1 /* ------------------------------------------------------------------------ *
2 * i2c-parport.c I2C bus over parallel port *
3 * ------------------------------------------------------------------------ *
4 Copyright (C) 2003-2011 Jean Delvare <jdelvare@suse.de>
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
23 #define pr_fmt(fmt) "i2c-parport: " fmt
24
25 #include <linux/kernel.h>
26 #include <linux/module.h>
27 #include <linux/init.h>
28 #include <linux/delay.h>
29 #include <linux/parport.h>
30 #include <linux/i2c.h>
31 #include <linux/i2c-algo-bit.h>
32 #include <linux/i2c-smbus.h>
33 #include <linux/slab.h>
34 #include <linux/list.h>
35 #include <linux/mutex.h>
36 #include "i2c-parport.h"
37
38 /* ----- Device list ------------------------------------------------------ */
39
40 struct i2c_par {
41 struct pardevice *pdev;
42 struct i2c_adapter adapter;
43 struct i2c_algo_bit_data algo_data;
44 struct i2c_smbus_alert_setup alert_data;
45 struct i2c_client *ara;
46 struct list_head node;
47 };
48
49 static LIST_HEAD(adapter_list);
50 static DEFINE_MUTEX(adapter_list_lock);
51 #define MAX_DEVICE 4
52 static int parport[MAX_DEVICE] = {0, -1, -1, -1};
53
54
55 /* ----- Low-level parallel port access ----------------------------------- */
56
port_write_data(struct parport * p,unsigned char d)57 static void port_write_data(struct parport *p, unsigned char d)
58 {
59 parport_write_data(p, d);
60 }
61
port_write_control(struct parport * p,unsigned char d)62 static void port_write_control(struct parport *p, unsigned char d)
63 {
64 parport_write_control(p, d);
65 }
66
port_read_data(struct parport * p)67 static unsigned char port_read_data(struct parport *p)
68 {
69 return parport_read_data(p);
70 }
71
port_read_status(struct parport * p)72 static unsigned char port_read_status(struct parport *p)
73 {
74 return parport_read_status(p);
75 }
76
port_read_control(struct parport * p)77 static unsigned char port_read_control(struct parport *p)
78 {
79 return parport_read_control(p);
80 }
81
82 static void (* const port_write[])(struct parport *, unsigned char) = {
83 port_write_data,
84 NULL,
85 port_write_control,
86 };
87
88 static unsigned char (* const port_read[])(struct parport *) = {
89 port_read_data,
90 port_read_status,
91 port_read_control,
92 };
93
94 /* ----- Unified line operation functions --------------------------------- */
95
line_set(struct parport * data,int state,const struct lineop * op)96 static inline void line_set(struct parport *data, int state,
97 const struct lineop *op)
98 {
99 u8 oldval = port_read[op->port](data);
100
101 /* Touch only the bit(s) needed */
102 if ((op->inverted && !state) || (!op->inverted && state))
103 port_write[op->port](data, oldval | op->val);
104 else
105 port_write[op->port](data, oldval & ~op->val);
106 }
107
line_get(struct parport * data,const struct lineop * op)108 static inline int line_get(struct parport *data,
109 const struct lineop *op)
110 {
111 u8 oldval = port_read[op->port](data);
112
113 return ((op->inverted && (oldval & op->val) != op->val)
114 || (!op->inverted && (oldval & op->val) == op->val));
115 }
116
117 /* ----- I2C algorithm call-back functions and structures ----------------- */
118
parport_setscl(void * data,int state)119 static void parport_setscl(void *data, int state)
120 {
121 line_set((struct parport *) data, state, &adapter_parm[type].setscl);
122 }
123
parport_setsda(void * data,int state)124 static void parport_setsda(void *data, int state)
125 {
126 line_set((struct parport *) data, state, &adapter_parm[type].setsda);
127 }
128
parport_getscl(void * data)129 static int parport_getscl(void *data)
130 {
131 return line_get((struct parport *) data, &adapter_parm[type].getscl);
132 }
133
parport_getsda(void * data)134 static int parport_getsda(void *data)
135 {
136 return line_get((struct parport *) data, &adapter_parm[type].getsda);
137 }
138
139 /* Encapsulate the functions above in the correct structure.
