---

yaml
---
r: 53264
b: refs/heads/master
c: 1c23af9
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 16538e6b32600f76ad212d42fc2b1f801e32ab4b
+refs/heads/master: 1c23af90dc44d05bbb6a3b5246ab664b1f943943

trunk/MAINTAINERS

@@ -1466,6 +1466,11 @@ L:	linux-scsi@vger.kernel.org
 W:	http://www.icp-vortex.com/
 S:	Supported
 
+GENERIC GPIO I2C DRIVER
+P:	Haavard Skinnemoen
+M:	hskinnemoen@atmel.com
+S:	Supported
+
 GENERIC HDLC DRIVER, N2, C101, PCI200SYN and WANXL DRIVERS
 P:	Krzysztof Halasa
 M:	khc@pm.waw.pl

trunk/drivers/i2c/busses/Kconfig

@@ -117,6 +117,14 @@ config I2C_ELEKTOR
 	  This support is also available as a module.  If so, the module 
 	  will be called i2c-elektor.
 
+config I2C_GPIO
+	tristate "GPIO-based bitbanging I2C"
+	depends on GENERIC_GPIO
+	select I2C_ALGOBIT
+	help
+	  This is a very simple bitbanging I2C driver utilizing the
+	  arch-neutral GPIO API to control the SCL and SDA lines.
+
 config I2C_HYDRA
 	tristate "CHRP Apple Hydra Mac I/O I2C interface"
 	depends on PCI && PPC_CHRP && EXPERIMENTAL

trunk/drivers/i2c/busses/Makefile

@@ -12,6 +12,7 @@ obj-$(CONFIG_I2C_AT91)		+= i2c-at91.o
 obj-$(CONFIG_I2C_AU1550)	+= i2c-au1550.o
 obj-$(CONFIG_I2C_BLACKFIN_TWI)	+= i2c-bfin-twi.o
 obj-$(CONFIG_I2C_ELEKTOR)	+= i2c-elektor.o
+obj-$(CONFIG_I2C_GPIO)		+= i2c-gpio.o
 obj-$(CONFIG_I2C_HYDRA)		+= i2c-hydra.o
 obj-$(CONFIG_I2C_I801)		+= i2c-i801.o
 obj-$(CONFIG_I2C_I810)		+= i2c-i810.o

