sandbox: gpio: add basic driver for simulating GPIOs

This provides a way of simulating GPIOs by setting values which are seen
by the normal gpio_get/set_value() calls.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/sandbox/include/asm/gpio.h

@@ -0,0 +1,81 @@
+/*
+ * This is the interface to the sandbox GPIO driver for test code which
+ * wants to change the GPIO values reported to U-Boot.
+ *
+ * Copyright (c) 2011 The Chromium OS Authors.
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#ifndef __ASM_SANDBOX_GPIO_H
+#define __ASM_SANDBOX_GPIO_H
+
+/*
+ * We use the generic interface, and add a back-channel.
+ *
+ * The back-channel functions are declared in this file. They should not be used
+ * except in test code.
+ *
+ * Test code can, for example, call sandbox_gpio_set_value() to set the value of
+ * a simulated GPIO. From then on, normal code in U-Boot will see this new
+ * value when it calls gpio_get_value().
+ *
+ * NOTE: DO NOT use the functions in this file except in test code!
+ */
+#include <asm-generic/gpio.h>
+
+/**
+ * Return the simulated value of a GPIO (used only in sandbox test code)
+ *
+ * @param gp	GPIO number
+ * @return -1 on error, 0 if GPIO is low, >0 if high
+ */
+int sandbox_gpio_get_value(unsigned gp);
+
+/**
+ * Set the simulated value of a GPIO (used only in sandbox test code)
+ *
+ * @param gp	GPIO number
+ * @param value	value to set (0 for low, non-zero for high)
+ * @return -1 on error, 0 if ok
+ */
+int sandbox_gpio_set_value(unsigned gp, int value);
+
+/**
+ * Return the simulated direction of a GPIO (used only in sandbox test code)
+ *
+ * @param gp	GPIO number
+ * @return -1 on error, 0 if GPIO is input, >0 if output
+ */
+int sandbox_gpio_get_direction(unsigned gp);
+
+/**
+ * Set the simulated direction of a GPIO (used only in sandbox test code)
+ *
+ * @param gp	GPIO number
+ * @param output 0 to set as input, 1 to set as output
+ * @return -1 on error, 0 if ok
+ */
+int sandbox_gpio_set_direction(unsigned gp, int output);
+
+/* Display information about each GPIO */
+void gpio_info(void);
+
+#define gpio_status()	gpio_info()
+
+#endif

drivers/gpio/Makefile

@@ -34,6 +34,7 @@ COBJS-$(CONFIG_MXS_GPIO)	+= mxs_gpio.o
 COBJS-$(CONFIG_PCA953X)		+= pca953x.o
 COBJS-$(CONFIG_PCA9698)		+= pca9698.o
 COBJS-$(CONFIG_S5P)		+= s5p_gpio.o
+COBJS-$(CONFIG_SANDBOX_GPIO)	+= sandbox.o
 COBJS-$(CONFIG_TEGRA2_GPIO)	+= tegra2_gpio.o
 COBJS-$(CONFIG_DA8XX_GPIO)	+= da8xx_gpio.o
 COBJS-$(CONFIG_ALTERA_PIO)	+= altera_pio.o

