1 /*
2  * STMicroelectronics hts221 spi driver
3  *
4  * Copyright 2016 STMicroelectronics Inc.
5  *
6  * Lorenzo Bianconi <lorenzo.bianconi@st.com>
7  *
8  * Licensed under the GPL-2.
9  */
10 
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/spi/spi.h>
14 #include <linux/slab.h>
15 #include "hts221.h"
16 
17 #define SENSORS_SPI_READ	0x80
18 #define SPI_AUTO_INCREMENT	0x40
19 
20 static int hts221_spi_read(struct device *dev, u8 addr, int len, u8 *data)
21 {
22 	int err;
23 	struct spi_device *spi = to_spi_device(dev);
24 	struct iio_dev *iio_dev = spi_get_drvdata(spi);
25 	struct hts221_hw *hw = iio_priv(iio_dev);
26 
27 	struct spi_transfer xfers[] = {
28 		{
29 			.tx_buf = hw->tb.tx_buf,
30 			.bits_per_word = 8,
31 			.len = 1,
32 		},
33 		{
34 			.rx_buf = hw->tb.rx_buf,
35 			.bits_per_word = 8,
36 			.len = len,
37 		}
38 	};
39 
40 	if (len > 1)
41 		addr |= SPI_AUTO_INCREMENT;
42 	hw->tb.tx_buf[0] = addr | SENSORS_SPI_READ;
43 
44 	err = spi_sync_transfer(spi, xfers,  ARRAY_SIZE(xfers));
45 	if (err < 0)
46 		return err;
47 
48 	memcpy(data, hw->tb.rx_buf, len * sizeof(u8));
49 
50 	return len;
51 }
52 
53 static int hts221_spi_write(struct device *dev, u8 addr, int len, u8 *data)
54 {
55 	struct spi_device *spi = to_spi_device(dev);
56 	struct iio_dev *iio_dev = spi_get_drvdata(spi);
57 	struct hts221_hw *hw = iio_priv(iio_dev);
58 
59 	struct spi_transfer xfers = {
60 		.tx_buf = hw->tb.tx_buf,
61 		.bits_per_word = 8,
62 		.len = len + 1,
63 	};
64 
65 	if (len >= HTS221_TX_MAX_LENGTH)
66 		return -ENOMEM;
67 
68 	if (len > 1)
69 		addr |= SPI_AUTO_INCREMENT;
70 	hw->tb.tx_buf[0] = addr;
71 	memcpy(&hw->tb.tx_buf[1], data, len);
72 
73 	return spi_sync_transfer(spi, &xfers, 1);
74 }
75 
76 static const struct hts221_transfer_function hts221_transfer_fn = {
77 	.read = hts221_spi_read,
78 	.write = hts221_spi_write,
79 };
80 
81 static int hts221_spi_probe(struct spi_device *spi)
82 {
83 	return hts221_probe(&spi->dev, spi->irq,
84 			    spi->modalias, &hts221_transfer_fn);
85 }
86 
87 static const struct of_device_id hts221_spi_of_match[] = {
88 	{ .compatible = "st,hts221", },
89 	{},
90 };
91 MODULE_DEVICE_TABLE(of, hts221_spi_of_match);
92 
93 static const struct spi_device_id hts221_spi_id_table[] = {
94 	{ HTS221_DEV_NAME },
95 	{},
96 };
97 MODULE_DEVICE_TABLE(spi, hts221_spi_id_table);
98 
99 static struct spi_driver hts221_driver = {
100 	.driver = {
101 		.name = "hts221_spi",
102 		.pm = &hts221_pm_ops,
103 		.of_match_table = of_match_ptr(hts221_spi_of_match),
104 	},
105 	.probe = hts221_spi_probe,
106 	.id_table = hts221_spi_id_table,
107 };
108 module_spi_driver(hts221_driver);
109 
110 MODULE_AUTHOR("Lorenzo Bianconi <lorenzo.bianconi@st.com>");
111 MODULE_DESCRIPTION("STMicroelectronics hts221 spi driver");
112 MODULE_LICENSE("GPL v2");
113