,7 @@ static int ep93xx_gpio_add_bank(struct bgpio_chip *bgc, struct device *dev,
 	void __iomem *dir =  mmio_base + bank->dir;
 	int err;
 
-	err = bgpio_init(bgc, dev, 1, data, NULL, NULL, dir, NULL, false);
+	err = bgpio_init(bgc, dev, 1, data, NULL, NULL, dir, NULL, 0);
 	if (err)
 		return err;
 

drivers/gpio/gpio-generic.c

@@ -364,7 +364,7 @@ EXPORT_SYMBOL_GPL(bgpio_remove);
 int bgpio_init(struct bgpio_chip *bgc, struct device *dev,
 	       unsigned long sz, void __iomem *dat, void __iomem *set,
 	       void __iomem *clr, void __iomem *dirout, void __iomem *dirin,
-	       bool big_endian)
+	       unsigned long flags)
 {
 	int ret;
 
@@ -385,7 +385,7 @@ int bgpio_init(struct bgpio_chip *bgc, struct device *dev,
 	if (ret)
 		return ret;
 
-	ret = bgpio_setup_accessors(dev, bgc, big_endian);
+	ret = bgpio_setup_accessors(dev, bgc, flags & BGPIOF_BIG_ENDIAN);
 	if (ret)
 		return ret;
 
@@ -394,6 +394,11 @@ int bgpio_init(struct bgpio_chip *bgc, struct device *dev,
 		return ret;
 
 	bgc->data = bgc->read_reg(bgc->reg_dat);
+	if (bgc->gc.set == bgpio_set_set &&
+			!(flags & BGPIOF_UNREADABLE_REG_SET))
+		bgc->data = bgc->read_reg(bgc->reg_set);
+	if (bgc->reg_dir && !(flags & BGPIOF_UNREADABLE_REG_DIR))
+		bgc->dir = bgc->read_reg(bgc->reg_dir);
 
 	return ret;
 }
@@ -449,7 +454,7 @@ static int __devinit bgpio_pdev_probe(struct platform_device *pdev)
 	void __iomem *dirout;
 	void __iomem *dirin;
 	unsigned long sz;
-	bool be;
+	unsigned long flags = 0;
 	int err;
 	struct bgpio_chip *bgc;
 	struct bgpio_pdata *pdata = dev_get_platdata(dev);
@@ -480,13 +485,14 @@ static int __devinit bgpio_pdev_probe(struct platform_device *pdev)
 	if (err)
 		return err;
 
-	be = !strcmp(platform_get_device_id(pdev)->name, "basic-mmio-gpio-be");
+	if (!strcmp(platform_get_device_id(pdev)->name, "basic-mmio-gpio-be"))
+		flags |= BGPIOF_BIG_ENDIAN;
 
 	bgc = devm_kzalloc(&pdev->dev, sizeof(*bgc), GFP_KERNEL);
 	if (!bgc)
 		return -ENOMEM;
 
-	err = bgpio_init(bgc, dev, sz, dat, set, clr, dirout, dirin, be);
+	err = bgpio_init(bgc, dev, sz, dat, set, clr, dirout, dirin, flags);
 	if (err)
 		return err;
 

drivers/gpio/gpio-mxc.c

@@ -417,7 +417,7 @@ static int __devinit mxc_gpio_probe(struct platform_device *pdev)
 	err = bgpio_init(&port->bgc, &pdev->dev, 4,
 			 port->base + GPIO_PSR,
 			 port->base + GPIO_DR, NULL,
-			 port->base + GPIO_GDIR, NULL, false);
+			 port->base + GPIO_GDIR, NULL, 0);
 	if (err)
 		goto out_iounmap;
 

drivers/gpio/gpio-mxs.c

@@ -244,7 +244,7 @@ static int __devinit mxs_gpio_probe(struct platform_device *pdev)
 	err = bgpio_init(&port->bgc, &pdev->dev, 4,
 			 port->base + PINCTRL_DIN(port->id),
 			 port->base + PINCTRL_DOUT(port->id), NULL,
-			 port->base + PINCTRL_DOE(port->id), NULL, false);
+			 port->base + PINCTRL_DOE(port->id), NULL, 0);
 	if (err)
 		goto out_iounmap;
 

drivers/gpio/gpio-sodaville.c

@@ -224,7 +224,7 @@ static int __devinit sdv_gpio_probe(struct pci_dev *pdev,
 
 	ret = bgpio_init(&sd->bgpio, &pdev->dev, 4,
 			sd->gpio_pub_base + GPINR, sd->gpio_pub_base + GPOUTR,
-			NULL, sd->gpio_pub_base + GPOER, NULL, false);
+			NULL, sd->gpio_pub_base + GPOER, NULL, 0);
 	if (ret)
 		goto unmap;
 	sd->bgpio.gc.ngpio = SDV_NUM_PUB_GPIOS;

include/linux/basic_mmio_gpio.h

@@ -67,6 +67,10 @@ int bgpio_remove(struct bgpio_chip *bgc);
 int bgpio_init(struct bgpio_chip *bgc, struct device *dev,
 	       unsigned long sz, void __iomem *dat, void __iomem *set,
 	       void __iomem *clr, void __iomem *dirout, void __iomem *dirin,
-	       bool big_endian);
+	       unsigned long flags);
+
+#define BGPIOF_BIG_ENDIAN		BIT(0)
+#define BGPIOF_UNREADABLE_REG_SET	BIT(1) /* reg_set is unreadable */
+#define BGPIOF_UNREADABLE_REG_DIR	BIT(2) /* reg_dir is unreadable */
 
 #endif /* __BASIC_MMIO_GPIO_H */