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         .id             = I2C_HW_B_LP,
 119         .algo_data      = &parport_algo_data,
 120         .name           = "Parallel port adapter (light)",
 121 };
 122
 123 static int __devinit i2c_parport_probe(struct platform_device *pdev)
 124 {
 125         int err;
 126
 127         /* Reset hardware to a sane state (SCL and SDA high) */
 128         parport_setsda(NULL, 1);
 129         parport_setscl(NULL, 1);
 130         /* Other init if needed (power on...) */
 131         if (adapter_parm[type].init.val)
 132                 line_set(1, &adapter_parm[type].init);
 133
 134         parport_adapter.dev.parent = &pdev->dev;
 135         err = i2c_bit_add_bus(&parport_adapter);
 136         if (err)
 137                 dev_err(&pdev->dev, "Unable to register with I2C\n");
 138         return err;
 139 }
 140
 141 static int __devexit i2c_parport_remove(struct platform_device *pdev)
 142 {
 143         i2c_del_adapter(&parport_adapter);
 144
 145         /* Un-init if needed (power off...) */
 146         if (adapter_parm[type].init.val)
 147                 line_set(0, &adapter_parm[type].init);
 148
 149         return 0;
 150 }
 151
 152 static struct platform_driver i2c_parport_driver = {
 153         .driver = {
 154                 .owner  = THIS_MODULE,
 155                 .name   = DRVNAME,
 156         },
 157         .probe          = i2c_parport_probe,
 158         .remove         = __devexit_p(i2c_parport_remove),
 159 };
 160
 161 static int __init i2c_parport_device_add(u16 address)
 162 {
 163         int err;
 164
 165         pdev = platform_device_alloc(DRVNAME, -1);
 166         if (!pdev) {
 167                 err = -ENOMEM;
 168                 printk(KERN_ERR DRVNAME ": Device allocation failed\n");
 169                 goto exit;
 170         }
 171
 172         err = platform_device_add(pdev);
 173         if (err) {
 174                 printk(KERN_ERR DRVNAME ": Device addition failed (%d)\n",
 175                        err);
 176                 goto exit_device_put;
 177         }
 178
 179         return 0;
 180
 181 exit_device_put:
 182         platform_device_put(pdev);
 183 exit:
 184         return err;
 185 }
 186
 187 static int __init i2c_parport_init(void)
 188 {
 189         int err;
 190
 191         if (type < 0) {
 192                 printk(KERN_ERR DRVNAME ": adapter type unspecified\n");
 193                 return -ENODEV;
 194         }
 195
 196         if (type >= ARRAY_SIZE(adapter_parm)) {
 197                 printk(KERN_ERR DRVNAME ": invalid type (%d)\n", type);
 198                 return -ENODEV;
 199         }
 200
 201         if (base == 0) {
 202                 pr_info(DRVNAME ": using default base 0x%x\n", DEFAULT_BASE);
 203                 base = DEFAULT_BASE;
 204         }
 205
 206         if (!request_region(base, 3, DRVNAME))
 207                 return -EBUSY;
 208
 209         if (!adapter_parm[type].getscl.val)
 210                 parport_algo_data.getscl = NULL;
 211
 212         /* Sets global pdev as a side effect */
 213         err = i2c_parport_device_add(base);
 214         if (err)
 215                 goto exit_release;
 216
 217         err = platform_driver_register(&i2c_parport_driver);
 218         if (err)
 219                 goto exit_device;
 220
 221         return 0;
 222
 223 exit_device:
 224         platform_device_unregister(pdev);
 225 exit_release:
 226         release_region(base, 3);
 227         return err;
 228 }
 229
 230 static void __exit i2c_parport_exit(void)
 231 {
 232         platform_driver_unregister(&i2c_parport_driver);
 233         platform_device_unregister(pdev);
 234         release_region(base, 3);
 235 }
 236
 237 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
 238 MODULE_DESCRIPTION("I2C bus over parallel port (light)");
 239 MODULE_LICENSE("GPL");
 240
 241 module_init(i2c_parport_init);
 242 module_exit(i2c_parport_exit);