1 /* ------------------------------------------------------------------------ * 2 * i2c-parport.c I2C bus over parallel port * 3 * ------------------------------------------------------------------------ * 4 Copyright (C) 2003-2010 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/delay.h> 31 #include <linux/parport.h> 32 #include <linux/i2c.h> 33 #include <linux/i2c-algo-bit.h> 34 #include <linux/i2c-smbus.h> 35 #include "i2c-parport.h" 36 37 /* ----- Device list ------------------------------------------------------ */ 38 39 struct i2c_par { 40 struct pardevice *pdev; 41 struct i2c_adapter adapter; 42 struct i2c_algo_bit_data algo_data; 43 struct i2c_smbus_alert_setup alert_data; 44 struct i2c_client *ara; 45 struct i2c_par *next; 46 }; 47 48 static struct i2c_par *adapter_list; 49 50 /* ----- Low-level parallel port access ----------------------------------- */ 51 52 static void port_write_data(struct parport *p, unsigned char d) 53 { 54 parport_write_data(p, d); 55 } 56 57 static void port_write_control(struct parport *p, unsigned char d) 58 { 59 parport_write_control(p, d); 60 } 61 62 static unsigned char port_read_data(struct parport *p) 63 { 64 return parport_read_data(p); 65 } 66 67 static unsigned char port_read_status(struct parport *p) 68 { 69 return parport_read_status(p); 70 } 71 72 static unsigned char port_read_control(struct parport *p) 73 { 74 return parport_read_control(p); 75 } 76 77 static void (*port_write[])(struct parport *, unsigned char) = { 78 port_write_data, 79 NULL, 80 port_write_control, 81 }; 82 83 static unsigned char (*port_read[])(struct parport *) = { 84 port_read_data, 85 port_read_status, 86 port_read_control, 87 }; 88 89 /* ----- Unified line operation functions --------------------------------- */ 90 91 static inline void line_set(struct parport *data, int state, 92 const struct lineop *op) 93 { 94 u8 oldval = port_read[op->port](data); 95 96 /* Touch only the bit(s) needed */ 97 if ((op->inverted && !state) || (!op->inverted && state)) 98 port_write[op->port](data, oldval | op->val); 99 else 100 port_write[op->port](data, oldval & ~op->val); 101 } 102 103 static inline int line_get(struct parport *data, 104 const struct lineop *op) 105 { 106 u8 oldval = port_read[op->port](data); 107 108 return ((op->inverted && (oldval & op->val) != op->val) 109 || (!op->inverted && (oldval & op->val) == op->val)); 110 } 111 112 /* ----- I2C algorithm call-back functions and structures ----------------- */ 113 114 static void parport_setscl(void *data, int state) 115 { 116 line_set((struct parport *) data, state, &adapter_parm[type].setscl); 117 } 118 119 static void parport_setsda(void *data, int state) 120 { 121 line_set((struct parport *) data, state, &adapter_parm[type].setsda); 122 } 123 124 static int parport_getscl(void *data) 125 { 126 return line_get((struct parport *) data, &adapter_parm[type].getscl); 127 } 128 129 static int parport_getsda(void *data) 130 { 131 return line_get((struct parport *) data, &adapter_parm[type].getsda); 132 } 133 134 /* Encapsulate the functions above in the correct structure. 135 Note that this is only a template, from which the real structures are 136 copied. The attaching code will set getscl to NULL for adapters that 137 cannot read SCL back, and will also make the data field point to 138 the parallel port structure. */ 139 static struct i2c_algo_bit_data parport_algo_data = { 140 .setsda = parport_setsda, 141 .setscl = parport_setscl, 142 .getsda = parport_getsda, 143 .getscl = parport_getscl, 144 .udelay = 10, /* ~50 kbps */ 145 .timeout = HZ, 146 }; 147 148 /* ----- I2c and parallel port call-back functions and structures --------- */ 149 150 void i2c_parport_irq(void *data) 151 { 152 struct i2c_par *adapter = data; 153 struct i2c_client *ara = adapter->ara; 154 155 if (ara) { 156 dev_dbg(&ara->dev, "SMBus alert received\n"); 157 i2c_handle_smbus_alert(ara); 158 } else 159 dev_dbg(&adapter->adapter.dev, 160 "SMBus alert received but no ARA client!