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![Marek Szyprowski](/assets/img/avatar_default.png)
GPIO driven I2C bus can be used for controlling the PMIC chip. The example of such configuration is Samsung Aquila board. This patch moves initialization code to subsys_initcall() to ensure that the i2c bus is available early so the regulators can be quickly probed and available for other devices on their probe() call. Such solution has been proposed by Mark Brown to fix the problem of the regulators not beeing available on the peripheral device probe(): http://lists.infradead.org/pipermail/linux-arm-kernel/2010-March/011971.html Cc: Mark Brown <broonie@opensource.wolfsonmicro.com> Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Acked-by: Wolfram Sang <w.sang@pengutronix.de> Signed-off-by: Jean Delvare <khali@linux-fr.org>
225 lines
5.3 KiB
C
225 lines
5.3 KiB
C
/*
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* Bitbanging I2C bus driver using the GPIO API
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*
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* Copyright (C) 2007 Atmel Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/i2c.h>
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#include <linux/i2c-algo-bit.h>
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#include <linux/i2c-gpio.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/platform_device.h>
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#include <asm/gpio.h>
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/* Toggle SDA by changing the direction of the pin */
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static void i2c_gpio_setsda_dir(void *data, int state)
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{
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struct i2c_gpio_platform_data *pdata = data;
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if (state)
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gpio_direction_input(pdata->sda_pin);
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else
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gpio_direction_output(pdata->sda_pin, 0);
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}
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/*
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* Toggle SDA by changing the output value of the pin. This is only
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* valid for pins configured as open drain (i.e. setting the value
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* high effectively turns off the output driver.)
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*/
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static void i2c_gpio_setsda_val(void *data, int state)
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{
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struct i2c_gpio_platform_data *pdata = data;
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gpio_set_value(pdata->sda_pin, state);
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}
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/* Toggle SCL by changing the direction of the pin. */
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static void i2c_gpio_setscl_dir(void *data, int state)
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{
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struct i2c_gpio_platform_data *pdata = data;
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if (state)
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gpio_direction_input(pdata->scl_pin);
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else
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gpio_direction_output(pdata->scl_pin, 0);
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}
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/*
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* Toggle SCL by changing the output value of the pin. This is used
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* for pins that are configured as open drain and for output-only
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* pins. The latter case will break the i2c protocol, but it will
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* often work in practice.
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*/
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static void i2c_gpio_setscl_val(void *data, int state)
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{
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struct i2c_gpio_platform_data *pdata = data;
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gpio_set_value(pdata->scl_pin, state);
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}
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static int i2c_gpio_getsda(void *data)
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{
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struct i2c_gpio_platform_data *pdata = data;
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return gpio_get_value(pdata->sda_pin);
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}
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static int i2c_gpio_getscl(void *data)
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{
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struct i2c_gpio_platform_data *pdata = data;
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return gpio_get_value(pdata->scl_pin);
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}
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static int __devinit i2c_gpio_probe(struct platform_device *pdev)
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{
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struct i2c_gpio_platform_data *pdata;
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struct i2c_algo_bit_data *bit_data;
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struct i2c_adapter *adap;
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int ret;
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pdata = pdev->dev.platform_data;
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if (!pdata)
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return -ENXIO;
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ret = -ENOMEM;
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adap = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL);
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if (!adap)
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goto err_alloc_adap;
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bit_data = kzalloc(sizeof(struct i2c_algo_bit_data), GFP_KERNEL);
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if (!bit_data)
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goto err_alloc_bit_data;
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ret = gpio_request(pdata->sda_pin, "sda");
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if (ret)
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goto err_request_sda;
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ret = gpio_request(pdata->scl_pin, "scl");
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if (ret)
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goto err_request_scl;
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if (pdata->sda_is_open_drain) {
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gpio_direction_output(pdata->sda_pin, 1);
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bit_data->setsda = i2c_gpio_setsda_val;
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} else {
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gpio_direction_input(pdata->sda_pin);
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bit_data->setsda = i2c_gpio_setsda_dir;
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}
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if (pdata->scl_is_open_drain || pdata->scl_is_output_only) {
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gpio_direction_output(pdata->scl_pin, 1);
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bit_data->setscl = i2c_gpio_setscl_val;
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} else {
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gpio_direction_input(pdata->scl_pin);
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bit_data->setscl = i2c_gpio_setscl_dir;
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}
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if (!pdata->scl_is_output_only)
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bit_data->getscl = i2c_gpio_getscl;
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bit_data->getsda = i2c_gpio_getsda;
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if (pdata->udelay)
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bit_data->udelay = pdata->udelay;
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else if (pdata->scl_is_output_only)
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bit_data->udelay = 50; /* 10 kHz */
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else
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bit_data->udelay = 5; /* 100 kHz */
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if (pdata->timeout)
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bit_data->timeout = pdata->timeout;
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else
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bit_data->timeout = HZ / 10; /* 100 ms */
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bit_data->data = pdata;
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adap->owner = THIS_MODULE;
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snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);
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adap->algo_data = bit_data;
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adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
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adap->dev.parent = &pdev->dev;
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/*
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* If "dev->id" is negative we consider it as zero.
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* The reason to do so is to avoid sysfs names that only make
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* sense when there are multiple adapters.
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*/
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adap->nr = (pdev->id != -1) ? pdev->id : 0;
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ret = i2c_bit_add_numbered_bus(adap);
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if (ret)
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goto err_add_bus;
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platform_set_drvdata(pdev, adap);
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dev_info(&pdev->dev, "using pins %u (SDA) and %u (SCL%s)\n",
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pdata->sda_pin, pdata->scl_pin,
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pdata->scl_is_output_only
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? ", no clock stretching" : "");
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return 0;
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err_add_bus:
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gpio_free(pdata->scl_pin);
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err_request_scl:
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gpio_free(pdata->sda_pin);
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err_request_sda:
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kfree(bit_data);
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err_alloc_bit_data:
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kfree(adap);
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err_alloc_adap:
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return ret;
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}
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static int __devexit i2c_gpio_remove(struct platform_device *pdev)
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{
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struct i2c_gpio_platform_data *pdata;
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struct i2c_adapter *adap;
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adap = platform_get_drvdata(pdev);
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pdata = pdev->dev.platform_data;
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i2c_del_adapter(adap);
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gpio_free(pdata->scl_pin);
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gpio_free(pdata->sda_pin);
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kfree(adap->algo_data);
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kfree(adap);
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return 0;
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}
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static struct platform_driver i2c_gpio_driver = {
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.driver = {
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.name = "i2c-gpio",
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.owner = THIS_MODULE,
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},
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.probe = i2c_gpio_probe,
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.remove = __devexit_p(i2c_gpio_remove),
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};
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static int __init i2c_gpio_init(void)
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{
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int ret;
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ret = platform_driver_register(&i2c_gpio_driver);
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if (ret)
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printk(KERN_ERR "i2c-gpio: probe failed: %d\n", ret);
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return ret;
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}
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subsys_initcall(i2c_gpio_init);
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static void __exit i2c_gpio_exit(void)
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{
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platform_driver_unregister(&i2c_gpio_driver);
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}
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module_exit(i2c_gpio_exit);
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MODULE_AUTHOR("Haavard Skinnemoen <hskinnemoen@atmel.com>");
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MODULE_DESCRIPTION("Platform-independent bitbanging I2C driver");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:i2c-gpio");
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