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_CAP_SEL BIT(0) 31 #define PCF85063_REG_CTRL1_STOP BIT(5) 32 33 #define PCF85063_REG_SC 0x04 /* datetime */ 34 #define PCF85063_REG_SC_OS 0x80 35 36 static struct i2c_driver pcf85063_driver; 37 38 static int pcf85063_stop_clock(struct i2c_client *client, u8 *ctrl1) 39 { 40 int rc; 41 u8 reg; 42 43 rc = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1); 44 if (rc < 0) { 45 dev_err(&client->dev, "Failing to stop the clock\n"); 46 return -EIO; 47 } 48 49 /* stop the clock */ 50 reg = rc | PCF85063_REG_CTRL1_STOP; 51 52 rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, reg); 53 if (rc < 0) { 54 dev_err(&client->dev, "Failing to stop the clock\n"); 55 return -EIO; 56 } 57 58 *ctrl1 = reg; 59 60 return 0; 61 } 62 63 static int pcf85063_start_clock(struct i2c_client *client, u8 ctrl1) 64 { 65 int rc; 66 67 /* start the clock */ 68 ctrl1 &= ~PCF85063_REG_CTRL1_STOP; 69 70 rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ctrl1); 71 if (rc < 0) { 72 dev_err(&client->dev, "Failing to start the clock\n"); 73 return -EIO; 74 } 75 76 return 0; 77 } 78 79 static int pcf85063_rtc_read_time(struct device *dev, struct rtc_time *tm) 80 { 81 struct i2c_client *client = to_i2c_client(dev); 82 int rc; 83 u8 regs[7]; 84 85 /* 86 * while reading, the time/date registers are blocked and not updated 87 * anymore until the access is finished. To not lose a second 88 * event, the access must be finished within one second. So, read all 89 * time/date registers in one turn. 90 */ 91 rc = i2c_smbus_read_i2c_block_data(client, PCF85063_REG_SC, 92 sizeof(regs), regs); 93 if (rc != sizeof(regs)) { 94 dev_err(&client->dev, "date/time register read error\n"); 95 return -EIO; 96 } 97 98 /* if the clock has lost its power it makes no sense to use its time */ 99 if (regs[0] & PCF85063_REG_SC_OS) { 100 dev_warn(&client->dev, "Power loss detected, invalid time\n"); 101 return -EINVAL; 102 } 103 104 tm->tm_sec = bcd2bin(regs[0] & 0x7F); 105 tm->tm_min = bcd2bin(regs[1] & 0x7F); 106 tm->tm_hour = bcd2bin(regs[2] & 0x3F); /* rtc hr 0-23 */ 107 tm->tm_mday = bcd2bin(regs[3] & 0x3F); 108 tm->tm_wday = regs[4] & 0x07; 109 tm->tm_mon = bcd2bin(regs[5] & 0x1F) - 1; /* rtc mn 1-12 */ 110 tm->tm_year = bcd2bin(regs[6]); 111 tm->tm_year += 100; 112 113 return 0; 114 } 115 116 static int pcf85063_rtc_set_time(struct device *dev, struct rtc_time *tm) 117 { 118 struct i2c_client *client = to_i2c_client(dev); 119 int rc; 120 u8 regs[7]; 121 u8 ctrl1; 122 123 if ((tm->tm_year < 100) || (tm->tm_year > 199)) 124 return -EINVAL; 125 126 /* 127 * to accurately set the time, reset the divider chain and keep it in 128 * reset state until all time/date registers are written 129 */ 130 rc = pcf85063_stop_clock(client, &ctrl1); 131 if (rc != 0) 132 return rc; 133 134 /* hours, minutes and seconds */ 135 regs[0] = bin2bcd(tm->tm_sec) & 0x7F; /* clear OS flag */ 136 137 regs[1] = bin2bcd(tm->tm_min); 138 regs[2] = bin2bcd(tm->tm_hour); 139 140 /* Day of month, 1 - 31 */ 141 regs[3] = bin2bcd(tm->tm_mday); 142 143 /* Day, 0 - 6 */ 144 