drivers/i2c/busses/scx200_i2c.c

   1 /* linux/drivers/i2c/busses/scx200_i2c.c
   2
   3    Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
   4
   5    National Semiconductor SCx200 I2C bus on GPIO pins
   6
   7    Based on i2c-velleman.c Copyright (C) 1995-96, 2000 Simon G. Vogl
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 2 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  22 */
  23
  24 #include <linux/module.h>
  25 #include <linux/errno.h>
  26 #include <linux/kernel.h>
  27 #include <linux/init.h>
  28 #include <linux/i2c.h>
  29 #include <linux/i2c-algo-bit.h>
  30 #include <asm/io.h>
  31
  32 #include <linux/scx200_gpio.h>
  33
  34 #define NAME "scx200_i2c"
  35
  36 MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
  37 MODULE_DESCRIPTION("NatSemi SCx200 I2C Driver");
  38 MODULE_LICENSE("GPL");
  39
  40 static int scl = CONFIG_SCx200_I2C_SCL;
  41 static int sda = CONFIG_SCx200_I2C_SDA;
  42
  43 module_param(scl, int, 0);
  44 MODULE_PARM_DESC(scl, "GPIO line for SCL");
  45 module_param(sda, int, 0);
  46 MODULE_PARM_DESC(sda, "GPIO line for SDA");
  47
  48 static void scx200_i2c_setscl(void *data, int state)
  49 {
  50         scx200_gpio_set(scl, state);
  51 }
  52
  53 static void scx200_i2c_setsda(void *data, int state)
  54 {
  55         scx200_gpio_set(sda, state);
  56 }
  57
  58 static int scx200_i2c_getscl(void *data)
  59 {
  60         return scx200_gpio_get(scl);
  61 }
  62
  63 static int scx200_i2c_getsda(void *data)
  64 {
  65         return scx200_gpio_get(sda);
  66 }
  67
  68 /* ------------------------------------------------------------------------
  69  * Encapsulate the above functions in the correct operations structure.
  70  * This is only done when more than one hardware adapter is supported.
  71  */
  72
  73 static struct i2c_algo_bit_data scx200_i2c_data = {
  74         .setsda         = scx200_i2c_setsda,
  75         .setscl         = scx200_i2c_setscl,
  76         .getsda         = scx200_i2c_getsda,
  77         .getscl         = scx200_i2c_getscl,
  78         .udelay         = 10,
  79         .timeout        = 100,
  80 };
  81
  82 static struct i2c_adapter scx200_i2c_ops = {
  83         .owner             = THIS_MODULE,
  84         .algo_data         = &scx200_i2c_data,
  85         .name   = "NatSemi SCx200 I2C",
  86 };
  87
  88 static int scx200_i2c_init(void)
  89 {
  90         pr_debug(NAME ": NatSemi SCx200 I2C Driver\n");
  91
  92         if (!scx200_gpio_present()) {
  93                 printk(KERN_ERR NAME ": no SCx200 gpio pins available\n");
  94                 return -ENODEV;
  95         }
  96
  97         pr_debug(NAME ": SCL=GPIO%02u, SDA=GPIO%02u\n", scl, sda);
  98
  99         if (scl == -1 || sda == -1 || scl == sda) {
 100                 printk(KERN_ERR NAME ": scl and sda must be specified\n");
 101                 return -EINVAL;
 102         }
 103
 104         /* Configure GPIOs as open collector outputs */
 105         scx200_gpio_configure(scl, ~2, 5);
 106         scx200_gpio_configure(sda, ~2, 5);
 107
 108         if (i2c_bit_add_bus(&scx200_i2c_ops) < 0) {
 109                 printk(KERN_ERR NAME ": adapter %s registration failed\n",
 110                        scx200_i2c_ops.name);
 111                 return -ENODEV;
 112         }
 113
 114         return 0;
 115 }
 116
 117 static void scx200_i2c_cleanup(void)
 118 {
 119         i2c_del_adapter(&scx200_i2c_ops);
 120 }
 121
 122 module_init(scx200_i2c_init);
 123 module_exit(scx200_i2c_cleanup);
 124
 125 /*
 126     Local variables:
 127         compile-command: "make -k -C ../.. SUBDIRS=drivers/i2c modules"
 128         c-basic-offset: 8
 129     End:
 130 */