drivers/i2c/busses/i2c-parport-light.c

   1 /* ------------------------------------------------------------------------ *
   2  * i2c-parport.c I2C bus over parallel port                                 *
   3  * ------------------------------------------------------------------------ *
   4    Copyright (C) 2003-2004 Jean Delvare <khali@linux-fr.org>
   5
   6    Based on older i2c-velleman.c driver
   7    Copyright (C) 1995-2000 Simon G. Vogl
   8    With some changes from:
   9    Frodo Looijaard <frodol@dds.nl>
  10    Kyösti Mälkki <kmalkki@cc.hut.fi>
  11
  12    This program is free software; you can redistribute it and/or modify
  13    it under the terms of the GNU General Public License as published by
  14    the Free Software Foundation; either version 2 of the License, or
  15    (at your option) any later version.
  16
  17    This program is distributed in the hope that it will be useful,
  18    but WITHOUT ANY WARRANTY; without even the implied warranty of
  19    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20    GNU General Public License for more details.
  21
  22    You should have received a copy of the GNU General Public License
  23    along with this program; if not, write to the Free Software
  24    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  25  * ------------------------------------------------------------------------ */
  26
  27 #include <linux/kernel.h>
  28 #include <linux/module.h>
  29 #include <linux/init.h>
  30 #include <linux/ioport.h>
  31 #include <linux/i2c.h>
  32 #include <linux/i2c-algo-bit.h>
  33 #include <asm/io.h>
  34 #include "i2c-parport.h"
  35
  36 #define DEFAULT_BASE 0x378
  37
  38 static u16 base;
  39 module_param(base, ushort, 0);
  40 MODULE_PARM_DESC(base, "Base I/O address");
  41
  42 /* ----- Low-level parallel port access ----------------------------------- */
  43
  44 static inline void port_write(unsigned char p, unsigned char d)
  45 {
  46         outb(d, base+p);
  47 }
  48
  49 static inline unsigned char port_read(unsigned char p)
  50 {
  51         return inb(base+p);
  52 }
  53
  54 /* ----- Unified line operation functions --------------------------------- */
  55
  56 static inline void line_set(int state, const struct lineop *op)
  57 {
  58         u8 oldval = port_read(op->port);
  59
  60         /* Touch only the bit(s) needed */
  61         if ((op->inverted && !state) || (!op->inverted && state))
  62                 port_write(op->port, oldval | op->val);
  63         else
  64                 port_write(op->port, oldval & ~op->val);
  65 }
  66
  67 static inline int line_get(const struct lineop *op)
  68 {
  69         u8 oldval = port_read(op->port);
  70
  71         return ((op->inverted && (oldval & op->val) != op->val)
  72             || (!op->inverted && (oldval & op->val) == op->val));
  73 }
  74
  75 /* ----- I2C algorithm call-back functions and structures ----------------- */
  76
  77 static void parport_setscl(void *data, int state)
  78 {
  79         line_set(state, &adapter_parm[type].setscl);
  80 }
  81
  82 static void parport_setsda(void *data, int state)
  83 {
  84         line_set(state, &adapter_parm[type].setsda);
  85 }
  86
  87 static int parport_getscl(void *data)
  88 {
  89         return line_get(&adapter_parm[type].getscl);
  90 }
  91
  92 static int parport_getsda(void *data)
  93 {
  94         return line_get(&adapter_parm[type].getsda);
  95 }
  96
  97 /* Encapsulate the functions above in the correct structure
  98    Note that getscl will be set to NULL by the attaching code for adapters
  99    that cannot read SCL back */
 100 static struct i2c_algo_bit_data parport_algo_data = {
 101         .setsda         = parport_setsda,
 102         .setscl         = parport_setscl,
 103         .getsda         = parport_getsda,
 104         .getscl         = parport_getscl,
 105         .udelay         = 50,
 106         .timeout        = HZ,
 107 };
 108
 109 /* ----- I2c structure ---------------------------------------------------- */
 110
 111 static struct i2c_adapter parport_adapter = {
 112         .owner          = THIS_MODULE,
 113         .class          = I2C_CLASS_HWMON,
 114         .id             = I2C_HW_B_LP,
 115         .algo_data      = &parport_algo_data,
 116         .name           = "Parallel port adapter (light)",
 117 };
 118
 119 /* ----- Module loading, unloading and information ------------------------ */
 120
 121 static int __init i2c_parport_init(void)
 122 {
 123         if (type < 0) {
 124                 printk(KERN_WARNING "i2c-parport: adapter type unspecified\n");
 125                 return -ENODEV;
 126         }
 127
 128         if (type >= ARRAY_SIZE(adapter_parm)) {
 129                 printk(KERN_WARNING "i2c-parport: invalid type (%d)\n", type);
 130                 return -ENODEV;
 131         }
 132
 133         if (base == 0) {
 134                 printk(KERN_INFO "i2c-parport: using default base 0x%x\n", DEFAULT_BASE);
 135                 base = DEFAULT_BASE;
 136         }
 137
 138         if (!request_region(base, 3, "i2c-parport"))
 139                 return -ENODEV;
 140
 141         if (!adapter_parm[type].getscl.val)
 142                 parport_algo_data.getscl = NULL;
 143
 144         /* Reset hardware to a sane state (SCL and SDA high) */
 145         parport_setsda(NULL, 1);
 146         parport_setscl(NULL, 1);
 147         /* Other init if needed (power on...) */
 148         if (adapter_parm[type].init.val)
 149                 line_set(1, &adapter_parm[type].init);
 150
 151         if (i2c_bit_add_bus(&parport_adapter) < 0) {
 152                 printk(KERN_ERR "i2c-parport: Unable to register with I2C\n");
 153                 release_region(base, 3);
 154                 return -ENODEV;
 155         }
 156
 157         return 0;
 158 }
 159
 160 static void __exit i2c_parport_exit(void)
 161 {
 162         /* Un-init if needed (power off...) */
 163         if (adapter_parm[type].init.val)
 164                 line_set(0, &adapter_parm[type].init);
 165
 166         i2c_del_adapter(&parport_adapter);
 167         release_region(base, 3);
 168 }
 169
 170 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
 171 MODULE_DESCRIPTION("I2C bus over parallel port (light)");
 172 MODULE_LICENSE("GPL");
 173
 174 module_init(i2c_parport_init);
 175 module_exit(i2c_parport_exit);