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/spi/spi.h> 11 12#include "ad7879.h" 13 14#define AD7879_DEVID 0x7A /* AD7879/AD7889 */ 15 16#define MAX_SPI_FREQ_HZ 5000000 17#define AD7879_CMD_MAGIC 0xE000 18#define AD7879_CMD_READ (1 << 10) 19#define AD7879_CMD(reg) (AD7879_CMD_MAGIC | ((reg) & 0xF)) 20#define AD7879_WRITECMD(reg) (AD7879_CMD(reg)) 21#define AD7879_READCMD(reg) (AD7879_CMD(reg) | AD7879_CMD_READ) 22 23#ifdef CONFIG_PM 24static int ad7879_spi_suspend(struct spi_device *spi, pm_message_t message) 25{ 26 struct ad7879 *ts = spi_get_drvdata(spi); 27 28 ad7879_suspend(ts); 29 30 return 0; 31} 32 33static int ad7879_spi_resume(struct spi_device *spi) 34{ 35 struct ad7879 *ts = spi_get_drvdata(spi); 36 37 ad7879_resume(ts); 38 39 return 0; 40} 41#else 42# define ad7879_spi_suspend NULL 43# define ad7879_spi_resume NULL 44#endif 45 46/* 47 * ad7879_read/write are only used for initial setup and for sysfs controls. 48 * The main traffic is done in ad7879_collect(). 49 */ 50 51static int ad7879_spi_xfer(struct spi_device *spi, 52 u16 cmd, u8 count, u16 *tx_buf, u16 *rx_buf) 53{ 54 struct spi_message msg; 55 struct spi_transfer *xfers; 56 void *spi_data; 57 u16 *command; 58 u16 *_rx_buf = _rx_buf; /* shut gcc up */ 59 u8 idx; 60 int ret; 61 62 xfers = spi_data = kzalloc(sizeof(*xfers) * (count + 2), GFP_KERNEL); 63 if (!spi_data) 64 return -ENOMEM; 65 66 spi_message_init(&msg); 67 68 command = spi_data; 69 command[0] = cmd; 70 if (count == 1) { 71 /* ad7879_spi_{read,write} gave us buf on stack */ 72 command[1] = *tx_buf; 73 tx_buf = &command[1]; 74 _rx_buf = rx_buf; 75 rx_buf = &command[2]; 76 } 77 78 ++xfers; 79 xfers[0].tx_buf = command; 80 xfers[0].len = 2; 81 spi_message_add_tail(&xfers[0], &msg); 82 ++xfers; 83 84 for (idx = 0; idx < count; ++idx) { 85 if (rx_buf) 86 xfers[idx].rx_buf = &rx_buf[idx]; 87 if (tx_buf) 88 xfers[idx].tx_buf = &tx_buf[idx]; 89 xfers[idx].len = 2; 90 spi_message_add_tail(&xfers[idx], &msg); 91 } 92 93 ret = spi_sync(spi, &msg); 94 95 if (count == 1) 96 _rx_buf[0] = command[2]; 97 98 kfree(spi_data); 99 100 return ret; 101} 102 103static int ad7879_spi_multi_read(struct device *dev, 104 u8 first_reg, u8 count, u16 *buf) 105{ 106 struct spi_device *spi = to_spi_device(dev); 107 108 return ad7879_spi_xfer(spi, AD7879_READCMD(first_reg), count, NULL, buf); 109} 110 111static int ad7879_spi_read(struct device *dev, u8 reg) 112{ 113 struct spi_device *spi = to_spi_device(dev); 114 u16 ret, dummy; 115 116 return ad7879_spi_xfer(spi, AD7879_READCMD(reg), 1, &dummy, &ret) ? : ret; 117} 118 119static int ad7879_spi_write(struct device *dev, u8 reg, u16 val) 120{ 121 struct spi_device *spi = to_spi_device(dev); 122 u16 dummy; 123 124 return ad7879_spi_xfer(spi, AD7879_WRITECMD(reg), 1, &val, &dummy); 125} 126 127static const struct ad7879_bus_ops ad7879_spi_bus_ops = { 128 .bustype = BUS_SPI, 129 .read = ad7879_spi_read, 130 .multi_read = ad7879_spi_multi_read, 131 .write = ad7879_spi_write, 132}; 133 134static int __devinit ad7879_spi_probe(struct spi_device *spi) 135{ 136 struct ad7879 *ts; 137 int err; 138 139 /* don't exceed max specified SPI CLK frequency */ 140 if (spi->max_speed_hz > MAX_SPI_FREQ_HZ) { 141 dev_err(&spi->dev, "SPI CLK %d Hz?\n", spi->max_speed_hz); 142 return -EINVAL; 143 } 144 145 spi->bits_per_word = 16; 146 err = spi_setup(spi); 147 if (err) { 148 dev_dbg(&spi->dev, "spi master doesn't support 16 bits/word\n"); 149 return err; 150 } 151 152 ts = ad7879_probe(&spi->dev, AD7879_DEVID, spi->irq, &ad7879_spi_bus_ops); 153 if (IS_ERR(ts)) 154 return PTR_ERR(ts); 155 156 spi_set_drvdata(spi, ts); 157 158 return 0; 159} 160 161static int __devexit ad7879_spi_remove(struct spi_device *spi) 162{ 163 struct ad7879 *ts = spi_get_drvdata(spi); 164 165 ad7879_remove(ts); 166 spi_set_drvdata(spi, NULL); 167 168 return 0; 169} 170 171static struct spi_driver ad7879_spi_driver = { 172 .driver = { 173 .name = "ad7879", 174 .bus = &spi_bus_type, 175 .owner = THIS_MODULE, 176 }, 177 .probe = ad7879_spi_probe, 178 .remove = __devexit_p(ad7879_spi_remove), 179 .suspend = ad7879_spi_suspend, 180 .resume = ad7879_spi_resume, 181}; 182 183static int __init ad7879_spi_init(void) 184{ 185 return spi_register_driver(&ad7879_spi_driver); 186} 187module_init(ad7879_spi_init); 188 189static void __exit ad7879_spi_exit(void) 190{ 191 spi_unregister_driver(&ad7879_spi_driver); 192} 193module_exit(ad7879_spi_exit); 194 195MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>"); 196MODULE_DESCRIPTION("AD7879(-1) touchscreen SPI bus driver"); 197MODULE_LICENSE("GPL"); 198MODULE_ALIAS("spi:ad7879"); 199