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/config.h>
  30 #ifdef CONFIG_I2C_DEBUG_BUS
  31 #define DEBUG   1
  32 #endif
  33
  34 #include <linux/kernel.h>
  35 #include <linux/init.h>
  36 #include <linux/device.h>
  37 #include <linux/module.h>
  38 #include <linux/i2c.h>
  39 #include <linux/i2c-algo-bit.h>
  40
  41 #include <asm/hardware.h>       /* Pick up IXP4xx-specific bits */
  42
  43 static inline int ixp4xx_scl_pin(void *data)
  44 {
  45         return ((struct ixp4xx_i2c_pins*)data)->scl_pin;
  46 }
  47
  48 static inline int ixp4xx_sda_pin(void *data)
  49 {
  50         return ((struct ixp4xx_i2c_pins*)data)->sda_pin;
  51 }
  52
  53 static void ixp4xx_bit_setscl(void *data, int val)
  54 {
  55         gpio_line_set(ixp4xx_scl_pin(data), 0);
  56         gpio_line_config(ixp4xx_scl_pin(data),
  57                 val ? IXP4XX_GPIO_IN : IXP4XX_GPIO_OUT );
  58 }
  59
  60 static void ixp4xx_bit_setsda(void *data, int val)
  61 {
  62         gpio_line_set(ixp4xx_sda_pin(data), 0);
  63         gpio_line_config(ixp4xx_sda_pin(data),
  64                 val ? IXP4XX_GPIO_IN : IXP4XX_GPIO_OUT );
  65 }
  66
  67 static int ixp4xx_bit_getscl(void *data)
  68 {
  69         int scl;
  70
  71         gpio_line_config(ixp4xx_scl_pin(data), IXP4XX_GPIO_IN );
  72         gpio_line_get(ixp4xx_scl_pin(data), &scl);
  73
  74         return scl;
  75 }
  76
  77 static int ixp4xx_bit_getsda(void *data)
  78 {
  79         int sda;
  80
  81         gpio_line_config(ixp4xx_sda_pin(data), IXP4XX_GPIO_IN );
  82         gpio_line_get(ixp4xx_sda_pin(data), &sda);
  83
  84         return sda;
  85 }
  86
  87 struct ixp4xx_i2c_data {
  88         struct ixp4xx_i2c_pins *gpio_pins;
  89         struct i2c_adapter adapter;
  90         struct i2c_algo_bit_data algo_data;
  91 };
  92
  93 static int ixp4xx_i2c_remove(struct device *dev)
  94 {
  95         struct platform_device *plat_dev = to_platform_device(dev);
  96         struct ixp4xx_i2c_data *drv_data = dev_get_drvdata(&plat_dev->dev);
  97
  98         dev_set_drvdata(&plat_dev->dev, NULL);
  99
 100         i2c_bit_del_bus(&drv_data->adapter);
 101
 102         kfree(drv_data);
 103
 104         return 0;
 105 }
 106
 107 static int ixp4xx_i2c_probe(struct device *dev)
 108 {
 109         int err;
 110         struct platform_device *plat_dev = to_platform_device(dev);
 111         struct ixp4xx_i2c_pins *gpio = plat_dev->dev.platform_data;
 112         struct ixp4xx_i2c_data *drv_data =
 113                 kmalloc(sizeof(struct ixp4xx_i2c_data), GFP_KERNEL);
 114
 115         if(!drv_data)
 116                 return -ENOMEM;
 117
 118         memzero(drv_data, sizeof(struct ixp4xx_i2c_data));
 119         drv_data->gpio_pins = gpio;
 120
 121         /*
 122          * We could make a lot of these structures static, but
 123          * certain platforms may have multiple GPIO-based I2C
 124          * buses for various device domains, so we need per-device
 125          * algo_data->data.
 126          */
 127         drv_data->algo_data.data = gpio;
 128         drv_data->algo_data.setsda = ixp4xx_bit_setsda;
 129         drv_data->algo_data.setscl = ixp4xx_bit_setscl;
 130         drv_data->algo_data.getsda = ixp4xx_bit_getsda;
 131         drv_data->algo_data.getscl = ixp4xx_bit_getscl;
 132         drv_data->algo_data.udelay = 10;
 133         drv_data->algo_data.mdelay = 10;
 134         drv_data->algo_data.timeout = 100;
 135
 136         drv_data->adapter.id = I2C_HW_B_IXP4XX;
 137         drv_data->adapter.algo_data = &drv_data->algo_data;
 138
 139         drv_data->adapter.dev.parent = &plat_dev->dev;
 140
 141         gpio_line_config(gpio->scl_pin, IXP4XX_GPIO_IN);
 142         gpio_line_config(gpio->sda_pin, IXP4XX_GPIO_IN);
 143         gpio_line_set(gpio->scl_pin, 0);
 144         gpio_line_set(gpio->sda_pin, 0);
 145
 146         if ((err = i2c_bit_add_bus(&drv_data->adapter) != 0)) {
 147                 printk(KERN_ERR "ERROR: Could not install %s\n", dev->bus_id);
 148
 149                 kfree(drv_data);
 150                 return err;
 151         }
 152
 153         dev_set_drvdata(&plat_dev->dev, drv_data);
 154
 155         return 0;
 156 }
 157
 158 static struct device_driver ixp4xx_i2c_driver = {
 159         .name           = "IXP4XX-I2C",
 160         .bus            = &platform_bus_type,
 161         .probe          = ixp4xx_i2c_probe,
 162         .remove         = ixp4xx_i2c_remove,
 163 };
 164
 165 static int __init ixp4xx_i2c_init(void)
 166 {
 167         return driver_register(&ixp4xx_i2c_driver);
 168 }
 169
 170 static void __exit ixp4xx_i2c_exit(void)
 171 {
 172         driver_unregister(&ixp4xx_i2c_driver);
 173 }
 174
 175 module_init(ixp4xx_i2c_init);
 176 module_exit(ixp4xx_i2c_exit);
 177
 178 MODULE_DESCRIPTION("GPIO-based I2C adapter for IXP4xx systems");
 179 MODULE_LICENSE("GPL");
 180 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
 181