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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 */ | |
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 | ||
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 | ||
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 | ||
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 | ||
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 | ||
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"); |