drivers/i2c/busses/i2c-ixp4xx.c

   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
  38 static inline int ixp4xx_scl_pin(void *data)
  39 {
  40         return ((struct ixp4xx_i2c_pins*)data)->scl_pin;
  41 }
  42
  43 static inline int ixp4xx_sda_pin(void *data)
  44 {
  45         return ((struct ixp4xx_i2c_pins*)data)->sda_pin;
  46 }
  47
  48 static 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
  55 static 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
  62 static 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
  72 static 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
  82 struct 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
  88 static 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
 101 static 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
 153 static 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
 162 static int __init ixp4xx_i2c_init(void)
 163 {
 164         return platform_driver_register(&ixp4xx_i2c_driver);
 165 }
 166
 167 static void __exit ixp4xx_i2c_exit(void)
 168 {
 169         platform_driver_unregister(&ixp4xx_i2c_driver);
 170 }
 171
 172 module_init(ixp4xx_i2c_init);
 173 module_exit(ixp4xx_i2c_exit);
 174
 175 MODULE_DESCRIPTION("GPIO-based I2C adapter for IXP4xx systems");
 176 MODULE_LICENSE("GPL");
 177 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
 178