regs[4] = tm->tm_wday & 0x07; 145 146 /* month, 1 - 12 */ 147 regs[5] = bin2bcd(tm->tm_mon + 1); 148 149 /* year and century */ 150 regs[6] = bin2bcd(tm->tm_year - 100); 151 152 /* write all registers at once */ 153 rc = i2c_smbus_write_i2c_block_data(client, PCF85063_REG_SC, 154 sizeof(regs), regs); 155 if (rc < 0) { 156 dev_err(&client->dev, "date/time register write error\n"); 157 return rc; 158 } 159 160 /* 161 * Write the control register as a separate action since the size of 162 * the register space is different between the PCF85063TP and 163 * PCF85063A devices. The rollover point can not be used. 164 */ 165 rc = pcf85063_start_clock(client, ctrl1); 166 if (rc != 0) 167 return rc; 168 169 return 0; 170 } 171 172 static const struct rtc_class_ops pcf85063_rtc_ops = { 173 .read_time = pcf85063_rtc_read_time, 174 .set_time = pcf85063_rtc_set_time 175 }; 176 177 static int pcf85063_load_capacitance(struct i2c_client *client) 178 { 179 u32 load; 180 int rc; 181 u8 reg; 182 183 rc = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1); 184 if (rc < 0) 185 return rc; 186 187 reg = rc; 188 load = 7000; 189 of_property_read_u32(client->dev.of_node, "quartz-load-femtofarads", 190 &load); 191 192 switch (load) { 193 default: 194 dev_warn(&client->dev, "Unknown quartz-load-femtofarads value: %d. Assuming 7000", 195 load); 196 /* fall through */ 197 case 7000: 198 reg &= ~PCF85063_REG_CTRL1_CAP_SEL; 199 break; 200 case 12500: 201 reg |= PCF85063_REG_CTRL1_CAP_SEL; 202 break; 203 } 204 205 rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, reg); 206 207 return rc; 208 } 209 210 static int pcf85063_probe(struct i2c_client *client, 211 const struct i2c_device_id *id) 212 { 213 struct rtc_device *rtc; 214 int err; 215 216 dev_dbg(&client->dev, "%s\n", __func__); 217 218 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 219 return -ENODEV; 220 221 err = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1); 222 if (err < 0) { 223 dev_err(&client->dev, "RTC chip is not present\n"); 224 return err; 225 } 226 227 err = pcf85063_load_capacitance(client); 228 if (err < 0) 229 dev_warn(&client->dev, "failed to set xtal load capacitance: %d", 230 err); 231 232 rtc = devm_rtc_device_register(&client->dev, 233 pcf85063_driver.driver.name, 234 &pcf85063_rtc_ops, THIS_MODULE); 235 236 return PTR_ERR_OR_ZERO(rtc); 237 } 238 239 static const struct i2c_device_id pcf85063_id[] = { 240 { "pcf85063", 0 }, 241 { } 242 }; 243 MODULE_DEVICE_TABLE(i2c, pcf85063_id); 244 245 #ifdef CONFIG_OF 246 static const struct of_device_id pcf85063_of_match[] = { 247 { .compatible = "nxp,pcf85063" }, 248 {} 249 }; 250 MODULE_DEVICE_TABLE(of, pcf85063_of_match); 251 #endif 252 253 static struct i2c_driver pcf85063_driver = { 254 .driver = { 255 .name = "rtc-pcf85063", 256 .of_match_table = of_match_ptr(pcf85063_of_match), 257 }, 258 .probe = pcf85063_probe, 259 .id_table = pcf85063_id, 260 }; 261 262 module_i2c_driver(pcf85063_driver); 263 264 MODULE_AUTHOR("Søren Andersen <san@rosetechnology.dk>"); 265 MODULE_DESCRIPTION("PCF85063 RTC driver"); 266 MODULE_LICENSE("GPL"); 267