[U-Boot] [RFC PATCH 1/3] sandbox: gpio: WIP 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>
---
 drivers/gpio/Makefile  |    1 +
 drivers/gpio/sandbox.c |  213 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/sandbox_gpio.h |   50 +++++++++++
 3 files changed, 264 insertions(+), 0 deletions(-)
 create mode 100644 drivers/gpio/sandbox.c
 create mode 100644 include/sandbox_gpio.h

diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index f505813..f427127 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -33,6 +33,7 @@ COBJS-$(CONFIG_MXC_GPIO)	+= mxc_gpio.o
 COBJS-$(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
 
diff --git a/drivers/gpio/sandbox.c b/drivers/gpio/sandbox.c
new file mode 100644
index 0000000..81ba803
--- /dev/null
+++ b/drivers/gpio/sandbox.c
@@ -0,0 +1,213 @@
+/*
+ * 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/arch/gpio.h>
+
+enum {
+	CMD_INFO,
+	CMD_PORT,
+	CMD_OUTPUT,
+	CMD_INPUT,
+};
+
+/* Flags for each GPIO */
+enum {
+	GPIOF_OUTPUT	= 1 << 1,
+	GPIOF_HIGH	= 1 << 2,
+};
+
+/* TODO: Put this into sandbox state */
+static u8 state[GPIO_COUNT];	/* State of GPIOs */
+
+
+/* Access routines for GPIO state */
+static u8 *get_gpio(int gp)
+{
+	assert(gp >= 0 && gp < GPIO_COUNT);
+	return &state[gp];
+}
+
+static int get_gpio_flag(int gp, int flag)
+{
+	return *get_gpio(gp) & flag;
+}
+
+static void set_gpio_flag(int gp, int flag, int value)
+{
+	u8 *gpio = get_gpio(gp);
+
+	if (value)
+		*gpio |= flag;
+	else
+		*gpio &= ~flag;
+}
+
+int sandbox_gpio_get_value(int 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(int gp, int value)
+{
+	set_gpio_flag(gp, GPIOF_HIGH, value);
+	return 0;
+}
+
+int sandbox_gpio_get_direction(int gp)
+{
+	return get_gpio_flag(gp, GPIOF_OUTPUT);
+}
+
+int sandbox_gpio_set_direction(int gp, int output)
+{
+	set_gpio_flag(gp, GPIOF_OUTPUT, output);
+	return 0;
+}
+
+
+/* These functions make up what could be a public interface within U-Boot */
+
+/* set GPIO port 'gp' as an input */
+int gpio_direction_input(int gp)
+{
+	debug("gpio_direction_input: gp = %d\n", gp);
+	set_gpio_flag(gp, GPIOF_OUTPUT, 0);
+	return 0;
+}
+
+/* set GPIO port 'gp' as an output, with polarity 'value' */
+int gpio_direction_output(int gp, int value)
+{
+	debug("gpio_direction_output: gp = %d, value = %d\n",
+	      gp, value);
+	set_gpio_flag(gp, GPIOF_OUTPUT, 1);
+	return 0;
+}
+
+/* read GPIO IN value of port 'gp' */
+int gpio_get_value(int gp)
+{
+	debug("gpio_get_value: gp = %d\n", 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;
+}
+
+/* write GPIO OUT value to port 'gp' */
+void gpio_set_value(int gp, int value)
+{
+	debug("gpio_set_value: gp = %d, value = %d\n", gp, value);
+	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);
+}
+
+/* Display GPIO information */
+static int gpio_info(int gp)
+{
+	printf("Sandbox GPIOs\n");
+	return 0;
+}
+
+cmd_tbl_t cmd_gpio[] = {
+	U_BOOT_CMD_MKENT(offset2port, 3, 0, (void *)CMD_PORT, "", ""),
+	U_BOOT_CMD_MKENT(output, 4, 0, (void *)CMD_OUTPUT, "", ""),
+	U_BOOT_CMD_MKENT(input, 3, 0, (void *)CMD_INPUT, "", ""),
+#ifdef CONFIG_CMD_GPIO_INFO
+	U_BOOT_CMD_MKENT(info, 3, 0, (void *)CMD_INFO, "", ""),
+#endif
+};
+
+int do_gpio(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	static uint8_t offset;
+	int val __attribute__((unused));
+	ulong ul_arg2, ul_arg3, ul_arg4;
+	cmd_tbl_t *c;
+
+	ul_arg2 = ul_arg3 = ul_arg4 = 0;
+
+	c = find_cmd_tbl(argv[1], cmd_gpio, ARRAY_SIZE(cmd_gpio));
+
+	/* All commands but "port" require 'maxargs' arguments */
+	if (!c || !((argc == (c->maxargs)) ||
+		(((long)c->cmd == CMD_PORT) &&
+		 (argc == (c->maxargs - 1))))) {
+		cmd_usage(cmdtp);
+		return 1;
+	}
+
+	/* arg2 used as offset */
+	if (argc > 2)
+		ul_arg2 = simple_strtoul(argv[2], NULL, 10);
+
+	/* arg3 used as output value, 0 or 1 */
+	if (argc > 3)
+		ul_arg3 = simple_strtoul(argv[3], NULL, 10) & 0x1;
+
+	switch ((long)c->cmd) {
+	case CMD_INFO:
+		if (argc == 3)
+			offset = (uint8_t)ul_arg2;
+		return gpio_info(offset);
+
+	case CMD_PORT:
+		if (argc == 3)
+			offset = (uint8_t)ul_arg2;
+		return 0;
+
+	case CMD_INPUT:
+		/* arg2 = offset */
+		gpio_direction_input(ul_arg2);
+		val = gpio_get_value(ul_arg2);
+		return 0;
+
+	case CMD_OUTPUT:
+		/* args = offset, value */
+		gpio_direction_output(ul_arg2, ul_arg3);
+		return 0;
+
+	default:
+		/* We should never get here */
+		return 1;
+	}
+}
+
+U_BOOT_CMD(
+	gpio,	5,	1,	do_gpio,
+	"GPIO access",
+	"offset2port offset\n"
+	"	- show GPIO port:bit based on 'offset'\n"
+#ifdef CONFIG_CMD_GPIO_INFO
+	"     info offset\n"
+	"	- display info for all bits in port based on 'offset'\n"
+#endif
+	"     output offset 0|1\n"
+	"	- using 'offset', set port:bit as output and drive low or high\n"
+	"     input offset\n"
+	"	- using 'offset', set port:bit as input and read value"
+);
diff --git a/include/sandbox_gpio.h b/include/sandbox_gpio.h
new file mode 100644
index 0000000..db92f7b
--- /dev/null
+++ b/include/sandbox_gpio.h
@@ -0,0 +1,50 @@
+/*
+ * 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
+ */
+
+/**
+ * Return the value of a GPIO
+ *
+ * @param gp	GPIO number
+ * @return -1 on error, 0 if GPIO is low, >0 if high
+ */
+int sandbox_gpio_get_value(int gp);
+
+/**
+ * @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(int gp, int value);
+
+/**
+ * Return the direction of a GPIO
+ *
+ * @param gp	GPIO number
+ * @return -1 on error, 0 if GPIO is input, >0 if output
+ */
+int sandbox_gpio_get_direction(int gp);
+
+/**
+ * @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(int gp, int output);
-- 
1.7.3.1