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 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 = 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); 268