/* * Copyright (C) 2012 Avionic Design GmbH * * 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/bcd.h> #include <linux/i2c.h> #include <linux/module.h> #include <linux/rtc.h> #include <linux/of.h> #define DRIVER_NAME "rtc-pcf8523" #define REG_CONTROL1 0x00 #define REG_CONTROL1_CAP_SEL (1 << 7) #define REG_CONTROL1_STOP (1 << 5) #define REG_CONTROL3 0x02 #define REG_CONTROL3_PM_BLD (1 << 7) /* battery low detection disabled */ #define REG_CONTROL3_PM_VDD (1 << 6) /* switch-over disabled */ #define REG_CONTROL3_PM_DSM (1 << 5) /* direct switching mode */ #define REG_CONTROL3_PM_MASK 0xe0 #define REG_CONTROL3_BLF (1 << 2) /* battery low bit, read-only */ #define REG_SECONDS 0x03 #define REG_SECONDS_OS (1 << 7) #define REG_MINUTES 0x04 #define REG_HOURS 0x05 #define REG_DAYS 0x06 #define REG_WEEKDAYS 0x07 #define REG_MONTHS 0x08 #define REG_YEARS 0x09 struct pcf8523 { struct rtc_device *rtc; }; static int pcf8523_read(struct i2c_client *client, u8 reg, u8 *valuep) { struct i2c_msg msgs[2]; u8 value = 0; int err; msgs[0].addr = client->addr; msgs[0].flags = 0; msgs[0].len = sizeof(reg); msgs[0].buf = ® msgs[1].addr = client->addr; msgs[1].flags = I2C_M_RD; msgs[1].len = sizeof(value); msgs[1].buf = &value; err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs)); if (err < 0) return err; *valuep = value; return 0; } static int pcf8523_write(struct i2c_client *client, u8 reg, u8 value) { u8 buffer[2] = { reg, value }; struct i2c_msg msg; int err; msg.addr = client->addr; msg.flags = 0; msg.len = sizeof(buffer); msg.buf = buffer; err = i2c_transfer(client->adapter, &msg, 1); if (err < 0) return err; return 0; } static int pcf8523_select_capacitance(struct i2c_client *client, bool high) { u8 value; int err; err = pcf8523_read(client, REG_CONTROL1, &value); if (err < 0) return err; if (!high) value &= ~REG_CONTROL1_CAP_SEL; else value |= REG_CONTROL1_CAP_SEL; err = pcf8523_write(client, REG_CONTROL1, value); if (err < 0) return err; return err; } static int pcf8523_set_pm(struct i2c_client *client, u8 pm) { u8 value; int err; err = pcf8523_read(client, REG_CONTROL3, &value); if (err < 0) return err; value = (value & ~REG_CONTROL3_PM_MASK) | pm; err = pcf8523_write(client, REG_CONTROL3, value); if (err < 0) return err; return 0; } static int pcf8523_stop_rtc(struct i2c_client *client) { u8 value; int err; err = pcf8523_read(client, REG_CONTROL1, &value); if (err < 0) return err; value |= REG_CONTROL1_STOP; err = pcf8523_write(client, REG_CONTROL1, value); if (err < 0) return err; return 0; } static int pcf8523_start_rtc(struct i2c_client *client) { u8 value; int err; err = pcf8523_read(client, REG_CONTROL1, &value); if (err < 0) return err; value &= ~REG_CONTROL1_STOP; err = pcf8523_write(client, REG_CONTROL1, value); if (err < 0) return err; return 0; } static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm) { struct i2c_client *client = to_i2c_client(dev); u8 start = REG_SECONDS, regs[7]; struct i2c_msg msgs[2]; int err; msgs[0].addr = client->addr; msgs[0].flags = 0; msgs[0].len = 1; msgs[0].buf = &start; msgs[1].addr = client->addr; msgs[1].flags = I2C_M_RD; msgs[1].len = sizeof(regs); msgs[1].buf = regs; err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs)); if (err < 0) return err; if (regs[0] & REG_SECONDS_OS) { /* * If the oscillator was stopped, try to clear the flag. Upon * power-up the flag is always set, but if we cannot