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/**
* Copyright (c) 2025 Lukas Gunnarsson <lukasgunnarsson@protonmail.com>
* SPDX-License-Identifier: Apache-2.0
*
* Supported features:
* - Base RTC functionality (set/get time)
* - Alarm interrupts
*/
#include <zephyr/kernel.h>
#include <zephyr/drivers/spi.h>
#include <zephyr/drivers/rtc.h>
#include <zephyr/logging/log.h>
#include <zephyr/sys/util.h>
#include "rtc_utils.h"
#define DT_DRV_COMPAT nxp_pcf2123
#if DT_ANY_INST_HAS_PROP_STATUS_OKAY(int1_gpios) && \
(defined(CONFIG_RTC_ALARM) || defined(CONFIG_RTC_UPDATE))
#define PCF2123_INT1_GPIOS_IN_USE 1
#endif
LOG_MODULE_REGISTER(pcf2123, CONFIG_RTC_LOG_LEVEL);
/**
* Datasheet: https://www.nxp.com/docs/en/data-sheet/PCF2123.pdf
*/
/* Control registers. */
#define PCF2123_REG_CTRL_1 0x00
#define PCF2123_REG_CTRL_2 0x01
/* Time and date registers. */
#define PCF2123_REG_SECONDS 0x02
#define PCF2123_REG_MINUTES 0x03
#define PCF2123_REG_HOURS 0x04
#define PCF2123_REG_DAYS 0x05
#define PCF2123_REG_WEEKDAYS 0x06
#define PCF2123_REG_MONTHS 0x07
#define PCF2123_REG_YEARS 0x08
/* Alarm registers. */
#define PCF2123_REG_ALARM_MINUTE 0x09
#define PCF2123_REG_ALARM_HOUR 0x0A
#define PCF2123_REG_ALARM_DAY 0x0B
#define PCF2123_REG_ALARM_WEEKDAY 0x0C
/* Offset register. */
#define PCF2123_REG_OFFSET 0x0D
/* Timer registers. */
#define PCF2123_TIMER_CLKOUT 0x0E
#define PCF2123_TIMER_COUNTDOWN 0x0F
/**
* Control register 1 bits (page 9 in the datasheet).
* Bits 6, 3 and 0 are unused.
*/
#define PCF2123_CTRL_1_EXT_TEST BIT(7)
#define PCF2123_CTRL_1_STOP BIT(5)
#define PCF2123_CTRL_1_SR BIT(4)
#define PCF2123_CTRL_1_12_24 BIT(2)
#define PCF2123_CTRL_1_CIE BIT(1)
/**
* Control register 2 bits (page 11 in the datasheet).
*/
#define PCF2123_CTRL_2_MI BIT(7)
#define PCF2123_CTRL_2_SI BIT(6)
#define PCF2123_CTRL_2_MSF BIT(5)
#define PCF2123_CTRL_2_TI_TP BIT(4)
#define PCF2123_CTRL_2_AF BIT(3)
#define PCF2123_CTRL_2_TF BIT(2)
#define PCF2123_CTRL_2_AIE BIT(1)
#define PCF2123_CTRL_2_TIE BIT(0)
/**
* Alarm register bits (page 17 in the datasheet).
*/
#define PCF2123_ALARM_MINUTE_AE_M (0UL << 7)
#define PCF2123_ALARM_HOUR_AE_H (0UL << 7)
#define PCF2123_ALARM_DAY_AE_D (0UL << 7)
#define PCF2123_ALARM_WEEKDAY_AE_W (0UL << 7)
/**
* The masks have been gathered from the register overview (page 8 in the datasheet).
