diff options
Diffstat (limited to 'drivers/rtc/rtc-pcf85063.c')
| -rw-r--r-- | drivers/rtc/rtc-pcf85063.c | 234 |
1 files changed, 234 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-pcf85063.c b/drivers/rtc/rtc-pcf85063.c new file mode 100644 index 000000000..283c2335b --- /dev/null +++ b/drivers/rtc/rtc-pcf85063.c @@ -0,0 +1,234 @@ +/* + * An I2C driver for the PCF85063 RTC + * Copyright 2014 Rose Technology + * + * Author: Søren Andersen <san@rosetechnology.dk> + * Maintainers: http://www.nslu2-linux.org/ + * + * based on the other drivers in this same directory. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ +#include <linux/i2c.h> +#include <linux/bcd.h> +#include <linux/rtc.h> +#include <linux/module.h> + +/* + * Information for this driver was pulled from the following datasheets. + * + * http://www.nxp.com/documents/data_sheet/PCF85063A.pdf + * http://www.nxp.com/documents/data_sheet/PCF85063TP.pdf + * + * PCF85063A -- Rev. 6 — 18 November 2015 + * PCF85063TP -- Rev. 4 — 6 May 2015 +*/ + +#define PCF85063_REG_CTRL1 0x00 /* status */ +#define PCF85063_REG_CTRL1_STOP BIT(5) +#define PCF85063_REG_CTRL2 0x01 + +#define PCF85063_REG_SC 0x04 /* datetime */ +#define PCF85063_REG_SC_OS 0x80 +#define PCF85063_REG_MN 0x05 +#define PCF85063_REG_HR 0x06 +#define PCF85063_REG_DM 0x07 +#define PCF85063_REG_DW 0x08 +#define PCF85063_REG_MO 0x09 +#define PCF85063_REG_YR 0x0A + +static struct i2c_driver pcf85063_driver; + +static int pcf85063_stop_clock(struct i2c_client *client, u8 *ctrl1) +{ + int rc; + u8 reg; + + rc = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1); + if (rc < 0) { + dev_err(&client->dev, "Failing to stop the clock\n"); + return -EIO; + } + + /* stop the clock */ + reg = rc | PCF85063_REG_CTRL1_STOP; + + rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, reg); + if (rc < 0) { + dev_err(&client->dev, "Failing to stop the clock\n"); + return -EIO; + } + + *ctrl1 = reg; + + return 0; +} + +static int pcf85063_start_clock(struct i2c_client *client, u8 ctrl1) +{ + int rc; + + /* start the clock */ + ctrl1 &= ~PCF85063_REG_CTRL1_STOP; + + rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ctrl1); + if (rc < 0) { + dev_err(&client->dev, "Failing to start the clock\n"); + return -EIO; + } + + return 0; +} + +static int pcf85063_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct i2c_client *client = to_i2c_client(dev); + int rc; + u8 regs[7]; + + /* + * while reading, the time/date registers are blocked and not updated + * anymore until the access is finished. To not lose a second + * event, the access must be finished within one second. So, read all + * time/date registers in one turn. + */ + rc = i2c_smbus_read_i2c_block_data(client, PCF85063_REG_SC, + sizeof(regs), regs); + if (rc != sizeof(regs)) { + dev_err(&client->dev, "date/time register read error\n"); + return -EIO; + } + + /* if the clock has lost its power it makes no sense to use its time */ + if (regs[0] & PCF85063_REG_SC_OS) { + dev_warn(&client->dev, "Power loss detected, invalid time\n"); + return -EINVAL; + } + + tm->tm_sec = bcd2bin(regs[0] & 0x7F); + tm->tm_min = bcd2bin(regs[1] & 0x7F); + tm->tm_hour = bcd2bin(regs[2] & 0x3F); /* rtc hr 0-23 */ + tm->tm_mday = bcd2bin(regs[3] & 0x3F); + tm->tm_wday = regs[4] & 0x07; + tm->tm_mon = bcd2bin(regs[5] & 0x1F) - 1; /* rtc mn 1-12 */ + tm->tm_year = bcd2bin(regs[6]); + tm->tm_year += 100; + + return 0; +} + +static int pcf85063_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct i2c_client *client = to_i2c_client(dev); + int rc; + u8 regs[7]; + u8 ctrl1; + + if ((tm->tm_year < 100) || (tm->tm_year > 199)) + return -EINVAL; + + /* + * to accurately set the time, reset the divider chain and keep it in + * reset state until all time/date registers are written + */ + rc = pcf85063_stop_clock(client, &ctrl1); + if (rc != 0) + return rc; + + /* hours, minutes and seconds */ + regs[0] = bin2bcd(tm->tm_sec) & 0x7F; /* clear OS flag */ + + regs[1] = bin2bcd(tm->tm_min); + regs[2] = bin2bcd(tm->tm_hour); + + /* Day of month, 1 - 31 */ + regs[3] = bin2bcd(tm->tm_mday); + + /* Day, 0 - 6 */ + regs[4] = tm->tm_wday & 0x07; + + /* month, 1 - 12 */ + regs[5] = bin2bcd(tm->tm_mon + 1); + + /* year and century */ + regs[6] = bin2bcd(tm->tm_year - 100); + + /* write all registers at once */ + rc = i2c_smbus_write_i2c_block_data(client, PCF85063_REG_SC, + sizeof(regs), regs); + if (rc < 0) { + dev_err(&client->dev, "date/time register write error\n"); + return rc; + } + + /* + * Write the control register as a separate action since the size of + * the register space is different between the PCF85063TP and + * PCF85063A devices. The rollover point can not be used. + */ + rc = pcf85063_start_clock(client, ctrl1); + if (rc != 0) + return rc; + + return 0; +} + +static const struct rtc_class_ops pcf85063_rtc_ops = { + .read_time = pcf85063_rtc_read_time, + .set_time = pcf85063_rtc_set_time +}; + +static int pcf85063_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct rtc_device *rtc; + int err; + + dev_dbg(&client->dev, "%s\n", __func__); + + if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) + return -ENODEV; + + err = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1); + if (err < 0) { + dev_err(&client->dev, "RTC chip is not present\n"); + return err; + } + + rtc = devm_rtc_device_register(&client->dev, + pcf85063_driver.driver.name, + &pcf85063_rtc_ops, THIS_MODULE); + + return PTR_ERR_OR_ZERO(rtc); +} + +static const struct i2c_device_id pcf85063_id[] = { + { "pcf85063", 0 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, pcf85063_id); + +#ifdef CONFIG_OF +static const struct of_device_id pcf85063_of_match[] = { + { .compatible = "nxp,pcf85063" }, + {} +}; +MODULE_DEVICE_TABLE(of, pcf85063_of_match); +#endif + +static struct i2c_driver pcf85063_driver = { + .driver = { + .name = "rtc-pcf85063", + .of_match_table = of_match_ptr(pcf85063_of_match), + }, + .probe = pcf85063_probe, + .id_table = pcf85063_id, +}; + +module_i2c_driver(pcf85063_driver); + +MODULE_AUTHOR("Søren Andersen <san@rosetechnology.dk>"); +MODULE_DESCRIPTION("PCF85063 RTC driver"); +MODULE_LICENSE("GPL"); |