diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-ixp4xx.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-ixp4xx.c | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-ixp4xx.c b/drivers/i2c/busses/i2c-ixp4xx.c new file mode 100644 index 000000000000..8c55eafc3a09 --- /dev/null +++ b/drivers/i2c/busses/i2c-ixp4xx.c @@ -0,0 +1,181 @@ +/* + * drivers/i2c/i2c-adap-ixp4xx.c + * + * Intel's IXP4xx XScale NPU chipsets (IXP420, 421, 422, 425) do not have + * an on board I2C controller but provide 16 GPIO pins that are often + * used to create an I2C bus. This driver provides an i2c_adapter + * interface that plugs in under algo_bit and drives the GPIO pins + * as instructed by the alogorithm driver. + * + * Author: Deepak Saxena <dsaxena@plexity.net> + * + * Copyright (c) 2003-2004 MontaVista Software Inc. + * + * This file is licensed under the terms of the GNU General Public + * License version 2. This program is licensed "as is" without any + * warranty of any kind, whether express or implied. + * + * NOTE: Since different platforms will use different GPIO pins for + * I2C, this driver uses an IXP4xx-specific platform_data + * pointer to pass the GPIO numbers to the driver. This + * allows us to support all the different IXP4xx platforms + * w/o having to put #ifdefs in this driver. + * + * See arch/arm/mach-ixp4xx/ixdp425.c for an example of building a + * device list and filling in the ixp4xx_i2c_pins data structure + * that is passed as the platform_data to this driver. + */ + +#include <linux/config.h> +#ifdef CONFIG_I2C_DEBUG_BUS +#define DEBUG 1 +#endif + +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/device.h> +#include <linux/module.h> +#include <linux/i2c.h> +#include <linux/i2c-algo-bit.h> + +#include <asm/hardware.h> /* Pick up IXP4xx-specific bits */ + +static inline int ixp4xx_scl_pin(void *data) +{ + return ((struct ixp4xx_i2c_pins*)data)->scl_pin; +} + +static inline int ixp4xx_sda_pin(void *data) +{ + return ((struct ixp4xx_i2c_pins*)data)->sda_pin; +} + +static void ixp4xx_bit_setscl(void *data, int val) +{ + gpio_line_set(ixp4xx_scl_pin(data), 0); + gpio_line_config(ixp4xx_scl_pin(data), + val ? IXP4XX_GPIO_IN : IXP4XX_GPIO_OUT ); +} + +static void ixp4xx_bit_setsda(void *data, int val) +{ + gpio_line_set(ixp4xx_sda_pin(data), 0); + gpio_line_config(ixp4xx_sda_pin(data), + val ? IXP4XX_GPIO_IN : IXP4XX_GPIO_OUT ); +} + +static int ixp4xx_bit_getscl(void *data) +{ + int scl; + + gpio_line_config(ixp4xx_scl_pin(data), IXP4XX_GPIO_IN ); + gpio_line_get(ixp4xx_scl_pin(data), &scl); + + return scl; +} + +static int ixp4xx_bit_getsda(void *data) +{ + int sda; + + gpio_line_config(ixp4xx_sda_pin(data), IXP4XX_GPIO_IN ); + gpio_line_get(ixp4xx_sda_pin(data), &sda); + + return sda; +} + +struct ixp4xx_i2c_data { + struct ixp4xx_i2c_pins *gpio_pins; + struct i2c_adapter adapter; + struct i2c_algo_bit_data algo_data; +}; + +static int ixp4xx_i2c_remove(struct device *dev) +{ + struct platform_device *plat_dev = to_platform_device(dev); + struct ixp4xx_i2c_data *drv_data = dev_get_drvdata(&plat_dev->dev); + + dev_set_drvdata(&plat_dev->dev, NULL); + + i2c_bit_del_bus(&drv_data->adapter); + + kfree(drv_data); + + return 0; +} + +static int ixp4xx_i2c_probe(struct device *dev) +{ + int err; + struct platform_device *plat_dev = to_platform_device(dev); + struct ixp4xx_i2c_pins *gpio = plat_dev->dev.platform_data; + struct ixp4xx_i2c_data *drv_data = + kmalloc(sizeof(struct ixp4xx_i2c_data), GFP_KERNEL); + + if(!drv_data) + return -ENOMEM; + + memzero(drv_data, sizeof(struct ixp4xx_i2c_data)); + drv_data->gpio_pins = gpio; + + /* + * We could make a lot of these structures static, but + * certain platforms may have multiple GPIO-based I2C + * buses for various device domains, so we need per-device + * algo_data->data. + */ + drv_data->algo_data.data = gpio; + drv_data->algo_data.setsda = ixp4xx_bit_setsda; + drv_data->algo_data.setscl = ixp4xx_bit_setscl; + drv_data->algo_data.getsda = ixp4xx_bit_getsda; + drv_data->algo_data.getscl = ixp4xx_bit_getscl; + drv_data->algo_data.udelay = 10; + drv_data->algo_data.mdelay = 10; + drv_data->algo_data.timeout = 100; + + drv_data->adapter.id = I2C_HW_B_IXP4XX; + drv_data->adapter.algo_data = &drv_data->algo_data; + + drv_data->adapter.dev.parent = &plat_dev->dev; + + gpio_line_config(gpio->scl_pin, IXP4XX_GPIO_IN); + gpio_line_config(gpio->sda_pin, IXP4XX_GPIO_IN); + gpio_line_set(gpio->scl_pin, 0); + gpio_line_set(gpio->sda_pin, 0); + + if ((err = i2c_bit_add_bus(&drv_data->adapter) != 0)) { + printk(KERN_ERR "ERROR: Could not install %s\n", dev->bus_id); + + kfree(drv_data); + return err; + } + + dev_set_drvdata(&plat_dev->dev, drv_data); + + return 0; +} + +static struct device_driver ixp4xx_i2c_driver = { + .name = "IXP4XX-I2C", + .bus = &platform_bus_type, + .probe = ixp4xx_i2c_probe, + .remove = ixp4xx_i2c_remove, +}; + +static int __init ixp4xx_i2c_init(void) +{ + return driver_register(&ixp4xx_i2c_driver); +} + +static void __exit ixp4xx_i2c_exit(void) +{ + driver_unregister(&ixp4xx_i2c_driver); +} + +module_init(ixp4xx_i2c_init); +module_exit(ixp4xx_i2c_exit); + +MODULE_DESCRIPTION("GPIO-based I2C adapter for IXP4xx systems"); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>"); + |