*/
#define PCF2123_SECONDS_MASK GENMASK(6, 0)
#define PCF2123_MINUTES_MASK GENMASK(6, 0)
#define PCF2123_HOURS_MASK GENMASK(5, 0)
#define PCF2123_DAYS_MASK GENMASK(5, 0)
#define PCF2123_WEEKDAYS_MASK GENMASK(2, 0)
#define PCF2123_MONTHS_MASK GENMASK(4, 0)
#define PCF2123_YEARS_MASK GENMASK(7, 0)
#define PCF2123_RTC_TIME_MASK \
(RTC_ALARM_TIME_MASK_SECOND | RTC_ALARM_TIME_MASK_MINUTE | RTC_ALARM_TIME_MASK_HOUR | \
RTC_ALARM_TIME_MASK_MONTHDAY | RTC_ALARM_TIME_MASK_WEEKDAY | RTC_ALARM_TIME_MASK_MONTH | \
RTC_ALARM_TIME_MASK_YEAR)
#define PCF2123_RTC_ALARM_TIME_MASK \
(RTC_ALARM_TIME_MASK_MINUTE | RTC_ALARM_TIME_MASK_HOUR | RTC_ALARM_TIME_MASK_MONTHDAY | \
RTC_ALARM_TIME_MASK_WEEKDAY)
/* The PCF2123 supports two-digit years (0-99). */
#define PCF2123_YEARS_OFFSET (2000 - 1900)
#define PCF2123_MONTHS_OFFSET 1
/**
* Command byte definition (page 36 in the datasheet).
* Bit 7: R/W (0 write, 1 read)
* Bit 6-4: SA (Subaddress, required to be 0b001)
* Bit 3-0: RA (Register address range)
*
* The PCF2123 starts from the address RA and auto-increments for every byte.
*/
#define PCF2123_CMD_READ ((1U << 7) | (0b001 << 4))
#define PCF2123_CMD_WRITE ((0U << 7) | (0b001 << 4))
#ifdef PCF2123_INT1_GPIOS_IN_USE
void callback_work_handler(struct k_work *work);
K_WORK_DEFINE(callback_work, callback_work_handler);
static void gpio_int1_callback(const struct device *dev, struct gpio_callback *cb, uint32_t pins);
#endif
struct pcf2123_config {
const struct spi_dt_spec spi;
#ifdef PCF2123_INT1_GPIOS_IN_USE
struct gpio_dt_spec int1;
#endif
};
struct pcf2123_data {
#ifdef PCF2123_INT1_GPIOS_IN_USE
const struct device *dev;
rtc_alarm_callback alarm_callback;
void *alarm_user_data;
struct gpio_callback int1_callback;
struct k_work callback_work;
#endif
};
/**
* @brief Read from a single or multiple PCF2123 registers.
*
* @param dev The RTC device.
* @param start_addr The first memory address to start reading from.
* @param buf Buffer to store read data.
* @param len Number of bytes to read.
* @retval 0 on success, else -ERRNO.
*
* @note The PCF2123 auto-increments the selected memory address for every byte sent.
*/
static int pcf2123_reg_read(const struct device *dev, const uint8_t start_addr, uint8_t *buf,
const size_t len)
{
if (!buf) {
return -EINVAL;
}
if (len <= 0) {
return -EINVAL;
}
const struct pcf2123_config *config = dev->config;
int ret;
uint8_t cmd_byte = PCF2123_CMD_READ | start_addr;
struct spi_buf tx_buf = {.buf = &cmd_byte, .len = sizeof(cmd_byte)};
const struct spi_buf_set tx_bufs = {.buffers = &tx_buf, .count = 1};
uint8_t rx_dummy; /* Dummy byte. */
struct spi_buf rx_buf[2] = {{.buf = &rx_dummy, .len = 1}, {.buf = buf, .len = len}};
const struct spi_buf_set rx_bufs = {.buffers = rx_buf, .count = 2};
ret = spi_transceive_dt(&config->spi, &tx_bufs, &rx_bufs);
if (ret < 0) {
LOG_ERR("Failed to read from register with start address %d (err %d)", start_addr,
ret);
return ret;
}
return 0;
}
/**
* @brief Write to a single or multiple PCF2123 registers.
*
* @param dev The RTC device.
* @param start_addr The first memory address to start writing towards.
* @param buf Data to write.
* @param len Data size in bytes.
* @retval 0 on success, else -ERRNO.
*
* @note The PCF2123 auto-increments the selected memory address for every byte sent.
