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 93 if (status == 0) 94 *data = chip->rx_buf[1]; 95 return status; 96 } 97 98 static int max6902_get_datetime(struct device *dev, struct rtc_time *dt) 99 { 100 unsigned char tmp; 101 int century; 102 int err; 103 struct spi_device *spi = to_spi_device(dev); 104 struct max6902 *chip = dev_get_drvdata(dev); 105 struct spi_message message; 106 struct spi_transfer xfer; 107 int status; 108 109 err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &tmp); 110 if (err) 111 return err; 112 113 /* build the message */ 114 spi_message_init(&message); 115 memset(&xfer, 0, sizeof(xfer)); 116 xfer.len = 1 + 7; /* Burst read command + 7 registers */ 117 xfer.tx_buf = chip->buf; 118 xfer.rx_buf = chip->buf; 119 chip->buf[0] = 0xbf; /* Burst read */ 120 spi_message_add_tail(&xfer, &message); 121 122 /* do the i/o */ 123 status = spi_sync(spi, &message); 124 if (status) 125 return status; 126 127 /* The chip sends data in this order: 128 * Seconds, Minutes, Hours, Date, Month, Day, Year */ 129 dt->tm_sec = BCD2BIN(chip->buf[1]); 130 dt->tm_min = BCD2BIN(chip->buf[2]); 131 dt->tm_hour = BCD2BIN(chip->buf[3]); 132 dt->tm_mday = BCD2BIN(chip->buf[4]); 133 dt->tm_mon = BCD2BIN(chip->buf[5]) - 1; 134 dt->tm_wday = BCD2BIN(chip->buf[6]); 135 dt->tm_year = BCD2BIN(chip->buf[7]); 136 137 century = BCD2BIN(tmp) * 100; 138 139 dt->tm_year += century; 140 dt->tm_year -= 1900; 141 142 #ifdef MAX6902_DEBUG 143 printk("\n%s : Read RTC values\n",__FUNCTION__); 144 printk("tm_hour: %i\n",dt->tm_hour); 145 printk("tm_min : %i\n",dt->tm_min); 146 printk("tm_sec : %i\n",dt->tm_sec); 147 printk("tm_year: %i\n",dt->tm_year); 148 printk("tm_mon : %i\n",dt->tm_mon); 149 printk("tm_mday: %i\n",dt->tm_mday); 150 printk("tm_wday: %i\n",dt->tm_wday); 151 #endif 152 153 return 0; 154 } 155 156 static int max6902_set_datetime(struct device *dev, struct rtc_time *dt) 157 { 158 dt->tm_year = dt->tm_year+1900; 159 160 #ifdef MAX6902_DEBUG 161 printk("\n%s : Setting RTC values\n",__FUNCTION__); 162 printk("tm_sec : %i\n",dt->tm_sec); 163 printk("tm_min : %i\n",dt->tm_min); 164 printk("tm_hour: %i\n",dt->tm_hour); 165 printk("tm_mday: %i\n",dt->tm_mday); 166 printk("tm_wday: %i\n",dt->tm_wday); 167 printk("tm_year: %i\n",dt->tm_year); 168 #endif 169 170 /* Remove write protection */ 171 max6902_set_reg(dev, 0xF, 0); 172 173 max6902_set_reg(dev, 0x01, BIN2BCD(dt->tm_sec)); 174 max6902_set_reg(dev, 0x03, BIN2BCD(dt->tm_min)); 175 max6902_set_reg(dev, 0x05, BIN2BCD(dt->tm_hour)); 176 177 max6902_set_reg(dev, 0x07, BIN2BCD(dt->tm_mday)); 178 max6902_set_reg(dev, 0x09, BIN2BCD(dt->tm_mon+1)); 179 max6902_set_reg(dev, 0x0B, BIN2BCD(dt->tm_wday)); 180 max6902_set_reg(dev, 0x0D, BIN2BCD(dt->tm_year%100)); 181 max6902_set_reg(dev, 0x13, BIN2BCD(dt->tm_year/100)); 182 183 /* Compulab used a delay here. However, the datasheet 184 * does not mention a delay being required anywhere... */ 185 /* delay(2000); */ 186 187 /* Write protect */ 188 max6902_set_reg(dev, 0xF, 0x80); 189 190 return 0; 191 } 192 193 static int max6902_read_time(struct device *dev, struct rtc_time *tm) 194 { 195 return max6902_get_datetime(dev, tm); 196 } 197 198 static int max6902_set_time(struct device *dev, struct rtc_time *tm) 199 { 200 return max6902_set_datetime(dev, tm); 201 } 202 203 static const struct rtc_class_ops max6902_rtc_ops = { 204 .read_time = max6902_read_time, 205 .set_time = max6902_set_time, 206 }; 207 208 static int __devinit max6902_probe(struct spi_device *spi) 209 { 210 struct rtc_device *rtc; 211 unsigned char tmp; 212 struct max6902 *chip; 213 int res; 214 215 rtc = rtc_device_register("max6902", 216 &spi->dev, &max6902_rtc_ops, THIS_MODULE); 217 if (IS_ERR(rtc)) 218 return PTR_ERR(rtc); 219 220 spi->mode = SPI_MODE_3; 221 spi->bits_per_word = 8; 222 spi_setup(spi); 223 224 chip = kzalloc(sizeof *chip, GFP_KERNEL); 225 if (!chip) { 226 rtc_device_unregister(rtc); 227 return -ENOMEM; 228 } 229 chip->rtc = rtc; 230 dev_set_drvdata(&spi->dev, chip); 231 232 res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp); 233 if (res) { 234 rtc_device_unregister(rtc); 235 return res; 236 } 237 238 return 0; 239 } 240 241 static int __devexit max6902_remove(struct spi_device *spi) 242 { 243 struct max6902 *chip = platform_get_drvdata(spi); 244 struct rtc_device *rtc = chip->rtc; 245 246 if (rtc) 247 rtc_device_unregister(rtc); 248 249 kfree(chip); 250 251 return 0; 252 } 253 254 static struct spi_driver max6902_driver = { 255 .driver = { 256 .name = "rtc-max6902", 257 .bus = &spi_bus_type, 258 .owner = THIS_MODULE, 259 }, 260 .probe = max6902_probe, 261 .remove = __devexit_p(max6902_remove), 262 }; 263 264 static __init int max6902_init(void) 265 { 266 printk("max6902 spi driver\n"); 267 return spi_register_driver(&max6902_driver); 268 } 269 module_init(max6902_init); 270 271 static __exit void max6902_exit(void) 272 { 273 spi_unregister_driver(&max6902_driver); 274 } 275 module_exit(max6902_exit); 276 277 MODULE_DESCRIPTION ("max6902 spi RTC driver"); 278 MODULE_AUTHOR ("Raphael Assenat"); 279 MODULE_LICENSE ("GPL"); 280