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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 | if (spi->dev.platform_data) |
60 | spi->bits_per_word = 16; |
61 | ret = spi_setup(spi); |
62 | if (ret < 0) |
63 | return ret; |
64 | |
65 | ts = devm_kzalloc(&spi->dev, sizeof(struct max7301), GFP_KERNEL); |
66 | if (!ts) |
67 | return -ENOMEM; |
68 | |
69 | ts->read = max7301_spi_read; |
70 | ts->write = max7301_spi_write; |
71 | ts->dev = &spi->dev; |
72 | |
73 | ret = __max730x_probe(ts); |
74 | return ret; |
75 | } |
76 | |
77 | static int max7301_remove(struct spi_device *spi) |
78 | { |
79 | return __max730x_remove(&spi->dev); |
80 | } |
81 | |
82 | static const struct spi_device_id max7301_id[] = { |
83 | { "max7301", 0 }, |
84 | { } |
85 | }; |
86 | MODULE_DEVICE_TABLE(spi, max7301_id); |
87 | |
88 | static struct spi_driver max7301_driver = { |
89 | .driver = { |
90 | .name = "max7301", |
91 | .owner = THIS_MODULE, |
92 | }, |
93 | .probe = max7301_probe, |
94 | .remove = max7301_remove, |
95 | .id_table = max7301_id, |
96 | }; |
97 | |
98 | static int __init max7301_init(void) |
99 | { |
100 | return spi_register_driver(&max7301_driver); |
101 | } |
102 | /* register after spi postcore initcall and before |
103 | * subsys initcalls that may rely on these GPIOs |
104 | */ |
105 | subsys_initcall(max7301_init); |
106 | |
107 | static void __exit max7301_exit(void) |
108 | { |
109 | spi_unregister_driver(&max7301_driver); |
110 | } |
111 | module_exit(max7301_exit); |
112 | |
113 | MODULE_AUTHOR("Juergen Beisert, Wolfram Sang"); |
114 | MODULE_LICENSE("GPL v2"); |
115 | MODULE_DESCRIPTION("MAX7301 GPIO-Expander"); |
116 |
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