*/
static int pcf2123_reg_write(const struct device *dev, const uint8_t start_addr, uint8_t *buf,
const size_t len)
{
if (!buf) {
return -EINVAL;
}
if (len <= 0) {
return -EINVAL;
}
const struct pcf2123_config *config = dev->config;
int ret;
uint8_t cmd_byte = PCF2123_CMD_WRITE | start_addr;
struct spi_buf cmd_buf = {.buf = &cmd_byte, .len = sizeof(cmd_byte)};
struct spi_buf data_buf = {.buf = buf, .len = len};
struct spi_buf tx_buf[] = {cmd_buf, data_buf};
const struct spi_buf_set tx_bufs = {.buffers = tx_buf, .count = 2};
ret = spi_write_dt(&config->spi, &tx_bufs);
if (ret < 0) {
LOG_ERR("Failed to set RTC time (err %d)", ret);
return ret;
}
return 0;
}
static int pcf2123_set_time(const struct device *dev, const struct rtc_time *timeptr)
{
LOG_DBG("Set time: year=%d mon=%d mday=%d wday=%d hour=%d min=%d sec=%d", timeptr->tm_year,
timeptr->tm_mon, timeptr->tm_mday, timeptr->tm_wday, timeptr->tm_hour,
timeptr->tm_min, timeptr->tm_sec);
if (!rtc_utils_validate_rtc_time(timeptr, PCF2123_RTC_TIME_MASK)) {
LOG_ERR("RTC time validation failed");
return -EINVAL;
}
if ((timeptr->tm_year < PCF2123_YEARS_OFFSET) ||
(timeptr->tm_year > PCF2123_YEARS_OFFSET + 99)) {
LOG_ERR("Invalid tm_year value: %d", timeptr->tm_year);
return -EINVAL;
}
/* There are 7 time registers ranging from 02h-08h. */
uint8_t regs[7];
/* Set seconds. */
regs[0] = bin2bcd(timeptr->tm_sec) & PCF2123_SECONDS_MASK;
/* Set minutes. */
regs[1] = bin2bcd(timeptr->tm_min) & PCF2123_MINUTES_MASK;
/* Set hours. */
regs[2] = bin2bcd(timeptr->tm_hour) & PCF2123_HOURS_MASK;
/* Set days. */
regs[3] = bin2bcd(timeptr->tm_mday) & PCF2123_DAYS_MASK;
/* Set weekdays. The values are not BCD encoded. */
regs[4] = timeptr->tm_wday;
/* Set month. */
regs[5] = bin2bcd(timeptr->tm_mon + PCF2123_MONTHS_OFFSET) & PCF2123_MONTHS_MASK;
/* Set year. */
regs[6] = bin2bcd(timeptr->tm_year - PCF2123_YEARS_OFFSET) & PCF2123_YEARS_MASK;
pcf2123_reg_write(dev, PCF2123_REG_SECONDS, regs, sizeof(regs));
return 0;
}
static int pcf2123_get_time(const struct device *dev, struct rtc_time *timeptr)
{
uint8_t regs[7];
int ret;
ret = pcf2123_reg_read(dev, PCF2123_REG_SECONDS, regs, sizeof(regs));
if (ret < 0) {
return -ENODATA;
}
/**
* Validate clock integrity.
* The seconds register use bit 7 for checking integrity (page 12 in the datasheet).
*/
if (bcd2bin(regs[0]) & BIT(7)) {
LOG_WRN("Clock integrity failed");
LOG_HEXDUMP_DBG(regs, sizeof(regs), "Read data");
return -ENODATA;
}
/* Nanoseconds, unused. */
timeptr->tm_nsec = 0;
/* Seconds. */
timeptr->tm_sec = bcd2bin(regs[0] & PCF2123_SECONDS_MASK);
/* Minutes. */
timeptr->tm_min = bcd2bin(regs[1] & PCF2123_MINUTES_MASK);
/* Hours. */
timeptr->tm_hour = bcd2bin(regs[2] & PCF2123_HOURS_MASK);
/* Days. */
timeptr->tm_mday = bcd2bin(regs[3] & PCF2123_DAYS_MASK);
/* Weekdays. */
timeptr->tm_wday = bcd2bin(regs[4] & PCF2123_WEEKDAYS_MASK);
/* Year days, unused. */
timeptr->tm_yday = -1;
/**
* Months range from 1-12 (table 5, page 8 in the datasheet).
* The struct rtc_time expects months in the 0-11 range therefore
* we need to offset the month by 1.
