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

   1 /* ------------------------------------------------------------------------ *
   2  * i2c-parport-light.c I2C bus over parallel port                           *
   3  * ------------------------------------------------------------------------ *
   4    Copyright (C) 2003-2010 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/delay.h>
  31 #include <linux/platform_device.h>
  32 #include <linux/ioport.h>
  33 #include <linux/i2c.h>
  34 #include <linux/i2c-algo-bit.h>
  35 #include <linux/i2c-smbus.h>
  36 #include <linux/io.h>
  37 #include "i2c-parport.h"
  38
  39 #define DEFAULT_BASE 0x378
  40 #define DRVNAME "i2c-parport-light"
  41
  42 static struct platform_device *pdev;
  43
  44 static u16 base;
  45 module_param(base, ushort, 0);
  46 MODULE_PARM_DESC(base, "Base I/O address");
  47
  48 static int irq;
  49 module_param(irq, int, 0);
  50 MODULE_PARM_DESC(irq, "IRQ (optional)");
  51
  52 /* ----- Low-level parallel port access ----------------------------------- */
  53
  54 static inline void port_write(unsigned char p, unsigned char d)
  55 {
  56         outb(d, base+p);
  57 }
  58
  59 static inline unsigned char port_read(unsigned char p)
  60 {
  61         return inb(base+p);
  62 }
  63
  64 /* ----- Unified line operation functions --------------------------------- */
  65
  66 static inline void line_set(int state, const struct lineop *op)
  67 {
  68         u8 oldval = port_read(op->port);
  69
  70         /* Touch only the bit(s) needed */
  71         if ((op->inverted && !state) || (!op->inverted && state))
  72                 port_write(op->port, oldval | op->val);
  73         else
  74                 port_write(op->port, oldval & ~op->val);
  75 }
  76
  77 static inline int line_get(const struct lineop *op)
  78 {
  79         u8 oldval = port_read(op->port);
  80
  81         return ((op->inverted && (oldval & op->val) != op->val)
  82             || (!op->inverted && (oldval & op->val) == op->val));
  83 }
  84
  85 /* ----- I2C algorithm call-back functions and structures ----------------- */
  86
  87 static void parport_setscl(void *data, int state)
  88 {
  89         line_set(state, &adapter_parm[type].setscl);
  90 }
  91
  92 static void parport_setsda(void *data, int state)
  93 {
  94         line_set(state, &adapter_parm[type].setsda);
  95 }
  96
  97 static int parport_getscl(void *data)
  98 {
  99         return line_get(&adapter_parm[type].getscl);
 100 }
 101
 102 static int parport_getsda(void *data)
 103 {
 104         return line_get(&adapter_parm[type].getsda);
 105 }
 106
 107 /* Encapsulate the functions above in the correct structure
 108    Note that getscl will be set to NULL by the attaching code for adapters
 109    that cannot read SCL back */
 110 static struct i2c_algo_bit_data parport_algo_data = {
 111         .setsda         = parport_setsda,
 112         .setscl         = parport_setscl,
 113         .getsda         = parport_getsda,
 114         .getscl         = parport_getscl,
 115         .udelay         = 50,
 116         .timeout        = HZ,
 117 };
 118
 119 /* ----- Driver registration ---------------------------------------------- */
 120
 121 static struct i2c_adapter parport_adapter = {
 122         .owner          = THIS_MODULE,
 123         .class          = I2C_CLASS_HWMON,
 124         .algo_data      = &parport_algo_data,
 125         .name           = "Parallel port adapter (light)",
 126 };
 127
 128 /* SMBus alert support */
 129 static struct i2c_smbus_alert_setup alert_data = {
 130         .alert_edge_triggered   = 1,
 131 };
 132 static struct i2c_client *ara;
 133 static struct lineop parport_ctrl_irq = {
 134         .val            = (1 << 4),
 135         .port           = CTRL,
 136 };
 137
 138 static int __devinit i2c_parport_probe(struct platform_device *pdev)
 139 {
 140         int err;
 141
 142         /* Reset hardware to a sane state (SCL and SDA high) */
 143         parport_setsda(NULL, 1);
 144         parport_setscl(NULL, 1);
 145         /* Other init if needed (power on...) */
 146         if (adapter_parm[type].init.val) {
 147                 line_set(1, &adapter_parm[type].init);
