1 /*
2 * Copyright (C) 2006 Juergen Beisert, Pengutronix
3 * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix
4 * Copyright (C) 2009 Wolfram Sang, Pengutronix
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * Check max730x.c for further details.
11 */
12
13 #include <linux/module.h>
14 #include <linux/init.h>
15 #include <linux/platform_device.h>
16 #include <linux/mutex.h>
17 #include <linux/slab.h>
18 #include <linux/spi/spi.h>
19 #include <linux/spi/max7301.h>
20
21 /* A write to the MAX7301 means one message with one transfer */
max7301_spi_write(struct device * dev,unsigned int reg,unsigned int val)22 static int max7301_spi_write(struct device *dev, unsigned int reg,
23 unsigned int val)
24 {
25 struct spi_device *spi = to_spi_device(dev);
26 u16 word = ((reg & 0x7F) << 8) | (val & 0xFF);
27
28 return spi_write(spi, (const u8 *)&word, sizeof(word));
29 }
30
31 /* A read from the MAX7301 means two transfers; here, one message each */
32
max7301_spi_read(struct device * dev,unsigned int reg)33 static int max7301_spi_read(struct device *dev, unsigned int reg)
34 {
35 int ret;
36 u16 word;
37 struct spi_device *spi = to_spi_device(dev);
38
39 word = 0x8000 | (reg << 8);
40 ret = spi_write(spi, (const u8 *)&word, sizeof(word));
41 if (ret)
42 return ret;
43 /*
44 * This relies on the fact, that a transfer with NULL tx_buf shifts out
45 * zero bytes (=NOOP for MAX7301)
46 */
47 ret = spi_read(spi, (u8 *)&word, sizeof(word));
48 if (ret)
49 return ret;
50 return word & 0xff;
51 }
52
max7301_probe(struct spi_device * spi)53 static int max7301_probe(struct spi_device *spi)
54 {
55 struct max7301 *ts;
56 int ret;
57
58 /* bits_per_word cannot be configured in platform data */
59 spi->bits_per_word = 16;
60 ret = spi_setup(spi);
61 if (ret < 0)
62 return ret;
63
64 ts = devm_kzalloc(&spi->dev, sizeof(struct max7301), GFP_KERNEL);
65 if (!ts)
66 return -ENOMEM;
67
68 ts->read = max7301_spi_read;
69 ts->write = max7301_spi_write;
70 ts->dev = &spi->dev;
71
72 ret = __max730x_probe(ts);
73 return ret;
74 }
75
max7301_remove(struct spi_device * spi)76 static int max7301_remove(struct spi_device *spi)
77 {
78 return __max730x_remove(&spi->dev);
79 }
80
81 static const struct spi_device_id max7301_id[] = {
82 { "max7301", 0 },
83 { }
84 };
85 MODULE_DEVICE_TABLE(spi, max7301_id);
86
87 static struct spi_driver max7301_driver = {
88 .driver = {
89 .name = "max7301",
90 },
91 .probe = max7301_probe,
92 .remove = max7301_remove,
93 .id_table = max7301_id,
94 };
95
max7301_init(void)96 static int __init max7301_init(void)
97 {
98 return spi_register_driver(&max7301_driver);
99 }
100 /* register after spi postcore initcall and before
101 * subsys initcalls that may rely on these GPIOs
102 */
103 subsys_initcall(max7301_init);
104
max7301_exit(void)105 static void __exit max7301_exit(void)
106 {
107 spi_unregister_driver(&max7301_driver);
108 }
109 module_exit(max7301_exit);
110
111 MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
112 MODULE_LICENSE("GPL v2");
113 MODULE_DESCRIPTION("MAX7301 GPIO-Expander");
114
