i2c: add i2c-gpio support

Based on linux 3.7-rc2

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

1 files changed, 177 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-gpio.c b/drivers/i2c/busses/i2c-gpio.c
new file mode 100644
index 0000000000..98ce2d59ab
--- /dev/null
+++ b/drivers/i2c/busses/i2c-gpio.c
@@ -0,0 +1,177 @@
+/*
+ * 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 <common.h>
+#include <driver.h>
+#include <i2c/i2c.h>
+#include <i2c/i2c-algo-bit.h>
+#include <i2c/i2c-gpio.h>
+#include <init.h>
+#include <gpio.h>
+
+struct i2c_gpio_private_data {
+	struct i2c_adapter adap;
+	struct i2c_algo_bit_data bit_data;
+	struct i2c_gpio_platform_data pdata;
+};
+
+/* 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);
+}
+
+static int i2c_gpio_getsda(void *data)
+{
+	struct i2c_gpio_platform_data *pdata = data;
+
+	return gpio_get_value(pdata->sda_pin);
+}
+
+static int i2c_gpio_getscl(void *data)
+{
+	struct i2c_gpio_platform_data *pdata = data;
+
+	return gpio_get_value(pdata->scl_pin);
+}
+
+static int i2c_gpio_probe(struct device_d *dev)
+{
+	struct i2c_gpio_private_data *priv;
+	struct i2c_gpio_platform_data *pdata;
+	struct i2c_algo_bit_data *bit_data;
+	struct i2c_adapter *adap;
+	int ret;
+
+	priv = xzalloc(sizeof(*priv));
+
+	adap = &priv->adap;
+	bit_data = &priv->bit_data;
+	pdata = &priv->pdata;
+
+	if (!dev->platform_data)
+		return -ENXIO;
+	memcpy(pdata, dev->platform_data, sizeof(*pdata));
+
+	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_ms)
+		bit_data->timeout_ms = pdata->timeout_ms;
+	else
+		bit_data->timeout_ms = 100;		/* 100 ms */
+
+	bit_data->data = pdata;
+
+	adap->algo_data = bit_data;
+	adap->dev.parent = dev;
+
+	adap->nr = dev->id;
+	ret = i2c_bit_add_numbered_bus(adap);
+	if (ret)
+		goto err_add_bus;
+
+	dev_info(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:
+	return ret;
+}
+
+static struct driver_d i2c_gpio_driver = {
+	.name	= "i2c-gpio",
+	.probe	= i2c_gpio_probe,
+};
+
+static int __init i2c_gpio_init(void)
+{
+	return platform_driver_register(&i2c_gpio_driver);
+}
+device_initcall(i2c_gpio_init);