arch/nios2nommu/drivers/i2c-gpio.c

   1 /*
   2  * drivers/i2c/busses/i2c-gpio.c for Nios2
   3  *
   4  * drivers/i2c/busses/i2c-ixp2000.c
   5  *
   6  * I2C adapter for IXP2000 systems using GPIOs for I2C bus
   7  *
   8  * Author: Deepak Saxena <dsaxena@plexity.net>
   9  * Based on IXDP2400 code by: Naeem M. Afzal <naeem.m.afzal@intel.com>
  10  * Made generic by: Jeff Daly <jeffrey.daly@intel.com>
  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  * From Jeff Daly:
  19  *
  20  * I2C adapter driver for Intel IXDP2xxx platforms. This should work for any
  21  * IXP2000 platform if it uses the HW GPIO in the same manner.  Basically,
  22  * SDA and SCL GPIOs have external pullups.  Setting the respective GPIO to
  23  * an input will make the signal a '1' via the pullup.  Setting them to
  24  * outputs will pull them down.
  25  *
  26  * The GPIOs are open drain signals and are used as configuration strap inputs
  27  * during power-up so there's generally a buffer on the board that needs to be
  28  * 'enabled' to drive the GPIOs.
  29  */
  30
  31 #include <linux/kernel.h>
  32 #include <linux/init.h>
  33 #include <linux/platform_device.h>
  34 #include <linux/module.h>
  35 #include <linux/i2c.h>
  36 #include <linux/i2c-algo-bit.h>
  37 #include <linux/i2c-id.h>
  38
  39 #include <asm/io.h>
  40 #include <asm/gpio.h>
  41
  42 static inline int gpio_scl_pin(void *data)
  43 {
  44         return ((struct gpio_i2c_pins*)data)->scl_pin;
  45 }
  46
  47 static inline int gpio_sda_pin(void *data)
  48 {
  49         return ((struct gpio_i2c_pins*)data)->sda_pin;
  50 }
  51
  52
  53 static void gpio_bit_setscl(void *data, int val)
  54 {
  55         int i = 5000;
  56
  57         if (val) {
  58                 outl(3,gpio_scl_pin(data));
  59                 while(!(inl(gpio_scl_pin(data)) & 1) && i--);
  60         } else {
  61                 outl(2,gpio_scl_pin(data));
  62         }
  63 }
  64
  65 static void gpio_bit_setsda(void *data, int val)
  66 {
  67         if (val) {
  68                 outl(1,gpio_sda_pin(data));
  69         } else {
  70                 outl(0,gpio_sda_pin(data));
  71         }
  72 }
  73
  74 static int gpio_bit_getscl(void *data)
  75 {
  76         return inl(gpio_scl_pin(data)) & 1;
  77 }
  78
  79 static int gpio_bit_getsda(void *data)
  80 {
  81         return inl(gpio_sda_pin(data)) & 1;
  82 }
  83
  84 struct gpio_i2c_data {
  85         struct gpio_i2c_pins *gpio_pins;
  86         struct i2c_adapter adapter;
  87         struct i2c_algo_bit_data algo_data;
  88 };
  89
  90 static int gpio_i2c_remove(struct platform_device *plat_dev)
  91 {
  92         struct gpio_i2c_data *drv_data = platform_get_drvdata(plat_dev);
  93
  94         platform_set_drvdata(plat_dev, NULL);
  95
  96         i2c_bit_del_bus(&drv_data->adapter);
  97
  98         kfree(drv_data);
  99
 100         return 0;
 101 }
 102
 103 static int gpio_i2c_probe(struct platform_device *plat_dev)
 104 {
 105         int err;
 106         struct gpio_i2c_pins *gpio = plat_dev->dev.platform_data;
 107         struct gpio_i2c_data *drv_data =
 108                 kzalloc(sizeof(struct gpio_i2c_data), GFP_KERNEL);
 109
 110         if (!drv_data)
 111                 return -ENOMEM;
 112         drv_data->gpio_pins = gpio;
 113
 114         drv_data->algo_data.data = gpio;
 115         drv_data->algo_data.setsda = gpio_bit_setsda;
 116         drv_data->algo_data.setscl = gpio_bit_setscl;
 117         drv_data->algo_data.getsda = gpio_bit_getsda;
 118         drv_data->algo_data.getscl = gpio_bit_getscl;
 119         drv_data->algo_data.udelay = 6;
 120         drv_data->algo_data.timeout = 100;
 121
 122         drv_data->adapter.id = I2C_HW_B_IXP2000,  // borrowed,
 123         strlcpy(drv_data->adapter.name, plat_dev->dev.driver->name,
 124                 I2C_NAME_SIZE);
 125         drv_data->adapter.algo_data = &drv_data->algo_data,
 126
 127         drv_data->adapter.dev.parent = &plat_dev->dev;
 128         drv_data->adapter.class = I2C_CLASS_ALL;
 129
 130         outl(1,gpio->sda_pin);
 131         outl(1,gpio->scl_pin);
 132
 133         if ((err = i2c_bit_add_bus(&drv_data->adapter)) != 0) {
 134                 dev_err(&plat_dev->dev, "Could not install, error %d\n", err);
 135                 kfree(drv_data);
 136                 return err;
 137         }
 138
 139         platform_set_drvdata(plat_dev, drv_data);
 140         printk("i2c-gpio driver at %08x\n",gpio->sda_pin);
 141
 142         return 0;
 143 }
 144
 145 static struct platform_driver gpio_i2c_driver = {
 146         .probe          = gpio_i2c_probe,
 147         .remove         = gpio_i2c_remove,
 148         .driver         = {
 149                 .name   = "GPIO-I2C",
 150                 .owner  = THIS_MODULE,
 151         },
 152 };
 153
 154 static int __init gpio_i2c_init(void)
 155 {
 156         return platform_driver_register(&gpio_i2c_driver);
 157 }
 158
 159 static void __exit gpio_i2c_exit(void)
 160 {
 161         platform_driver_unregister(&gpio_i2c_driver);
 162 }
 163
 164 module_init(gpio_i2c_init);
 165 module_exit(gpio_i2c_exit);
 166