1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Freescale MPL115A1 pressure/temperature sensor
4  *
5  * Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com>
6  *
7  * Datasheet: http://www.nxp.com/files/sensors/doc/data_sheet/MPL115A1.pdf
8  */
9 
10 #include <linux/module.h>
11 #include <linux/spi/spi.h>
12 
13 #include "mpl115.h"
14 
15 #define MPL115_SPI_WRITE(address)	((address) << 1)
16 #define MPL115_SPI_READ(address)	(0x80 | (address) << 1)
17 
18 struct mpl115_spi_buf {
19 	u8 tx[4];
20 	u8 rx[4];
21 };
22 
23 static int mpl115_spi_init(struct device *dev)
24 {
25 	struct spi_device *spi = to_spi_device(dev);
26 	struct mpl115_spi_buf *buf;
27 
28 	buf = devm_kzalloc(dev, sizeof(*buf), GFP_KERNEL);
29 	if (!buf)
30 		return -ENOMEM;
31 
32 	spi_set_drvdata(spi, buf);
33 
34 	return 0;
35 }
36 
37 static int mpl115_spi_read(struct device *dev, u8 address)
38 {
39 	struct spi_device *spi = to_spi_device(dev);
40 	struct mpl115_spi_buf *buf = spi_get_drvdata(spi);
41 	struct spi_transfer xfer = {
42 		.tx_buf = buf->tx,
43 		.rx_buf = buf->rx,
44 		.len = 4,
45 	};
46 	int ret;
47 
48 	buf->tx[0] = MPL115_SPI_READ(address);
49 	buf->tx[2] = MPL115_SPI_READ(address + 1);
50 
51 	ret = spi_sync_transfer(spi, &xfer, 1);
52 	if (ret)
53 		return ret;
54 
55 	return (buf->rx[1] << 8) | buf->rx[3];
56 }
57 
58 static int mpl115_spi_write(struct device *dev, u8 address, u8 value)
59 {
60 	struct spi_device *spi = to_spi_device(dev);
61 	struct mpl115_spi_buf *buf = spi_get_drvdata(spi);
62 	struct spi_transfer xfer = {
63 		.tx_buf = buf->tx,
64 		.len = 2,
65 	};
66 
67 	buf->tx[0] = MPL115_SPI_WRITE(address);
68 	buf->tx[1] = value;
69 
70 	return spi_sync_transfer(spi, &xfer, 1);
71 }
72 
73 static const struct mpl115_ops mpl115_spi_ops = {
74 	.init = mpl115_spi_init,
75 	.read = mpl115_spi_read,
76 	.write = mpl115_spi_write,
77 };
78 
79 static int mpl115_spi_probe(struct spi_device *spi)
80 {
81 	const struct spi_device_id *id = spi_get_device_id(spi);
82 
83 	return mpl115_probe(&spi->dev, id->name, &mpl115_spi_ops);
84 }
85 
86 static const struct spi_device_id mpl115_spi_ids[] = {
87 	{ "mpl115", 0 },
88 	{}
89 };
90 MODULE_DEVICE_TABLE(spi, mpl115_spi_ids);
91 
92 static struct spi_driver mpl115_spi_driver = {
93 	.driver = {
94 		.name   = "mpl115",
95 	},
96 	.probe = mpl115_spi_probe,
97 	.id_table = mpl115_spi_ids,
98 };
99 module_spi_driver(mpl115_spi_driver);
100 
101 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
102 MODULE_DESCRIPTION("Freescale MPL115A1 pressure/temperature driver");
103 MODULE_LICENSE("GPL");
104