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 <asm/hardware.h>       /* Pick up IXP2000-specific bits */
  37 #include <asm/arch/gpio.h>
  38
  39 static inline int ixp2000_scl_pin(void *data)
  40 {
  41         return ((struct ixp2000_i2c_pins*)data)->scl_pin;
  42 }
  43
  44 static inline int ixp2000_sda_pin(void *data)
  45 {
  46         return ((struct ixp2000_i2c_pins*)data)->sda_pin;
  47 }
  48
  49
  50 static 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
  62 static 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
  71 static int ixp2000_bit_getscl(void *data)
  72 {
  73         return gpio_line_get(ixp2000_scl_pin(data));
  74 }
  75
  76 static int ixp2000_bit_getsda(void *data)
  77 {
  78         return gpio_line_get(ixp2000_sda_pin(data));
  79 }
  80
  81 struct 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
  87 static 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
 100 static 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 = 100;
 118
 119         drv_data->adapter.id = I2C_HW_B_IXP2000,
 120         strlcpy(drv_data->adapter.name, plat_dev->dev.driver->name,
 121                 sizeof(drv_data->adapter.name));
 122         drv_data->adapter.algo_data = &drv_data->algo_data,
 123
 124         drv_data->adapter.dev.parent = &plat_dev->dev;
 125
 126         gpio_line_config(gpio->sda_pin, GPIO_IN);
 127         gpio_line_config(gpio->scl_pin, GPIO_IN);
 128         gpio_line_set(gpio->scl_pin, 0);
 129         gpio_line_set(gpio->sda_pin, 0);
 130
 131         if ((err = i2c_bit_add_bus(&drv_data->adapter)) != 0) {
 132                 dev_err(&plat_dev->dev, "Could not install, error %d\n", err);
 133                 kfree(drv_data);
 134                 return err;
 135         }
 136
 137         platform_set_drvdata(plat_dev, drv_data);
 138
 139         return 0;
 140 }
 141
 142 static struct platform_driver ixp2000_i2c_driver = {
 143         .probe          = ixp2000_i2c_probe,
 144         .remove         = ixp2000_i2c_remove,
 145         .driver         = {
 146                 .name   = "IXP2000-I2C",
 147                 .owner  = THIS_MODULE,
 148         },
 149 };
 150
 151 static int __init ixp2000_i2c_init(void)
 152 {
 153         return platform_driver_register(&ixp2000_i2c_driver);
 154 }
 155
 156 static void __exit ixp2000_i2c_exit(void)
 157 {
 158         platform_driver_unregister(&ixp2000_i2c_driver);
 159 }
 160
 161 module_init(ixp2000_i2c_init);
 162 module_exit(ixp2000_i2c_exit);
 163
 164 MODULE_AUTHOR ("Deepak Saxena <dsaxena@plexity.net>");
 165 MODULE_DESCRIPTION("IXP2000 GPIO-based I2C bus driver");
 166 MODULE_LICENSE("GPL");
 167