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 Ky�sti M�lkki <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); 266