1 /* ------------------------------------------------------------------------ *
2 * i2c-parport-light.c I2C bus over parallel port *
3 * ------------------------------------------------------------------------ *
4 Copyright (C) 2003-2010 Jean Delvare <jdelvare@suse.de>
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
23 #include <linux/kernel.h>
24 #include <linux/module.h>
25 #include <linux/init.h>
26 #include <linux/delay.h>
27 #include <linux/platform_device.h>
28 #include <linux/ioport.h>
29 #include <linux/i2c.h>
30 #include <linux/i2c-algo-bit.h>
31 #include <linux/i2c-smbus.h>
32 #include <linux/io.h>
33 #include "i2c-parport.h"
34
35 #define DEFAULT_BASE 0x378
36 #define DRVNAME "i2c-parport-light"
37
38 static struct platform_device *pdev;
39
40 static u16 base;
41 module_param(base, ushort, 0);
42 MODULE_PARM_DESC(base, "Base I/O address");
43
44 static int irq;
45 module_param(irq, int, 0);
46 MODULE_PARM_DESC(irq, "IRQ (optional)");
47
48 /* ----- Low-level parallel port access ----------------------------------- */
49
port_write(unsigned char p,unsigned char d)50 static inline void port_write(unsigned char p, unsigned char d)
51 {
52 outb(d, base+p);
53 }
54
port_read(unsigned char p)55 static inline unsigned char port_read(unsigned char p)
56 {
57 return inb(base+p);
58 }
59
60 /* ----- Unified line operation functions --------------------------------- */
61
line_set(int state,const struct lineop * op)62 static inline void line_set(int state, const struct lineop *op)
63 {
64 u8 oldval = port_read(op->port);
65
66 /* Touch only the bit(s) needed */
67 if ((op->inverted && !state) || (!op->inverted && state))
68 port_write(op->port, oldval | op->val);
69 else
70 port_write(op->port, oldval & ~op->val);
71 }
72
line_get(const struct lineop * op)73 static inline int line_get(const struct lineop *op)
74 {
75 u8 oldval = port_read(op->port);
76
77 return ((op->inverted && (oldval & op->val) != op->val)
78 || (!op->inverted && (oldval & op->val) == op->val));
79 }
80
81 /* ----- I2C algorithm call-back functions and structures ----------------- */
82
parport_setscl(void * data,int state)83 static void parport_setscl(void *data, int state)
84 {
85 line_set(state, &adapter_parm[type].setscl);
86 }
87
parport_setsda(void * data,int state)88 static void parport_setsda(void *data, int state)
89 {
90 line_set(state, &adapter_parm[type].setsda);
91 }
92
parport_getscl(void * data)93 static int parport_getscl(void *data)
94 {
95 return line_get(&adapter_parm[type].getscl);
96 }
97
parport_getsda(void * data)98 static int parport_getsda(void *data)
99 {
100 return line_get(&adapter_parm[type].getsda);
101 }
102
103 /* Encapsulate the functions above in the correct structure
104 Note that getscl will be set to NULL by the attaching code for adapters
105 that cannot read SCL back */
106 static struct i2c_algo_bit_data parport_algo_data = {
107 .setsda = parport_setsda,
108 .setscl = parport_setscl,
109 .getsda = parport_getsda,
110 .getscl = parport_getscl,
111 .udelay = 50,
112 .timeout = HZ,
113 };
114
115 /* ----- Driver registration ---------------------------------------------- */
116
117 static struct i2c_adapter parport_adapter = {
118 .owner = THIS_MODULE,
119 .class = I2C_CLASS_HWMON,
120 .algo_data = &parport_algo_data,
121 .name = "Parallel port adapter (light)",
122 };
123
124 /* SMBus alert support */
125 static struct i2c_smbus_alert_setup alert_data = {
126 .alert_edge_triggered = 1,
127 };
128 static struct i2c_client *ara;
129 static struct lineop parport_ctrl_irq = {
130 .val = (1 << 4),
131 .port = PORT_CTRL,
132 };
