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 #include <linux/of.h> 14 15 #include "ad7879.h" 16 17 #define AD7879_DEVID 0x7A /* AD7879/AD7889 */ 18 19 #define MAX_SPI_FREQ_HZ 5000000 20 #define AD7879_CMD_MAGIC 0xE000 21 #define AD7879_CMD_READ (1 << 10) 22 #define AD7879_CMD(reg) (AD7879_CMD_MAGIC | ((reg) & 0xF)) 23 #define AD7879_WRITECMD(reg) (AD7879_CMD(reg)) 24 #define AD7879_READCMD(reg) (AD7879_CMD(reg) | AD7879_CMD_READ) 25 26 /* 27 * ad7879_read/write are only used for initial setup and for sysfs controls. 28 * The main traffic is done in ad7879_collect(). 29 */ 30 31 static int ad7879_spi_xfer(struct spi_device *spi, 32 u16 cmd, u8 count, u16 *tx_buf, u16 *rx_buf) 33 { 34 struct spi_message msg; 35 struct spi_transfer *xfers; 36 void *spi_data; 37 u16 *command; 38 u16 *_rx_buf = _rx_buf; /* shut gcc up */ 39 u8 idx; 40 int ret; 41 42 xfers = spi_data = kzalloc(sizeof(*xfers) * (count + 2), GFP_KERNEL); 43 if (!spi_data) 44 return -ENOMEM; 45 46 spi_message_init(&msg); 47 48 command = spi_data; 49 command[0] = cmd; 50 if (count == 1) { 51 /* ad7879_spi_{read,write} gave us buf on stack */ 52 command[1] = *tx_buf; 53 tx_buf = &command[1]; 54 _rx_buf = rx_buf; 55 rx_buf = &command[2]; 56 } 57 58 ++xfers; 59 xfers[0].tx_buf = command; 60 xfers[0].len = 2; 61 spi_message_add_tail(&xfers[0], &msg); 62 ++xfers; 63 64 for (idx = 0; idx < count; ++idx) { 65 if (rx_buf) 66 xfers[idx].rx_buf = &rx_buf[idx]; 67 if (tx_buf) 68 xfers[idx].tx_buf = &tx_buf[idx]; 69 xfers[idx].len = 2; 70 spi_message_add_tail(&xfers[idx], &msg); 71 } 72 73 ret = spi_sync(spi, &msg); 74 75 if (count == 1) 76 _rx_buf[0] = command[2]; 77 78 kfree(spi_data); 79 80 return ret; 81 } 82 83 static int ad7879_spi_multi_read(struct device *dev, 84 u8 first_reg, u8 count, u16 *buf) 85 { 86 struct spi_device *spi = to_spi_device(dev); 87 88 return ad7879_spi_xfer(spi, AD7879_READCMD(first_reg), count, NULL, buf); 89 } 90 91 static int ad7879_spi_read(struct device *dev, u8 reg) 92 { 93 struct spi_device *spi = to_spi_device(dev); 94 u16 ret, dummy; 95 96 return ad7879_spi_xfer(spi, AD7879_READCMD(reg), 1, &dummy, &ret) ? : ret; 97 } 98 99 static int ad7879_spi_write(struct device *dev, u8 reg, u16 val) 100 { 101 struct spi_device *spi = to_spi_device(dev); 102 u16 dummy; 103 104 return ad7879_spi_xfer(spi, AD7879_WRITECMD(reg), 1, &val, &dummy); 105 } 106 107 static const struct ad7879_bus_ops ad7879_spi_bus_ops = { 108 .bustype = BUS_SPI, 109 .read = ad7879_spi_read, 110 .multi_read = ad7879_spi_multi_read, 111 .write = ad7879_spi_write, 112 }; 113 114 static int ad7879_spi_probe(struct spi_device *spi) 115 { 116 struct ad7879 *ts; 117 int err; 118 119 /* don't exceed max specified SPI CLK frequency */ 120 if (spi->max_speed_hz > MAX_SPI_FREQ_HZ) { 121 dev_err(&spi->dev, "SPI CLK %d Hz?\n", spi->max_speed_hz); 122 return -EINVAL; 123 } 124 125 spi->bits_per_word = 16; 126 err = spi_setup(spi); 127 if (err) { 128 dev_dbg(&spi->dev, "spi master doesn't support 16 bits/word\n"); 129 return err; 130 } 131 132 ts = ad7879_probe(&spi->dev, AD7879_DEVID, spi->irq, &ad7879_spi_bus_ops); 133 if (IS_ERR(ts)) 134 return PTR_ERR(ts); 135 136 spi_set_drvdata(spi, ts); 137 138 return 0; 139 } 140 141 static int ad7879_spi_remove(struct spi_device *spi) 142 { 143 struct ad7879 *ts = spi_get_drvdata(spi); 144 145 ad7879_remove(ts); 146 147 return 0; 148 } 149 150 #ifdef CONFIG_OF 151 static const struct of_device_id ad7879_spi_dt_ids[] = { 152 { .compatible = "adi,ad7879", }, 153 { } 154 }; 155 MODULE_DEVICE_TABLE(of, ad7879_spi_dt_ids); 156 #endif 157 158 static struct spi_driver ad7879_spi_driver = { 159 .driver = { 160 .name = "ad7879", 161 .pm = &ad7879_pm_ops, 162 .of_match_table = of_match_ptr(ad7879_spi_dt_ids), 163 }, 164 .probe = ad7879_spi_probe, 165 .remove = ad7879_spi_remove, 166 }; 167 168 module_spi_driver(ad7879_spi_driver); 169 170 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>"); 171 MODULE_DESCRIPTION("AD7879(-1) touchscreen SPI bus driver"); 172 MODULE_LICENSE("GPL"); 173 MODULE_ALIAS("spi:ad7879"); 174