267 lines
6.3 KiB
C
267 lines
6.3 KiB
C
/*
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* An I2C driver for the PCF85063 RTC
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* Copyright 2014 Rose Technology
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*
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* Author: Søren Andersen <san@rosetechnology.dk>
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* Maintainers: http://www.nslu2-linux.org/
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*
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* based on the other drivers in this same directory.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/i2c.h>
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#include <linux/bcd.h>
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#include <linux/rtc.h>
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#include <linux/module.h>
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/*
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* Information for this driver was pulled from the following datasheets.
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*
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* http://www.nxp.com/documents/data_sheet/PCF85063A.pdf
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* http://www.nxp.com/documents/data_sheet/PCF85063TP.pdf
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*
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* PCF85063A -- Rev. 6 — 18 November 2015
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* PCF85063TP -- Rev. 4 — 6 May 2015
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*/
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#define PCF85063_REG_CTRL1 0x00 /* status */
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#define PCF85063_REG_CTRL1_CAP_SEL BIT(0)
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#define PCF85063_REG_CTRL1_STOP BIT(5)
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#define PCF85063_REG_SC 0x04 /* datetime */
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#define PCF85063_REG_SC_OS 0x80
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static struct i2c_driver pcf85063_driver;
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static int pcf85063_stop_clock(struct i2c_client *client, u8 *ctrl1)
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{
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int rc;
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u8 reg;
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rc = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
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if (rc < 0) {
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dev_err(&client->dev, "Failing to stop the clock\n");
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return -EIO;
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}
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/* stop the clock */
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reg = rc | PCF85063_REG_CTRL1_STOP;
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rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, reg);
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if (rc < 0) {
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dev_err(&client->dev, "Failing to stop the clock\n");
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return -EIO;
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}
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*ctrl1 = reg;
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return 0;
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}
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static int pcf85063_start_clock(struct i2c_client *client, u8 ctrl1)
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{
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int rc;
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/* start the clock */
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ctrl1 &= ~PCF85063_REG_CTRL1_STOP;
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rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ctrl1);
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if (rc < 0) {
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dev_err(&client->dev, "Failing to start the clock\n");
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return -EIO;
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}
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return 0;
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}
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static int pcf85063_rtc_read_time(struct device *dev, struct rtc_time *tm)
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{
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struct i2c_client *client = to_i2c_client(dev);
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int rc;
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u8 regs[7];
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/*
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* while reading, the time/date registers are blocked and not updated
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* anymore until the access is finished. To not lose a second
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* event, the access must be finished within one second. So, read all
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* time/date registers in one turn.
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*/
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rc = i2c_smbus_read_i2c_block_data(client, PCF85063_REG_SC,
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sizeof(regs), regs);
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if (rc != sizeof(regs)) {
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dev_err(&client->dev, "date/time register read error\n");
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return -EIO;
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}
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/* if the clock has lost its power it makes no sense to use its time */
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if (regs[0] & PCF85063_REG_SC_OS) {
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dev_warn(&client->dev, "Power loss detected, invalid time\n");
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return -EINVAL;
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}
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tm->tm_sec = bcd2bin(regs[0] & 0x7F);
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tm->tm_min = bcd2bin(regs[1] & 0x7F);
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tm->tm_hour = bcd2bin(regs[2] & 0x3F); /* rtc hr 0-23 */
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tm->tm_mday = bcd2bin(regs[3] & 0x3F);
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tm->tm_wday = regs[4] & 0x07;
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tm->tm_mon = bcd2bin(regs[5] & 0x1F) - 1; /* rtc mn 1-12 */
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tm->tm_year = bcd2bin(regs[6]);
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tm->tm_year += 100;
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return 0;
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}
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static int pcf85063_rtc_set_time(struct device *dev, struct rtc_time *tm)
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{
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struct i2c_client *client = to_i2c_client(dev);
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int rc;
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u8 regs[7];
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u8 ctrl1;
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if ((tm->tm_year < 100) || (tm->tm_year > 199))
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return -EINVAL;
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/*
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* to accurately set the time, reset the divider chain and keep it in
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* reset state until all time/date registers are written
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*/
