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 s32 ret; 47 48 ret = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1); 49 if (ret < 0) { 50 dev_err(&client->dev, "Failing to stop the clock\n"); 51 return -EIO; 52 } 53 54 /* stop the clock */ 55 ret |= PCF85063_REG_CTRL1_STOP; 56 57 ret = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ret); 58 if (ret < 0) { 59 dev_err(&client->dev, "Failing to stop the clock\n"); 60 return -EIO; 61 } 62 63 *ctrl1 = ret; 64 65 return 0; 66 } 67 68 static int pcf85063_start_clock(struct i2c_client *client, u8 ctrl1) 69 { 70 s32 ret; 71 72 /* start the clock */ 73 ctrl1 &= PCF85063_REG_CTRL1_STOP; 74 75 ret = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ctrl1); 76 if (ret < 0) { 77 dev_err(&client->dev, "Failing to start the clock\n"); 78 return -EIO; 79 } 80 81 return 0; 82 } 83 84 static int pcf85063_get_datetime(struct i2c_client *client, struct rtc_time *tm) 85 { 86 int rc; 87 u8 regs[7]; 88 89 /* 90 * while reading, the time/date registers are blocked and not updated 91 * anymore until the access is finished. To not lose a second 92 * event, the access must be finished within one second. So, read all 93 * time/date registers in one turn. 94 */ 95 rc = i2c_smbus_read_i2c_block_data(client, PCF85063_REG_SC, 96 sizeof(regs), regs); 97 if (rc != sizeof(regs)) { 98 dev_err(&client->dev, "date/time register read error\n"); 99 return -EIO; 100 } 101 102 /* if the clock has lost its power it makes no sense to use its time */ 103 if (regs[0] & PCF85063_REG_SC_OS) { 104 dev_warn(&client->dev, "Power loss detected, invalid time\n"); 105 return -EINVAL; 106 } 107 108 tm->tm_sec = bcd2bin(regs[0] & 0x7F); 109 tm->tm_min = bcd2bin(regs[1] & 0x7F); 110 tm->tm_hour = bcd2bin(regs[2] & 0x3F); /* rtc hr 0-23 */ 111 tm->tm_mday = bcd2bin(regs[3] & 0x3F); 112 tm->tm_wday = regs[4] & 0x07; 113 tm->tm_mon = bcd2bin(regs[5] & 0x1F) - 1; /* rtc mn 1-12 */ 114 tm->tm_year = bcd2bin(regs[6]); 115 tm->tm_year += 100; 116 117 return rtc_valid_tm(tm); 118 } 119 120 static int pcf85063_set_datetime(struct i2c_client *client, struct rtc_time *tm) 121 { 122 int rc; 123 u8 regs[7]; 124 u8 ctrl1; 125 126 if ((tm->tm_year < 100) || (tm->tm_year > 199)) 127 return -EINVAL; 128 129 /* 130 * to accurately set the time, reset the divider chain and keep it in 131 * reset state until all time/date registers are written 132 */ 133 rc = pcf85063_stop_clock(client, &ctrl1); 134 if (rc != 0) 135 return rc; 136 137 /* hours, minutes and seconds */ 138 regs[0] = bin2bcd(tm->tm_sec) & 0x7F; /* clear OS flag */ 139 140 regs[1] = bin2bcd(tm->tm_min); 141 regs[2] = bin2bcd(tm->tm_hour); 142 143 /* Day of month, 1 - 31 */ 144 regs[3] = bin2bcd(tm->tm_mday); 145 146 /* Day, 0 - 6 */ 147 regs[4] = tm->tm_wday & 0x07; 148 149 /* month, 1 - 12 */ 150 regs[5] = bin2bcd(tm->tm_mon + 1); 151 152 /* year and century */ 153 regs[6] = bin2bcd(tm->tm_year - 100); 154 155 /* write all registers at once */ 156 rc = i2c_smbus_write_i2c_block_data(client, PCF85063_REG_SC, 157 sizeof(regs), regs); 158 if (rc < 0) { 159 dev_err(&client->dev, "date/time register write error\n"); 160 return rc; 161 } 162 163 /* 164 * Write the control register as a separate action since the size of 165 * the register space is different between the PCF85063TP and 166 * PCF85063A devices. The rollover point can not be used. 167 */ 168 rc = pcf85063_start_clock(client, ctrl1); 169 if (rc != 0) 170 return rc; 171 172 return 0; 173 } 174 175 static int pcf85063_rtc_read_time(struct device *dev, struct rtc_time *tm) 176 { 177 return pcf85063_get_datetime(to_i2c_client(dev), tm); 178 } 179 180 static int pcf85063_rtc_set_time(struct device *dev, struct rtc_time *tm) 181 { 182 return pcf85063_set_datetime(to_i2c_client(dev), tm); 183 } 184 185 static const struct rtc_class_ops pcf85063_rtc_ops = { 186 .read_time = pcf85063_rtc_read_time, 187 .set_time = pcf85063_rtc_set_time 188 }; 189 190 static int pcf85063_probe(struct i2c_client *client, 191 const struct i2c_device_id *id) 192 { 193 struct rtc_device *rtc; 194 int err; 195 196 dev_dbg(&client->dev, "%s\n", __func__); 197 198 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 199 return -ENODEV; 200 201 err = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1); 202 if (err < 0) { 203 dev_err(&client->dev, "RTC chip is not present\n"); 204 return err; 205 } 206 207 rtc = devm_rtc_device_register(&client->dev, 208 pcf85063_driver.driver.name, 209 &pcf85063_rtc_ops, THIS_MODULE); 210 211 return PTR_ERR_OR_ZERO(rtc); 212 } 213 214 static const struct i2c_device_id pcf85063_id[] = { 215 { "pcf85063", 0 }, 216 { } 217 }; 218 MODULE_DEVICE_TABLE(i2c, pcf85063_id); 219 220 #ifdef CONFIG_OF 221 static const struct of_device_id pcf85063_of_match[] = { 222 { .compatible = "nxp,pcf85063" }, 223 {} 224 }; 225 MODULE_DEVICE_TABLE(of, pcf85063_of_match); 226 #endif 227 228 static struct i2c_driver pcf85063_driver = { 229 .driver = { 230 .name = "rtc-pcf85063", 231 .of_match_table = of_match_ptr(pcf85063_of_match), 232 }, 233 .probe = pcf85063_probe, 234 .id_table = pcf85063_id, 235 }; 236 237 module_i2c_driver(pcf85063_driver); 238 239 MODULE_AUTHOR("Søren Andersen <san@rosetechnology.dk>"); 240 MODULE_DESCRIPTION("PCF85063 RTC driver"); 241 MODULE_LICENSE("GPL"); 242