drivers/i2c/busses/i2c-parport.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-philips-par.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/parport.h>
  31 #include <linux/i2c.h>
  32 #include <linux/i2c-algo-bit.h>
  33 #include "i2c-parport.h"
  34
  35 /* ----- Device list ------------------------------------------------------ */
  36
  37 struct i2c_par {
  38         struct pardevice *pdev;
  39         struct i2c_adapter adapter;
  40         struct i2c_algo_bit_data algo_data;
  41         struct i2c_par *next;
  42 };
  43
  44 static struct i2c_par *adapter_list;
  45
  46 /* ----- Low-level parallel port access ----------------------------------- */
  47
  48 static void port_write_data(struct parport *p, unsigned char d)
  49 {
  50         parport_write_data(p, d);
  51 }
  52
  53 static void port_write_control(struct parport *p, unsigned char d)
  54 {
  55         parport_write_control(p, d);
  56 }
  57
  58 static unsigned char port_read_data(struct parport *p)
  59 {
  60         return parport_read_data(p);
  61 }
  62
  63 static unsigned char port_read_status(struct parport *p)
  64 {
  65         return parport_read_status(p);
  66 }
  67
  68 static unsigned char port_read_control(struct parport *p)
  69 {
  70         return parport_read_control(p);
  71 }
  72
  73 static void (*port_write[])(struct parport *, unsigned char) = {
  74         port_write_data,
  75         NULL,
  76         port_write_control,
  77 };
  78
  79 static unsigned char (*port_read[])(struct parport *) = {
  80         port_read_data,
  81         port_read_status,
  82         port_read_control,
  83 };
  84
  85 /* ----- Unified line operation functions --------------------------------- */
  86
  87 static inline void line_set(struct parport *data, int state,
  88         const struct lineop *op)
  89 {
  90         u8 oldval = port_read[op->port](data);
  91
  92         /* Touch only the bit(s) needed */
  93         if ((op->inverted && !state) || (!op->inverted && state))
  94                 port_write[op->port](data, oldval | op->val);
  95         else
  96                 port_write[op->port](data, oldval & ~op->val);
  97 }
  98
  99 static inline int line_get(struct parport *data,
 100         const struct lineop *op)
 101 {
 102         u8 oldval = port_read[op->port](data);
 103
 104         return ((op->inverted && (oldval & op->val) != op->val)
 105             || (!op->inverted && (oldval & op->val) == op->val));
 106 }
 107
 108 /* ----- I2C algorithm call-back functions and structures ----------------- */
 109
 110 static void parport_setscl(void *data, int state)
 111 {
 112         line_set((struct parport *) data, state, &adapter_parm[type].setscl);
 113 }
 114
 115 static void parport_setsda(void *data, int state)
 116 {
 117         line_set((struct parport *) data, state, &adapter_parm[type].setsda);
 118 }
 119
 120 static int parport_getscl(void *data)
 121 {
 122         return line_get((struct parport *) data, &adapter_parm[type].getscl);
 123 }
 124
 125 static int parport_getsda(void *data)
 126 {
 127         return line_get((struct parport *) data, &adapter_parm[type].getsda);
 128 }
 129
 130 /* Encapsulate the functions above in the correct structure.
