powerpc/86xx: Basic GPIO support for GE Fanuc SBC610

Basic support for the GPIO available on the SBC610 VPX Single Board Computer
from GE Fanuc (PowerPC MPC8641D).

This patch adds basic support for the GPIO in the devices I/O FPGA, the GPIO
functionality is exposed through the AFIX pins on the backplane, unless used
by an AFIX card.

This code currently does not support switching between totem-pole and
open-drain outputs (when used as outputs, GPIOs default to totem-pole).
The interrupt capabilites of the GPIO lines is also not currently supported.
Signed-off-by: Martyn Welch <martyn.welch@gefanuc.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/powerpc/boot/dts/gef_sbc610.dts

@@ -98,6 +98,12 @@
 			interrupt-parent = <&mpic>;
 
 		};
+		gef_gpio: gpio@7,14000 {
+			#gpio-cells = <2>;
+			compatible = "gef,sbc610-gpio";
+			reg = <0x7 0x14000 0x24>;
+			gpio-controller;
+		};
 	};
 
 	soc@fef00000 {

arch/powerpc/platforms/86xx/Kconfig

@@ -34,6 +34,8 @@ config MPC8610_HPCD
 config GEF_SBC610
 	bool "GE Fanuc SBC610"
 	select DEFAULT_UIMAGE
+	select GENERIC_GPIO
+	select ARCH_REQUIRE_GPIOLIB
 	select HAS_RAPIDIO
 	help
 	  This option enables support for GE Fanuc's SBC610.

arch/powerpc/platforms/86xx/Makefile

@@ -7,4 +7,5 @@ obj-$(CONFIG_SMP)		+= mpc86xx_smp.o
 obj-$(CONFIG_MPC8641_HPCN)	+= mpc86xx_hpcn.o
 obj-$(CONFIG_SBC8641D)		+= sbc8641d.o
 obj-$(CONFIG_MPC8610_HPCD)	+= mpc8610_hpcd.o
-obj-$(CONFIG_GEF_SBC610)	+= gef_sbc610.o gef_pic.o
+gef-gpio-$(CONFIG_GPIOLIB)	+= gef_gpio.o
+obj-$(CONFIG_GEF_SBC610)	+= gef_sbc610.o gef_pic.o $(gef-gpio-y)

arch/powerpc/platforms/86xx/gef_gpio.c

+/*
+ * Driver for GE Fanuc's FPGA based GPIO pins
+ *
+ * Author: Martyn Welch <martyn.welch@gefanuc.com>
+ *
+ * 2008 (c) GE Fanuc Intelligent Platforms Embedded Systems, Inc.
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2.  This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ */
+
+/* TODO
+ *
+ * Configuration of output modes (totem-pole/open-drain)
+ * Interrupt configuration - interrupts are always generated the FPGA relies on
+ * 	the I/O interrupt controllers mask to stop them propergating
+ */
+
+#include <linux/kernel.h>
+#include <linux/compiler.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_platform.h>
+#include <linux/of_gpio.h>
+#include <linux/gpio.h>
+
+#define GEF_GPIO_DIRECT		0x00
+#define GEF_GPIO_IN		0x04
+#define GEF_GPIO_OUT		0x08
+#define GEF_GPIO_TRIG		0x0C
+#define GEF_GPIO_POLAR_A	0x10
+#define GEF_GPIO_POLAR_B	0x14
+#define GEF_GPIO_INT_STAT	0x18
+#define GEF_GPIO_OVERRUN	0x1C
+#define GEF_GPIO_MODE		0x20
+
+#define NUM_GPIO 19
+
+static void _gef_gpio_set(void __iomem *reg, unsigned int offset, int value)
+{
+	unsigned int data;
+
+	data = ioread32be(reg);
+	/* value: 0=low; 1=high */
+	if (value & 0x1)
+		data = data | (0x1 << offset);
+	else
+		data = data & ~(0x1 << offset);
+
+	iowrite32be(data, reg);
+}
+
+
+static int gef_gpio_dir_in(struct gpio_chip *chip, unsigned offset)
+{
+	unsigned int data;
+	struct of_mm_gpio_chip *mmchip = to_of_mm_gpio_chip(chip);
+
+	data = ioread32be(mmchip->regs + GEF_GPIO_DIRECT);
+	data = data | (0x1 << offset);
+	iowrite32be(data, mmchip->regs + GEF_GPIO_DIRECT);
+
+	return 0;
+}
+
+static int gef_gpio_dir_out(struct gpio_chip *chip, unsigned offset, int value)
+{
+	unsigned int data;
+	struct of_mm_gpio_chip *mmchip = to_of_mm_gpio_chip(chip);
+
+	/* Set direction before switching to input */
+	_gef_gpio_set(mmchip->regs + GEF_GPIO_OUT, offset, value);
+
+	data = ioread32be(mmchip->regs + GEF_GPIO_DIRECT);
+	data = data & ~(0x1 << offset);
+	iowrite32be(data, mmchip->regs + GEF_GPIO_DIRECT);
+
+	return 0;
+}
+
+static int gef_gpio_get(struct gpio_chip *chip, unsigned offset)
+{
+	unsigned int data;
+	int state = 0;
+	struct of_mm_gpio_chip *mmchip = to_of_mm_gpio_chip(chip);
+
+	data = ioread32be(mmchip->regs + GEF_GPIO_IN);
+	state = (int)((data >> offset) & 0x1);
+
+	return state;
+}
+
+static void gef_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+	struct of_mm_gpio_chip *mmchip = to_of_mm_gpio_chip(chip);
+
+	_gef_gpio_set(mmchip->regs + GEF_GPIO_OUT, offset, value);
+}
+
+static int __init gef_gpio_init(void)
+{
+	struct device_node *np;
+
+	for_each_compatible_node(np, NULL, "gef,sbc610-gpio") {
+		int retval;
+		struct of_mm_gpio_chip *gef_gpio_chip;
+
+		pr_debug("%s: Initialising GEF GPIO\n", np->full_name);
+
+		/* Allocate chip structure */
+		gef_gpio_chip = kzalloc(sizeof(*gef_gpio_chip), GFP_KERNEL);
+		if (!gef_gpio_chip) {
+			pr_err("%s: Unable to allocate structure\n",
+				np->full_name);
+			continue;
+		}
+
+		/* Setup pointers to chip functions */
+		gef_gpio_chip->of_gc.gpio_cells = 2;
+		gef_gpio_chip->of_gc.gc.ngpio = NUM_GPIO;
+		gef_gpio_chip->of_gc.gc.direction_input = gef_gpio_dir_in;
+		gef_gpio_chip->of_gc.gc.direction_output = gef_gpio_dir_out;
+		gef_gpio_chip->of_gc.gc.get = gef_gpio_get;
+		gef_gpio_chip->of_gc.gc.set = gef_gpio_set;
+
+		/* This function adds a memory mapped GPIO chip */
+		retval = of_mm_gpiochip_add(np, gef_gpio_chip);
+		if (retval) {
+			kfree(gef_gpio_chip);
+			pr_err("%s: Unable to add GPIO\n", np->full_name);
+		}
+	}
+
+	return 0;
+};
+arch_initcall(gef_gpio_init);
+
+MODULE_DESCRIPTION("GE Fanuc I/O FPGA GPIO driver");
+MODULE_AUTHOR("Martyn Welch <martyn.welch@gefanuc.com");
+MODULE_LICENSE("GPL");