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

   1 /* ------------------------------------------------------------------------ *
   2  * i2c-parport-light.c I2C bus over parallel port                           *
   3  * ------------------------------------------------------------------------ *
   4    Copyright (C) 2003-2007 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/platform_device.h>
  31 #include <linux/ioport.h>
  32 #include <linux/i2c.h>
  33 #include <linux/i2c-algo-bit.h>
  34 #include <asm/io.h>
  35 #include "i2c-parport.h"
  36
  37 #define DEFAULT_BASE 0x378
  38 #define DRVNAME "i2c-parport-light"
  39
  40 static struct platform_device *pdev;
  41
  42 static u16 base;
  43 module_param(base, ushort, 0);
  44 MODULE_PARM_DESC(base, "Base I/O address");
  45
  46 /* ----- Low-level parallel port access ----------------------------------- */
  47
  48 static inline void port_write(unsigned char p, unsigned char d)
  49 {
  50         outb(d, base+p);
  51 }
  52
  53 static inline unsigned char port_read(unsigned char p)
  54 {
  55         return inb(base+p);
  56 }
  57
  58 /* ----- Unified line operation functions --------------------------------- */
  59
  60 static inline void line_set(int state, const struct lineop *op)
  61 {
  62         u8 oldval = port_read(op->port);
  63
  64         /* Touch only the bit(s) needed */
  65         if ((op->inverted && !state) || (!op->inverted && state))
  66                 port_write(op->port, oldval | op->val);
  67         else
  68                 port_write(op->port, oldval & ~op->val);
  69 }
  70
  71 static inline int line_get(const struct lineop *op)
  72 {
  73         u8 oldval = port_read(op->port);
  74
  75         return ((op->inverted && (oldval & op->val) != op->val)
  76             || (!op->inverted && (oldval & op->val) == op->val));
  77 }
  78
  79 /* ----- I2C algorithm call-back functions and structures ----------------- */
  80
  81 static void parport_setscl(void *data, int state)
  82 {
  83         line_set(state, &adapter_parm[type].setscl);
  84 }
  85
  86 static void parport_setsda(void *data, int state)
  87 {
  88         line_set(state, &adapter_parm[type].setsda);
  89 }
  90
  91 static int parport_getscl(void *data)
  92 {
  93         return line_get(&adapter_parm[type].getscl);
  94 }
  95
  96 static int parport_getsda(void *data)
  97 {
  98         return line_get(&adapter_parm[type].getsda);
  99 }
 100
 101 /* Encapsulate the functions above in the correct structure
 102    Note that getscl will be set to NULL by the attaching code for adapters
 103    that cannot read SCL back */
 104 static struct i2c_algo_bit_data parport_algo_data = {
 105         .setsda         = parport_setsda,
 106         .setscl         = parport_setscl,
 107         .getsda         = parport_getsda,
 108         .getscl         = parport_getscl,
 109         .udelay         = 50,
 110         .timeout        = HZ,
 111 };
 112
 113 /* ----- Driver registration ---------------------------------------------- */
 114
 115 static struct i2c_adapter parport_adapter = {
 116         .owner          = THIS_MODULE,
 117         .class          = I2C_CLASS_HWMON,
 118         .algo_data      = &parport_algo_data,
 119         .name           = "Parallel port adapter (light)",
 120 };
 121
 122 static int __devinit i2c_parport_probe(struct platform_device *pdev)
 123 {
 124         int err;
 125
 126         /* Reset hardware to a sane state (SCL and SDA high) */
 127         parport_setsda(NULL, 1);
 128         parport_setscl(NULL, 1);
 129         /* Other init if needed (power on...) */
 130         if (adapter_parm[type].init.val)
 131                 line_set(1, &adapter_parm[type].init);
 132
 133         parport_adapter.dev.parent = &pdev->dev;
 134         err = i2c_bit_add_bus(&parport_adapter);
 135         if (err)
 136                 dev_err(&pdev->dev, "Unable to register with I2C\n");
 137         return err;
 138 }
 139
 140 static int __devexit i2c_parport_remove(struct platform_device *pdev)
 141 {
 142         i2c_del_adapter(&parport_adapter);
 143
 144         /* Un-init if needed (power off...) */
 145         if (adapter_parm[type].init.val)
 146                 line_set(0, &adapter_parm[type].init);
 147
 148         return 0;
 149 }
 150
 151 static struct platform_driver i2c_parport_driver = {
 152         .driver = {
 153                 .owner  = THIS_MODULE,
 154                 .name   = DRVNAME,
 155         },
 156         .probe          = i2c_parport_probe,
 157         .remove         = __devexit_p(i2c_parport_remove),
 158 };
 159
 160 static int __init i2c_parport_device_add(u16 address)
 161 {
 162         int err;
 163
 164         pdev = platform_device_alloc(DRVNAME, -1);
 165         if (!pdev) {
 166                 err = -ENOMEM;
 167                 printk(KERN_ERR DRVNAME ": Device allocation failed\n");
 168                 goto exit;
 169         }
 170
 171         err = platform_device_add(pdev);
 172         if (err) {
 173                 printk(KERN_ERR DRVNAME ": Device addition failed (%d)\n",
 174                        err);
 175                 goto exit_device_put;
 176         }
 177
 178         return 0;
 179
 180 exit_device_put:
 181         platform_device_put(pdev);
 182 exit:
 183         return err;
 184 }
 185
 186 static int __init i2c_parport_init(void)
 187 {
 188         int err;
 189
 190         if (type < 0) {
 191                 printk(KERN_ERR DRVNAME ": adapter type unspecified\n");
 192                 return -ENODEV;
 193         }
 194
 195         if (type >= ARRAY_SIZE(adapter_parm)) {
 196                 printk(KERN_ERR DRVNAME ": invalid type (%d)\n", type);
 197                 return -ENODEV;
 198         }
 199
 200         if (base == 0) {
 201                 pr_info(DRVNAME ": using default base 0x%x\n", DEFAULT_BASE);
 202                 base = DEFAULT_BASE;
 203         }
 204
 205         if (!request_region(base, 3, DRVNAME))
 206                 return -EBUSY;
 207
 208         if (!adapter_parm[type].getscl.val)
 209                 parport_algo_data.getscl = NULL;
 210
 211         /* Sets global pdev as a side effect */
 212         err = i2c_parport_device_add(base);
 213         if (err)
 214                 goto exit_release;
 215
 216         err = platform_driver_register(&i2c_parport_driver);
 217         if (err)
 218                 goto exit_device;
 219
 220         return 0;
 221
 222 exit_device:
 223         platform_device_unregister(pdev);
 224 exit_release:
 225         release_region(base, 3);
 226         return err;
 227 }
 228
 229 static void __exit i2c_parport_exit(void)
 230 {
 231         platform_driver_unregister(&i2c_parport_driver);
 232         platform_device_unregister(pdev);
 233         release_region(base, 3);
 234 }
 235
 236 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
 237 MODULE_DESCRIPTION("I2C bus over parallel port (light)");
 238 MODULE_LICENSE("GPL");
 239
 240 module_init(i2c_parport_init);
 241 module_exit(i2c_parport_exit);