1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Copyright (C) 2006 Juergen Beisert, Pengutronix |
4 | * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix |
5 | * Copyright (C) 2009 Wolfram Sang, Pengutronix |
6 | * |
7 | * Check max730x.c for further details. |
8 | */ |
9 | |
10 | #include <linux/module.h> |
11 | #include <linux/init.h> |
12 | #include <linux/platform_device.h> |
13 | #include <linux/mutex.h> |
14 | #include <linux/slab.h> |
15 | #include <linux/spi/spi.h> |
16 | #include <linux/spi/max7301.h> |
17 | |
18 | /* A write to the MAX7301 means one message with one transfer */ |
19 | static int max7301_spi_write(struct device *dev, unsigned int reg, |
20 | unsigned int val) |
21 | { |
22 | struct spi_device *spi = to_spi_device(dev); |
23 | u16 word = ((reg & 0x7F) << 8) | (val & 0xFF); |
24 | |
25 | return spi_write_then_read(spi, txbuf: &word, n_tx: sizeof(word), NULL, n_rx: 0); |
26 | } |
27 | |
28 | /* A read from the MAX7301 means two transfers; here, one message each */ |
29 | |
30 | static int max7301_spi_read(struct device *dev, unsigned int reg) |
31 | { |
32 | int ret; |
33 | u16 word; |
34 | struct spi_device *spi = to_spi_device(dev); |
35 | |
36 | word = 0x8000 | (reg << 8); |
37 | ret = spi_write_then_read(spi, txbuf: &word, n_tx: sizeof(word), rxbuf: &word, |
38 | n_rx: sizeof(word)); |
39 | if (ret) |
40 | return ret; |
41 | return word & 0xff; |
42 | } |
43 | |
44 | static int max7301_probe(struct spi_device *spi) |
45 | { |
46 | struct max7301 *ts; |
47 | int ret; |
48 | |
49 | /* bits_per_word cannot be configured in platform data */ |
50 | spi->bits_per_word = 16; |
51 | ret = spi_setup(spi); |
52 | if (ret < 0) |
53 | return ret; |
54 | |
55 | ts = devm_kzalloc(dev: &spi->dev, size: sizeof(struct max7301), GFP_KERNEL); |
56 | if (!ts) |
57 | return -ENOMEM; |
58 | |
59 | ts->read = max7301_spi_read; |
60 | ts->write = max7301_spi_write; |
61 | ts->dev = &spi->dev; |
62 | |
63 | ret = __max730x_probe(ts); |
64 | return ret; |
65 | } |
66 | |
67 | static void max7301_remove(struct spi_device *spi) |
68 | { |
69 | __max730x_remove(dev: &spi->dev); |
70 | } |
71 | |
72 | static const struct spi_device_id max7301_id[] = { |
73 | { "max7301" , 0 }, |
74 | { } |
75 | }; |
76 | MODULE_DEVICE_TABLE(spi, max7301_id); |
77 | |
78 | static struct spi_driver max7301_driver = { |
79 | .driver = { |
80 | .name = "max7301" , |
81 | }, |
82 | .probe = max7301_probe, |
83 | .remove = max7301_remove, |
84 | .id_table = max7301_id, |
85 | }; |
86 | |
87 | static int __init max7301_init(void) |
88 | { |
89 | return spi_register_driver(&max7301_driver); |
90 | } |
91 | /* register after spi postcore initcall and before |
92 | * subsys initcalls that may rely on these GPIOs |
93 | */ |
94 | subsys_initcall(max7301_init); |
95 | |
96 | static void __exit max7301_exit(void) |
97 | { |
98 | spi_unregister_driver(sdrv: &max7301_driver); |
99 | } |
100 | module_exit(max7301_exit); |
101 | |
102 | MODULE_AUTHOR("Juergen Beisert, Wolfram Sang" ); |
103 | MODULE_LICENSE("GPL v2" ); |
104 | MODULE_DESCRIPTION("MAX7301 GPIO-Expander" ); |
105 | |