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 */
max7301_spi_write(struct device * dev,unsigned int reg,unsigned int val)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, &word, sizeof(word), NULL, 0);
26 }
27
28 /* A read from the MAX7301 means two transfers; here, one message each */
29
max7301_spi_read(struct device * dev,unsigned int reg)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, &word, sizeof(word), &word,
38 sizeof(word));
39 if (ret)
40 return ret;
41 return word & 0xff;
42 }
43
max7301_probe(struct spi_device * spi)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(&spi->dev, 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
max7301_remove(struct spi_device * spi)67 static void max7301_remove(struct spi_device *spi)
68 {
69 __max730x_remove(&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
max7301_init(void)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
max7301_exit(void)96 static void __exit max7301_exit(void)
97 {
98 spi_unregister_driver(&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