LXR linux/drivers/i2c/busses/i2c-ixp2000.c

   1/*
   2 * drivers/i2c/busses/i2c-ixp2000.c
   3 *
   4 * I2C adapter for IXP2000 systems using GPIOs for I2C bus
   5 *
   6 * Author: Deepak Saxena <dsaxena@plexity.net>
   7 * Based on IXDP2400 code by: Naeem M. Afzal <naeem.m.afzal@intel.com>
   8 * Made generic by: Jeff Daly <jeffrey.daly@intel.com>
   9 *
  10 * Copyright (c) 2003-2004 MontaVista Software Inc.
  11 *
  12 * This file is licensed under  the terms of the GNU General Public 
  13 * License version 2. This program is licensed "as is" without any 
  14 * warranty of any kind, whether express or implied.
  15 *
  16 * From Jeff Daly:
  17 *
  18 * I2C adapter driver for Intel IXDP2xxx platforms. This should work for any
  19 * IXP2000 platform if it uses the HW GPIO in the same manner.  Basically, 
  20 * SDA and SCL GPIOs have external pullups.  Setting the respective GPIO to 
  21 * an input will make the signal a '1' via the pullup.  Setting them to 
  22 * outputs will pull them down. 
  23 *
  24 * The GPIOs are open drain signals and are used as configuration strap inputs
  25 * during power-up so there's generally a buffer on the board that needs to be 
  26 * 'enabled' to drive the GPIOs.
  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 <mach/hardware.h>      /* Pick up IXP2000-specific bits */
  37#include <mach/gpio.h>
  38
  39static inline int ixp2000_scl_pin(void *data)
  40{
  41        return ((struct ixp2000_i2c_pins*)data)->scl_pin;
  42}
  43
  44static inline int ixp2000_sda_pin(void *data)
  45{
  46        return ((struct ixp2000_i2c_pins*)data)->sda_pin;
  47}
  48
  49
  50static void ixp2000_bit_setscl(void *data, int val)
  51{
  52        int i = 5000;
  53
  54        if (val) {
  55                gpio_line_config(ixp2000_scl_pin(data), GPIO_IN);
  56                while(!gpio_line_get(ixp2000_scl_pin(data)) && i--);
  57        } else {
  58                gpio_line_config(ixp2000_scl_pin(data), GPIO_OUT);
  59        }
  60}
  61
  62static void ixp2000_bit_setsda(void *data, int val)
  63{
  64        if (val) {
  65                gpio_line_config(ixp2000_sda_pin(data), GPIO_IN);
  66        } else {
  67                gpio_line_config(ixp2000_sda_pin(data), GPIO_OUT);
  68        }
  69}
  70
  71static int ixp2000_bit_getscl(void *data)
  72{
  73        return gpio_line_get(ixp2000_scl_pin(data));
  74}
  75
  76static int ixp2000_bit_getsda(void *data)
  77{
  78        return gpio_line_get(ixp2000_sda_pin(data));
  79}
  80
  81struct ixp2000_i2c_data {
  82        struct ixp2000_i2c_pins *gpio_pins;
  83        struct i2c_adapter adapter;
  84        struct i2c_algo_bit_data algo_data;
  85};
  86
  87static int ixp2000_i2c_remove(struct platform_device *plat_dev)
  88{
  89        struct ixp2000_i2c_data *drv_data = platform_get_drvdata(plat_dev);
  90
  91        platform_set_drvdata(plat_dev, NULL);
  92
  93        i2c_del_adapter(&drv_data->adapter);
  94
  95        kfree(drv_data);
  96
  97        return 0;
  98}
  99
 100static int ixp2000_i2c_probe(struct platform_device *plat_dev)
 101{
 102        int err;
 103        struct ixp2000_i2c_pins *gpio = plat_dev->dev.platform_data;
 104        struct ixp2000_i2c_data *drv_data = 
 105                kzalloc(sizeof(struct ixp2000_i2c_data), GFP_KERNEL);
 106
 107        if (!drv_data)
 108                return -ENOMEM;
 109        drv_data->gpio_pins = gpio;
 110
 111        drv_data->algo_data.data = gpio;
 112        drv_data->algo_data.setsda = ixp2000_bit_setsda;
 113        drv_data->algo_data.setscl = ixp2000_bit_setscl;
 114        drv_data->algo_data.getsda = ixp2000_bit_getsda;
 115        drv_data->algo_data.getscl = ixp2000_bit_getscl;
 116        drv_data->algo_data.udelay = 6;
 117        drv_data->algo_data.timeout = HZ;
 118
 119        strlcpy(drv_data->adapter.name, plat_dev->dev.driver->name,
 120                sizeof(drv_data->adapter.name));
 121        drv_data->adapter.algo_data = &drv_data->algo_data,
 122
 123        drv_data->adapter.dev.parent = &plat_dev->dev;
 124
 125        gpio_line_config(gpio->sda_pin, GPIO_IN);
 126        gpio_line_config(gpio->scl_pin, GPIO_IN);
 127        gpio_line_set(gpio->scl_pin, 0);
 128        gpio_line_set(gpio->sda_pin, 0);
 129
 130        if ((err = i2c_bit_add_bus(&drv_data->adapter)) != 0) {
 131                dev_err(&plat_dev->dev, "Could not install, error %d\n", err);
 132                kfree(drv_data);
 133                return err;
 134        } 
 135
 136        platform_set_drvdata(plat_dev, drv_data);
 137
 138        return 0;
 139}
 140
 141static struct platform_driver ixp2000_i2c_driver = {
 142        .probe          = ixp2000_i2c_probe,
 143        .remove         = ixp2000_i2c_remove,
 144        .driver         = {
 145                .name   = "IXP2000-I2C",
 146                .owner  = THIS_MODULE,
 147        },
 148};
 149
 150static int __init ixp2000_i2c_init(void)
 151{
 152        return platform_driver_register(&ixp2000_i2c_driver);
 153}
 154
 155static void __exit ixp2000_i2c_exit(void)
 156{
 157        platform_driver_unregister(&ixp2000_i2c_driver);
 158}
 159
 160module_init(ixp2000_i2c_init);
 161module_exit(ixp2000_i2c_exit);
 162
 163MODULE_AUTHOR ("Deepak Saxena <dsaxena@plexity.net>");
 164MODULE_DESCRIPTION("IXP2000 GPIO-based I2C bus driver");
 165MODULE_LICENSE("GPL");
 166MODULE_ALIAS("platform:IXP2000-I2C");
 167
 168