1-wire: add gpio bus

Based on linux implementation.

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

drivers/w1/masters/Kconfig

@@ -4,4 +4,11 @@
 
 menu "1-wire Bus Masters"
 
+config W1_MASTER_GPIO
+	bool "GPIO 1-wire busmaster"
+	depends on GENERIC_GPIO
+	help
+	  Say Y here if you want to communicate with your 1-wire devices using
+	  GPIO pins. This driver uses the GPIO API to control the wire.
+
 endmenu

drivers/w1/masters/Makefile

@@ -2,3 +2,4 @@
 # Makefile for 1-wire bus master drivers.
 #
 
+obj-$(CONFIG_W1_MASTER_GPIO)		+= w1-gpio.o

drivers/w1/masters/w1-gpio.c

@@ -0,0 +1,116 @@
+/*
+ * w1-gpio - GPIO w1 bus master driver
+ *
+ * Copyright (C) 2007 Ville Syrjala <syrjala@sci.fi>
+ * Copyright (c) 2012 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ */
+
+#include <common.h>
+#include <init.h>
+#include <malloc.h>
+#include <xfuncs.h>
+#include <driver.h>
+#include <linux/w1-gpio.h>
+#include <gpio.h>
+
+#include "../w1.h"
+
+static void w1_gpio_write_bit_dir(struct w1_bus *bus, u8 bit)
+{
+	struct w1_gpio_platform_data *pdata = bus->data;
+
+	if (bit)
+		gpio_direction_input(pdata->pin);
+	else
+		gpio_direction_output(pdata->pin, 0);
+}
+
+static void w1_gpio_write_bit_val(struct w1_bus *bus, u8 bit)
+{
+	struct w1_gpio_platform_data *pdata = bus->data;
+
+	gpio_set_value(pdata->pin, bit);
+}
+
+static u8 w1_gpio_read_bit(struct w1_bus *bus)
+{
+	struct w1_gpio_platform_data *pdata = bus->data;
+
+	return gpio_get_value(pdata->pin) ? 1 : 0;
+}
+
+static int __init w1_gpio_probe(struct device_d *dev)
+{
+	struct w1_bus *master;
+	struct w1_gpio_platform_data *pdata;
+	int err;
+
+	pdata = dev->platform_data;
+
+	if (!pdata)
+		return -ENXIO;
+
+	master = xzalloc(sizeof(struct w1_bus));
+
+	err = gpio_request(pdata->pin, "w1");
+	if (err)
+		goto free_master;
+
+	if (gpio_is_valid(pdata->ext_pullup_enable_pin)) {
+		err = gpio_request(pdata->pin, "w1 pullup");
+		if (err < 0)
+			goto free_gpio;
+
+		gpio_direction_output(pdata->pin, 0);
+	}
+
+	master->data = pdata;
+	master->read_bit = w1_gpio_read_bit;
+
+	if (pdata->is_open_drain) {
+		gpio_direction_output(pdata->pin, 1);
+		master->write_bit = w1_gpio_write_bit_val;
+	} else {
+		gpio_direction_input(pdata->pin);
+		master->write_bit = w1_gpio_write_bit_dir;
+	}
+
+	master->parent = dev;
+
+	err = w1_bus_register(master);
+	if (err)
+		goto free_gpio_ext_pu;
+
+	if (pdata->enable_external_pullup)
+		pdata->enable_external_pullup(1);
+
+	if (gpio_is_valid(pdata->ext_pullup_enable_pin))
+		gpio_set_value(pdata->ext_pullup_enable_pin, 1);
+
+	return 0;
+
+ free_gpio_ext_pu:
+	if (gpio_is_valid(pdata->ext_pullup_enable_pin))
+		gpio_free(pdata->ext_pullup_enable_pin);
+ free_gpio:
+	gpio_free(pdata->pin);
+ free_master:
+	kfree(master);
+
+	return err;
+}
+
+static struct driver_d w1_gpio_driver = {
+	.name	= "w1-gpio",
+	.probe	= w1_gpio_probe,
+};
+
+static int __init w1_gpio_init(void)
+{
+	return platform_driver_register(&w1_gpio_driver);
+}
+device_initcall(w1_gpio_init);

include/linux/w1-gpio.h

@@ -0,0 +1,25 @@
+/*
+ * w1-gpio interface to platform code
+ *
+ * Copyright (C) 2007 Ville Syrjala <syrjala@sci.fi>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ */
+#ifndef _LINUX_W1_GPIO_H
+#define _LINUX_W1_GPIO_H
+
+/**
+ * struct w1_gpio_platform_data - Platform-dependent data for w1-gpio
+ * @pin: GPIO pin to use
+ * @is_open_drain: GPIO pin is configured as open drain
+ */
+struct w1_gpio_platform_data {
+	unsigned int pin;
+	unsigned int is_open_drain:1;
+	void (*enable_external_pullup)(int enable);
+	unsigned int ext_pullup_enable_pin;
+};
+
+#endif /* _LINUX_W1_GPIO_H */