164 lines
3.6 KiB
C
164 lines
3.6 KiB
C
/*
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* AD7879/AD7889 touchscreen (SPI bus)
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*
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* Copyright (C) 2008-2010 Michael Hennerich, Analog Devices Inc.
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*
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* Licensed under the GPL-2 or later.
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*/
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#include <linux/input.h> /* BUS_SPI */
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#include <linux/pm.h>
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#include <linux/spi/spi.h>
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#include <linux/module.h>
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#include "ad7879.h"
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#define AD7879_DEVID 0x7A /* AD7879/AD7889 */
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#define MAX_SPI_FREQ_HZ 5000000
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#define AD7879_CMD_MAGIC 0xE000
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#define AD7879_CMD_READ (1 << 10)
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#define AD7879_CMD(reg) (AD7879_CMD_MAGIC | ((reg) & 0xF))
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#define AD7879_WRITECMD(reg) (AD7879_CMD(reg))
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#define AD7879_READCMD(reg) (AD7879_CMD(reg) | AD7879_CMD_READ)
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/*
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* ad7879_read/write are only used for initial setup and for sysfs controls.
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* The main traffic is done in ad7879_collect().
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*/
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static int ad7879_spi_xfer(struct spi_device *spi,
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u16 cmd, u8 count, u16 *tx_buf, u16 *rx_buf)
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{
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struct spi_message msg;
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struct spi_transfer *xfers;
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void *spi_data;
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u16 *command;
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u16 *_rx_buf = _rx_buf; /* shut gcc up */
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u8 idx;
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int ret;
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xfers = spi_data = kzalloc(sizeof(*xfers) * (count + 2), GFP_KERNEL);
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if (!spi_data)
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return -ENOMEM;
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spi_message_init(&msg);
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command = spi_data;
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command[0] = cmd;
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if (count == 1) {
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/* ad7879_spi_{read,write} gave us buf on stack */
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command[1] = *tx_buf;
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tx_buf = &command[1];
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_rx_buf = rx_buf;
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rx_buf = &command[2];
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}
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++xfers;
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xfers[0].tx_buf = command;
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xfers[0].len = 2;
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spi_message_add_tail(&xfers[0], &msg);
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++xfers;
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for (idx = 0; idx < count; ++idx) {
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if (rx_buf)
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xfers[idx].rx_buf = &rx_buf[idx];
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if (tx_buf)
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xfers[idx].tx_buf = &tx_buf[idx];
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xfers[idx].len = 2;
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spi_message_add_tail(&xfers[idx], &msg);
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}
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ret = spi_sync(spi, &msg);
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if (count == 1)
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_rx_buf[0] = command[2];
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kfree(spi_data);
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return ret;
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}
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static int ad7879_spi_multi_read(struct device *dev,
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u8 first_reg, u8 count, u16 *buf)
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{
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struct spi_device *spi = to_spi_device(dev);
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return ad7879_spi_xfer(spi, AD7879_READCMD(first_reg), count, NULL, buf);
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}
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static int ad7879_spi_read(struct device *dev, u8 reg)
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{
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struct spi_device *spi = to_spi_device(dev);
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u16 ret, dummy;
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return ad7879_spi_xfer(spi, AD7879_READCMD(reg), 1, &dummy, &ret) ? : ret;
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}
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static int ad7879_spi_write(struct device *dev, u8 reg, u16 val)
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{
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struct spi_device *spi = to_spi_device(dev);
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u16 dummy;
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return ad7879_spi_xfer(spi, AD7879_WRITECMD(reg), 1, &val, &dummy);
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}
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static const struct ad7879_bus_ops ad7879_spi_bus_ops = {
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.bustype = BUS_SPI,
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.read = ad7879_spi_read,
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.multi_read = ad7879_spi_multi_read,
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.write = ad7879_spi_write,
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};
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static int ad7879_spi_probe(struct spi_device *spi)
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{
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struct ad7879 *ts;
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int err;
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/* don't exceed max specified SPI CLK frequency */
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if (spi->max_speed_hz > MAX_SPI_FREQ_HZ) {
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dev_err(&spi->dev, "SPI CLK %d Hz?\n", spi->max_speed_hz);
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return -EINVAL;
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}
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spi->bits_per_word = 16;
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err = spi_setup(spi);
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if (err) {
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dev_dbg(&spi->dev, "spi master doesn't support 16 bits/word\n");
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return err;
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}
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ts = ad7879_probe(&spi->dev, AD7879_DEVID, spi->irq, &ad7879_spi_bus_ops);
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if (IS_ERR(ts))
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return PTR_ERR(ts);
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spi_set_drvdata(spi, ts);
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return 0;
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}
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static int ad7879_spi_remove(struct spi_device *spi)
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{
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struct ad7879 *ts = spi_get_drvdata(spi);
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ad7879_remove(ts);
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return 0;
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}
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static struct spi_driver ad7879_spi_driver = {
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.driver = {
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.name = "ad7879",
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.pm = &ad7879_pm_ops,
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},
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.probe = ad7879_spi_probe,
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.remove = ad7879_spi_remove,
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};
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module_spi_driver(ad7879_spi_driver);
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MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
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MODULE_DESCRIPTION("AD7879(-1) touchscreen SPI bus driver");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("spi:ad7879");
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