140 Note that this is only a template, from which the real structures are
141 copied. The attaching code will set getscl to NULL for adapters that
142 cannot read SCL back, and will also make the data field point to
143 the parallel port structure. */
144 static const struct i2c_algo_bit_data parport_algo_data = {
145 .setsda = parport_setsda,
146 .setscl = parport_setscl,
147 .getsda = parport_getsda,
148 .getscl = parport_getscl,
149 .udelay = 10, /* ~50 kbps */
150 .timeout = HZ,
151 };
152
153 /* ----- I2c and parallel port call-back functions and structures --------- */
154
i2c_parport_irq(void * data)155 static void i2c_parport_irq(void *data)
156 {
157 struct i2c_par *adapter = data;
158 struct i2c_client *ara = adapter->ara;
159
160 if (ara) {
161 dev_dbg(&ara->dev, "SMBus alert received\n");
162 i2c_handle_smbus_alert(ara);
163 } else
164 dev_dbg(&adapter->adapter.dev,
165 "SMBus alert received but no ARA client!\n");
166 }
167
i2c_parport_attach(struct parport * port)168 static void i2c_parport_attach(struct parport *port)
169 {
170 struct i2c_par *adapter;
171 int i;
172 struct pardev_cb i2c_parport_cb;
173
174 for (i = 0; i < MAX_DEVICE; i++) {
175 if (parport[i] == -1)
176 continue;
177 if (port->number == parport[i])
178 break;
179 }
180 if (i == MAX_DEVICE) {
181 pr_debug("Not using parport%d.\n", port->number);
182 return;
183 }
184
185 adapter = kzalloc(sizeof(struct i2c_par), GFP_KERNEL);
186 if (!adapter)
187 return;
188 memset(&i2c_parport_cb, 0, sizeof(i2c_parport_cb));
189 i2c_parport_cb.flags = PARPORT_FLAG_EXCL;
190 i2c_parport_cb.irq_func = i2c_parport_irq;
191 i2c_parport_cb.private = adapter;
192
193 pr_debug("attaching to %s\n", port->name);
194 parport_disable_irq(port);
195 adapter->pdev = parport_register_dev_model(port, "i2c-parport",
196 &i2c_parport_cb, i);
197 if (!adapter->pdev) {
198 pr_err("Unable to register with parport\n");
199 goto err_free;
200 }
201
202 /* Fill the rest of the structure */
203 adapter->adapter.owner = THIS_MODULE;
204 adapter->adapter.class = I2C_CLASS_HWMON;
205 strlcpy(adapter->adapter.name, "Parallel port adapter",
206 sizeof(adapter->adapter.name));
207 adapter->algo_data = parport_algo_data;
208 /* Slow down if we can't sense SCL */
209 if (!adapter_parm[type].getscl.val) {
210 adapter->algo_data.getscl = NULL;
211 adapter->algo_data.udelay = 50; /* ~10 kbps */
212 }
213 adapter->algo_data.data = port;
214 adapter->adapter.algo_data = &adapter->algo_data;
215 adapter->adapter.dev.parent = port->physport->dev;
216
217 if (parport_claim_or_block(adapter->pdev) < 0) {
218 dev_err(&adapter->pdev->dev,
219 "Could not claim parallel port\n");
220 goto err_unregister;
221 }
222
223 /* Reset hardware to a sane state (SCL and SDA high) */
224 parport_setsda(port, 1);
225 parport_setscl(port, 1);
226 /* Other init if needed (power on...) */
227 if (adapter_parm[type].init.val) {
228 line_set(port, 1, &adapter_parm[type].init);
229 /* Give powered devices some time to settle */
230 msleep(100);
231 }
232
233 if (i2c_bit_add_bus(&adapter->adapter) < 0) {
234 dev_err(&adapter->pdev->dev, "Unable to register with I2C\n");
235 goto err_unregister;
236 }
237
238 /* Setup SMBus alert if supported */
239 if (adapter_parm[type].smbus_alert) {
240 adapter->ara = i2c_setup_smbus_alert(&adapter->adapter,
241 &adapter->alert_data);
242 if (adapter->ara)
243 parport_enable_irq(port);
244 else
245 dev_warn(&adapter->pdev->dev,
246 "Failed to register ARA client\n");
247 }
248
249 /* Add the new adapter to the list */
250 mutex_lock(&adapter_list_lock);
251 list_add_tail(&adapter->node, &adapter_list);
252 mutex_unlock(&adapter_list_lock);
253 return;
254
255 err_unregister:
256 parport_release(adapter->pdev);
257 parport_unregister_device(adapter->pdev);
258 err_free:
259 kfree(adapter);
260 }
261
i2c_parport_detach(struct parport * port)262 static void i2c_parport_detach(struct parport *port)
263 {
264 struct i2c_par *adapter, *_n;
265
266 /* Walk the list */
267 mutex_lock(&adapter_list_lock);
268 list_for_each_entry_safe(adapter, _n, &adapter_list, node) {
269 if (adapter->pdev->port == port) {
270 if (adapter->ara) {
271 parport_disable_irq(port);
272 i2c_unregister_device(adapter->ara);
273 }
274 i2c_del_adapter(&adapter->adapter);
275
276 /* Un-init if needed (power off...) */
277 if (adapter_parm[type].init.val)
278 line_set(port, 0, &adapter_parm[type].init);
279
280 parport_release(adapter->pdev);
281 parport_unregister_device(adapter->pdev);
282 list_del(&adapter->node);
283 kfree(adapter);
284 }
285 }
286 mutex_unlock(&adapter_list_lock);
287 }
288
289 static struct parport_driver i2c_parport_driver = {
290 .name = "i2c-parport",
291 .match_port = i2c_parport_attach,
292 .detach = i2c_parport_detach,
293 .devmodel = true,
294 };
295
296 /* ----- Module loading, unloading and information ------------------------ */
297
i2c_parport_init(void)298 static int __init i2c_parport_init(void)
299 {
300 if (type < 0) {
301 pr_warn("adapter type unspecified\n");
302 return -ENODEV;
303 }
304
305 if (type >= ARRAY_SIZE(adapter_parm)) {
306 pr_warn("invalid type (%d)\n", type);
307 return -ENODEV;
308 }
309
310 return parport_register_driver(&i2c_parport_driver);
311 }
312
i2c_parport_exit(void)313 static void __exit i2c_parport_exit(void)
314 {
315 parport_unregister_driver(&i2c_parport_driver);
316 }
317
318 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
319 MODULE_DESCRIPTION("I2C bus over parallel port");
320 MODULE_LICENSE("GPL");
321
322 module_param_array(parport, int, NULL, 0);
323 MODULE_PARM_DESC(parport,
324 "List of parallel ports to bind to, by index.\n"
325 " Atmost " __stringify(MAX_DEVICE) " devices are supported.\n"
326 " Default is one device connected to parport0.\n"
327 );
328
329 module_init(i2c_parport_init);
330 module_exit(i2c_parport_exit);
331
