[U-Boot] [PATCH v4 3/8] sandbox: gpio: Add basic driver for simulating GPIOs

[Simon Glass]

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 at chromium.org>
---
Changes in v2:
- Fix gpio_direction_output() to actually set the value
- Use generic GPIO command and interface

Changes in v3:
- Change GPIO numbers to unsigned as per new asm-generic/gpio.h
- Implement GPIO interface more fully (reservation, gpio state)
- Use __func__ when function names are required

Changes in v4:
- Add comments to clearly explain the purpose of the sandbox GPIO interface

 arch/sandbox/include/asm/gpio.h |   81 ++++++++++++++++
 drivers/gpio/Makefile           |    1 +
 drivers/gpio/sandbox.c          |  194 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 276 insertions(+), 0 deletions(-)
 create mode 100644 arch/sandbox/include/asm/gpio.h
 create mode 100644 drivers/gpio/sandbox.c

diff --git a/arch/sandbox/include/asm/gpio.h b/arch/sandbox/include/asm/gpio.h
new file mode 100644
index 0000000..0500c53
--- /dev/null
+++ b/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
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 4375a55..fb3b09a 100644
--- a/drivers/gpio/Makefile
+++ b/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
diff --git a/drivers/gpio/sandbox.c b/drivers/gpio/sandbox.c
new file mode 100644
index 0000000..17e601d
--- /dev/null
+++ b/drivers/gpio/sandbox.c
@@ -0,0 +1,194 @@
+/*
+ * 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/io.h>
+#include <asm/bitops.h>
+#include <asm-generic/gpio.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(unsigned gp)
+{
+	assert(gp < CONFIG_SANDBOX_GPIO_COUNT);
+	return &state[gp].flags;
+}
+
+static int get_gpio_flag(unsigned gp, int flag)
+{
+	return (*get_gpio(gp) & flag) != 0;
+}
+
+static void set_gpio_flag(unsigned gp, int flag, int value)
+{
+	u8 *gpio = get_gpio(gp);
+
+	if (value)
+		*gpio |= flag;
+	else
+		*gpio &= ~flag;
+}
+
+int sandbox_gpio_get_value(unsigned gp)
+{
+	if (get_gpio_flag(gp, GPIOF_OUTPUT))
+		printf("sandbox_gpio: get_value on output GPIO %d\n", gp);
+	return *get_gpio(gp) & GPIOF_HIGH;
+}
+
+int sandbox_gpio_set_value(unsigned gp, int value)
+{
+	set_gpio_flag(gp, GPIOF_HIGH, value);
+	return 0;
+}
+
+int sandbox_gpio_get_direction(unsigned gp)
+{
+	return get_gpio_flag(gp, GPIOF_OUTPUT);
+}
+
+int sandbox_gpio_set_direction(unsigned gp, int output)
+{
+	set_gpio_flag(gp, GPIOF_OUTPUT, output);
+	return 0;
+}
+
+static int check_reserved(unsigned gpio, const char *op_name)
+{
+	if (!get_gpio_flag(gpio, GPIOF_RESERVED)) {
+		printf("sandbox_gpio: '%s' on unreserved GPIO\n", op_name);
+		return -1;
+	}
+
+	return 0;
+}
+
+/* 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 = %d\n", __func__, gp);
+	if (check_reserved(gp, __func__))
+		return -1;
+	set_gpio_flag(gp, GPIOF_OUTPUT, 0);
+
+	return 0;
+}
+
+/* set GPIO port 'gp' as an output, with polarity 'value' */
+int gpio_direction_output(unsigned gp, int value)
+{
+	debug("%s: gp = %d, value = %d\n", __func__, gp, value);
+	if (check_reserved(gp, __func__))
+		return -1;
+	set_gpio_flag(gp, GPIOF_OUTPUT, 1);
+	set_gpio_flag(gp, GPIOF_HIGH, value);
+
+	return 0;
+}
+
+/* read GPIO IN value of port 'gp' */
+int gpio_get_value(unsigned gp)
+{
+	debug("%s: gp = %d\n", __func__, gp);
+	if (check_reserved(gp, __func__))
+		return -1;
+	if (get_gpio_flag(gp, GPIOF_OUTPUT))
+		printf("sandbox_gpio: get_value on output GPIO %d\n", gp);
+
+	return get_gpio_flag(gp, GPIOF_HIGH);
+}
+
+/* write GPIO OUT value to port 'gp' */
+int gpio_set_value(unsigned gp, int value)
+{
+	debug("%s: gp = %d, value = %d\n", __func__, gp, value);
+	if (check_reserved(gp, __func__))
+		return -1;
+	if (get_gpio_flag(gp, GPIOF_OUTPUT)) {
+		set_gpio_flag(gp, GPIOF_HIGH, value);
+	} else {
+		printf("sandbox_gpio: set_value on input GPIO %d\n", gp);
+		return -1;
+	}
+
+	return 0;
+}
+
+int gpio_request(unsigned gp, const char *label)
+{
+	debug("%s: gp = %d, label= %s\n", __func__, gp, label);
+	if (get_gpio_flag(gp, GPIOF_RESERVED)) {
+		printf("sandbox_gpio: request on reserved GPIO\n");
+		return -1;
+	}
+	set_gpio_flag(gp, GPIOF_RESERVED, 1);
+	state[gp].label = label;
+
+	return 0;
+}
+
+int gpio_free(unsigned gp)
+{
+	debug("%s: gp = %d\n", __func__, gp);
+	if (check_reserved(gp, __func__))
+		return -1;
+	set_gpio_flag(gp, GPIOF_RESERVED, 0);
+	state[gp].label = NULL;
+
+	return 0;
+}
+
+/* Display GPIO information */
+void gpio_info(void)
+{
+	unsigned gpio;
+
+	printf("Sandbox GPIOs\n");
+
+	for (gpio = 0; gpio < CONFIG_SANDBOX_GPIO_COUNT; ++gpio) {
+		const char *label = state[gpio].label;
+
+		printf("%4d: %s: %d [%c] %s\n",
+			gpio,
+			get_gpio_flag(gpio, GPIOF_OUTPUT) ? "out" : " in",
+			get_gpio_flag(gpio, GPIOF_HIGH),
+			get_gpio_flag(gpio, GPIOF_RESERVED) ? 'x' : ' ',
+			label ? label : "");
+	}
+}
-- 
1.7.7.3