1 /* ------------------------------------------------------------------------ *
2 * i2c-parport.c I2C bus over parallel port *
3 * ------------------------------------------------------------------------ *
4 Copyright (C) 2003-2010 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/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"
37 /* ----- Device list ------------------------------------------------------ */
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;
48 static struct i2c_par *adapter_list;
50 /* ----- Low-level parallel port access ----------------------------------- */
52 static void port_write_data(struct parport *p, unsigned char d)
54 parport_write_data(p, d);
57 static void port_write_control(struct parport *p, unsigned char d)
59 parport_write_control(p, d);
62 static unsigned char port_read_data(struct parport *p)
64 return parport_read_data(p);
67 static unsigned char port_read_status(struct parport *p)
69 return parport_read_status(p);
72 static unsigned char port_read_control(struct parport *p)
74 return parport_read_control(p);
77 static void (*port_write[])(struct parport *, unsigned char) = {
83 static unsigned char (*port_read[])(struct parport *) = {
89 /* ----- Unified line operation functions --------------------------------- */
91 static inline void line_set(struct parport *data, int state,
92 const struct lineop *op)
94 u8 oldval = port_read[op->port](data);
96 /* Touch only the bit(s) needed */
97 if ((op->inverted && !state) || (!op->inverted && state))
98 port_write[op->port](data, oldval | op->val);
100 port_write[op->port](data, oldval & ~op->val);
103 static inline int line_get(struct parport *data,
104 const struct lineop *op)
106 u8 oldval = port_read[op->port](data);
108 return ((op->inverted && (oldval & op->val) != op->val)
109 || (!op->inverted && (oldval & op->val) == op->val));
112 /* ----- I2C algorithm call-back functions and structures ----------------- */
114 static void parport_setscl(void *data, int state)
116 line_set((struct parport *) data, state, &adapter_parm[type].setscl);
119 static void parport_setsda(void *data, int state)
121 line_set((struct parport *) data, state, &adapter_parm[type].setsda);
124 static int parport_getscl(void *data)
126 return line_get((struct parport *) data, &adapter_parm[type].getscl);
129 static int parport_getsda(void *data)
131 return line_get((struct parport *) data, &adapter_parm[type].getsda);
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 */
148 /* ----- I2c and parallel port call-back functions and structures --------- */
150 void i2c_parport_irq(void *data)
152 struct i2c_par *adapter = data;
153 struct i2c_client *ara = adapter->ara;
156 dev_dbg(&ara->dev, "SMBus alert received\n");
157 i2c_handle_smbus_alert(ara);
159 dev_dbg(&adapter->adapter.dev,
160 "SMBus alert received but no ARA client!\n");
163 static void i2c_parport_attach (struct parport *port)
165 struct i2c_par *adapter;
167 adapter = kzalloc(sizeof(struct i2c_par), GFP_KERNEL);
168 if (adapter == NULL) {
169 printk(KERN_ERR "i2c-parport: Failed to kzalloc\n");
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");
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 */
193 adapter->algo_data.data = port;
194 adapter->adapter.algo_data = &adapter->algo_data;
195 adapter->adapter.dev.parent = port->physport->dev;
197 if (parport_claim_or_block(adapter->pdev) < 0) {
198 printk(KERN_ERR "i2c-parport: Could not claim parallel port\n");
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 */
212 if (i2c_bit_add_bus(&adapter->adapter) < 0) {
213 printk(KERN_ERR "i2c-parport: Unable to register with I2C\n");
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);
223 parport_enable_irq(port);
225 printk(KERN_WARNING "i2c-parport: Failed to register "
229 /* Add the new adapter to the list */
230 adapter->next = adapter_list;
231 adapter_list = adapter;
235 parport_release(adapter->pdev);
236 parport_unregister_device(adapter->pdev);
241 static void i2c_parport_detach (struct parport *port)
243 struct i2c_par *adapter, *prev;
246 for (prev = NULL, adapter = adapter_list; adapter;
247 prev = adapter, adapter = adapter->next) {
248 if (adapter->pdev->port == port) {
250 parport_disable_irq(port);
251 i2c_unregister_device(adapter->ara);
253 i2c_del_adapter(&adapter->adapter);
255 /* Un-init if needed (power off...) */
256 if (adapter_parm[type].init.val)
257 line_set(port, 0, &adapter_parm[type].init);
259 parport_release(adapter->pdev);
260 parport_unregister_device(adapter->pdev);
262 prev->next = adapter->next;
264 adapter_list = adapter->next;
271 static struct parport_driver i2c_parport_driver = {
272 .name = "i2c-parport",
273 .attach = i2c_parport_attach,
274 .detach = i2c_parport_detach,
277 /* ----- Module loading, unloading and information ------------------------ */
279 static int __init i2c_parport_init(void)
282 printk(KERN_WARNING "i2c-parport: adapter type unspecified\n");
286 if (type >= ARRAY_SIZE(adapter_parm)) {
287 printk(KERN_WARNING "i2c-parport: invalid type (%d)\n", type);
291 return parport_register_driver(&i2c_parport_driver);
294 static void __exit i2c_parport_exit(void)
296 parport_unregister_driver(&i2c_parport_driver);
299 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
300 MODULE_DESCRIPTION("I2C bus over parallel port");
301 MODULE_LICENSE("GPL");
303 module_init(i2c_parport_init);
304 module_exit(i2c_parport_exit);