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rc = pcf85063_stop_clock(client, &ctrl1);
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if (rc != 0)
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return rc;
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/* hours, minutes and seconds */
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regs[0] = bin2bcd(tm->tm_sec) & 0x7F; /* clear OS flag */
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regs[1] = bin2bcd(tm->tm_min);
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regs[2] = bin2bcd(tm->tm_hour);
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/* Day of month, 1 - 31 */
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regs[3] = bin2bcd(tm->tm_mday);
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/* Day, 0 - 6 */
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regs[4] = tm->tm_wday & 0x07;
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/* month, 1 - 12 */
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regs[5] = bin2bcd(tm->tm_mon + 1);
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/* year and century */
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regs[6] = bin2bcd(tm->tm_year - 100);
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/* write all registers at once */
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rc = i2c_smbus_write_i2c_block_data(client, PCF85063_REG_SC,
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sizeof(regs), regs);
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if (rc < 0) {
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dev_err(&client->dev, "date/time register write error\n");
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return rc;
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}
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/*
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* Write the control register as a separate action since the size of
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* the register space is different between the PCF85063TP and
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* PCF85063A devices. The rollover point can not be used.
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*/
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rc = pcf85063_start_clock(client, ctrl1);
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if (rc != 0)
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return rc;
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return 0;
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}
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static const struct rtc_class_ops pcf85063_rtc_ops = {
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.read_time = pcf85063_rtc_read_time,
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.set_time = pcf85063_rtc_set_time
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};
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static int pcf85063_load_capacitance(struct i2c_client *client)
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{
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u32 load;
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int rc;
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u8 reg;
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rc = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
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if (rc < 0)
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return rc;
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reg = rc;
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load = 7000;
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of_property_read_u32(client->dev.of_node, "quartz-load-femtofarads",
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&load);
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switch (load) {
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default:
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dev_warn(&client->dev, "Unknown quartz-load-femtofarads value: %d. Assuming 7000",
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load);
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/* fall through */
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case 7000:
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reg &= ~PCF85063_REG_CTRL1_CAP_SEL;
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break;
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case 12500:
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reg |= PCF85063_REG_CTRL1_CAP_SEL;
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break;
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}
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rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, reg);
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return rc;
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}
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static int pcf85063_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct rtc_device *rtc;
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int err;
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dev_dbg(&client->dev, "%s\n", __func__);
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if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
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return -ENODEV;
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err = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
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if (err < 0) {
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dev_err(&client->dev, "RTC chip is not present\n");
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return err;
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}
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err = pcf85063_load_capacitance(client);
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if (err < 0)
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dev_warn(&client->dev, "failed to set xtal load capacitance: %d",
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err);
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rtc = devm_rtc_device_register(&client->dev,
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pcf85063_driver.driver.name,
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&pcf85063_rtc_ops, THIS_MODULE);
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return PTR_ERR_OR_ZERO(rtc);
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}
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static const struct i2c_device_id pcf85063_id[] = {
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{ "pcf85063", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, pcf85063_id);
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#ifdef CONFIG_OF
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static const struct of_device_id pcf85063_of_match[] = {
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{ .compatible = "nxp,pcf85063" },
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{}
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};
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MODULE_DEVICE_TABLE(of, pcf85063_of_match);
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#endif
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static struct i2c_driver pcf85063_driver = {
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.driver = {
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.name = "rtc-pcf85063",
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.of_match_table = of_match_ptr(pcf85063_of_match),
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},
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.probe = pcf85063_probe,
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.id_table = pcf85063_id,
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};
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module_i2c_driver(pcf85063_driver);
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MODULE_AUTHOR("Søren Andersen <san@rosetechnology.dk>");
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MODULE_DESCRIPTION("PCF85063 RTC driver");
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MODULE_LICENSE("GPL");
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