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/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 device *dev)
  88 {
  89         struct platform_device *plat_dev = to_platform_device(dev);
  90         struct ixp2000_i2c_data *drv_data = dev_get_drvdata(&plat_dev->dev);
  91
  92         dev_set_drvdata(&plat_dev->dev, NULL);
  93
  94         i2c_bit_del_bus(&drv_data->adapter);
  95
  96         kfree(drv_data);
  97
  98         return 0;
  99 }
 100
 101 static int ixp2000_i2c_probe(struct device *dev)
 102 {
 103         int err;
 104         struct platform_device *plat_dev = to_platform_device(dev);
 105         struct ixp2000_i2c_pins *gpio = plat_dev->dev.platform_data;
 106         struct ixp2000_i2c_data *drv_data =
 107                 kmalloc(sizeof(struct ixp2000_i2c_data), GFP_KERNEL);
 108
 109         if (!drv_data)
 110                 return -ENOMEM;
 111         memzero(drv_data, sizeof(*drv_data));
 112         drv_data->gpio_pins = gpio;
 113
 114         drv_data->algo_data.data = gpio;
 115         drv_data->algo_data.setsda = ixp2000_bit_setsda;
 116         drv_data->algo_data.setscl = ixp2000_bit_setscl;
 117         drv_data->algo_data.getsda = ixp2000_bit_getsda;
 118         drv_data->algo_data.getscl = ixp2000_bit_getscl;
 119         drv_data->algo_data.udelay = 6;
 120         drv_data->algo_data.mdelay = 6;
 121         drv_data->algo_data.timeout = 100;
 122
 123         drv_data->adapter.id = I2C_HW_B_IXP2000,
 124         drv_data->adapter.algo_data = &drv_data->algo_data,
 125
 126         drv_data->adapter.dev.parent = &plat_dev->dev;
 127
 128         gpio_line_config(gpio->sda_pin, GPIO_IN);
 129         gpio_line_config(gpio->scl_pin, GPIO_IN);
 130         gpio_line_set(gpio->scl_pin, 0);
 131         gpio_line_set(gpio->sda_pin, 0);
 132
 133         if ((err = i2c_bit_add_bus(&drv_data->adapter)) != 0) {
 134                 dev_err(dev, "Could not install, error %d\n", err);
 135                 kfree(drv_data);
 136                 return err;
 137         }
 138
 139         dev_set_drvdata(&plat_dev->dev, drv_data);
 140
 141         return 0;
 142 }
 143
 144 static struct device_driver ixp2000_i2c_driver = {
 145         .name           = "IXP2000-I2C",
 146         .bus            = &platform_bus_type,
 147         .probe          = ixp2000_i2c_probe,
 148         .remove         = ixp2000_i2c_remove,
 149 };
 150
 151 static int __init ixp2000_i2c_init(void)
 152 {
 153         return driver_register(&ixp2000_i2c_driver);
 154 }
 155
 156 static void __exit ixp2000_i2c_exit(void)
 157 {
 158         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