*/
timeptr->tm_mon = bcd2bin(regs[5] & PCF2123_MONTHS_MASK) - PCF2123_MONTHS_OFFSET;
/* Years range from 0-99 (table 5, page 8 in the datasheet). */
timeptr->tm_year = bcd2bin(regs[6] & PCF2123_YEARS_MASK) + PCF2123_YEARS_OFFSET;
timeptr->tm_isdst = -1; /* Unused. */
LOG_DBG("Get time: year=%d mon=%d mday=%d wday=%d hour=%d min=%d sec=%d", timeptr->tm_year,
timeptr->tm_mon, timeptr->tm_mday, timeptr->tm_wday, timeptr->tm_hour,
timeptr->tm_min, timeptr->tm_sec);
return 0;
}
#ifdef CONFIG_RTC_ALARM
static int pcf2123_clear_alarm_flag(const struct device *dev)
{
/* Clearing of the alarm flag can be found in page 19 in the datasheet. */
uint8_t ctrl2;
int ret;
ret = pcf2123_reg_read(dev, PCF2123_REG_CTRL_2, &ctrl2, 1);
if (ret < 0) {
LOG_ERR("Failed to read from control register 2 to clear AF bit (err %d)", ret);
return ret;
}
/* Clear the AF bit. */
ctrl2 &= ~PCF2123_CTRL_2_AF;
ret = pcf2123_reg_write(dev, PCF2123_REG_CTRL_2, &ctrl2, 1);
if (ret < 0) {
LOG_ERR("Failed write to control register 2 to clear the AF bit (err %d)", ret);
return ret;
}
return 0;
}
static int pcf2123_alarm_get_supported_fields(const struct device *dev, uint16_t id, uint16_t *mask)
{
ARG_UNUSED(dev);
if (id != 0U) {
LOG_ERR("Invalid ID: %d", id);
return -EINVAL;
}
*mask = PCF2123_RTC_ALARM_TIME_MASK;
return 0;
}
static int pcf2123_alarm_set_time(const struct device *dev, uint16_t id, uint16_t mask,
const struct rtc_time *timeptr)
{
if (id != 0) {
LOG_ERR("Invalid ID: %d", id);
return -EINVAL;
}
if ((mask & ~(PCF2123_RTC_ALARM_TIME_MASK)) != 0) {
LOG_ERR("Invalid alarm mask: 0x%04X", mask);
return -EINVAL;
}
if (!rtc_utils_validate_rtc_time(timeptr, mask)) {
LOG_ERR("Failed to validate the RTC time");
return -EINVAL;
}
uint8_t regs[4];
int ret;
/* The alarms are disabled if bit 7 is 1 (page 17 in the datasheet). */
/* Alarm register: MINUTE */
if ((mask & RTC_ALARM_TIME_MASK_MINUTE) != 0) {
regs[0] = bin2bcd(timeptr->tm_min) & PCF2123_MINUTES_MASK;
} else {
regs[0] = BIT(7);
}
/* Alarm register: HOUR */
if ((mask & RTC_ALARM_TIME_MASK_HOUR) != 0) {
regs[1] = bin2bcd(timeptr->tm_hour) & PCF2123_HOURS_MASK;
} else {
regs[1] = BIT(7);
}
/* Alarm register: DAY */
if ((mask & RTC_ALARM_TIME_MASK_MONTHDAY) != 0) {
regs[2] = bin2bcd(timeptr->tm_mday) & PCF2123_DAYS_MASK;
} else {
regs[2] = BIT(7);
}
/* Alarm register: WEEKDAY */
if ((mask & RTC_ALARM_TIME_MASK_WEEKDAY) != 0) {
regs[3] = bin2bcd(timeptr->tm_wday) & PCF2123_WEEKDAYS_MASK;
} else {
regs[3] = BIT(7);
}
/* Clear the alarm flag. */
ret = pcf2123_clear_alarm_flag(dev);
if (ret < 0) {
LOG_ERR("Failed to clear alarm flag (err %d)", ret);
return -ENOMSG;
}
ret = pcf2123_reg_write(dev, PCF2123_REG_ALARM_MINUTE, regs, sizeof(regs));
if (ret) {
LOG_ERR("Failed to write to alarm registers (err %d)", ret);
return -ENOMSG;
}
/* Make sure interrupts are enabled. */
uint8_t ctrl2;