 131    Note that this is only a template, from which the real structures are
 132    copied. The attaching code will set getscl to NULL for adapters that
 133    cannot read SCL back, and will also make the data field point to
 134    the parallel port structure. */
 135 static struct i2c_algo_bit_data parport_algo_data = {
 136         .setsda         = parport_setsda,
 137         .setscl         = parport_setscl,
 138         .getsda         = parport_getsda,
 139         .getscl         = parport_getscl,
 140         .udelay         = 60,
 141         .mdelay         = 60,
 142         .timeout        = HZ,
 143 };
 144
 145 /* ----- I2c and parallel port call-back functions and structures --------- */
 146
 147 static struct i2c_adapter parport_adapter = {
 148         .owner          = THIS_MODULE,
 149         .class          = I2C_CLASS_HWMON,
 150         .id             = I2C_HW_B_LP,
 151         .name           = "Parallel port adapter",
 152 };
 153
 154 static void i2c_parport_attach (struct parport *port)
 155 {
 156         struct i2c_par *adapter;
 157
 158         adapter = kzalloc(sizeof(struct i2c_par), GFP_KERNEL);
 159         if (adapter == NULL) {
 160                 printk(KERN_ERR "i2c-parport: Failed to kzalloc\n");
 161                 return;
 162         }
 163
 164         pr_debug("i2c-parport: attaching to %s\n", port->name);
 165         adapter->pdev = parport_register_device(port, "i2c-parport",
 166                 NULL, NULL, NULL, PARPORT_FLAG_EXCL, NULL);
 167         if (!adapter->pdev) {
 168                 printk(KERN_ERR "i2c-parport: Unable to register with parport\n");
 169                 goto ERROR0;
 170         }
 171
 172         /* Fill the rest of the structure */
 173         adapter->adapter = parport_adapter;
 174         adapter->algo_data = parport_algo_data;
 175         if (!adapter_parm[type].getscl.val)
 176                 adapter->algo_data.getscl = NULL;
 177         adapter->algo_data.data = port;
 178         adapter->adapter.algo_data = &adapter->algo_data;
 179
 180         if (parport_claim_or_block(adapter->pdev) < 0) {
 181                 printk(KERN_ERR "i2c-parport: Could not claim parallel port\n");
 182                 goto ERROR1;
 183         }
 184
 185         /* Reset hardware to a sane state (SCL and SDA high) */
 186         parport_setsda(port, 1);
 187         parport_setscl(port, 1);
 188         /* Other init if needed (power on...) */
 189         if (adapter_parm[type].init.val)
 190                 line_set(port, 1, &adapter_parm[type].init);
 191
 192         parport_release(adapter->pdev);
 193
 194         if (i2c_bit_add_bus(&adapter->adapter) < 0) {
 195                 printk(KERN_ERR "i2c-parport: Unable to register with I2C\n");
 196                 goto ERROR1;
 197         }
 198
 199         /* Add the new adapter to the list */
 200         adapter->next = adapter_list;
 201         adapter_list = adapter;
 202         return;
 203
 204 ERROR1:
 205         parport_unregister_device(adapter->pdev);
 206 ERROR0:
 207         kfree(adapter);
 208 }
 209
 210 static void i2c_parport_detach (struct parport *port)
 211 {
 212         struct i2c_par *adapter, *prev;
 213
 214         /* Walk the list */
 215         for (prev = NULL, adapter = adapter_list; adapter;
 216              prev = adapter, adapter = adapter->next) {
 217                 if (adapter->pdev->port == port) {
 218                         /* Un-init if needed (power off...) */
 219                         if (adapter_parm[type].init.val)
 220                                 line_set(port, 0, &adapter_parm[type].init);
 221
 222                         i2c_bit_del_bus(&adapter->adapter);
 223                         parport_unregister_device(adapter->pdev);
 224                         if (prev)
 225                                 prev->next = adapter->next;
 226                         else
 227                                 adapter_list = adapter->next;
 228                         kfree(adapter);
 229                         return;
 230                 }
 231         }
 232 }
 233
 234 static struct parport_driver i2c_parport_driver = {
 235         .name   = "i2c-parport",
 236         .attach = i2c_parport_attach,
 237         .detach = i2c_parport_detach,
 238 };
 239
 240 /* ----- Module loading, unloading and information ------------------------ */
 241
 242 static int __init i2c_parport_init(void)
 243 {
 244         int type_count;
 245
 246         type_count = sizeof(adapter_parm)/sizeof(struct adapter_parm);
 247         if (type < 0 || type >= type_count) {
 248                 printk(KERN_WARNING "i2c-parport: invalid type (%d)\n", type);
 249                 type = 0;
 250         }
 251
 252         return parport_register_driver(&i2c_parport_driver);
 253 }
 254
 255 static void __exit i2c_parport_exit(void)
 256 {
 257         parport_unregister_driver(&i2c_parport_driver);
 258 }
 259
 260 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
 261 MODULE_DESCRIPTION("I2C bus over parallel port");
 262 MODULE_LICENSE("GPL");
 263
 264 module_init(i2c_parport_init);
 265 module_exit(i2c_parport_exit);