1 /* drivers/rtc/rtc-max6902.c 2 * 3 * Copyright (C) 2006 8D Technologies inc. 4 * Copyright (C) 2004 Compulab Ltd. 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * Driver for MAX6902 spi RTC 11 * 12 * Changelog: 13 * 14 * 24-May-2006: Raphael Assenat <raph@8d.com> 15 * - Major rework 16 * Converted to rtc_device and uses the SPI layer. 17 * 18 * ??-???-2005: Someone at Compulab 19 * - Initial driver creation. 20 */ 21 22 #include <linux/module.h> 23 #include <linux/version.h> 24 25 #include <linux/kernel.h> 26 #include <linux/platform_device.h> 27 #include <linux/init.h> 28 #include <linux/rtc.h> 29 #include <linux/spi/spi.h> 30 #include <linux/bcd.h> 31 #include <linux/delay.h> 32 33 #define MAX6902_REG_SECONDS 0x01 34 #define MAX6902_REG_MINUTES 0x03 35 #define MAX6902_REG_HOURS 0x05 36 #define MAX6902_REG_DATE 0x07 37 #define MAX6902_REG_MONTH 0x09 38 #define MAX6902_REG_DAY 0x0B 39 #define MAX6902_REG_YEAR 0x0D 40 #define MAX6902_REG_CONTROL 0x0F 41 #define MAX6902_REG_CENTURY 0x13 42 43 #undef MAX6902_DEBUG 44 45 struct max6902 { 46 struct rtc_device *rtc; 47 u8 buf[9]; /* Burst read cmd + 8 registers */ 48 u8 tx_buf[2]; 49 u8 rx_buf[2]; 50 }; 51 52 static void max6902_set_reg(struct device *dev, unsigned char address, 53 unsigned char data) 54 { 55 struct spi_device *spi = to_spi_device(dev); 56 unsigned char buf[2]; 57 58 /* MSB must be '0' to write */ 59 buf[0] = address & 0x7f; 60 buf[1] = data; 61 62 spi_write(spi, buf, 2); 63 } 64 65 static int max6902_get_reg(struct device *dev, unsigned char address, 66 unsigned char *data) 67 { 68 struct spi_device *spi = to_spi_device(dev); 69 struct max6902 *chip = dev_get_drvdata(dev); 70 struct spi_message message; 71 struct spi_transfer xfer; 72 int status; 73 74 if (!data) 75 return -EINVAL; 76 77 /* Build our spi message */ 78 spi_message_init(&message); 79 memset(&xfer, 0, sizeof(xfer)); 80 xfer.len = 2; 81 /* Can tx_buf and rx_buf be equal? The doc in spi.h is not sure... */ 82 xfer.tx_buf = chip->tx_buf; 83 xfer.rx_buf = chip->rx_buf; 84 85 /* Set MSB to indicate read */ 86 chip->tx_buf[0] = address | 0x80; 87 88 spi_message_add_tail(&xfer, &message); 89 90 /* do the i/o */ 91 status = spi_sync(spi, &message); 92 if (status == 0) 93 status = message.status; 94 else 95 return status; 96 97 *data = chip->rx_buf[1]; 98 99 return status; 100 } 101 102 static int max6902_get_datetime(struct device *dev, struct rtc_time *dt) 103 { 104 unsigned char tmp; 105 int century; 106 int err; 107 struct spi_device *spi = to_spi_device(dev); 108 struct max6902 *chip = dev_get_drvdata(dev); 109 struct spi_message message; 110 struct spi_transfer xfer; 111 int status; 112 113 err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &tmp); 114 if (err) 115 return err; 116 117 /* build the message */ 118 spi_message_init(&message); 119 memset(&xfer, 0, sizeof(xfer)); 120 xfer.len = 1 + 7; /* Burst read command + 7 registers */ 121 xfer.tx_buf = chip->buf; 122 xfer.rx_buf = chip->buf; 123 chip->buf[0] = 0xbf; /* Burst read */ 124 spi_message_add_tail(&xfer, &message); 125 126 /* do the i/o */ 127 status = spi_sync(spi, &message); 128 if (status == 0) 129 status = message.status; 130 else 131 return status; 132 133 /* The chip sends data in this order: 134 * Seconds, Minutes, Hours, Date, Month, Day, Year */ 135 dt->tm_sec = BCD2BIN(chip->buf[1]); 136 dt->tm_min = BCD2BIN(chip->buf[2]); 137 dt->tm_hour = BCD2BIN(chip->buf[3]); 138 dt->tm_mday = BCD2BIN(chip->buf[4]); 139 dt->tm_mon = BCD2BIN(chip->buf[5] - 1); 140 dt->tm_wday = BCD2BIN(chip->buf[6]); 141 dt->tm_year = BCD2BIN(chip->buf[7]); 142 143 century = BCD2BIN(tmp) * 100; 144 145 dt->tm_year += century; 146 dt->tm_year -= 1900; 147 148 #ifdef MAX6902_DEBUG 149 printk("\n%s : Read RTC values\n",__FUNCTION__); 150 printk("tm_hour: %i\n",dt->tm_hour); 151 printk("tm_min : %i\n",dt->tm_min); 152 printk("tm_sec : %i\n",dt->tm_sec); 153 printk("tm_year: %i\n",dt->tm_year); 154 printk("tm_mon : %i\n",dt->tm_mon); 155 printk("tm_mday: %i\n",dt->tm_mday); 156 printk("tm_wday: %i\n",dt->tm_wday); 157 #endif 158 159 return 0; 160 } 161 162 static int max6902_set_datetime(struct device *dev, struct rtc_time *dt) 163 { 164 dt->tm_year = dt->tm_year+1900; 165 166 #ifdef MAX6902_DEBUG 167 printk("\n%s : Setting RTC values\n",__FUNCTION__); 168 printk("tm_sec : %i\n",dt->tm_sec); 169 printk("tm_min : %i\n",dt->tm_min); 170 printk("tm_hour: %i\n",dt->tm_hour); 171 printk("tm_mday: %i\n",dt->tm_mday); 172 printk("tm_wday: %i\n",dt->tm_wday); 173 printk("tm_year: %i\n",dt->tm_year); 174 #endif 175 176 /* Remove write protection */ 177 max6902_set_reg(dev, 0xF, 0); 178 179 max6902_set_reg(dev, 0x01, BIN2BCD(dt->tm_sec)); 180 max6902_set_reg(dev, 0x03, BIN2BCD(dt->tm_min)); 181 max6902_set_reg(dev, 0x05, BIN2BCD(dt->tm_hour)); 182 183 max6902_set_reg(dev, 0x07, BIN2BCD(dt->tm_mday)); 184 max6902_set_reg(dev, 0x09, BIN2BCD(dt->tm_mon+1)); 185 max6902_set_reg(dev, 0x0B, BIN2BCD(dt->tm_wday)); 186 max6902_set_reg(dev, 0x0D, BIN2BCD(dt->tm_year%100)); 187 max6902_set_reg(dev, 0x13, BIN2BCD(dt->tm_year/100)); 188 189 /* Compulab used a delay here. However, the datasheet 190 * does not mention a delay being required anywhere... */ 191 /* delay(2000); */ 192 193 /* Write protect */ 194 max6902_set_reg(dev, 0xF, 0x80); 195 196 return 0; 197 } 198 199 static int max6902_read_time(struct device *dev, struct rtc_time *tm) 200 { 201 return max6902_get_datetime(dev, tm); 202 } 203 204 static int max6902_set_time(struct device *dev, struct rtc_time *tm) 205 { 206 return max6902_set_datetime(dev, tm); 207 } 208 209 static const struct rtc_class_ops max6902_rtc_ops = { 210 .read_time = max6902_read_time, 211 .set_time = max6902_set_time, 212 }; 213 214 static int __devinit max6902_probe(struct spi_device *spi) 215 { 216 struct rtc_device *rtc; 217 unsigned char tmp; 218 struct max6902 *chip; 219 int res; 220 221 rtc = rtc_device_register("max6902", 222 &spi->dev, &max6902_rtc_ops, THIS_MODULE); 223 if (IS_ERR(rtc)) 224 return PTR_ERR(rtc); 225 226 spi->mode = SPI_MODE_3; 227 spi->bits_per_word = 8; 228 spi_setup(spi); 229 230 chip = kzalloc(sizeof *chip, GFP_KERNEL); 231 if (!chip) { 232 rtc_device_unregister(rtc); 233 return -ENOMEM; 234 } 235 chip->rtc = rtc; 236 dev_set_drvdata(&spi->dev, chip); 237 238 res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp); 239 if (res) { 240 rtc_device_unregister(rtc); 241 return res; 242 } 243 244 return 0; 245 } 246 247 static int __devexit max6902_remove(struct spi_device *spi) 248 { 249 struct max6902 *chip = platform_get_drvdata(spi); 250 struct rtc_device *rtc = chip->rtc; 251 252 if (rtc) 253 rtc_device_unregister(rtc); 254 255 kfree(chip); 256 257 return 0; 258 } 259 260 static struct spi_driver max6902_driver = { 261 .driver = { 262 .name = "max6902", 263 .bus = &spi_bus_type, 264 .owner = THIS_MODULE, 265 }, 266 .probe = max6902_probe, 267 .remove = __devexit_p(max6902_remove), 268 }; 269 270 static __init int max6902_init(void) 271 { 272 printk("max6902 spi driver\n"); 273 return spi_register_driver(&max6902_driver); 274 } 275 module_init(max6902_init); 276 277 static __exit void max6902_exit(void) 278 { 279 spi_unregister_driver(&max6902_driver); 280 } 281 module_exit(max6902_exit); 282 283 MODULE_DESCRIPTION ("max6902 spi RTC driver"); 284 MODULE_AUTHOR ("Raphael Assenat"); 285 MODULE_LICENSE ("GPL"); 286