2 * AD7879/AD7889 touchscreen (SPI bus)
4 * Copyright (C) 2008-2010 Michael Hennerich, Analog Devices Inc.
6 * Licensed under the GPL-2 or later.
9 #include <linux/input.h> /* BUS_SPI */
11 #include <linux/spi/spi.h>
15 #define AD7879_DEVID 0x7A /* AD7879/AD7889 */
17 #define MAX_SPI_FREQ_HZ 5000000
18 #define AD7879_CMD_MAGIC 0xE000
19 #define AD7879_CMD_READ (1 << 10)
20 #define AD7879_CMD(reg) (AD7879_CMD_MAGIC | ((reg) & 0xF))
21 #define AD7879_WRITECMD(reg) (AD7879_CMD(reg))
22 #define AD7879_READCMD(reg) (AD7879_CMD(reg) | AD7879_CMD_READ)
25 * ad7879_read/write are only used for initial setup and for sysfs controls.
26 * The main traffic is done in ad7879_collect().
29 static int ad7879_spi_xfer(struct spi_device *spi,
30 u16 cmd, u8 count, u16 *tx_buf, u16 *rx_buf)
32 struct spi_message msg;
33 struct spi_transfer *xfers;
36 u16 *_rx_buf = _rx_buf; /* shut gcc up */
40 xfers = spi_data = kzalloc(sizeof(*xfers) * (count + 2), GFP_KERNEL);
44 spi_message_init(&msg);
49 /* ad7879_spi_{read,write} gave us buf on stack */
57 xfers[0].tx_buf = command;
59 spi_message_add_tail(&xfers[0], &msg);
62 for (idx = 0; idx < count; ++idx) {
64 xfers[idx].rx_buf = &rx_buf[idx];
66 xfers[idx].tx_buf = &tx_buf[idx];
68 spi_message_add_tail(&xfers[idx], &msg);
71 ret = spi_sync(spi, &msg);
74 _rx_buf[0] = command[2];
81 static int ad7879_spi_multi_read(struct device *dev,
82 u8 first_reg, u8 count, u16 *buf)
84 struct spi_device *spi = to_spi_device(dev);
86 return ad7879_spi_xfer(spi, AD7879_READCMD(first_reg), count, NULL, buf);
89 static int ad7879_spi_read(struct device *dev, u8 reg)
91 struct spi_device *spi = to_spi_device(dev);
94 return ad7879_spi_xfer(spi, AD7879_READCMD(reg), 1, &dummy, &ret) ? : ret;
97 static int ad7879_spi_write(struct device *dev, u8 reg, u16 val)
99 struct spi_device *spi = to_spi_device(dev);
102 return ad7879_spi_xfer(spi, AD7879_WRITECMD(reg), 1, &val, &dummy);
105 static const struct ad7879_bus_ops ad7879_spi_bus_ops = {
107 .read = ad7879_spi_read,
108 .multi_read = ad7879_spi_multi_read,
109 .write = ad7879_spi_write,
112 static int __devinit ad7879_spi_probe(struct spi_device *spi)
117 /* don't exceed max specified SPI CLK frequency */
118 if (spi->max_speed_hz > MAX_SPI_FREQ_HZ) {
119 dev_err(&spi->dev, "SPI CLK %d Hz?\n", spi->max_speed_hz);
123 spi->bits_per_word = 16;
124 err = spi_setup(spi);
126 dev_dbg(&spi->dev, "spi master doesn't support 16 bits/word\n");
130 ts = ad7879_probe(&spi->dev, AD7879_DEVID, spi->irq, &ad7879_spi_bus_ops);
134 spi_set_drvdata(spi, ts);
139 static int __devexit ad7879_spi_remove(struct spi_device *spi)
141 struct ad7879 *ts = spi_get_drvdata(spi);
144 spi_set_drvdata(spi, NULL);
149 static struct spi_driver ad7879_spi_driver = {
152 .bus = &spi_bus_type,
153 .owner = THIS_MODULE,
154 .pm = &ad7879_pm_ops,
156 .probe = ad7879_spi_probe,
157 .remove = __devexit_p(ad7879_spi_remove),
160 static int __init ad7879_spi_init(void)
162 return spi_register_driver(&ad7879_spi_driver);
164 module_init(ad7879_spi_init);
166 static void __exit ad7879_spi_exit(void)
168 spi_unregister_driver(&ad7879_spi_driver);
170 module_exit(ad7879_spi_exit);
172 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
173 MODULE_DESCRIPTION("AD7879(-1) touchscreen SPI bus driver");
174 MODULE_LICENSE("GPL");
175 MODULE_ALIAS("spi:ad7879");