ret = pcf2123_reg_read(dev, PCF2123_REG_CTRL_2, &ctrl2, 1);
if (ret < 0) {
LOG_ERR("Failed to read from control register 2 (err %d)", ret);
return ret;
}
if ((ctrl2 & PCF2123_CTRL_2_AIE) == 0) {
ctrl2 |= PCF2123_CTRL_2_AIE;
ret = pcf2123_reg_write(dev, PCF2123_REG_CTRL_2, &ctrl2, 1);
if (ret < 0) {
LOG_ERR("Failed to enable interrupts in control register 2 (err %d)", ret);
return ret;
}
}
return 0;
}
static int pcf2123_alarm_get_time(const struct device *dev, uint16_t id, uint16_t *mask,
struct rtc_time *timeptr)
{
uint8_t regs[4];
int ret;
ret = pcf2123_reg_read(dev, PCF2123_REG_ALARM_MINUTE, regs, sizeof(regs));
if (ret < 0) {
LOG_ERR("Failed to read alarm registers (err %d)", ret);
return ret;
}
*mask = 0;
/* Alarm register: MINUTE */
if ((regs[0] & BIT(7)) == 0) {
*mask |= RTC_ALARM_TIME_MASK_MINUTE;
timeptr->tm_min = bcd2bin(regs[0] & PCF2123_MINUTES_MASK);
} else {
timeptr->tm_min = 0;
}
/* Alarm register: HOUR */
if ((regs[1] & BIT(7)) == 0) {
*mask |= RTC_ALARM_TIME_MASK_HOUR;
timeptr->tm_hour = bcd2bin(regs[1] & PCF2123_HOURS_MASK);
} else {
timeptr->tm_hour = 0;
}
/* Alarm register: DAY */
if ((regs[2] & BIT(7)) == 0) {
*mask |= RTC_ALARM_TIME_MASK_MONTHDAY;
timeptr->tm_mday = bcd2bin(regs[2] & PCF2123_DAYS_MASK);
} else {
timeptr->tm_mday = 1;
}
/* Alarm register: WEEKDAY */
if ((regs[3] & BIT(7)) == 0) {
*mask |= RTC_ALARM_TIME_MASK_WEEKDAY;
timeptr->tm_wday = bcd2bin(regs[3] & PCF2123_WEEKDAYS_MASK);
} else {
timeptr->tm_wday = -1;
}
return 0;
}
static int pcf2123_alarm_is_pending(const struct device *dev, uint16_t id)
{
int ret;
uint8_t ctrl2;
if (id != 0) {
LOG_ERR("Invalid ID: %d", id);
return -EINVAL;
}
ret = pcf2123_reg_read(dev, PCF2123_REG_CTRL_2, &ctrl2, 1);
if (ret < 0) {
LOG_ERR("Failed to read from control register 2 (err %d)", ret);
return ret;
}
/* Clear the alarm flag. */
if (ctrl2 & PCF2123_CTRL_2_AF) {
ret = pcf2123_clear_alarm_flag(dev);
if (ret < 0) {
LOG_ERR("Failed to clear alarm flag (err %d)", ret);
return -ENOMSG;
}
return 1;
}
return 0;
}
#endif /* CONFIG_RTC_ALARM */
static int pcf2123_alarm_set_callback(const struct device *dev, uint16_t id,
rtc_alarm_callback callback, void *user_data)
{
#ifndef PCF2123_INT1_GPIOS_IN_USE
ARG_UNUSED(dev);
ARG_UNUSED(id);
ARG_UNUSED(callback);
ARG_UNUSED(user_data);
return -ENOTSUP;
#else
const struct pcf2123_config *config = dev->config;
struct pcf2123_data *data = dev->data;
int ret;
if (config->int1.port == NULL) {
LOG_ERR("The int1 port is NULL");
return -ENOTSUP;
}
if (id != 0U) {
LOG_ERR("Invalid ID %d", id);
return -EINVAL;
}
data->dev = dev;
data->alarm_callback = callback;
data->alarm_user_data = user_data;
ret = gpio_pin_configure_dt(&config->int1, GPIO_INPUT | GPIO_PULL_UP);
if (ret < 0) {
LOG_ERR("Failed to configure int1 (err %d)", ret);
return ret;
}
ret = gpio_pin_interrupt_configure_dt(&config->int1, GPIO_INT_EDGE_FALLING);