clear it * the oscillator isn't running properly for some reason. The * sensible thing therefore is to return an error, signalling * that the clock cannot be assumed to be correct. */ regs[0] &= ~REG_SECONDS_OS; err = pcf8523_write(client, REG_SECONDS, regs[0]); if (err < 0) return err; err = pcf8523_read(client, REG_SECONDS, ®s[0]); if (err < 0) return err; if (regs[0] & REG_SECONDS_OS) return -EAGAIN; } tm->tm_sec = bcd2bin(regs[0] & 0x7f); tm->tm_min = bcd2bin(regs[1] & 0x7f); tm->tm_hour = bcd2bin(regs[2] & 0x3f); tm->tm_mday = bcd2bin(regs[3] & 0x3f); tm->tm_wday = regs[4] & 0x7; tm->tm_mon = bcd2bin(regs[5] & 0x1f) - 1; tm->tm_year = bcd2bin(regs[6]) + 100; return rtc_valid_tm(tm); } static int pcf8523_rtc_set_time(struct device *dev, struct rtc_time *tm) { struct i2c_client *client = to_i2c_client(dev); struct i2c_msg msg; u8 regs[8]; int err; err = pcf8523_stop_rtc(client); if (err < 0) return err; regs[0] = REG_SECONDS; regs[1] = bin2bcd(tm->tm_sec); regs[2] = bin2bcd(tm->tm_min); regs[3] = bin2bcd(tm->tm_hour); regs[4] = bin2bcd(tm->tm_mday); regs[5] = tm->tm_wday; regs[6] = bin2bcd(tm->tm_mon + 1); regs[7] = bin2bcd(tm->tm_year - 100); msg.addr = client->addr; msg.flags = 0; msg.len = sizeof(regs); msg.buf = regs; err = i2c_transfer(client->adapter, &msg, 1); if (err < 0) { /* * If the time cannot be set, restart the RTC anyway. Note * that errors are ignored if the RTC cannot be started so * that we have a chance to propagate the original error. */ pcf8523_start_rtc(client); return err; } return pcf8523_start_rtc(client); } #ifdef CONFIG_RTC_INTF_DEV static int pcf8523_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg) { struct i2c_client *client = to_i2c_client(dev); u8 value; int ret = 0, err; switch (cmd) { case RTC_VL_READ: err = pcf8523_read(client, REG_CONTROL3, &value); if (err < 0) return err; if (value & REG_CONTROL3_BLF) ret = 1; if (copy_to_user((void __user *)arg, &ret, sizeof(int))) return -EFAULT; return 0; default: return -ENOIOCTLCMD; } } #else #define pcf8523_rtc_ioctl NULL #endif static const struct rtc_class_ops pcf8523_rtc_ops = { .read_time = pcf8523_rtc_read_time, .set_time = pcf8523_rtc_set_time, .ioctl = pcf8523_rtc_ioctl, }; static int pcf8523_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct pcf8523 *pcf; int err; if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) return -ENODEV; pcf = devm_kzalloc(&client->dev, sizeof(*pcf), GFP_KERNEL); if (!pcf) return -ENOMEM; err = pcf8523_select_capacitance(client, true); if (err < 0) return err; err = pcf8523_set_pm(client, 0); if (err < 0) return err; pcf->rtc = devm_rtc_device_register(&client->dev, DRIVER_NAME, &pcf8523_rtc_ops, THIS_MODULE); if (IS_ERR(pcf->rtc)) return PTR_ERR(pcf->rtc); i2c_set_clientdata(client, pcf); return 0; } static const struct i2c_device_id pcf8523_id[] = { { "pcf8523", 0 }, { } }; MODULE_DEVICE_TABLE(i2c, pcf8523_id); #ifdef CONFIG_OF static const struct of_device_id pcf8523_of_match[] = { { .compatible = "nxp,pcf8523" }, { } }; MODULE_DEVICE_TABLE(of, pcf8523_of_match); #endif static struct i2c_driver pcf8523_driver = { .driver = { .name = DRIVER_NAME, .of_match_table = of_match_ptr(pcf8523_of_match), }, .probe = pcf8523_probe, .id_table = pcf8523_id, }; module_i2c_driver(pcf8523_driver); MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>"); MODULE_DESCRIPTION("NXP PCF8523 RTC driver"); MODULE_LICENSE("GPL v2");