xref: /openbmc/linux/drivers/gpio/gpio-max7301.c (revision a0386bba)
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