if (ret < 0) {
LOG_ERR("Failed to configure edge on int1 (err %d)", ret);
return ret;
}
gpio_init_callback(&data->int1_callback, gpio_int1_callback, BIT(config->int1.pin));
ret = gpio_add_callback(config->int1.port, &data->int1_callback);
if (ret < 0) {
LOG_ERR("Failed to add callback to int1 (err %d)", ret);
return ret;
}
return 0;
#endif
}
#ifdef PCF2123_INT1_GPIOS_IN_USE
static void gpio_int1_callback(const struct device *dev, struct gpio_callback *cb, uint32_t pins)
{
struct pcf2123_data *data = CONTAINER_OF(cb, struct pcf2123_data, int1_callback);
LOG_DBG("PCF2123 interrupt detected");
k_work_submit(&(data->callback_work));
}
void callback_work_handler(struct k_work *work)
{
struct pcf2123_data *data = CONTAINER_OF(work, struct pcf2123_data, callback_work);
if (data->alarm_callback) {
data->alarm_callback(data->dev, 0, data->alarm_user_data);
} else {
LOG_WRN("Missing PCF2123 alarm callback");
}
}
#endif /* PCF2123_INT1_GPIOS_IN_USE */
static DEVICE_API(rtc, pcf2123_driver_api) = {
.set_time = pcf2123_set_time,
.get_time = pcf2123_get_time,
#ifdef CONFIG_RTC_ALARM
.alarm_get_supported_fields = pcf2123_alarm_get_supported_fields,
.alarm_set_time = pcf2123_alarm_set_time,
.alarm_get_time = pcf2123_alarm_get_time,
.alarm_is_pending = pcf2123_alarm_is_pending,
.alarm_set_callback = pcf2123_alarm_set_callback,
#endif
};
int pcf2123_init(const struct device *dev)
{
const struct pcf2123_config *config = dev->config;
int ret;
uint8_t dummy_check;
#ifdef PCF2123_INT1_GPIOS_IN_USE
struct pcf2123_data *data = dev->data;
data->callback_work = callback_work;
#endif
if (!device_is_ready(config->spi.bus)) {
LOG_ERR("SPI device not ready: %s", config->spi.bus->name);
return -ENODEV;
}
/* Determine if the SPI device is alive by attempting to read from control register 1. */
ret = pcf2123_reg_read(dev, PCF2123_REG_CTRL_1, &dummy_check, 1);
if (ret < 0) {
LOG_ERR("Failed to communicate with PCF2123 (err %d)", ret);
return -ENODEV;
}
#ifdef PCF2123_INT1_GPIOS_IN_USE
uint8_t ctrl2 = PCF2123_CTRL_2_AIE; /* Enable alarm interrupts (AIE). */
ret = pcf2123_reg_write(dev, PCF2123_REG_CTRL_2, &ctrl2, 1);
if (ret < 0) {
LOG_ERR("Failed to write to control register 2 during initialization");
return -ENODEV;
}
#endif
LOG_DBG("%s initialized", dev->name);
return 0;
}
#define PCF2123_INIT(inst) \
static const struct pcf2123_config pcf2123_config_##inst = { \
.spi = SPI_DT_SPEC_INST_GET(inst, SPI_WORD_SET(8) | SPI_TRANSFER_MSB, 0U), \
IF_ENABLED(PCF2123_INT1_GPIOS_IN_USE,\
(.int1 = GPIO_DT_SPEC_INST_GET_OR(inst, int1_gpios, {0})) \
)}; \
\
static struct pcf2123_data pcf2123_data_##inst; \
\
DEVICE_DT_INST_DEFINE(inst, &pcf2123_init, NULL, &pcf2123_data_##inst, \
&pcf2123_config_##inst, POST_KERNEL, CONFIG_RTC_INIT_PRIORITY, \
&pcf2123_driver_api);
DT_INST_FOREACH_STATUS_OKAY(PCF2123_INIT)