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