drivers/i2c/busses/scx200_i2c.c

   1 /* linux/drivers/i2c/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/config.h>
  25 #include <linux/module.h>
  26 #include <linux/errno.h>
  27 #include <linux/kernel.h>
  28 #include <linux/init.h>
  29 #include <linux/i2c.h>
  30 #include <linux/i2c-algo-bit.h>
  31 #include <asm/io.h>
  32
  33 #include <linux/scx200_gpio.h>
  34
  35 #define NAME "scx200_i2c"
  36
  37 MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
  38 MODULE_DESCRIPTION("NatSemi SCx200 I2C Driver");
  39 MODULE_LICENSE("GPL");
  40
  41 static int scl = CONFIG_SCx200_I2C_SCL;
  42 static int sda = CONFIG_SCx200_I2C_SDA;
  43
  44 module_param(scl, int, 0);
  45 MODULE_PARM_DESC(scl, "GPIO line for SCL");
  46 module_param(sda, int, 0);
  47 MODULE_PARM_DESC(sda, "GPIO line for SDA");
  48
  49 static void scx200_i2c_setscl(void *data, int state)
  50 {
  51         scx200_gpio_set(scl, state);
  52 }
  53
  54 static void scx200_i2c_setsda(void *data, int state)
  55 {
  56         scx200_gpio_set(sda, state);
  57 }
  58
  59 static int scx200_i2c_getscl(void *data)
  60 {
  61         return scx200_gpio_get(scl);
  62 }
  63
  64 static int scx200_i2c_getsda(void *data)
  65 {
  66         return scx200_gpio_get(sda);
  67 }
  68
  69 /* ------------------------------------------------------------------------
  70  * Encapsulate the above functions in the correct operations structure.
  71  * This is only done when more than one hardware adapter is supported.
  72  */
  73
  74 static struct i2c_algo_bit_data scx200_i2c_data = {
  75         NULL,
  76         scx200_i2c_setsda,
  77         scx200_i2c_setscl,
  78         scx200_i2c_getsda,
  79         scx200_i2c_getscl,
  80         10, 10, 100,            /* waits, timeout */
  81 };
  82
  83 static struct i2c_adapter scx200_i2c_ops = {
  84         .owner             = THIS_MODULE,
  85         .algo_data         = &scx200_i2c_data,
  86         .name   = "NatSemi SCx200 I2C",
  87 };
  88
  89 static int scx200_i2c_init(void)
  90 {
  91         pr_debug(NAME ": NatSemi SCx200 I2C Driver\n");
  92
  93         if (!scx200_gpio_present()) {
  94                 printk(KERN_ERR NAME ": no SCx200 gpio pins available\n");
  95                 return -ENODEV;
  96         }
  97
  98         pr_debug(NAME ": SCL=GPIO%02u, SDA=GPIO%02u\n", scl, sda);
  99
 100         if (scl == -1 || sda == -1 || scl == sda) {
 101                 printk(KERN_ERR NAME ": scl and sda must be specified\n");
 102                 return -EINVAL;
 103         }
 104
 105         /* Configure GPIOs as open collector outputs */
 106         scx200_gpio_configure(scl, ~2, 5);
 107         scx200_gpio_configure(sda, ~2, 5);
 108
 109         if (i2c_bit_add_bus(&scx200_i2c_ops) < 0) {
 110                 printk(KERN_ERR NAME ": adapter %s registration failed\n",
 111                        scx200_i2c_ops.name);
 112                 return -ENODEV;
 113         }
 114
 115         return 0;
 116 }
 117
 118 static void scx200_i2c_cleanup(void)
 119 {
 120         i2c_bit_del_bus(&scx200_i2c_ops);
 121 }
 122
 123 module_init(scx200_i2c_init);
 124 module_exit(scx200_i2c_cleanup);
 125
 126 /*
 127     Local variables:
 128         compile-command: "make -k -C ../.. SUBDIRS=drivers/i2c modules"
 129         c-basic-offset: 8
 130     End:
 131 */