| /* |
| * 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 |
| |
| #define REG_OFFSET 0x0e |
| #define REG_OFFSET_MODE BIT(7) |
| |
| 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_voltage_low(struct i2c_client *client) |
| { |
| u8 value; |
| int err; |
| |
| err = pcf8523_read(client, REG_CONTROL3, &value); |
| if (err < 0) |
| return err; |
| |
| return !!(value & REG_CONTROL3_BLF); |
| } |
| |
| 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; |
| |
| err = pcf8523_voltage_low(client); |
| if (err < 0) { |
| return err; |
| } else if (err > 0) { |
| dev_err(dev, "low voltage detected, time is unreliable\n"); |
| return -EINVAL; |
| } |
| |
| 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) |
| return -EINVAL; |
| |
| 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 0; |
| } |
| |
| 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; |
| |
| /* |
| * The hardware can only store values between 0 and 99 in it's YEAR |
| * register (with 99 overflowing to 0 on increment). |
| * After 2100-02-28 we could start interpreting the year to be in the |
| * interval [2100, 2199], but there is no path to switch in a smooth way |
| * because the chip handles YEAR=0x00 (and the out-of-spec |
| * YEAR=0xa0) as a leap year, but 2100 isn't. |
| */ |
| if (tm->tm_year < 100 || tm->tm_year >= 200) |
| return -EINVAL; |
| |
| err = pcf8523_stop_rtc(client); |
| if (err < 0) |
| return err; |
| |
| regs[0] = REG_SECONDS; |
| /* This will purposely overwrite REG_SECONDS_OS */ |
| 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); |
| int ret; |
| |
| switch (cmd) { |
| case RTC_VL_READ: |
| ret = pcf8523_voltage_low(client); |
| if (ret < 0) |
| return ret; |
| |
| 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 int pcf8523_rtc_read_offset(struct device *dev, long *offset) |
| { |
| struct i2c_client *client = to_i2c_client(dev); |
| int err; |
| u8 value; |
| s8 val; |
| |
| err = pcf8523_read(client, REG_OFFSET, &value); |
| if (err < 0) |
| return err; |
| |
| /* sign extend the 7-bit offset value */ |
| val = value << 1; |
| *offset = (value & REG_OFFSET_MODE ? 4069 : 4340) * (val >> 1); |
| |
| return 0; |
| } |
| |
| static int pcf8523_rtc_set_offset(struct device *dev, long offset) |
| { |
| struct i2c_client *client = to_i2c_client(dev); |
| long reg_m0, reg_m1; |
| u8 value; |
| |
| reg_m0 = clamp(DIV_ROUND_CLOSEST(offset, 4340), -64L, 63L); |
| reg_m1 = clamp(DIV_ROUND_CLOSEST(offset, 4069), -64L, 63L); |
| |
| if (abs(reg_m0 * 4340 - offset) < abs(reg_m1 * 4069 - offset)) |
| value = reg_m0 & 0x7f; |
| else |
| value = (reg_m1 & 0x7f) | REG_OFFSET_MODE; |
| |
| return pcf8523_write(client, REG_OFFSET, value); |
| } |
| |
| 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, |
| .read_offset = pcf8523_rtc_read_offset, |
| .set_offset = pcf8523_rtc_set_offset, |
| }; |
| |
| 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"); |
