gpio: add gpio framework

Define the gpio ops in gpio driver.
Signed-off-by: Haojian Zhuang <haojian.zhuang@linaro.org>

drivers/gpio/gpio.c

+/*
+ * Copyright (c) 2016, ARM Limited and Contributors. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of ARM nor the names of its contributors may be used
+ * to endorse or promote products derived from this software without specific
+ * prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * GPIO -- General Purpose Input/Output
+ *
+ * Defines a simple and generic interface to access GPIO device.
+ *
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <gpio.h>
+
+/*
+ * The gpio implementation
+ */
+static const gpio_ops_t *ops;
+
+int gpio_get_direction(int gpio)
+{
+	assert(ops);
+	assert(ops->get_direction != 0);
+	assert(gpio >= 0);
+
+	return ops->get_direction(gpio);
+}
+
+void gpio_set_direction(int gpio, int direction)
+{
+	assert(ops);
+	assert(ops->set_direction != 0);
+	assert((direction == GPIO_DIR_OUT) || (direction == GPIO_DIR_IN));
+	assert(gpio >= 0);
+
+	ops->set_direction(gpio, direction);
+}
+
+int gpio_get_value(int gpio)
+{
+	assert(ops);
+	assert(ops->get_value != 0);
+	assert(gpio >= 0);
+
+	return ops->get_value(gpio);
+}
+
+void gpio_set_value(int gpio, int value)
+{
+	assert(ops);
+	assert(ops->set_value != 0);
+	assert((value == GPIO_LEVEL_LOW) || (value == GPIO_LEVEL_HIGH));
+	assert(gpio >= 0);
+
+	ops->set_value(gpio, value);
+}
+
+/*
+ * Initialize the gpio. The fields in the provided gpio
+ * ops pointer must be valid.
+ */
+void gpio_init(const gpio_ops_t *ops_ptr)
+{
+	assert(ops_ptr != 0  &&
+	       (ops_ptr->get_direction != 0) &&
+	       (ops_ptr->set_direction != 0) &&
+	       (ops_ptr->get_value != 0) &&
+	       (ops_ptr->set_value != 0));
+
+	ops = ops_ptr;
+}

include/drivers/gpio.h

+/*
+ * Copyright (c) 2016, ARM Limited and Contributors. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of ARM nor the names of its contributors may be used
+ * to endorse or promote products derived from this software without specific
+ * prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef __GPIO_H__
+#define __GPIO_H__
+
+#define GPIO_DIR_OUT		0
+#define GPIO_DIR_IN		1
+
+#define GPIO_LEVEL_LOW		0
+#define GPIO_LEVEL_HIGH		1
+
+typedef struct gpio_ops {
+	int (*get_direction)(int gpio);
+	void (*set_direction)(int gpio, int direction);
+	int (*get_value)(int gpio);
+	void (*set_value)(int gpio, int value);
+} gpio_ops_t;
+
+int gpio_get_direction(int gpio);
+void gpio_set_direction(int gpio, int direction);
+int gpio_get_value(int gpio);
+void gpio_set_value(int gpio, int value);
+void gpio_init(const gpio_ops_t *ops);
+
+#endif	/* __GPIO_H__ */