drivers/gpio/sandbox.c

@@ -0,0 +1,209 @@
+/*
+ * Copyright (c) 2011 The Chromium OS Authors.
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <asm/gpio.h>
+
+/* Flags for each GPIO */
+#define GPIOF_OUTPUT	(1 << 0)	/* Currently set as an output */
+#define GPIOF_HIGH	(1 << 1)	/* Currently set high */
+#define GPIOF_RESERVED	(1 << 2)	/* Is in use / requested */
+
+struct gpio_state {
+	const char *label;	/* label given by requester */
+	u8 flags;		/* flags (GPIOF_...) */
+};
+
+/*
+ * State of GPIOs
+ * TODO: Put this into sandbox state
+ */
+static struct gpio_state state[CONFIG_SANDBOX_GPIO_COUNT];
+
+/* Access routines for GPIO state */
+static u8 *get_gpio_flags(unsigned gp)
+{
+	/* assert()'s could be disabled, so make sure we handle that */
+	assert(gp < ARRAY_SIZE(state));
+	if (gp >= ARRAY_SIZE(state)) {
+		static u8 invalid_flags;
+		printf("sandbox_gpio: error: invalid gpio %u\n", gp);
+		return &invalid_flags;
+	}
+
+	return &state[gp].flags;
+}
+
+static int get_gpio_flag(unsigned gp, int flag)
+{
+	return (*get_gpio_flags(gp) & flag) != 0;
+}
+
+static int set_gpio_flag(unsigned gp, int flag, int value)
+{
+	u8 *gpio = get_gpio_flags(gp);
+
+	if (value)
+		*gpio |= flag;
+	else
+		*gpio &= ~flag;
+
+	return 0;
+}
+
+static int check_reserved(unsigned gpio, const char *func)
+{
+	if (!get_gpio_flag(gpio, GPIOF_RESERVED)) {
+		printf("sandbox_gpio: %s: error: gpio %u not reserved\n",
+			func, gpio);
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * Back-channel sandbox-internal-only access to GPIO state
+ */
+
+int sandbox_gpio_get_value(unsigned gp)
+{
+	if (get_gpio_flag(gp, GPIOF_OUTPUT))
+		debug("sandbox_gpio: get_value on output gpio %u\n", gp);
+	return get_gpio_flag(gp, GPIOF_HIGH);
+}
+
+int sandbox_gpio_set_value(unsigned gp, int value)
+{
+	return set_gpio_flag(gp, GPIOF_HIGH, value);
+}
+
+int sandbox_gpio_get_direction(unsigned gp)
+{
+	return get_gpio_flag(gp, GPIOF_OUTPUT);
+}
+
+int sandbox_gpio_set_direction(unsigned gp, int output)
+{
+	return set_gpio_flag(gp, GPIOF_OUTPUT, output);
+}
+
+/*
+ * These functions implement the public interface within U-Boot
+ */
+
+/* set GPIO port 'gp' as an input */
+int gpio_direction_input(unsigned gp)
+{
+	debug("%s: gp:%u\n", __func__, gp);
+
+	if (check_reserved(gp, __func__))
+		return -1;
+
+	return sandbox_gpio_set_direction(gp, 0);
+}
+
+/* set GPIO port 'gp' as an output, with polarity 'value' */
+int gpio_direction_output(unsigned gp, int value)
+{
+	debug("%s: gp:%u, value = %d\n", __func__, gp, value);
+
+	if (check_reserved(gp, __func__))
+		return -1;
+
+	return sandbox_gpio_set_direction(gp, 1) |
+		sandbox_gpio_set_value(gp, value);
+}
+
+/* read GPIO IN value of port 'gp' */
+int gpio_get_value(unsigned gp)
+{
+	debug("%s: gp:%u\n", __func__, gp);
+
+	if (check_reserved(gp, __func__))
+		return -1;
+
+	return sandbox_gpio_get_value(gp);
+}
+
+/* write GPIO OUT value to port 'gp' */
+int gpio_set_value(unsigned gp, int value)
+{
+	debug("%s: gp:%u, value = %d\n", __func__, gp, value);
+
+	if (check_reserved(gp, __func__))
+		return -1;
+
+	if (!sandbox_gpio_get_direction(gp)) {
+		printf("sandbox_gpio: error: set_value on input gpio %u\n", gp);
+		return -1;
+	}
+
+	return sandbox_gpio_set_value(gp, value);
+}
+
+int gpio_request(unsigned gp, const char *label)
+{
+	debug("%s: gp:%u, label:%s\n", __func__, gp, label);
+
+	if (gp >= ARRAY_SIZE(state)) {
+		printf("sandbox_gpio: error: invalid gpio %u\n", gp);
+		return -1;
+	}
+
+	if (get_gpio_flag(gp, GPIOF_RESERVED)) {
+		printf("sandbox_gpio: error: gpio %u already reserved\n", gp);
+		return -1;
+	}
+
+	state[gp].label = label;
+	return set_gpio_flag(gp, GPIOF_RESERVED, 1);
+}
+
+int gpio_free(unsigned gp)
+{
+	debug("%s: gp:%u\n", __func__, gp);
+
+	if (check_reserved(gp, __func__))
+		return -1;
+
+	state[gp].label = NULL;
+	return set_gpio_flag(gp, GPIOF_RESERVED, 0);
+}
+
+/* Display GPIO information */
+void gpio_info(void)
+{
+	unsigned gpio;
+
+	puts("Sandbox GPIOs\n");
+
+	for (gpio = 0; gpio < ARRAY_SIZE(state); ++gpio) {
+		const char *label = state[gpio].label;
+
+		printf("%4d: %s: %d [%c] %s\n",
+			gpio,
+			sandbox_gpio_get_direction(gpio) ? "out" : " in",
+			sandbox_gpio_get_value(gpio),
+			get_gpio_flag(gpio, GPIOF_RESERVED) ? 'x' : ' ',
+			label ? label : "");
+	}
+}