trunk/drivers/i2c/busses/i2c-gpio.c

@@ -0,0 +1,215 @@
+/*
+ * Bitbanging I2C bus driver using the GPIO API
+ *
+ * Copyright (C) 2007 Atmel Corporation
+ *
+ * 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 <linux/i2c.h>
+#include <linux/i2c-algo-bit.h>
+#include <linux/i2c-gpio.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#include <asm/gpio.h>
+
+/* Toggle SDA by changing the direction of the pin */
+static void i2c_gpio_setsda_dir(void *data, int state)
+{
+	struct i2c_gpio_platform_data *pdata = data;
+
+	if (state)
+		gpio_direction_input(pdata->sda_pin);
+	else
+		gpio_direction_output(pdata->sda_pin, 0);
+}
+
+/*
+ * Toggle SDA by changing the output value of the pin. This is only
+ * valid for pins configured as open drain (i.e. setting the value
+ * high effectively turns off the output driver.)
+ */
+static void i2c_gpio_setsda_val(void *data, int state)
+{
+	struct i2c_gpio_platform_data *pdata = data;
+
+	gpio_set_value(pdata->sda_pin, state);
+}
+
+/* Toggle SCL by changing the direction of the pin. */
+static void i2c_gpio_setscl_dir(void *data, int state)
+{
+	struct i2c_gpio_platform_data *pdata = data;
+
+	if (state)
+		gpio_direction_input(pdata->scl_pin);
+	else
+		gpio_direction_output(pdata->scl_pin, 0);
+}
+
+/*
+ * Toggle SCL by changing the output value of the pin. This is used
+ * for pins that are configured as open drain and for output-only
+ * pins. The latter case will break the i2c protocol, but it will
+ * often work in practice.
+ */
+static void i2c_gpio_setscl_val(void *data, int state)
+{
+	struct i2c_gpio_platform_data *pdata = data;
+
+	gpio_set_value(pdata->scl_pin, state);
+}
+
+int i2c_gpio_getsda(void *data)
+{
+	struct i2c_gpio_platform_data *pdata = data;
+
+	return gpio_get_value(pdata->sda_pin);
+}
+
+int i2c_gpio_getscl(void *data)
+{
+	struct i2c_gpio_platform_data *pdata = data;
+
+	return gpio_get_value(pdata->scl_pin);
+}
+
+static int __init i2c_gpio_probe(struct platform_device *pdev)
+{
+	struct i2c_gpio_platform_data *pdata;
+	struct i2c_algo_bit_data *bit_data;
+	struct i2c_adapter *adap;
+	int ret;
+
+	pdata = pdev->dev.platform_data;
+	if (!pdata)
+		return -ENXIO;
+
+	ret = -ENOMEM;
+	adap = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL);
+	if (!adap)
+		goto err_alloc_adap;
+	bit_data = kzalloc(sizeof(struct i2c_algo_bit_data), GFP_KERNEL);
+	if (!bit_data)
+		goto err_alloc_bit_data;
+
+	ret = gpio_request(pdata->sda_pin, "sda");
+	if (ret)
+		goto err_request_sda;
+	ret = gpio_request(pdata->scl_pin, "scl");
+	if (ret)
+		goto err_request_scl;
+
+	if (pdata->sda_is_open_drain) {
+		gpio_direction_output(pdata->sda_pin, 1);
+		bit_data->setsda = i2c_gpio_setsda_val;
+	} else {
+		gpio_direction_input(pdata->sda_pin);
+		bit_data->setsda = i2c_gpio_setsda_dir;
+	}
+
+	if (pdata->scl_is_open_drain || pdata->scl_is_output_only) {
+		gpio_direction_output(pdata->scl_pin, 1);
+		bit_data->setscl = i2c_gpio_setscl_val;
+	} else {
+		gpio_direction_input(pdata->scl_pin);
+		bit_data->setscl = i2c_gpio_setscl_dir;
+	}
+
+	if (!pdata->scl_is_output_only)
+		bit_data->getscl = i2c_gpio_getscl;
+	bit_data->getsda = i2c_gpio_getsda;
+
+	if (pdata->udelay)
+		bit_data->udelay = pdata->udelay;
+	else if (pdata->scl_is_output_only)
+		bit_data->udelay = 50;			/* 10 kHz */
+	else
+		bit_data->udelay = 5;			/* 100 kHz */
+
+	if (pdata->timeout)
+		bit_data->timeout = pdata->timeout;
+	else
+		bit_data->timeout = HZ / 10;		/* 100 ms */
+
+	bit_data->data = pdata;
+
+	adap->owner = THIS_MODULE;
+	snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);
+	adap->algo_data = bit_data;
+	adap->dev.parent = &pdev->dev;
+
+	ret = i2c_bit_add_bus(adap);
+	if (ret)
+		goto err_add_bus;
+
+	platform_set_drvdata(pdev, adap);
+
+	dev_info(&pdev->dev, "using pins %u (SDA) and %u (SCL%s)\n",
+		 pdata->sda_pin, pdata->scl_pin,
+		 pdata->scl_is_output_only
+		 ? ", no clock stretching" : "");
+
+	return 0;
+
+err_add_bus:
+	gpio_free(pdata->scl_pin);
+err_request_scl:
+	gpio_free(pdata->sda_pin);
+err_request_sda:
+	kfree(bit_data);
+err_alloc_bit_data:
+	kfree(adap);
+err_alloc_adap:
+	return ret;
+}
+
+static int __exit i2c_gpio_remove(struct platform_device *pdev)
+{
+	struct i2c_gpio_platform_data *pdata;
+	struct i2c_adapter *adap;
+
+	adap = platform_get_drvdata(pdev);
+	pdata = pdev->dev.platform_data;
+
+	i2c_del_adapter(adap);
+	gpio_free(pdata->scl_pin);
+	gpio_free(pdata->sda_pin);
+	kfree(adap->algo_data);
+	kfree(adap);
+
+	return 0;
+}
+
+static struct platform_driver i2c_gpio_driver = {
+	.driver		= {
+		.name	= "i2c-gpio",
+		.owner	= THIS_MODULE,
+	},
+	.remove		= __exit_p(i2c_gpio_remove),
+};
+
+static int __init i2c_gpio_init(void)
+{
+	int ret;
+
+	ret = platform_driver_probe(&i2c_gpio_driver, i2c_gpio_probe);
+	if (ret)
+		printk(KERN_ERR "i2c-gpio: probe failed: %d\n", ret);
+
+	return ret;
+}
+module_init(i2c_gpio_init);
+
+static void __exit i2c_gpio_exit(void)
+{
+	platform_driver_unregister(&i2c_gpio_driver);
+}
+module_exit(i2c_gpio_exit);
+
+MODULE_AUTHOR("Haavard Skinnemoen <hskinnemoen@atmel.com>");
+MODULE_DESCRIPTION("Platform-independent bitbanging I2C driver");
+MODULE_LICENSE("GPL");

trunk/include/linux/i2c-gpio.h

@@ -0,0 +1,38 @@
+/*
+ * i2c-gpio interface to platform code
+ *
+ * Copyright (C) 2007 Atmel Corporation
+ *
+ * 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_I2C_GPIO_H
+#define _LINUX_I2C_GPIO_H
+
+/**
+ * struct i2c_gpio_platform_data - Platform-dependent data for i2c-gpio
+ * @sda_pin: GPIO pin ID to use for SDA
+ * @scl_pin: GPIO pin ID to use for SCL
+ * @udelay: signal toggle delay. SCL frequency is (500 / udelay) kHz
+ * @timeout: clock stretching timeout in jiffies. If the slave keeps
+ *	SCL low for longer than this, the transfer will time out.
+ * @sda_is_open_drain: SDA is configured as open drain, i.e. the pin
+ *	isn't actively driven high when setting the output value high.
+ *	gpio_get_value() must return the actual pin state even if the
+ *	pin is configured as an output.
+ * @scl_is_open_drain: SCL is set up as open drain. Same requirements
+ *	as for sda_is_open_drain apply.
+ * @scl_is_output_only: SCL output drivers cannot be turned off.
+ */
+struct i2c_gpio_platform_data {
+	unsigned int	sda_pin;
+	unsigned int	scl_pin;
+	int		udelay;
+	int		timeout;
+	unsigned int	sda_is_open_drain:1;
+	unsigned int	scl_is_open_drain:1;
+	unsigned int	scl_is_output_only:1;
+};
+
+#endif /* _LINUX_I2C_GPIO_H */