1 /* 2 * An I2C driver for the PCF85063 RTC 3 * Copyright 2014 Rose Technology 4 * 5 * Author: Søren Andersen <san@rosetechnology.dk> 6 * Maintainers: http://www.nslu2-linux.org/ 7 * 8 * based on the other drivers in this same directory. 9 * 10 * This program is free software; you can redistribute it and/or modify 11 * it under the terms of the GNU General Public License version 2 as 12 * published by the Free Software Foundation. 13 */ 14 #include <linux/i2c.h> 15 #include <linux/bcd.h> 16 #include <linux/rtc.h> 17 #include <linux/module.h> 18 19 #define PCF85063_REG_CTRL1 0x00 /* status */ 20 #define PCF85063_REG_CTRL1_STOP BIT(5) 21 #define PCF85063_REG_CTRL2 0x01 22 23 #define PCF85063_REG_SC 0x04 /* datetime */ 24 #define PCF85063_REG_SC_OS 0x80 25 #define PCF85063_REG_MN 0x05 26 #define PCF85063_REG_HR 0x06 27 #define PCF85063_REG_DM 0x07 28 #define PCF85063_REG_DW 0x08 29 #define PCF85063_REG_MO 0x09 30 #define PCF85063_REG_YR 0x0A 31 32 static struct i2c_driver pcf85063_driver; 33 34 static int pcf85063_stop_clock(struct i2c_client *client, u8 *ctrl1) 35 { 36 s32 ret; 37 38 ret = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1); 39 if (ret < 0) { 40 dev_err(&client->dev, "Failing to stop the clock\n"); 41 return -EIO; 42 } 43 44 /* stop the clock */ 45 ret |= PCF85063_REG_CTRL1_STOP; 46 47 ret = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ret); 48 if (ret < 0) { 49 dev_err(&client->dev, "Failing to stop the clock\n"); 50 return -EIO; 51 } 52 53 *ctrl1 = ret; 54 55 return 0; 56 } 57 58 /* 59 * In the routines that deal directly with the pcf85063 hardware, we use 60 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch. 61 */ 62 static int pcf85063_get_datetime(struct i2c_client *client, struct rtc_time *tm) 63 { 64 int rc; 65 u8 regs[7]; 66 67 /* 68 * while reading, the time/date registers are blocked and not updated 69 * anymore until the access is finished. To not lose a second 70 * event, the access must be finished within one second. So, read all 71 * time/date registers in one turn. 72 */ 73 rc = i2c_smbus_read_i2c_block_data(client, PCF85063_REG_SC, 74 sizeof(regs), regs); 75 if (rc != sizeof(regs)) { 76 dev_err(&client->dev, "date/time register read error\n"); 77 return -EIO; 78 } 79 80 /* if the clock has lost its power it makes no sense to use its time */ 81 if (regs[0] & PCF85063_REG_SC_OS) { 82 dev_warn(&client->dev, "Power loss detected, invalid time\n"); 83 return -EINVAL; 84 } 85 86 tm->tm_sec = bcd2bin(regs[0] & 0x7F); 87 tm->tm_min = bcd2bin(regs[1] & 0x7F); 88 tm->tm_hour = bcd2bin(regs[2] & 0x3F); /* rtc hr 0-23 */ 89 tm->tm_mday = bcd2bin(regs[3] & 0x3F); 90 tm->tm_wday = regs[4] & 0x07; 91 tm->tm_mon = bcd2bin(regs[5] & 0x1F) - 1; /* rtc mn 1-12 */ 92 tm->tm_year = bcd2bin(regs[6]); 93 if (tm->tm_year < 70) 94 tm->tm_year += 100; /* assume we are in 1970...2069 */ 95 96 return rtc_valid_tm(tm); 97 } 98 99 static int pcf85063_set_datetime(struct i2c_client *client, struct rtc_time *tm) 100 { 101 int rc; 102 u8 regs[8]; 103 104 /* 105 * to accurately set the time, reset the divider chain and keep it in 106 * reset state until all time/date registers are written 107 */ 108 rc = pcf85063_stop_clock(client, ®s[7]); 109 if (rc != 0) 110 return rc; 111 112 /* hours, minutes and seconds */ 113 regs[0] = bin2bcd(tm->tm_sec) & 0x7F; /* clear OS flag */ 114 115 regs[1] = bin2bcd(tm->tm_min); 116 regs[2] = bin2bcd(tm->tm_hour); 117 118 /* Day of month, 1 - 31 */ 119 regs[3] = bin2bcd(tm->tm_mday); 120 121 /* Day, 0 - 6 */ 122 regs[4] = tm->tm_wday & 0x07; 123 124 /* month, 1 - 12 */ 125 regs[5] = bin2bcd(tm->tm_mon + 1); 126 127 /* year and century */ 128 regs[6] = bin2bcd(tm->tm_year % 100); 129 130 /* 131 * after all time/date registers are written, let the 'address auto 132 * increment' feature wrap around and write register CTRL1 to re-enable 133 * the clock divider chain again 134 */ 135 regs[7] &= ~PCF85063_REG_CTRL1_STOP; 136 137 /* write all registers at once */ 138 rc = i2c_smbus_write_i2c_block_data(client, PCF85063_REG_SC, 139 sizeof(regs), regs); 140 if (rc < 0) { 141 dev_err(&client->dev, "date/time register write error\n"); 142 return rc; 143 } 144 145 return 0; 146 } 147 148 static int pcf85063_rtc_read_time(struct device *dev, struct rtc_time *tm) 149 { 150 return pcf85063_get_datetime(to_i2c_client(dev), tm); 151 } 152 153 static int pcf85063_rtc_set_time(struct device *dev, struct rtc_time *tm) 154 { 155 return pcf85063_set_datetime(to_i2c_client(dev), tm); 156 } 157 158 static const struct rtc_class_ops pcf85063_rtc_ops = { 159 .read_time = pcf85063_rtc_read_time, 160 .set_time = pcf85063_rtc_set_time 161 }; 162 163 static int pcf85063_probe(struct i2c_client *client, 164 const struct i2c_device_id *id) 165 { 166 struct rtc_device *rtc; 167 168 dev_dbg(&client->dev, "%s\n", __func__); 169 170 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 171 return -ENODEV; 172 173 rtc = devm_rtc_device_register(&client->dev, 174 pcf85063_driver.driver.name, 175 &pcf85063_rtc_ops, THIS_MODULE); 176 177 return PTR_ERR_OR_ZERO(rtc); 178 } 179 180 static const struct i2c_device_id pcf85063_id[] = { 181 { "pcf85063", 0 }, 182 { } 183 }; 184 MODULE_DEVICE_TABLE(i2c, pcf85063_id); 185 186 #ifdef CONFIG_OF 187 static const struct of_device_id pcf85063_of_match[] = { 188 { .compatible = "nxp,pcf85063" }, 189 {} 190 }; 191 MODULE_DEVICE_TABLE(of, pcf85063_of_match); 192 #endif 193 194 static struct i2c_driver pcf85063_driver = { 195 .driver = { 196 .name = "rtc-pcf85063", 197 .of_match_table = of_match_ptr(pcf85063_of_match), 198 }, 199 .probe = pcf85063_probe, 200 .id_table = pcf85063_id, 201 }; 202 203 module_i2c_driver(pcf85063_driver); 204 205 MODULE_AUTHOR("Søren Andersen <san@rosetechnology.dk>"); 206 MODULE_DESCRIPTION("PCF85063 RTC driver"); 207 MODULE_LICENSE("GPL"); 208