Initial import

1 files changed, 290 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-gpio.c b/drivers/i2c/busses/i2c-gpio.c
new file mode 100644
index 000000000..34cfc0ebd
--- /dev/null
+++ b/drivers/i2c/busses/i2c-gpio.c
@@ -0,0 +1,290 @@
+/*
+ * 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/slab.h>
+#include <linux/platform_device.h>
+#include <linux/gpio.h>
+#include <linux/of.h>
+#include <linux/of_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 of_i2c_gpio_get_pins(struct device_node *np,
+				unsigned int *sda_pin, unsigned int *scl_pin)
+{
+	if (of_gpio_count(np) < 2)
+		return -ENODEV;
+
+	*sda_pin = of_get_gpio(np, 0);
+	*scl_pin = of_get_gpio(np, 1);
+
+	if (*sda_pin == -EPROBE_DEFER || *scl_pin == -EPROBE_DEFER)
+		return -EPROBE_DEFER;
+
+	if (!gpio_is_valid(*sda_pin) || !gpio_is_valid(*scl_pin)) {
+		pr_err("%s: invalid GPIO pins, sda=%d/scl=%d\n",
+		       np->full_name, *sda_pin, *scl_pin);
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static void of_i2c_gpio_get_props(struct device_node *np,
+				  struct i2c_gpio_platform_data *pdata)
+{
+	u32 reg;
+
+	of_property_read_u32(np, "i2c-gpio,delay-us", &pdata->udelay);
+
+	if (!of_property_read_u32(np, "i2c-gpio,timeout-ms", &reg))
+		pdata->timeout = msecs_to_jiffies(reg);
+
+	pdata->sda_is_open_drain =
+		of_property_read_bool(np, "i2c-gpio,sda-open-drain");
+	pdata->scl_is_open_drain =
+		of_property_read_bool(np, "i2c-gpio,scl-open-drain");
+	pdata->scl_is_output_only =
+		of_property_read_bool(np, "i2c-gpio,scl-output-only");
+}
+
+static int i2c_gpio_probe(struct platform_device *pdev)
+{
+	struct i2c_gpio_private_data *priv;
+	struct i2c_gpio_platform_data *pdata;
+	struct i2c_algo_bit_data *bit_data;
+	struct i2c_adapter *adap;
+	unsigned int sda_pin, scl_pin;
+	int ret;
+
+	/* First get the GPIO pins; if it fails, we'll defer the probe. */
+	if (pdev->dev.of_node) {
+		ret = of_i2c_gpio_get_pins(pdev->dev.of_node,
+					   &sda_pin, &scl_pin);
+		if (ret)
+			return ret;
+	} else {
+		if (!dev_get_platdata(&pdev->dev))
+			return -ENXIO;
+		pdata = dev_get_platdata(&pdev->dev);
+		sda_pin = pdata->sda_pin;
+		scl_pin = pdata->scl_pin;
+	}
+
+	ret = devm_gpio_request(&pdev->dev, sda_pin, "sda");
+	if (ret) {
+		if (ret == -EINVAL)
+			ret = -EPROBE_DEFER;	/* Try again later */
+		return ret;
+	}
+	ret = devm_gpio_request(&pdev->dev, scl_pin, "scl");
+	if (ret) {
+		if (ret == -EINVAL)
+			ret = -EPROBE_DEFER;	/* Try again later */
+		return ret;
+	}
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+	adap = &priv->adap;
+	bit_data = &priv->bit_data;
+	pdata = &priv->pdata;
+
+	if (pdev->dev.of_node) {
+		pdata->sda_pin = sda_pin;
+		pdata->scl_pin = scl_pin;
+		of_i2c_gpio_get_props(pdev->dev.of_node, pdata);
+	} else {
+		memcpy(pdata, dev_get_platdata(&pdev->dev), sizeof(*pdata));
+	}
+
+	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;
+	if (pdev->dev.of_node)
+		strlcpy(adap->name, dev_name(&pdev->dev), sizeof(adap->name));
+	else
+		snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);
+
+	adap->algo_data = bit_data;
+	adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
+	adap->dev.parent = &pdev->dev;
+	adap->dev.of_node = pdev->dev.of_node;
+
+	adap->nr = pdev->id;
+	ret = i2c_bit_add_numbered_bus(adap);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, priv);
+
+	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;
+}
+
+static int i2c_gpio_remove(struct platform_device *pdev)
+{
+	struct i2c_gpio_private_data *priv;
+	struct i2c_adapter *adap;
+
+	priv = platform_get_drvdata(pdev);
+	adap = &priv->adap;
+
+	i2c_del_adapter(adap);
+
+	return 0;
+}
+
+#if defined(CONFIG_OF)
+static const struct of_device_id i2c_gpio_dt_ids[] = {
+	{ .compatible = "i2c-gpio", },
+	{ /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, i2c_gpio_dt_ids);
+#endif
+
+static struct platform_driver i2c_gpio_driver = {
+	.driver		= {
+		.name	= "i2c-gpio",
+		.of_match_table	= of_match_ptr(i2c_gpio_dt_ids),
+	},
+	.probe		= i2c_gpio_probe,
+	.remove		= i2c_gpio_remove,
+};
+
+static int __init i2c_gpio_init(void)
+{
+	int ret;
+
+	ret = platform_driver_register(&i2c_gpio_driver);
+	if (ret)
+		printk(KERN_ERR "i2c-gpio: probe failed: %d\n", ret);
+
+	return ret;
+}
+subsys_initcall(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 (Atmel)");
+MODULE_DESCRIPTION("Platform-independent bitbanging I2C driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:i2c-gpio");