395 lines
8.4 KiB
C
395 lines
8.4 KiB
C
/*
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* Copyright (C) 2012 Avionic Design GmbH
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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/bcd.h>
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#include <linux/i2c.h>
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#include <linux/module.h>
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#include <linux/rtc.h>
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#include <linux/of.h>
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#define DRIVER_NAME "rtc-pcf8523"
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#define REG_CONTROL1 0x00
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#define REG_CONTROL1_CAP_SEL (1 << 7)
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#define REG_CONTROL1_STOP (1 << 5)
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#define REG_CONTROL3 0x02
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#define REG_CONTROL3_PM_BLD (1 << 7) /* battery low detection disabled */
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#define REG_CONTROL3_PM_VDD (1 << 6) /* switch-over disabled */
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#define REG_CONTROL3_PM_DSM (1 << 5) /* direct switching mode */
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#define REG_CONTROL3_PM_MASK 0xe0
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#define REG_CONTROL3_BLF (1 << 2) /* battery low bit, read-only */
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#define REG_SECONDS 0x03
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#define REG_SECONDS_OS (1 << 7)
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#define REG_MINUTES 0x04
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#define REG_HOURS 0x05
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#define REG_DAYS 0x06
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#define REG_WEEKDAYS 0x07
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#define REG_MONTHS 0x08
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#define REG_YEARS 0x09
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#define REG_OFFSET 0x0e
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#define REG_OFFSET_MODE BIT(7)
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struct pcf8523 {
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struct rtc_device *rtc;
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};
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static int pcf8523_read(struct i2c_client *client, u8 reg, u8 *valuep)
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{
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struct i2c_msg msgs[2];
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u8 value = 0;
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int err;
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msgs[0].addr = client->addr;
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msgs[0].flags = 0;
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msgs[0].len = sizeof(reg);
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msgs[0].buf = ®
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msgs[1].addr = client->addr;
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msgs[1].flags = I2C_M_RD;
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msgs[1].len = sizeof(value);
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msgs[1].buf = &value;
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err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
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if (err < 0)
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return err;
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*valuep = value;
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return 0;
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}
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static int pcf8523_write(struct i2c_client *client, u8 reg, u8 value)
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{
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u8 buffer[2] = { reg, value };
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struct i2c_msg msg;
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int err;
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msg.addr = client->addr;
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msg.flags = 0;
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msg.len = sizeof(buffer);
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msg.buf = buffer;
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err = i2c_transfer(client->adapter, &msg, 1);
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if (err < 0)
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return err;
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return 0;
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}
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static int pcf8523_voltage_low(struct i2c_client *client)
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{
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u8 value;
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int err;
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err = pcf8523_read(client, REG_CONTROL3, &value);
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if (err < 0)
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return err;
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return !!(value & REG_CONTROL3_BLF);
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}
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static int pcf8523_select_capacitance(struct i2c_client *client, bool high)
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{
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u8 value;
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int err;
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err = pcf8523_read(client, REG_CONTROL1, &value);
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if (err < 0)
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return err;
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if (!high)
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value &= ~REG_CONTROL1_CAP_SEL;
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else
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value |= REG_CONTROL1_CAP_SEL;
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err = pcf8523_write(client, REG_CONTROL1, value);
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if (err < 0)
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return err;
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return err;
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}
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static int pcf8523_set_pm(struct i2c_client *client, u8 pm)
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{
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u8 value;
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int err;
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err = pcf8523_read(client, REG_CONTROL3, &value);
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if (err < 0)
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return err;
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value = (value & ~REG_CONTROL3_PM_MASK) | pm;
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err = pcf8523_write(client, REG_CONTROL3, value);
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if (err < 0)
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return err;
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return 0;
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}
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static int pcf8523_stop_rtc(struct i2c_client *client)
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{
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u8 value;
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int err;
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err = pcf8523_read(client, REG_CONTROL1, &value);
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if (err < 0)
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return err;
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value |= REG_CONTROL1_STOP;
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err = pcf8523_write(client, REG_CONTROL1, value);
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if (err < 0)
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return err;
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return 0;
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}
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static int pcf8523_start_rtc(struct i2c_client *client)
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{
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u8 value;
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int err;
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err = pcf8523_read(client, REG_CONTROL1, &value);
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if (err < 0)
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return err;
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value &= ~REG_CONTROL1_STOP;
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err = pcf8523_write(client, REG_CONTROL1, value);
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if (err < 0)
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return err;
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return 0;
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}
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static int pcf8523_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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u8 start = REG_SECONDS, regs[7];
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struct i2c_msg msgs[2];
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int err;
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err = pcf8523_voltage_low(client);
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if (err < 0) {
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return err;
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} else if (err > 0) {
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dev_err(dev, "low voltage detected, time is unreliable\n");
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return -EINVAL;
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}
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msgs[0].addr = client->addr;
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msgs[0].flags = 0;
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msgs[0].len = 1;
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msgs[0].buf = &start;
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msgs[1].addr = client->addr;
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msgs[1].flags = I2C_M_RD;
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msgs[1].len = sizeof(regs);
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msgs[1].buf = regs;
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err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
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if (err < 0)
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return err;
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if (regs[0] & REG_SECONDS_OS)
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return -EINVAL;
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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);
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tm->tm_mday = bcd2bin(regs[3] & 0x3f);
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tm->tm_wday = regs[4] & 0x7;
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tm->tm_mon = bcd2bin(regs[5] & 0x1f) - 1;
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tm->tm_year = bcd2bin(regs[6]) + 100;
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return 0;
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}
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static int pcf8523_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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struct i2c_msg msg;
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u8 regs[8];
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int err;
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/*
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* The hardware can only store values between 0 and 99 in it's YEAR
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* register (with 99 overflowing to 0 on increment).
