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 /* 20 * Information for this driver was pulled from the following datasheets. 21 * 22 * http://www.nxp.com/documents/data_sheet/PCF85063A.pdf 23 * http://www.nxp.com/documents/data_sheet/PCF85063TP.pdf 24 * 25 * PCF85063A -- Rev. 6 — 18 November 2015 26 * PCF85063TP -- Rev. 4 — 6 May 2015 27 */ 28 29 #define PCF85063_REG_CTRL1 0x00 /* status */ 30 #define PCF85063_REG_CTRL1_STOP BIT(5) 31 #define PCF85063_REG_CTRL2 0x01 32 33 #define PCF85063_REG_SC 0x04 /* datetime */ 34 #define PCF85063_REG_SC_OS 0x80 35 #define PCF85063_REG_MN 0x05 36 #define PCF85063_REG_HR 0x06 37 #define PCF85063_REG_DM 0x07 38 #define PCF85063_REG_DW 0x08 39 #define PCF85063_REG_MO 0x09 40 #define PCF85063_REG_YR 0x0A 41 42 static struct i2c_driver pcf85063_driver; 43 44 static int pcf85063_stop_clock(struct i2c_client *client, u8 *ctrl1) 45 { 46 int rc; 47 u8 reg; 48 49 rc = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1); 50 if (rc < 0) { 51 dev_err(&client->dev, "Failing to stop the clock\n"); 52 return -EIO; 53 } 54 55 /* stop the clock */ 56 reg = rc | PCF85063_REG_CTRL1_STOP; 57 58 rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, reg); 59 if (rc < 0) { 60 dev_err(&client->dev, "Failing to stop the clock\n"); 61 return -EIO; 62 } 63 64 *ctrl1 = reg; 65 66 return 0; 67 } 68 69 static int pcf85063_start_clock(struct i2c_client *client, u8 ctrl1) 70 { 71 int rc; 72 73 /* start the clock */ 74 ctrl1 &= ~PCF85063_REG_CTRL1_STOP; 75 76 rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ctrl1); 77 if (rc < 0) { 78 dev_err(&client->dev, "Failing to start the clock\n"); 79 return -EIO; 80 } 81 82 return 0; 83 } 84 85 static int pcf85063_rtc_read_time(struct device *dev, struct rtc_time *tm) 86 { 87 struct i2c_client *client = to_i2c_client(dev); 88 int rc; 89 u8 regs[7]; 90 91 /* 92 * while reading, the time/date registers are blocked and not updated 93 * anymore until the access is finished. To not lose a second 94 * event, the access must be finished within one second. So, read all 95 * time/date registers in one turn. 96 */ 97 rc = i2c_smbus_read_i2c_block_data(client, PCF85063_REG_SC, 98 sizeof(regs), regs); 99 if (rc != sizeof(regs)) { 100 dev_err(&client->dev, "date/time register read error\n"); 101 return -EIO; 102 } 103 104 /* if the clock has lost its power it makes no sense to use its time */ 105 if (regs[0] & PCF85063_REG_SC_OS) { 106 dev_warn(&client->dev, "Power loss detected, invalid time\n"); 107 return -EINVAL; 108 } 109 110 tm->tm_sec = bcd2bin(regs[0] & 0x7F); 111 tm->tm_min = bcd2bin(regs[1] & 0x7F); 112 tm->tm_hour = bcd2bin(regs[2] & 0x3F); /* rtc hr 0-23 */ 113 tm->tm_mday = bcd2bin(regs[3] & 0x3F); 114 tm->tm_wday = regs[4] & 0x07; 115 tm->tm_mon = bcd2bin(regs[5] & 0x1F) - 1; /* rtc mn 1-12 */ 116 tm->tm_year = bcd2bin(regs[6]); 117 tm->tm_year += 100; 118 119 return 0; 120 } 121 122 static int pcf85063_rtc_set_time(struct device *dev, struct rtc_time *tm) 123 { 124 struct i2c_client *client = to_i2c_client(dev); 125 int rc; 126 u8 regs[7]; 127 u8 ctrl1; 128 129 if ((tm->tm_year < 100) || (tm->tm_year > 199)) 130 return -EINVAL; 131 132 /* 133 * to accurately set the time, reset the divider chain and keep it in 134 * reset state until all time/date registers are written 135 */ 136 rc = pcf85063_stop_clock(client, &ctrl1); 137 if (rc != 0) 138 return rc; 139 140 /* hours, minutes and seconds */ 141 regs[0] = bin2bcd(tm->tm_sec) & 0x7F; /* clear OS flag */ 142 143 regs[1] = bin2bcd(tm->tm_min); 144 regs[2] = bin2bcd(tm->tm_hour); 145 146 /* Day of month, 1 - 31 */ 147 regs[3] = bin2bcd(tm->tm_mday); 148 149 /* Day, 0 - 6 */ 150 regs[4] = tm->tm_wday & 0x07; 151 152 /* month, 1 - 12 */ 153 regs[5] = bin2bcd(tm->tm_mon + 1); 154 155 /* year and century */ 156 regs[6] = bin2bcd(tm->tm_year - 100); 157 158 /* write all registers at once */ 159 rc = i2c_smbus_write_i2c_block_data(client, PCF85063_REG_SC, 160 sizeof(regs), regs); 161 if (rc < 0) { 162 dev_err(&client->dev, "date/time register write error\n"); 163 return rc; 164 } 165 166 /* 167 * Write the control register as a separate action since the size of 168 * the register space is different between the PCF85063TP and 169 * PCF85063A devices. The rollover point can not be used. 170 */ 171 rc = pcf85063_start_clock(client, ctrl1); 172 if (rc != 0) 173 return rc; 174 175 return 0; 176 } 177 178 static const struct rtc_class_ops pcf85063_rtc_ops = { 179 .read_time = pcf85063_rtc_read_time, 180 .set_time = pcf85063_rtc_set_time 181 }; 182 183 static int pcf85063_probe(struct i2c_client *client, 184 const struct i2c_device_id *id) 185 { 186 struct rtc_device *rtc; 187 int err; 188 189 dev_dbg(&client->dev, "%s\n", __func__); 190 191 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 192 return -ENODEV; 193 194 err = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1); 195 if (err < 0) { 196 dev_err(&client->dev, "RTC chip is not present\n"); 197 return err; 198 } 199 200 rtc = devm_rtc_device_register(&client->dev, 201 pcf85063_driver.driver.name, 202 &pcf85063_rtc_ops, THIS_MODULE); 203 204 return PTR_ERR_OR_ZERO(rtc); 205 } 206 207 static const struct i2c_device_id pcf85063_id[] = { 208 { "pcf85063", 0 }, 209 { } 210 }; 211 MODULE_DEVICE_TABLE(i2c, pcf85063_id); 212 213 #ifdef CONFIG_OF 214 static const struct of_device_id pcf85063_of_match[] = { 215 { .compatible = "nxp,pcf85063" }, 216 {} 217 }; 218 MODULE_DEVICE_TABLE(of, pcf85063_of_match); 219 #endif 220 221 static struct i2c_driver pcf85063_driver = { 222 .driver = { 223 .name = "rtc-pcf85063", 224 .of_match_table = of_match_ptr(pcf85063_of_match), 225 }, 226 .probe = pcf85063_probe, 227 .id_table = pcf85063_id, 228 }; 229 230 module_i2c_driver(pcf85063_driver); 231 232 MODULE_AUTHOR("Søren Andersen <san@rosetechnology.dk>"); 233 MODULE_DESCRIPTION("PCF85063 RTC driver"); 234 MODULE_LICENSE("GPL"); 235