133
i2c_parport_probe(struct platform_device * pdev)134 static int i2c_parport_probe(struct platform_device *pdev)
135 {
136 int err;
137
138 /* Reset hardware to a sane state (SCL and SDA high) */
139 parport_setsda(NULL, 1);
140 parport_setscl(NULL, 1);
141 /* Other init if needed (power on...) */
142 if (adapter_parm[type].init.val) {
143 line_set(1, &adapter_parm[type].init);
144 /* Give powered devices some time to settle */
145 msleep(100);
146 }
147
148 parport_adapter.dev.parent = &pdev->dev;
149 err = i2c_bit_add_bus(&parport_adapter);
150 if (err) {
151 dev_err(&pdev->dev, "Unable to register with I2C\n");
152 return err;
153 }
154
155 /* Setup SMBus alert if supported */
156 if (adapter_parm[type].smbus_alert && irq) {
157 alert_data.irq = irq;
158 ara = i2c_setup_smbus_alert(&parport_adapter, &alert_data);
159 if (ara)
160 line_set(1, &parport_ctrl_irq);
161 else
162 dev_warn(&pdev->dev, "Failed to register ARA client\n");
163 }
164
165 return 0;
166 }
167
i2c_parport_remove(struct platform_device * pdev)168 static int i2c_parport_remove(struct platform_device *pdev)
169 {
170 if (ara) {
171 line_set(0, &parport_ctrl_irq);
172 i2c_unregister_device(ara);
173 ara = NULL;
174 }
175 i2c_del_adapter(&parport_adapter);
176
177 /* Un-init if needed (power off...) */
178 if (adapter_parm[type].init.val)
179 line_set(0, &adapter_parm[type].init);
180
181 return 0;
182 }
183
184 static struct platform_driver i2c_parport_driver = {
185 .driver = {
186 .name = DRVNAME,
187 },
188 .probe = i2c_parport_probe,
189 .remove = i2c_parport_remove,
190 };
191
i2c_parport_device_add(u16 address)192 static int __init i2c_parport_device_add(u16 address)
193 {
194 int err;
195
196 pdev = platform_device_alloc(DRVNAME, -1);
197 if (!pdev) {
198 err = -ENOMEM;
199 printk(KERN_ERR DRVNAME ": Device allocation failed\n");
200 goto exit;
201 }
202
203 err = platform_device_add(pdev);
204 if (err) {
205 printk(KERN_ERR DRVNAME ": Device addition failed (%d)\n",
206 err);
207 goto exit_device_put;
208 }
209
210 return 0;
211
212 exit_device_put:
213 platform_device_put(pdev);
214 exit:
215 return err;
216 }
217
i2c_parport_init(void)218 static int __init i2c_parport_init(void)
219 {
220 int err;
221
222 if (type < 0) {
223 printk(KERN_ERR DRVNAME ": adapter type unspecified\n");
224 return -ENODEV;
225 }
226
227 if (type >= ARRAY_SIZE(adapter_parm)) {
228 printk(KERN_ERR DRVNAME ": invalid type (%d)\n", type);
229 return -ENODEV;
230 }
231
232 if (base == 0) {
233 pr_info(DRVNAME ": using default base 0x%x\n", DEFAULT_BASE);
234 base = DEFAULT_BASE;
235 }
236
237 if (!request_region(base, 3, DRVNAME))
238 return -EBUSY;
239
240 if (irq != 0)
241 pr_info(DRVNAME ": using irq %d\n", irq);
242
243 if (!adapter_parm[type].getscl.val)
244 parport_algo_data.getscl = NULL;
245
246 /* Sets global pdev as a side effect */
247 err = i2c_parport_device_add(base);
248 if (err)
249 goto exit_release;
250
251 err = platform_driver_register(&i2c_parport_driver);
252 if (err)
253 goto exit_device;
254
255 return 0;
256
257 exit_device:
258 platform_device_unregister(pdev);
259 exit_release:
260 release_region(base, 3);
261 return err;
262 }
263
i2c_parport_exit(void)264 static void __exit i2c_parport_exit(void)
265 {
266 platform_driver_unregister(&i2c_parport_driver);
267 platform_device_unregister(pdev);
268 release_region(base, 3);
269 }
270
271 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
272 MODULE_DESCRIPTION("I2C bus over parallel port (light)");
273 MODULE_LICENSE("GPL");
274
275 module_init(i2c_parport_init);
276 module_exit(i2c_parport_exit);
277