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/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 IXP42000-specific bits */
  42
  43 static inline int ixp2000_scl_pin(void *data)
  44 {
  45         return ((struct ixp2000_i2c_pins*)data)->scl_pin;
  46 }
  47
  48 static inline int ixp2000_sda_pin(void *data)
  49 {
  50         return ((struct ixp2000_i2c_pins*)data)->sda_pin;
  51 }
  52
  53
  54 static void ixp2000_bit_setscl(void *data, int val)
  55 {
  56         int i = 5000;
  57
  58         if (val) {
  59                 gpio_line_config(ixp2000_scl_pin(data), GPIO_IN);
  60                 while(!gpio_line_get(ixp2000_scl_pin(data)) && i--);
  61         } else {
  62                 gpio_line_config(ixp2000_scl_pin(data), GPIO_OUT);
  63         }
  64 }
  65
  66 static void ixp2000_bit_setsda(void *data, int val)
  67 {
  68         if (val) {
  69                 gpio_line_config(ixp2000_sda_pin(data), GPIO_IN);
  70         } else {
  71                 gpio_line_config(ixp2000_sda_pin(data), GPIO_OUT);
  72         }
  73 }
  74
  75 static int ixp2000_bit_getscl(void *data)
  76 {
  77         return gpio_line_get(ixp2000_scl_pin(data));
  78 }
  79
  80 static int ixp2000_bit_getsda(void *data)
  81 {
  82         return gpio_line_get(ixp2000_sda_pin(data));
  83 }
  84
  85 struct ixp2000_i2c_data {
  86         struct ixp2000_i2c_pins *gpio_pins;
  87         struct i2c_adapter adapter;
  88         struct i2c_algo_bit_data algo_data;
  89 };
  90
  91 static int ixp2000_i2c_remove(struct device *dev)
  92 {
  93         struct platform_device *plat_dev = to_platform_device(dev);
  94         struct ixp2000_i2c_data *drv_data = dev_get_drvdata(&plat_dev->dev);
  95
  96         dev_set_drvdata(&plat_dev->dev, NULL);
  97
  98         i2c_bit_del_bus(&drv_data->adapter);
  99
 100         kfree(drv_data);
 101
 102         return 0;
 103 }
 104
 105 static int ixp2000_i2c_probe(struct device *dev)
 106 {
 107         int err;
 108         struct platform_device *plat_dev = to_platform_device(dev);
 109         struct ixp2000_i2c_pins *gpio = plat_dev->dev.platform_data;
 110         struct ixp2000_i2c_data *drv_data =
 111                 kmalloc(sizeof(struct ixp2000_i2c_data), GFP_KERNEL);
 112
 113         if (!drv_data)
 114                 return -ENOMEM;
 115         memzero(drv_data, sizeof(*drv_data));
 116         drv_data->gpio_pins = gpio;
 117
 118         drv_data->algo_data.data = gpio;
 119         drv_data->algo_data.setsda = ixp2000_bit_setsda;
 120         drv_data->algo_data.setscl = ixp2000_bit_setscl;
 121         drv_data->algo_data.getsda = ixp2000_bit_getsda;
 122         drv_data->algo_data.getscl = ixp2000_bit_getscl;
 123         drv_data->algo_data.udelay = 6;
 124         drv_data->algo_data.mdelay = 6;
 125         drv_data->algo_data.timeout = 100;
 126
 127         drv_data->adapter.id = I2C_HW_B_IXP2000,
 128         drv_data->adapter.algo_data = &drv_data->algo_data,
 129
 130         drv_data->adapter.dev.parent = &plat_dev->dev;
 131
 132         gpio_line_config(gpio->sda_pin, GPIO_IN);
 133         gpio_line_config(gpio->scl_pin, GPIO_IN);
 134         gpio_line_set(gpio->scl_pin, 0);
 135         gpio_line_set(gpio->sda_pin, 0);
 136
 137         if ((err = i2c_bit_add_bus(&drv_data->adapter)) != 0) {
 138                 dev_err(dev, "Could not install, error %d\n", err);
 139                 kfree(drv_data);
 140                 return err;
 141         }
 142
 143         dev_set_drvdata(&plat_dev->dev, drv_data);
 144
 145         return 0;
 146 }
 147
 148 static struct device_driver ixp2000_i2c_driver = {
 149         .name           = "IXP2000-I2C",
 150         .bus            = &platform_bus_type,
 151         .probe          = ixp2000_i2c_probe,
 152         .remove         = ixp2000_i2c_remove,
 153 };
 154
 155 static int __init ixp2000_i2c_init(void)
 156 {
 157         return driver_register(&ixp2000_i2c_driver);
 158 }
 159
 160 static void __exit ixp2000_i2c_exit(void)
 161 {
 162         driver_unregister(&ixp2000_i2c_driver);
 163 }
 164
 165 module_init(ixp2000_i2c_init);
 166 module_exit(ixp2000_i2c_exit);
 167
 168 MODULE_AUTHOR ("Deepak Saxena <dsaxena@plexity.net>");
 169 MODULE_DESCRIPTION("IXP2000 GPIO-based I2C bus driver");
 170 MODULE_LICENSE("GPL");
 171