1/* 2 * drivers/i2c/busses/i2c-ixp4xx.c 3 * 4 * Intel's IXP4xx XScale NPU chipsets (IXP420, 421, 422, 425) do not have 5 * an on board I2C controller but provide 16 GPIO pins that are often 6 * used to create an I2C bus. This driver provides an i2c_adapter 7 * interface that plugs in under algo_bit and drives the GPIO pins 8 * as instructed by the alogorithm driver. 9 * 10 * Author: Deepak Saxena <dsaxena@plexity.net> 11 * 12 * Copyright (c) 2003-2004 MontaVista Software Inc. 13 * 14 * This file is licensed under the terms of the GNU General Public 15 * License version 2. This program is licensed "as is" without any 16 * warranty of any kind, whether express or implied. 17 * 18 * NOTE: Since different platforms will use different GPIO pins for 19 * I2C, this driver uses an IXP4xx-specific platform_data 20 * pointer to pass the GPIO numbers to the driver. This 21 * allows us to support all the different IXP4xx platforms 22 * w/o having to put #ifdefs in this driver. 23 * 24 * See arch/arm/mach-ixp4xx/ixdp425.c for an example of building a 25 * device list and filling in the ixp4xx_i2c_pins data structure 26 * that is passed as the platform_data to this driver. 27 */ 28 29#include <linux/kernel.h> 30#include <linux/init.h> 31#include <linux/platform_device.h> 32#include <linux/module.h> 33#include <linux/i2c.h> 34#include <linux/i2c-algo-bit.h> 35 36#include <asm/hardware.h> /* Pick up IXP4xx-specific bits */ 37 38static inline int ixp4xx_scl_pin(void *data) 39{ 40 return ((struct ixp4xx_i2c_pins*)data)->scl_pin; 41} 42 43static inline int ixp4xx_sda_pin(void *data) 44{ 45 return ((struct ixp4xx_i2c_pins*)data)->sda_pin; 46} 47 48static void ixp4xx_bit_setscl(void *data, int val) 49{ 50 gpio_line_set(ixp4xx_scl_pin(data), 0); 51 gpio_line_config(ixp4xx_scl_pin(data), 52 val ? IXP4XX_GPIO_IN : IXP4XX_GPIO_OUT ); 53} 54 55static void ixp4xx_bit_setsda(void *data, int val) 56{ 57 gpio_line_set(ixp4xx_sda_pin(data), 0); 58 gpio_line_config(ixp4xx_sda_pin(data), 59 val ? IXP4XX_GPIO_IN : IXP4XX_GPIO_OUT ); 60} 61 62static int ixp4xx_bit_getscl(void *data) 63{ 64 int scl; 65 66 gpio_line_config(ixp4xx_scl_pin(data), IXP4XX_GPIO_IN ); 67 gpio_line_get(ixp4xx_scl_pin(data), &scl); 68 69 return scl; 70} 71 72static int ixp4xx_bit_getsda(void *data) 73{ 74 int sda; 75 76 gpio_line_config(ixp4xx_sda_pin(data), IXP4XX_GPIO_IN ); 77 gpio_line_get(ixp4xx_sda_pin(data), &sda); 78 79 return sda; 80} 81 82struct ixp4xx_i2c_data { 83 struct ixp4xx_i2c_pins *gpio_pins; 84 struct i2c_adapter adapter; 85 struct i2c_algo_bit_data algo_data; 86}; 87 88static int ixp4xx_i2c_remove(struct platform_device *plat_dev) 89{ 90 struct ixp4xx_i2c_data *drv_data = platform_get_drvdata(plat_dev); 91 92 platform_set_drvdata(plat_dev, NULL); 93 94 i2c_del_adapter(&drv_data->adapter); 95 96 kfree(drv_data); 97 98 return 0; 99} 100 101static int ixp4xx_i2c_probe(struct platform_device *plat_dev) 102{ 103 int err; 104 struct ixp4xx_i2c_pins *gpio = plat_dev->dev.platform_data; 105 struct ixp4xx_i2c_data *drv_data = 106 kzalloc(sizeof(struct ixp4xx_i2c_data), GFP_KERNEL); 107 108 if(!drv_data) 109 return -ENOMEM; 110 111 drv_data->gpio_pins = gpio; 112 113 /* 114 * We could make a lot of these structures static, but 115 * certain platforms may have multiple GPIO-based I2C 116 * buses for various device domains, so we need per-device 117 * algo_data->data. 118 */ 119 drv_data->algo_data.data = gpio; 120 drv_data->algo_data.setsda = ixp4xx_bit_setsda; 121 drv_data->algo_data.setscl = ixp4xx_bit_setscl; 122 drv_data->algo_data.getsda = ixp4xx_bit_getsda; 123 drv_data->algo_data.getscl = ixp4xx_bit_getscl; 124 drv_data->algo_data.udelay = 10; 125 drv_data->algo_data.timeout = 100; 126 127 drv_data->adapter.id = I2C_HW_B_IXP4XX; 128 drv_data->adapter.class = I2C_CLASS_HWMON; 129 strlcpy(drv_data->adapter.name, plat_dev->dev.driver->name, 130 sizeof(drv_data->adapter.name)); 131 drv_data->adapter.algo_data = &drv_data->algo_data; 132 133 drv_data->adapter.dev.parent = &plat_dev->dev; 134 135 gpio_line_config(gpio->scl_pin, IXP4XX_GPIO_IN); 136 gpio_line_config(gpio->sda_pin, IXP4XX_GPIO_IN); 137 gpio_line_set(gpio->scl_pin, 0); 138 gpio_line_set(gpio->sda_pin, 0); 139 140 err = i2c_bit_add_bus(&drv_data->adapter); 141 if (err) { 142 printk(KERN_ERR "ERROR: Could not install %s\n", plat_dev->dev.bus_id); 143 144 kfree(drv_data); 145 return err; 146 } 147 148 platform_set_drvdata(plat_dev, drv_data); 149 150 return 0; 151} 152 153static struct platform_driver ixp4xx_i2c_driver = { 154 .probe = ixp4xx_i2c_probe, 155 .remove = ixp4xx_i2c_remove, 156 .driver = { 157 .name = "IXP4XX-I2C", 158 .owner = THIS_MODULE, 159 }, 160}; 161 162static int __init ixp4xx_i2c_init(void) 163{ 164 return platform_driver_register(&ixp4xx_i2c_driver); 165} 166 167static void __exit ixp4xx_i2c_exit(void) 168{ 169 platform_driver_unregister(&ixp4xx_i2c_driver); 170} 171 172module_init(ixp4xx_i2c_init); 173module_exit(ixp4xx_i2c_exit); 174 175MODULE_DESCRIPTION("GPIO-based I2C adapter for IXP4xx systems"); 176MODULE_LICENSE("GPL"); 177MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>"); 178