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* After 2100-02-28 we could start interpreting the year to be in the
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* interval [2100, 2199], but there is no path to switch in a smooth way
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* because the chip handles YEAR=0x00 (and the out-of-spec
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* YEAR=0xa0) as a leap year, but 2100 isn't.
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*/
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if (tm->tm_year < 100 || tm->tm_year >= 200)
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return -EINVAL;
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err = pcf8523_stop_rtc(client);
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if (err < 0)
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return err;
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regs[0] = REG_SECONDS;
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/* This will purposely overwrite REG_SECONDS_OS */
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regs[1] = bin2bcd(tm->tm_sec);
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regs[2] = bin2bcd(tm->tm_min);
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regs[3] = bin2bcd(tm->tm_hour);
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regs[4] = bin2bcd(tm->tm_mday);
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regs[5] = tm->tm_wday;
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regs[6] = bin2bcd(tm->tm_mon + 1);
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regs[7] = bin2bcd(tm->tm_year - 100);
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msg.addr = client->addr;
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msg.flags = 0;
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msg.len = sizeof(regs);
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msg.buf = regs;
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err = i2c_transfer(client->adapter, &msg, 1);
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if (err < 0) {
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/*
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* If the time cannot be set, restart the RTC anyway. Note
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* that errors are ignored if the RTC cannot be started so
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* that we have a chance to propagate the original error.
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*/
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pcf8523_start_rtc(client);
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return err;
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}
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return pcf8523_start_rtc(client);
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}
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#ifdef CONFIG_RTC_INTF_DEV
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static int pcf8523_rtc_ioctl(struct device *dev, unsigned int cmd,
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unsigned long arg)
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{
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struct i2c_client *client = to_i2c_client(dev);
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int ret;
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switch (cmd) {
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case RTC_VL_READ:
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ret = pcf8523_voltage_low(client);
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if (ret < 0)
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return ret;
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if (copy_to_user((void __user *)arg, &ret, sizeof(int)))
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return -EFAULT;
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return 0;
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default:
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return -ENOIOCTLCMD;
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}
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}
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#else
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#define pcf8523_rtc_ioctl NULL
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#endif
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static int pcf8523_rtc_read_offset(struct device *dev, long *offset)
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{
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struct i2c_client *client = to_i2c_client(dev);
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int err;
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u8 value;
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s8 val;
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err = pcf8523_read(client, REG_OFFSET, &value);
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if (err < 0)
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return err;
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/* sign extend the 7-bit offset value */
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val = value << 1;
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*offset = (value & REG_OFFSET_MODE ? 4069 : 4340) * (val >> 1);
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return 0;
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}
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static int pcf8523_rtc_set_offset(struct device *dev, long offset)
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{
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struct i2c_client *client = to_i2c_client(dev);
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long reg_m0, reg_m1;
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u8 value;
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reg_m0 = clamp(DIV_ROUND_CLOSEST(offset, 4340), -64L, 63L);
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reg_m1 = clamp(DIV_ROUND_CLOSEST(offset, 4069), -64L, 63L);
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if (abs(reg_m0 * 4340 - offset) < abs(reg_m1 * 4069 - offset))
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value = reg_m0 & 0x7f;
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else
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value = (reg_m1 & 0x7f) | REG_OFFSET_MODE;
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return pcf8523_write(client, REG_OFFSET, value);
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}
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static const struct rtc_class_ops pcf8523_rtc_ops = {
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.read_time = pcf8523_rtc_read_time,
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.set_time = pcf8523_rtc_set_time,
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.ioctl = pcf8523_rtc_ioctl,
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.read_offset = pcf8523_rtc_read_offset,
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.set_offset = pcf8523_rtc_set_offset,
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};
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static int pcf8523_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct pcf8523 *pcf;
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int err;
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if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
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return -ENODEV;
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pcf = devm_kzalloc(&client->dev, sizeof(*pcf), GFP_KERNEL);
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if (!pcf)
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return -ENOMEM;
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err = pcf8523_select_capacitance(client, true);
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if (err < 0)
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return err;
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err = pcf8523_set_pm(client, 0);
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if (err < 0)
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return err;
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pcf->rtc = devm_rtc_device_register(&client->dev, DRIVER_NAME,
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&pcf8523_rtc_ops, THIS_MODULE);
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if (IS_ERR(pcf->rtc))
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return PTR_ERR(pcf->rtc);
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i2c_set_clientdata(client, pcf);
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return 0;
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}
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static const struct i2c_device_id pcf8523_id[] = {
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{ "pcf8523", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, pcf8523_id);
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#ifdef CONFIG_OF
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static const struct of_device_id pcf8523_of_match[] = {
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{ .compatible = "nxp,pcf8523" },
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{ }
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};
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MODULE_DEVICE_TABLE(of, pcf8523_of_match);
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#endif
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static struct i2c_driver pcf8523_driver = {
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.driver = {
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.name = DRIVER_NAME,
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.of_match_table = of_match_ptr(pcf8523_of_match),
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},
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.probe = pcf8523_probe,
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.id_table = pcf8523_id,
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};
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module_i2c_driver(pcf8523_driver);
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MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
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MODULE_DESCRIPTION("NXP PCF8523 RTC driver");
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MODULE_LICENSE("GPL v2");
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