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 30 static 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 82 static 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 90 static 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 98 static 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 } 105 106 static 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 }; 112 113 static 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 } 139 140 static 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 } 148 149 static struct spi_driver ad7879_spi_driver = { 150 .driver = { 151 .name = "ad7879", 152 .pm = &ad7879_pm_ops, 153 }, 154 .probe = ad7879_spi_probe, 155 .remove = ad7879_spi_remove, 156 }; 157 158 module_spi_driver(ad7879_spi_driver); 159 160 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>"); 161 MODULE_DESCRIPTION("AD7879(-1) touchscreen SPI bus driver"); 162 MODULE_LICENSE("GPL"); 163 MODULE_ALIAS("spi:ad7879"); 164