/* * 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, }; device_platform_driver(i2c_gpio_driver);