drivers/i2c/busses/i2c-ixp4xx.c

   1 /*
   2  * drivers/i2c/i2c-adap-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
  38 static struct device_driver ixp4xx_i2c_driver;
  39
  40 static inline int ixp4xx_scl_pin(void *data)
  41 {
  42         return ((struct ixp4xx_i2c_pins*)data)->scl_pin;
  43 }
  44
  45 static inline int ixp4xx_sda_pin(void *data)
  46 {
  47         return ((struct ixp4xx_i2c_pins*)data)->sda_pin;
  48 }
  49
  50 static void ixp4xx_bit_setscl(void *data, int val)
  51 {
  52         gpio_line_set(ixp4xx_scl_pin(data), 0);
  53         gpio_line_config(ixp4xx_scl_pin(data),
  54                 val ? IXP4XX_GPIO_IN : IXP4XX_GPIO_OUT );
  55 }
  56
  57 static void ixp4xx_bit_setsda(void *data, int val)
  58 {
  59         gpio_line_set(ixp4xx_sda_pin(data), 0);
  60         gpio_line_config(ixp4xx_sda_pin(data),
  61                 val ? IXP4XX_GPIO_IN : IXP4XX_GPIO_OUT );
  62 }
  63
  64 static int ixp4xx_bit_getscl(void *data)
  65 {
  66         int scl;
  67
  68         gpio_line_config(ixp4xx_scl_pin(data), IXP4XX_GPIO_IN );
  69         gpio_line_get(ixp4xx_scl_pin(data), &scl);
  70
  71         return scl;
  72 }
  73
  74 static int ixp4xx_bit_getsda(void *data)
  75 {
  76         int sda;
  77
  78         gpio_line_config(ixp4xx_sda_pin(data), IXP4XX_GPIO_IN );
  79         gpio_line_get(ixp4xx_sda_pin(data), &sda);
  80
  81         return sda;
  82 }
  83
  84 struct ixp4xx_i2c_data {
  85         struct ixp4xx_i2c_pins *gpio_pins;
  86         struct i2c_adapter adapter;
  87         struct i2c_algo_bit_data algo_data;
  88 };
  89
  90 static int ixp4xx_i2c_remove(struct device *dev)
  91 {
  92         struct platform_device *plat_dev = to_platform_device(dev);
  93         struct ixp4xx_i2c_data *drv_data = dev_get_drvdata(&plat_dev->dev);
  94
  95         dev_set_drvdata(&plat_dev->dev, NULL);
  96
  97         i2c_bit_del_bus(&drv_data->adapter);
  98
  99         kfree(drv_data);
 100
 101         return 0;
 102 }
 103
 104 static int ixp4xx_i2c_probe(struct device *dev)
 105 {
 106         int err;
 107         struct platform_device *plat_dev = to_platform_device(dev);
 108         struct ixp4xx_i2c_pins *gpio = plat_dev->dev.platform_data;
 109         struct ixp4xx_i2c_data *drv_data =
 110                 kzalloc(sizeof(struct ixp4xx_i2c_data), GFP_KERNEL);
 111
 112         if(!drv_data)
 113                 return -ENOMEM;
 114
 115         drv_data->gpio_pins = gpio;
 116
 117         /*
 118          * We could make a lot of these structures static, but
 119          * certain platforms may have multiple GPIO-based I2C
 120          * buses for various device domains, so we need per-device
 121          * algo_data->data.
 122          */
 123         drv_data->algo_data.data = gpio;
 124         drv_data->algo_data.setsda = ixp4xx_bit_setsda;
 125         drv_data->algo_data.setscl = ixp4xx_bit_setscl;
 126         drv_data->algo_data.getsda = ixp4xx_bit_getsda;
 127         drv_data->algo_data.getscl = ixp4xx_bit_getscl;
 128         drv_data->algo_data.udelay = 10;
 129         drv_data->algo_data.mdelay = 10;
 130         drv_data->algo_data.timeout = 100;
 131
 132         drv_data->adapter.id = I2C_HW_B_IXP4XX;
 133         strlcpy(drv_data->adapter.name, ixp4xx_i2c_driver.name,
 134                 I2C_NAME_SIZE);
 135         drv_data->adapter.algo_data = &drv_data->algo_data;
 136
 137         drv_data->adapter.dev.parent = &plat_dev->dev;
 138
 139         gpio_line_config(gpio->scl_pin, IXP4XX_GPIO_IN);
 140         gpio_line_config(gpio->sda_pin, IXP4XX_GPIO_IN);
 141         gpio_line_set(gpio->scl_pin, 0);
 142         gpio_line_set(gpio->sda_pin, 0);
 143
 144         if ((err = i2c_bit_add_bus(&drv_data->adapter) != 0)) {
 145                 printk(KERN_ERR "ERROR: Could not install %s\n", dev->bus_id);
 146
 147                 kfree(drv_data);
 148                 return err;
 149         }
 150
 151         dev_set_drvdata(&plat_dev->dev, drv_data);
 152
 153         return 0;
 154 }
 155
 156 static struct device_driver ixp4xx_i2c_driver = {
 157         .owner          = THIS_MODULE,
 158         .name           = "IXP4XX-I2C",
 159         .bus            = &platform_bus_type,
 160         .probe          = ixp4xx_i2c_probe,
 161         .remove         = ixp4xx_i2c_remove,
 162 };
 163
 164 static int __init ixp4xx_i2c_init(void)
 165 {
 166         return driver_register(&ixp4xx_i2c_driver);
 167 }
 168
 169 static void __exit ixp4xx_i2c_exit(void)
 170 {
 171         driver_unregister(&ixp4xx_i2c_driver);
 172 }
 173
 174 module_init(ixp4xx_i2c_init);
 175 module_exit(ixp4xx_i2c_exit);
 176
 177 MODULE_DESCRIPTION("GPIO-based I2C adapter for IXP4xx systems");
 178 MODULE_LICENSE("GPL");
 179 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
 180