1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* ------------------------------------------------------------------------ *
3 * i2c-parport-light.c I2C bus over parallel port *
4 * ------------------------------------------------------------------------ *
5 Copyright (C) 2003-2010 Jean Delvare <jdelvare@suse.de>
6
7 Based on older i2c-velleman.c driver
8 Copyright (C) 1995-2000 Simon G. Vogl
9 With some changes from:
10 Frodo Looijaard <frodol@dds.nl>
11 Kyösti Mälkki <kmalkki@cc.hut.fi>
12
13 * ------------------------------------------------------------------------ */
14
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/init.h>
18 #include <linux/delay.h>
19 #include <linux/platform_device.h>
20 #include <linux/ioport.h>
21 #include <linux/i2c.h>
22 #include <linux/i2c-algo-bit.h>
23 #include <linux/i2c-smbus.h>
24 #include <linux/io.h>
25 #include "i2c-parport.h"
26
27 #define DEFAULT_BASE 0x378
28 #define DRVNAME "i2c-parport-light"
29
30 static struct platform_device *pdev;
31
32 static u16 base;
33 module_param_hw(base, ushort, ioport, 0);
34 MODULE_PARM_DESC(base, "Base I/O address");
35
36 static int irq;
37 module_param_hw(irq, int, irq, 0);
38 MODULE_PARM_DESC(irq, "IRQ (optional)");
39
40 /* ----- Low-level parallel port access ----------------------------------- */
41
port_write(unsigned char p,unsigned char d)42 static inline void port_write(unsigned char p, unsigned char d)
43 {
44 outb(d, base+p);
45 }
46
port_read(unsigned char p)47 static inline unsigned char port_read(unsigned char p)
48 {
49 return inb(base+p);
50 }
51
52 /* ----- Unified line operation functions --------------------------------- */
53
line_set(int state,const struct lineop * op)54 static inline void line_set(int state, const struct lineop *op)
55 {
56 u8 oldval = port_read(op->port);
57
58 /* Touch only the bit(s) needed */
59 if ((op->inverted && !state) || (!op->inverted && state))
60 port_write(op->port, oldval | op->val);
61 else
62 port_write(op->port, oldval & ~op->val);
63 }
64
line_get(const struct lineop * op)65 static inline int line_get(const struct lineop *op)
66 {
67 u8 oldval = port_read(op->port);
68
69 return ((op->inverted && (oldval & op->val) != op->val)
70 || (!op->inverted && (oldval & op->val) == op->val));
71 }
72
73 /* ----- I2C algorithm call-back functions and structures ----------------- */
74
parport_setscl(void * data,int state)75 static void parport_setscl(void *data, int state)
76 {
77 line_set(state, &adapter_parm[type].setscl);
78 }
79
parport_setsda(void * data,int state)80 static void parport_setsda(void *data, int state)
81 {
82 line_set(state, &adapter_parm[type].setsda);
83 }
84
parport_getscl(void * data)85 static int parport_getscl(void *data)
86 {
87 return line_get(&adapter_parm[type].getscl);
88 }
89
parport_getsda(void * data)90 static int parport_getsda(void *data)
91 {
92 return line_get(&adapter_parm[type].getsda);
93 }
94
95 /* Encapsulate the functions above in the correct structure
96 Note that getscl will be set to NULL by the attaching code for adapters
97 that cannot read SCL back */
98 static struct i2c_algo_bit_data parport_algo_data = {
99 .setsda = parport_setsda,
100 .setscl = parport_setscl,
101 .getsda = parport_getsda,
102 .getscl = parport_getscl,
103 .udelay = 50,
104 .timeout = HZ,
105 };
106
107 /* ----- Driver registration ---------------------------------------------- */
108
109 static struct i2c_adapter parport_adapter = {
110 .owner = THIS_MODULE,
111 .class = I2C_CLASS_HWMON,
