1 /* ------------------------------------------------------------------------ *
2 * i2c-parport.c I2C bus over parallel port *
3 * ------------------------------------------------------------------------ *
4 Copyright (C) 2003-2004 Jean Delvare <khali@linux-fr.org>
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>
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.
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.
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 * ------------------------------------------------------------------------ */
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"
35 /* ----- Device list ------------------------------------------------------ */
38 struct pardevice *pdev;
39 struct i2c_adapter adapter;
40 struct i2c_algo_bit_data algo_data;
44 static struct i2c_par *adapter_list;
46 /* ----- Low-level parallel port access ----------------------------------- */
48 static void port_write_data(struct parport *p, unsigned char d)
50 parport_write_data(p, d);
53 static void port_write_control(struct parport *p, unsigned char d)
55 parport_write_control(p, d);
58 static unsigned char port_read_data(struct parport *p)
60 return parport_read_data(p);
63 static unsigned char port_read_status(struct parport *p)
65 return parport_read_status(p);
68 static unsigned char port_read_control(struct parport *p)
70 return parport_read_control(p);
73 static void (*port_write[])(struct parport *, unsigned char) = {
79 static unsigned char (*port_read[])(struct parport *) = {
85 /* ----- Unified line operation functions --------------------------------- */
87 static inline void line_set(struct parport *data, int state,
88 const struct lineop *op)
90 u8 oldval = port_read[op->port](data);
92 /* Touch only the bit(s) needed */
93 if ((op->inverted && !state) || (!op->inverted && state))
94 port_write[op->port](data, oldval | op->val);
96 port_write[op->port](data, oldval & ~op->val);
99 static inline int line_get(struct parport *data,
100 const struct lineop *op)
102 u8 oldval = port_read[op->port](data);
104 return ((op->inverted && (oldval & op->val) != op->val)
105 || (!op->inverted && (oldval & op->val) == op->val));
108 /* ----- I2C algorithm call-back functions and structures ----------------- */
110 static void parport_setscl(void *data, int state)
112 line_set((struct parport *) data, state, &adapter_parm[type].setscl);
115 static void parport_setsda(void *data, int state)
117 line_set((struct parport *) data, state, &adapter_parm[type].setsda);
120 static int parport_getscl(void *data)
122 return line_get((struct parport *) data, &adapter_parm[type].getscl);
125 static int parport_getsda(void *data)
127 return line_get((struct parport *) data, &adapter_parm[type].getsda);
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,
144 /* ----- I2c and parallel port call-back functions and structures --------- */
146 static void i2c_parport_attach (struct parport *port)
148 struct i2c_par *adapter;
150 adapter = kzalloc(sizeof(struct i2c_par), GFP_KERNEL);
151 if (adapter == NULL) {
152 printk(KERN_ERR "i2c-parport: Failed to kzalloc\n");
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");
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 if (!adapter_parm[type].getscl.val)
172 adapter->algo_data.getscl = NULL;
173 adapter->algo_data.data = port;
174 adapter->adapter.algo_data = &adapter->algo_data;
176 if (parport_claim_or_block(adapter->pdev) < 0) {
177 printk(KERN_ERR "i2c-parport: Could not claim parallel port\n");
181 /* Reset hardware to a sane state (SCL and SDA high) */
182 parport_setsda(port, 1);
183 parport_setscl(port, 1);
184 /* Other init if needed (power on...) */
185 if (adapter_parm[type].init.val)
186 line_set(port, 1, &adapter_parm[type].init);
188 parport_release(adapter->pdev);
190 if (i2c_bit_add_bus(&adapter->adapter) < 0) {
191 printk(KERN_ERR "i2c-parport: Unable to register with I2C\n");
195 /* Add the new adapter to the list */
196 adapter->next = adapter_list;
197 adapter_list = adapter;
201 parport_unregister_device(adapter->pdev);
206 static void i2c_parport_detach (struct parport *port)
208 struct i2c_par *adapter, *prev;
211 for (prev = NULL, adapter = adapter_list; adapter;
212 prev = adapter, adapter = adapter->next) {
213 if (adapter->pdev->port == port) {
214 /* Un-init if needed (power off...) */
215 if (adapter_parm[type].init.val)
216 line_set(port, 0, &adapter_parm[type].init);
218 i2c_del_adapter(&adapter->adapter);
219 parport_unregister_device(adapter->pdev);
221 prev->next = adapter->next;
223 adapter_list = adapter->next;
230 static struct parport_driver i2c_parport_driver = {
231 .name = "i2c-parport",
232 .attach = i2c_parport_attach,
233 .detach = i2c_parport_detach,
236 /* ----- Module loading, unloading and information ------------------------ */
238 static int __init i2c_parport_init(void)
241 printk(KERN_WARNING "i2c-parport: adapter type unspecified\n");
245 if (type >= ARRAY_SIZE(adapter_parm)) {
246 printk(KERN_WARNING "i2c-parport: invalid type (%d)\n", type);
250 return parport_register_driver(&i2c_parport_driver);
253 static void __exit i2c_parport_exit(void)
255 parport_unregister_driver(&i2c_parport_driver);
258 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
259 MODULE_DESCRIPTION("I2C bus over parallel port");
260 MODULE_LICENSE("GPL");
262 module_init(i2c_parport_init);
263 module_exit(i2c_parport_exit);