\n"); 161 } 162 163 static void i2c_parport_attach (struct parport *port) 164 { 165 struct i2c_par *adapter; 166 167 adapter = kzalloc(sizeof(struct i2c_par), GFP_KERNEL); 168 if (adapter == NULL) { 169 printk(KERN_ERR "i2c-parport: Failed to kzalloc\n"); 170 return; 171 } 172 173 pr_debug("i2c-parport: attaching to %s\n", port->name); 174 parport_disable_irq(port); 175 adapter->pdev = parport_register_device(port, "i2c-parport", 176 NULL, NULL, i2c_parport_irq, PARPORT_FLAG_EXCL, adapter); 177 if (!adapter->pdev) { 178 printk(KERN_ERR "i2c-parport: Unable to register with parport\n"); 179 goto ERROR0; 180 } 181 182 /* Fill the rest of the structure */ 183 adapter->adapter.owner = THIS_MODULE; 184 adapter->adapter.class = I2C_CLASS_HWMON; 185 strlcpy(adapter->adapter.name, "Parallel port adapter", 186 sizeof(adapter->adapter.name)); 187 adapter->algo_data = parport_algo_data; 188 /* Slow down if we can't sense SCL */ 189 if (!adapter_parm[type].getscl.val) { 190 adapter->algo_data.getscl = NULL; 191 adapter->algo_data.udelay = 50; /* ~10 kbps */ 192 } 193 adapter->algo_data.data = port; 194 adapter->adapter.algo_data = &adapter->algo_data; 195 adapter->adapter.dev.parent = port->physport->dev; 196 197 if (parport_claim_or_block(adapter->pdev) < 0) { 198 printk(KERN_ERR "i2c-parport: Could not claim parallel port\n"); 199 goto ERROR1; 200 } 201 202 /* Reset hardware to a sane state (SCL and SDA high) */ 203 parport_setsda(port, 1); 204 parport_setscl(port, 1); 205 /* Other init if needed (power on...) */ 206 if (adapter_parm[type].init.val) { 207 line_set(port, 1, &adapter_parm[type].init); 208 /* Give powered devices some time to settle */ 209 msleep(100); 210 } 211 212 if (i2c_bit_add_bus(&adapter->adapter) < 0) { 213 printk(KERN_ERR "i2c-parport: Unable to register with I2C\n"); 214 goto ERROR1; 215 } 216 217 /* Setup SMBus alert if supported */ 218 if (adapter_parm[type].smbus_alert) { 219 adapter->alert_data.alert_edge_triggered = 1; 220 adapter->ara = i2c_setup_smbus_alert(&adapter->adapter, 221 &adapter->alert_data); 222 if (adapter->ara) 223 parport_enable_irq(port); 224 else 225 printk(KERN_WARNING "i2c-parport: Failed to register " 226 "ARA client\n"); 227 } 228 229 /* Add the new adapter to the list */ 230 adapter->next = adapter_list; 231 adapter_list = adapter; 232 return; 233 234 ERROR1: 235 parport_release(adapter->pdev); 236 parport_unregister_device(adapter->pdev); 237 ERROR0: 238 kfree(adapter); 239 } 240 241 static void i2c_parport_detach (struct parport *port) 242 { 243 struct i2c_par *adapter, *prev; 244 245 /* Walk the list */ 246 for (prev = NULL, adapter = adapter_list; adapter; 247 prev = adapter, adapter = adapter->next) { 248 if (adapter->pdev->port == port) { 249 if (adapter->ara) { 250 parport_disable_irq(port); 251 i2c_unregister_device(adapter->ara); 252 } 253 i2c_del_adapter(&adapter->adapter); 254 255 /* Un-init if needed (power off...) */ 256 if (adapter_parm[type].init.val) 257 line_set(port, 0, &adapter_parm[type].init); 258 259 parport_release(adapter->pdev); 260 parport_unregister_device(adapter->pdev); 261 if (prev) 262 prev->next = adapter->next; 263 else 264 adapter_list = adapter->next; 265 kfree(adapter); 266 return; 267 } 268 } 269 } 270 271 static struct parport_driver i2c_parport_driver = { 272 .name = "i2c-parport", 273 .attach = i2c_parport_attach, 274 .detach = i2c_parport_detach, 275 }; 276 277 /* ----- Module loading, unloading and information ------------------------ */ 278 279 static int __init i2c_parport_init(void) 280 { 281 if (type < 0) { 282 printk(KERN_WARNING "i2c-parport: adapter type unspecified\n"); 283 return -ENODEV; 284 } 285 286 if (type >= ARRAY_SIZE(adapter_parm)) { 287 printk(KERN_WARNING "i2c-parport: invalid type (%d)\n", type); 288 return -ENODEV; 289 } 290 291 return parport_register_driver(&i2c_parport_driver); 292 } 293 294 static void __exit i2c_parport_exit(void) 295 { 296 parport_unregister_driver(&i2c_parport_driver); 297 } 298 299 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>"); 300 MODULE_DESCRIPTION("I2C bus over parallel port"); 301 MODULE_LICENSE("GPL"); 302 303 module_init(i2c_parport_init); 304 module_exit(i2c_parport_exit); 305