[PATCH V3] added device tree support to gpio-generic driver

[Romain Baeriswyl <romain.baeriswyl@xxxxxxxxxxx>]

This patch adds support of device tree to the gpio-generic driver.

Signed-off-by: Romain Baeriswyl <romain.baeriswyl@xxxxxxxxxxx> 
---
 .../devicetree/bindings/gpio/gpio-generic.txt      |   62 ++++++++++++++++++++
 drivers/gpio/gpio-generic.c                        |   60 ++++++++++++++++++-
 include/linux/basic_mmio_gpio.h                    |    1 +
 3 files changed, 120 insertions(+), 3 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/gpio/gpio-generic.txt

diff --git a/Documentation/devicetree/bindings/gpio/gpio-generic.txt b/Documentation/devicetree/bindings/gpio/gpio-generic.txt
new file mode 100644
index 0000000..5259b2c
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/gpio-generic.txt
@@ -0,0 +1,62 @@
+Bindings for gpio-generic
+
+Required properties:
+- compatible : should be "single-register-gpio"
+- ngpios: specifies the number of gpio mapped in the register from bit 0 to
+          bit ngpios-1. The value is limited to the number of bits of the
+	  LONG type.
+- reg-names: must contain
+      "dat" - data register
+  may contain
+      "set" - data set register
+      "clr" - data clear register
+      "dirout" - direction output register
+      "dirin" - direction input register
+- reg: address + size pairs describing the GPIO register sets; order must
+       correspond with the order of entries in reg-names
+- #gpio-cells = must be set to 2
+
+Optional property:
+- big-endian: tells that register is big endian.
+
+For setting GPIO's there are three supported configurations:
+- single input/output register resource (named "dat"),
+- set/clear pair (named "set" and "clr"),
+- single output register resource and single input resource ("set" and dat").
+
+For the single output register, this drives a 1 by setting a bit and a zero
+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.
+
+Examples:
+
+	/* Configuration with single input/output register and
+	 * simple bidirection GPIO.
+	 */
+	gpio_a {
+		compatible = "basic-mmio-gpio";
+		ngpios = <32>;
+		reg = <0x18000000 0x4>;
+		reg-names = "dat";
+		#gpio-cells = <2>;
+	};
+
+	/* Configuration with set/clear pair registers and with an output
+	 * direction register
+	 */
+	gpio_b {
+		compatible = "single-register-gpio";
+		ngpios = <32>;
+		reg = <0x18000000 0x4>, <0x18000010 0x4>,
+		      <0x18000004 0x4>, <0x18000008 0x4>;
+		reg-names = "dat", "set", "clr", "dirout";
+		#gpio-cells = <2>;
+	};
diff --git a/drivers/gpio/gpio-generic.c b/drivers/gpio/gpio-generic.c
index b92a690..da1408a 100644
--- a/drivers/gpio/gpio-generic.c
+++ b/drivers/gpio/gpio-generic.c
@@ -61,6 +61,8 @@ o        `                     ~~~~\___/~~~~    ` controller in FPGA is ,.`
 #include <linux/platform_device.h>
 #include <linux/mod_devicetable.h>
 #include <linux/basic_mmio_gpio.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
 
 static void bgpio_write8(void __iomem *reg, unsigned long data)
 {
@@ -564,6 +566,35 @@ static void __iomem *bgpio_map(struct platform_device *pdev,
 	return ret;
 }
 
+#ifdef CONFIG_OF
+static int bgpio_parse_dt(struct device *dev)
+{
+	struct bgpio_pdata *pdata;
+
+	pdata = devm_kzalloc(dev, sizeof(struct bgpio_pdata),
+			     GFP_KERNEL);
+	if (!pdata)
+		return -ENOMEM;
+
+	if (of_property_read_u32(dev->of_node, "ngpio", &pdata->ngpio)) {
+		dev_err(dev, "Failed to get field ngpio");
+		return -EINVAL;
+	}
+	pdata->base = -1;
+
+	if (of_device_is_big_endian(dev->of_node))
+		pdata->flags = BGPIOF_BIG_ENDIAN;
+
+	dev->platform_data = pdata;
+	return 0;
+}
+#else
+static int bgpio_parse_dt(struct device *dev)
+{
+	return 0;
+}
+#endif /* CONFIG_OF */
+
 static int bgpio_pdev_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -574,10 +605,21 @@ static int bgpio_pdev_probe(struct platform_device *pdev)
 	void __iomem *dirout;
 	void __iomem *dirin;
 	unsigned long sz;
-	unsigned long flags = pdev->id_entry->driver_data;
 	int err;
 	struct bgpio_chip *bgc;
-	struct bgpio_pdata *pdata = dev_get_platdata(dev);
+	struct bgpio_pdata *pdata;
+
+	if (of_have_populated_dt()) {
+		err = bgpio_parse_dt(dev);
+		if (err < 0) {
+			dev_err(dev, "Failed to get DT data\n");
+			return err;
+		}
+	}
+	pdata = dev_get_platdata(dev);
+
+	if (!of_have_populated_dt())
+		pdata->flags = pdev->id_entry->driver_data;
 
 	r = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dat");
 	if (!r)
@@ -609,7 +651,8 @@ static int bgpio_pdev_probe(struct platform_device *pdev)
 	if (!bgc)
 		return -ENOMEM;
 
-	err = bgpio_init(bgc, dev, sz, dat, set, clr, dirout, dirin, flags);
+	err = bgpio_init(bgc, dev, sz, dat, set, clr, dirout, dirin,
+			 pdata->flags);
 	if (err)
 		return err;
 
@@ -633,6 +676,14 @@ static int bgpio_pdev_remove(struct platform_device *pdev)
 	return bgpio_remove(bgc);
 }
 
+#ifdef CONFIG_OF
+static const struct of_device_id  bgpio_of_match[] = {
+	{ .compatible = "basic-mmio-gpio" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, bgpio_of_match);
+#endif
+
 static const struct platform_device_id bgpio_id_table[] = {
 	{
 		.name		= "basic-mmio-gpio",
@@ -648,6 +699,9 @@ MODULE_DEVICE_TABLE(platform, bgpio_id_table);
 static struct platform_driver bgpio_driver = {
 	.driver = {
 		.name = "basic-mmio-gpio",
+#ifdef CONFIG_OF
+		.of_match_table = of_match_ptr(bgpio_of_match),
+#endif
 	},
 	.id_table = bgpio_id_table,
 	.probe = bgpio_pdev_probe,
diff --git a/include/linux/basic_mmio_gpio.h b/include/linux/basic_mmio_gpio.h
index 0e97856..d85d9ca 100644
--- a/include/linux/basic_mmio_gpio.h
+++ b/include/linux/basic_mmio_gpio.h
@@ -22,6 +22,7 @@ struct bgpio_pdata {
 	const char *label;
 	int base;
 	int ngpio;
+	int flags;
 };
 
 struct device;
-- 
1.7.1

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