1 /* ------------------------------------------------------------------------ *
2 * i2c-parport-light.c I2C bus over parallel port *
3 * ------------------------------------------------------------------------ *
4 Copyright (C) 2003-2007 Jean Delvare <khali@linux-fr.org>
5
6 Based on older i2c-velleman.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 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/platform_device.h>
31 #include <linux/ioport.h>
32 #include <linux/i2c.h>
33 #include <linux/i2c-algo-bit.h>
34 #include <asm/io.h>
35 #include "i2c-parport.h"
36
37 #define DEFAULT_BASE 0x378
38 #define DRVNAME "i2c-parport-light"
39
40 static struct platform_device *pdev;
41
42 static u16 base;
43 module_param(base, ushort, 0);
44 MODULE_PARM_DESC(base, "Base I/O address");
45
46 /* ----- Low-level parallel port access ----------------------------------- */
47
48 static inline void port_write(unsigned char p, unsigned char d)
49 {
50 outb(d, base+p);
51 }
52
53 static inline unsigned char port_read(unsigned char p)
54 {
55 return inb(base+p);
56 }
57
58 /* ----- Unified line operation functions --------------------------------- */
59
60 static inline void line_set(int state, const struct lineop *op)
61 {
62 u8 oldval = port_read(op->port);
63
64 /* Touch only the bit(s) needed */
65 if ((op->inverted && !state) || (!op->inverted && state))
66 port_write(op->port, oldval | op->val);
67 else
68 port_write(op->port, oldval & ~op->val);
69 }
70
71 static inline int line_get(const struct lineop *op)
72 {
73 u8 oldval = port_read(op->port);
74
75 return ((op->inverted && (oldval & op->val) != op->val)
76 || (!op->inverted && (oldval & op->val) == op->val));
77 }
78
79 /* ----- I2C algorithm call-back functions and structures ----------------- */
80
81 static void parport_setscl(void *data, int state)
82 {
83 line_set(state, &adapter_parm[type].setscl);
84 }
85
86 static void parport_setsda(void *data, int state)
87 {
88 line_set(state, &adapter_parm[type].setsda);
89 }
90
91 static int parport_getscl(void *data)
92 {
93 return line_get(&adapter_parm[type].getscl);
94 }
95
96 static int parport_getsda(void *data)
97 {
98 return line_get(&adapter_parm[type].getsda);
99 }
100
101 /* Encapsulate the functions above in the correct structure
102 Note that getscl will be set to NULL by the attaching code for adapters
103 that cannot read SCL back */
104 static struct i2c_algo_bit_data parport_algo_data = {
105 .setsda = parport_setsda,
106 .setscl = parport_setscl,
107 .getsda = parport_getsda,
108 .getscl = parport_getscl,
109 .udelay = 50,
110 .timeout = HZ,
111 };
112
113 /* ----- Driver registration ---------------------------------------------- */
114
115 static struct i2c_adapter parport_adapter = {
116 .owner = THIS_MODULE,
117 .class = I2C_CLASS_HWMON,
118 .id = I2C_HW_B_LP,
119 .algo_data = &parport_algo_data,
120 .name = "Parallel port adapter (light)",
121 };
122
123 static int __devinit i2c_parport_probe(struct platform_device *pdev)
124 {
125 int err;
126 struct resource *res;
127
128 res = platform_get_resource(pdev, IORESOURCE_IO, 0);
129 if (!request_region(res->start, res->end - res->start + 1, DRVNAME))
130 return -EBUSY;
131
132 /* Reset hardware to a sane state (SCL and SDA high) */
133 parport_setsda(NULL, 1);
134 parport_setscl(NULL, 1);
135 /* Other init if needed (power on...) */
136 if (adapter_parm[type].init.val)
137 line_set(1, &adapter_parm[type].init);
138
139 parport_adapter.dev.parent = &pdev->dev;
140 err = i2c_bit_add_bus(&parport_adapter);
141 if (err) {
142 dev_err(&pdev->dev, "Unable to register with I2C\n");
143 goto exit_region;
144 }
145 return 0;
146
147 exit_region:
148 release_region(res->start, res->end - res->start + 1);
149 return err;
150 }
151
152 static int __devexit i2c_parport_remove(struct platform_device *pdev)
153 {
154 struct resource *res;
155
156 i2c_del_adapter(&parport_adapter);
157
158 /* Un-init if needed (power off...) */
159 if (adapter_parm[type].init.val)
160 line_set(0, &adapter_parm[type].init);
161
162 res = platform_get_resource(pdev, IORESOURCE_IO, 0);
163 release_region(res->start, res->end - res->start + 1);
164 return 0;
165 }
166
167 static struct platform_driver i2c_parport_driver = {
168 .driver = {
169 .owner = THIS_MODULE,
170 .name = DRVNAME,
171 },
172 .probe = i2c_parport_probe,
173 .remove = __devexit_p(i2c_parport_remove),
174 };
175
176 static int __init i2c_parport_device_add(u16 address)
177 {
178 struct resource res = {
179 .start = address,
180 .end = address + 2,
181 .name = DRVNAME,
182 .flags = IORESOURCE_IO,
183 };
184 int err;
185
186 pdev = platform_device_alloc(DRVNAME, -1);
187 if (!pdev) {
188 err = -ENOMEM;
189 printk(KERN_ERR DRVNAME ": Device allocation failed\n");
190 goto exit;
191 }
192
193 err = platform_device_add_resources(pdev, &res, 1);
194 if (err) {
195 printk(KERN_ERR DRVNAME ": Device resource addition failed "
196 "(%d)\n", err);
197 goto exit_device_put;
198 }
199
200 err = platform_device_add(pdev);
201 if (err) {
202 printk(KERN_ERR DRVNAME ": Device addition failed (%d)\n",
203 err);
204 goto exit_device_put;
205 }
206
207 return 0;
208
209 exit_device_put:
210 platform_device_put(pdev);
211 exit:
212 return err;
213 }
214
215 static int __init i2c_parport_init(void)
216 {
217 int err;
218
219 if (type < 0) {
220 printk(KERN_ERR DRVNAME ": adapter type unspecified\n");
221 return -ENODEV;
222 }
223
224 if (type >= ARRAY_SIZE(adapter_parm)) {
225 printk(KERN_ERR DRVNAME ": invalid type (%d)\n", type);
226 return -ENODEV;
227 }
228
229 if (base == 0) {
230 pr_info(DRVNAME ": using default base 0x%x\n", DEFAULT_BASE);
231 base = DEFAULT_BASE;
232 }
233
234 if (!adapter_parm[type].getscl.val)
235 parport_algo_data.getscl = NULL;
236
237 /* Sets global pdev as a side effect */
238 err = i2c_parport_device_add(base);
239 if (err)
240 goto exit;
241
242 err = platform_driver_register(&i2c_parport_driver);
243 if (err)
244 goto exit_device;
245
246 return 0;
247
248 exit_device:
249 platform_device_unregister(pdev);
250 exit:
251 return err;
252 }
253
254 static void __exit i2c_parport_exit(void)
255 {
256 platform_driver_unregister(&i2c_parport_driver);
257 platform_device_unregister(pdev);
258 }
259
260 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
261 MODULE_DESCRIPTION("I2C bus over parallel port (light)");
262 MODULE_LICENSE("GPL");
263
264 module_init(i2c_parport_init);
265 module_exit(i2c_parport_exit);
266
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