drivers/i2c/busses/i2c-parport.c

   1 /* ------------------------------------------------------------------------ *
   2  * i2c-parport.c I2C bus over parallel port                                 *
   3  * ------------------------------------------------------------------------ *
   4    Copyright (C) 2003-2007 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         = 10, /* ~50 kbps */
 141         .timeout        = HZ,
 142 };
 143
 144 /* ----- I2c and parallel port call-back functions and structures --------- */
 145
 146 static void i2c_parport_attach (struct parport *port)
 147 {
 148         struct i2c_par *adapter;
 149
 150         adapter = kzalloc(sizeof(struct i2c_par), GFP_KERNEL);
 151         if (adapter == NULL) {
 152                 printk(KERN_ERR "i2c-parport: Failed to kzalloc\n");
 153                 return;
 154         }
 155
 156         pr_debug("i2c-parport: attaching to %s\n", port->name);
 157         adapter->pdev = parport_register_device(port, "i2c-parport",
 158                 NULL, NULL, NULL, PARPORT_FLAG_EXCL, NULL);
 159         if (!adapter->pdev) {
 160                 printk(KERN_ERR "i2c-parport: Unable to register with parport\n");
 161                 goto ERROR0;
 162         }
 163
 164         /* Fill the rest of the structure */
 165         adapter->adapter.owner = THIS_MODULE;
 166         adapter->adapter.class = I2C_CLASS_HWMON;
 167         adapter->adapter.id = I2C_HW_B_LP;
 168         strlcpy(adapter->adapter.name, "Parallel port adapter",
 169                 sizeof(adapter->adapter.name));
 170         adapter->algo_data = parport_algo_data;
 171         /* Slow down if we can't sense SCL */
 172         if (!adapter_parm[type].getscl.val) {
 173                 adapter->algo_data.getscl = NULL;
 174                 adapter->algo_data.udelay = 50; /* ~10 kbps */
 175         }
 176         adapter->algo_data.data = port;
 177         adapter->adapter.algo_data = &adapter->algo_data;
 178
 179         if (parport_claim_or_block(adapter->pdev) < 0) {
 180                 printk(KERN_ERR "i2c-parport: Could not claim parallel port\n");
 181                 goto ERROR1;
 182         }
 183
 184         /* Reset hardware to a sane state (SCL and SDA high) */
 185         parport_setsda(port, 1);
 186         parport_setscl(port, 1);
 187         /* Other init if needed (power on...) */
 188         if (adapter_parm[type].init.val)
 189                 line_set(port, 1, &adapter_parm[type].init);
 190
 191         parport_release(adapter->pdev);
 192
 193         if (i2c_bit_add_bus(&adapter->adapter) < 0) {
 194                 printk(KERN_ERR "i2c-parport: Unable to register with I2C\n");
 195                 goto ERROR1;
 196         }
 197
 198         /* Add the new adapter to the list */
 199         adapter->next = adapter_list;
 200         adapter_list = adapter;
 201         return;
 202
 203 ERROR1:
 204         parport_unregister_device(adapter->pdev);
 205 ERROR0:
 206         kfree(adapter);
 207 }
 208
 209 static void i2c_parport_detach (struct parport *port)
 210 {
 211         struct i2c_par *adapter, *prev;
 212
 213         /* Walk the list */
 214         for (prev = NULL, adapter = adapter_list; adapter;
 215              prev = adapter, adapter = adapter->next) {
 216                 if (adapter->pdev->port == port) {
 217                         i2c_del_adapter(&adapter->adapter);
 218
 219                         /* Un-init if needed (power off...) */
 220                         if (adapter_parm[type].init.val)
 221                                 line_set(port, 0, &adapter_parm[type].init);
 222
 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         if (type < 0) {
 245                 printk(KERN_WARNING "i2c-parport: adapter type unspecified\n");
 246                 return -ENODEV;
 247         }
 248
 249         if (type >= ARRAY_SIZE(adapter_parm)) {
 250                 printk(KERN_WARNING "i2c-parport: invalid type (%d)\n", type);
 251                 return -ENODEV;
 252         }
 253
 254         return parport_register_driver(&i2c_parport_driver);
 255 }
 256
 257 static void __exit i2c_parport_exit(void)
 258 {
 259         parport_unregister_driver(&i2c_parport_driver);
 260 }
 261
 262 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
 263 MODULE_DESCRIPTION("I2C bus over parallel port");
 264 MODULE_LICENSE("GPL");
 265
 266 module_init(i2c_parport_init);
 267 module_exit(i2c_parport_exit);