112 .algo_data = &parport_algo_data,
113 .name = "Parallel port adapter (light)",
114 };
115
116 /* SMBus alert support */
117 static struct i2c_smbus_alert_setup alert_data = {
118 };
119 static struct i2c_client *ara;
120 static struct lineop parport_ctrl_irq = {
121 .val = (1 << 4),
122 .port = PORT_CTRL,
123 };
124
i2c_parport_probe(struct platform_device * pdev)125 static int i2c_parport_probe(struct platform_device *pdev)
126 {
127 int err;
128
129 /* Reset hardware to a sane state (SCL and SDA high) */
130 parport_setsda(NULL, 1);
131 parport_setscl(NULL, 1);
132 /* Other init if needed (power on...) */
133 if (adapter_parm[type].init.val) {
134 line_set(1, &adapter_parm[type].init);
135 /* Give powered devices some time to settle */
136 msleep(100);
137 }
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 return err;
144 }
145
146 /* Setup SMBus alert if supported */
147 if (adapter_parm[type].smbus_alert && irq) {
148 alert_data.irq = irq;
149 ara = i2c_setup_smbus_alert(&parport_adapter, &alert_data);
150 if (ara)
151 line_set(1, &parport_ctrl_irq);
152 else
153 dev_warn(&pdev->dev, "Failed to register ARA client\n");
154 }
155
156 return 0;
157 }
158
i2c_parport_remove(struct platform_device * pdev)159 static int i2c_parport_remove(struct platform_device *pdev)
160 {
161 if (ara) {
162 line_set(0, &parport_ctrl_irq);
163 i2c_unregister_device(ara);
164 ara = NULL;
165 }
166 i2c_del_adapter(&parport_adapter);
167
168 /* Un-init if needed (power off...) */
169 if (adapter_parm[type].init.val)
170 line_set(0, &adapter_parm[type].init);
171
172 return 0;
173 }
174
175 static struct platform_driver i2c_parport_driver = {
176 .driver = {
177 .name = DRVNAME,
178 },
179 .probe = i2c_parport_probe,
180 .remove = i2c_parport_remove,
181 };
182
i2c_parport_device_add(u16 address)183 static int __init i2c_parport_device_add(u16 address)
184 {
185 int err;
186
187 pdev = platform_device_alloc(DRVNAME, -1);
188 if (!pdev) {
189 err = -ENOMEM;
190 printk(KERN_ERR DRVNAME ": Device allocation failed\n");
191 goto exit;
192 }
193
194 err = platform_device_add(pdev);
195 if (err) {
196 printk(KERN_ERR DRVNAME ": Device addition failed (%d)\n",
197 err);
198 goto exit_device_put;
199 }
200
201 return 0;
202
203 exit_device_put:
204 platform_device_put(pdev);
205 exit:
206 return err;
207 }
208
i2c_parport_init(void)209 static int __init i2c_parport_init(void)
210 {
211 int err;
212
213 if (type < 0) {
214 printk(KERN_ERR DRVNAME ": adapter type unspecified\n");
215 return -ENODEV;
216 }
217
218 if (type >= ARRAY_SIZE(adapter_parm)) {
219 printk(KERN_ERR DRVNAME ": invalid type (%d)\n", type);
220 return -ENODEV;
221 }
222
223 if (base == 0) {
224 pr_info(DRVNAME ": using default base 0x%x\n", DEFAULT_BASE);
225 base = DEFAULT_BASE;
226 }
227
228 if (!request_region(base, 3, DRVNAME))
229 return -EBUSY;
230
231 if (irq != 0)
232 pr_info(DRVNAME ": using irq %d\n", irq);
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_release;
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_release:
251 release_region(base, 3);
252 return err;
253 }
254
i2c_parport_exit(void)255 static void __exit i2c_parport_exit(void)
256 {
257 platform_driver_unregister(&i2c_parport_driver);
258 platform_device_unregister(pdev);
259 release_region(base, 3);
260 }
261
262 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
263 MODULE_DESCRIPTION("I2C bus over parallel port (light)");
264 MODULE_LICENSE("GPL");
265
266 module_init(i2c_parport_init);
267 module_exit(i2c_parport_exit);
268
