1/*
2 * AD7879/AD7889 touchscreen (SPI bus)
3 *
4 * Copyright (C) 2008-2010 Michael Hennerich, Analog Devices Inc.
5 *
6 * Licensed under the GPL-2 or later.
7 */
8
9#include <linux/input.h>	/* BUS_SPI */
10#include <linux/pm.h>
11#include <linux/spi/spi.h>
12#include <linux/module.h>
13
14#include "ad7879.h"
15
16#define AD7879_DEVID		0x7A	/* AD7879/AD7889 */
17
18#define MAX_SPI_FREQ_HZ      5000000
19#define AD7879_CMD_MAGIC     0xE000
20#define AD7879_CMD_READ      (1 << 10)
21#define AD7879_CMD(reg)      (AD7879_CMD_MAGIC | ((reg) & 0xF))
22#define AD7879_WRITECMD(reg) (AD7879_CMD(reg))
23#define AD7879_READCMD(reg)  (AD7879_CMD(reg) | AD7879_CMD_READ)
24
25/*
26 * ad7879_read/write are only used for initial setup and for sysfs controls.
27 * The main traffic is done in ad7879_collect().
28 */
29
30static int ad7879_spi_xfer(struct spi_device *spi,
31			   u16 cmd, u8 count, u16 *tx_buf, u16 *rx_buf)
32{
33	struct spi_message msg;
34	struct spi_transfer *xfers;
35	void *spi_data;
36	u16 *command;
37	u16 *_rx_buf = _rx_buf; /* shut gcc up */
38	u8 idx;
39	int ret;
40
41	xfers = spi_data = kzalloc(sizeof(*xfers) * (count + 2), GFP_KERNEL);
42	if (!spi_data)
43		return -ENOMEM;
44
45	spi_message_init(&msg);
46
47	command = spi_data;
48	command[0] = cmd;
49	if (count == 1) {
50		/* ad7879_spi_{read,write} gave us buf on stack */
51		command[1] = *tx_buf;
52		tx_buf = &command[1];
53		_rx_buf = rx_buf;
54		rx_buf = &command[2];
55	}
56
57	++xfers;
58	xfers[0].tx_buf = command;
59	xfers[0].len = 2;
60	spi_message_add_tail(&xfers[0], &msg);
61	++xfers;
62
63	for (idx = 0; idx < count; ++idx) {
64		if (rx_buf)
65			xfers[idx].rx_buf = &rx_buf[idx];
66		if (tx_buf)
67			xfers[idx].tx_buf = &tx_buf[idx];
68		xfers[idx].len = 2;
69		spi_message_add_tail(&xfers[idx], &msg);
70	}
71
72	ret = spi_sync(spi, &msg);
73
74	if (count == 1)
75		_rx_buf[0] = command[2];
76
77	kfree(spi_data);
78
79	return ret;
80}
81
82static int ad7879_spi_multi_read(struct device *dev,
83				 u8 first_reg, u8 count, u16 *buf)
84{
85	struct spi_device *spi = to_spi_device(dev);
86
87	return ad7879_spi_xfer(spi, AD7879_READCMD(first_reg), count, NULL, buf);
88}
89
90static int ad7879_spi_read(struct device *dev, u8 reg)
91{
92	struct spi_device *spi = to_spi_device(dev);
93	u16 ret, dummy;
94
95	return ad7879_spi_xfer(spi, AD7879_READCMD(reg), 1, &dummy, &ret) ? : ret;
96}
97
98static int ad7879_spi_write(struct device *dev, u8 reg, u16 val)
99{
100	struct spi_device *spi = to_spi_device(dev);
101	u16 dummy;
102
103	return ad7879_spi_xfer(spi, AD7879_WRITECMD(reg), 1, &val, &dummy);
104}
105
106static const struct ad7879_bus_ops ad7879_spi_bus_ops = {
107	.bustype	= BUS_SPI,
108	.read		= ad7879_spi_read,
109	.multi_read	= ad7879_spi_multi_read,
110	.write		= ad7879_spi_write,
111};
112
113static int ad7879_spi_probe(struct spi_device *spi)
114{
115	struct ad7879 *ts;
116	int err;
117
118	/* don't exceed max specified SPI CLK frequency */
119	if (spi->max_speed_hz > MAX_SPI_FREQ_HZ) {
120		dev_err(&spi->dev, "SPI CLK %d Hz?\n", spi->max_speed_hz);
121		return -EINVAL;
122	}
123
124	spi->bits_per_word = 16;
125	err = spi_setup(spi);
126	if (err) {
127	        dev_dbg(&spi->dev, "spi master doesn't support 16 bits/word\n");
128	        return err;
129	}
130
131	ts = ad7879_probe(&spi->dev, AD7879_DEVID, spi->irq, &ad7879_spi_bus_ops);
132	if (IS_ERR(ts))
133		return PTR_ERR(ts);
134
135	spi_set_drvdata(spi, ts);
136
137	return 0;
138}
139
140static int ad7879_spi_remove(struct spi_device *spi)
141{
142	struct ad7879 *ts = spi_get_drvdata(spi);
143
144	ad7879_remove(ts);
145
146	return 0;
147}
148
149static struct spi_driver ad7879_spi_driver = {
150	.driver = {
151		.name	= "ad7879",
152		.owner	= THIS_MODULE,
153		.pm	= &ad7879_pm_ops,
154	},
155	.probe		= ad7879_spi_probe,
156	.remove		= ad7879_spi_remove,
157};
158
159module_spi_driver(ad7879_spi_driver);
160
161MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
162MODULE_DESCRIPTION("AD7879(-1) touchscreen SPI bus driver");
163MODULE_LICENSE("GPL");
164MODULE_ALIAS("spi:ad7879");
165