 148                 /* Give powered devices some time to settle */
 149                 msleep(100);
 150         }
 151
 152         parport_adapter.dev.parent = &pdev->dev;
 153         err = i2c_bit_add_bus(&parport_adapter);
 154         if (err) {
 155                 dev_err(&pdev->dev, "Unable to register with I2C\n");
 156                 return err;
 157         }
 158
 159         /* Setup SMBus alert if supported */
 160         if (adapter_parm[type].smbus_alert && irq) {
 161                 alert_data.irq = irq;
 162                 ara = i2c_setup_smbus_alert(&parport_adapter, &alert_data);
 163                 if (ara)
 164                         line_set(1, &parport_ctrl_irq);
 165                 else
 166                         dev_warn(&pdev->dev, "Failed to register ARA client\n");
 167         }
 168
 169         return 0;
 170 }
 171
 172 static int __devexit i2c_parport_remove(struct platform_device *pdev)
 173 {
 174         if (ara) {
 175                 line_set(0, &parport_ctrl_irq);
 176                 i2c_unregister_device(ara);
 177                 ara = NULL;
 178         }
 179         i2c_del_adapter(&parport_adapter);
 180
 181         /* Un-init if needed (power off...) */
 182         if (adapter_parm[type].init.val)
 183                 line_set(0, &adapter_parm[type].init);
 184
 185         return 0;
 186 }
 187
 188 static struct platform_driver i2c_parport_driver = {
 189         .driver = {
 190                 .owner  = THIS_MODULE,
 191                 .name   = DRVNAME,
 192         },
 193         .probe          = i2c_parport_probe,
 194         .remove         = __devexit_p(i2c_parport_remove),
 195 };
 196
 197 static int __init i2c_parport_device_add(u16 address)
 198 {
 199         int err;
 200
 201         pdev = platform_device_alloc(DRVNAME, -1);
 202         if (!pdev) {
 203                 err = -ENOMEM;
 204                 printk(KERN_ERR DRVNAME ": Device allocation failed\n");
 205                 goto exit;
 206         }
 207
 208         err = platform_device_add(pdev);
 209         if (err) {
 210                 printk(KERN_ERR DRVNAME ": Device addition failed (%d)\n",
 211                        err);
 212                 goto exit_device_put;
 213         }
 214
 215         return 0;
 216
 217 exit_device_put:
 218         platform_device_put(pdev);
 219 exit:
 220         return err;
 221 }
 222
 223 static int __init i2c_parport_init(void)
 224 {
 225         int err;
 226
 227         if (type < 0) {
 228                 printk(KERN_ERR DRVNAME ": adapter type unspecified\n");
 229                 return -ENODEV;
 230         }
 231
 232         if (type >= ARRAY_SIZE(adapter_parm)) {
 233                 printk(KERN_ERR DRVNAME ": invalid type (%d)\n", type);
 234                 return -ENODEV;
 235         }
 236
 237         if (base == 0) {
 238                 pr_info(DRVNAME ": using default base 0x%x\n", DEFAULT_BASE);
 239                 base = DEFAULT_BASE;
 240         }
 241
 242         if (!request_region(base, 3, DRVNAME))
 243                 return -EBUSY;
 244
 245         if (irq != 0)
 246                 pr_info(DRVNAME ": using irq %d\n", irq);
 247
 248         if (!adapter_parm[type].getscl.val)
 249                 parport_algo_data.getscl = NULL;
 250
 251         /* Sets global pdev as a side effect */
 252         err = i2c_parport_device_add(base);
 253         if (err)
 254                 goto exit_release;
 255
 256         err = platform_driver_register(&i2c_parport_driver);
 257         if (err)
 258                 goto exit_device;
 259
 260         return 0;
 261
 262 exit_device:
 263         platform_device_unregister(pdev);
 264 exit_release:
 265         release_region(base, 3);
 266         return err;
 267 }
 268
 269 static void __exit i2c_parport_exit(void)
 270 {
 271         platform_driver_unregister(&i2c_parport_driver);
 272         platform_device_unregister(pdev);
 273         release_region(base, 3);
 274 }
 275
 276 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
 277 MODULE_DESCRIPTION("I2C bus over parallel port (light)");
 278 MODULE_LICENSE("GPL");
 279
 280 module_init(i2c_parport_init);
 281 module_exit(i2c_parport_exit);