drivers: rtc: new maxim ds1307 rtc driver

Added rtc driver for ds1307. It allows to read and set the date and time

Signed-off-by: Arunmani Alagarsamy <[email protected]>

drivers/rtc/CMakeLists.txt

@@ -6,6 +6,7 @@ zephyr_syscall_header(${ZEPHYR_BASE}/include/zephyr/drivers/rtc.h)
 zephyr_library()
 
 zephyr_library_sources_ifdef(CONFIG_RTC_AM1805 rtc_am1805.c)
+zephyr_library_sources_ifdef(CONFIG_RTC_DS1307 rtc_ds1307.c)
 zephyr_library_sources_ifdef(CONFIG_USERSPACE rtc_handlers.c)
 zephyr_library_sources_ifdef(CONFIG_RTC_EMUL rtc_emul.c)
 zephyr_library_sources_ifdef(CONFIG_RTC_PCF8523 rtc_pcf8523.c)

drivers/rtc/Kconfig

@@ -42,6 +42,7 @@ config RTC_SHELL
 	  RTC Shell commands
 
 source "drivers/rtc/Kconfig.am1805"
+source "drivers/rtc/Kconfig.ds1307"
 source "drivers/rtc/Kconfig.emul"
 source "drivers/rtc/Kconfig.fake"
 source "drivers/rtc/Kconfig.pcf8523"

drivers/rtc/Kconfig.ds1307

@@ -0,0 +1,11 @@
+# SPDX-License-Identifier: Apache-2.0
+# Copyright (c) 2023 Arunmani Alagarsamy
+# Author: Arunmani Alagarsamy <[email protected]>
+
+config RTC_DS1307
+	bool "MAXIM DS1307 RTC driver"
+	default y
+	depends on DT_HAS_MAXIM_DS1307_ENABLED
+	select I2C
+	help
+	  Enable the MAXIM DS1307 RTC driver.

drivers/rtc/rtc_ds1307.c

@@ -0,0 +1,161 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Copyright (c) 2023 Arunmani Alagarsamy
+ * Author: Arunmani Alagarsamy  <[email protected]>
+ */
+
+#include <zephyr/drivers/gpio.h>
+#include <zephyr/drivers/i2c.h>
+#include <zephyr/drivers/rtc.h>
+#include <zephyr/logging/log.h>
+#include <zephyr/pm/device.h>
+#include <zephyr/sys/util.h>
+
+#define DT_DRV_COMPAT maxim_ds1307
+
+LOG_MODULE_REGISTER(ds1307, CONFIG_RTC_LOG_LEVEL);
+
+#define DS1307_I2C_ADDR 0x68
+
+/* DS1307 registers */
+#define DS1307_REG_SECONDS 0x00
+#define DS1307_REG_MINUTES 0x01
+#define DS1307_REG_HOURS   0x02
+#define DS1307_REG_DAY     0x03
+#define DS1307_REG_DATE    0x04
+#define DS1307_REG_MONTH   0x05
+#define DS1307_REG_YEAR    0x06
+#define DS1307_REG_CTRL    0x07
+
+#define SECONDS_BITS GENMASK(6, 0)
+#define MINUTES_BITS GENMASK(7, 0)
+#define HOURS_BITS   GENMASK(5, 0)
+#define DATE_BITS    GENMASK(5, 0)
+#define MONTHS_BITS  GENMASK(4, 0)
+#define WEEKDAY_BITS GENMASK(2, 0)
+#define YEAR_BITS    GENMASK(7, 0)
+
+struct ds1307_config {
+	struct i2c_dt_spec i2c_bus;
+};
+
+struct ds1307_data {
+	struct k_spinlock lock;
+};
+
+static int ds1307_set_time(const struct device *dev, const struct rtc_time *tm)
+{
+	int err;
+	uint8_t regs[7];
+
+	struct ds1307_data *data = dev->data;
+	const struct ds1307_config *config = dev->config;
+
+	k_spinlock_key_t key = k_spin_lock(&data->lock);
+
+	LOG_DBG("set time: year = %d, mon = %d, mday = %d, wday = %d, hour = %d, "
+		"min = %d, sec = %d",
+		tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_wday, tm->tm_hour, tm->tm_min,
+		tm->tm_sec);
+
+	regs[0] = bin2bcd(tm->tm_sec) & SECONDS_BITS;
+	regs[1] = bin2bcd(tm->tm_min);
+	regs[2] = bin2bcd(tm->tm_hour);
+	regs[3] = bin2bcd(tm->tm_wday);
+	regs[4] = bin2bcd(tm->tm_mday);
+	regs[5] = bin2bcd(tm->tm_mon);
+	regs[6] = bin2bcd(tm->tm_year);
+
+	err = i2c_burst_write_dt(&config->i2c_bus, DS1307_REG_SECONDS, regs, sizeof(regs));
+
+	k_spin_unlock(&data->lock, key);
+
+	return err;
+}
+
+static int ds1307_get_time(const struct device *dev, struct rtc_time *timeptr)
+{
+	int err;
+	uint8_t regs[7];
+
+	struct ds1307_data *data = dev->data;
+	const struct ds1307_config *config = dev->config;
+
+	k_spinlock_key_t key = k_spin_lock(&data->lock);
+
+	err = i2c_burst_read_dt(&config->i2c_bus, DS1307_REG_SECONDS, regs, sizeof(regs));
+	if (err != 0) {
+		goto unlock;
+	}
+
+	timeptr->tm_sec = bcd2bin(regs[0] & SECONDS_BITS);
+	timeptr->tm_min = bcd2bin(regs[1] & MINUTES_BITS);
+	timeptr->tm_hour = bcd2bin(regs[2] & HOURS_BITS); /* 24hr mode */
+	timeptr->tm_wday = bcd2bin(regs[3] & WEEKDAY_BITS);
+	timeptr->tm_mday = bcd2bin(regs[4] & DATE_BITS);
+	timeptr->tm_mon = bcd2bin(regs[5] & MONTHS_BITS);
+	timeptr->tm_year = bcd2bin(regs[6] & YEAR_BITS);
+
+	/* Validate the chip in 24hr mode */
+	if (regs[2] & (1 << 6)) {
+		return -ENODATA;
+	}
+
+	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);
+
+unlock:
+	k_spin_unlock(&data->lock, key);
+
+	return err;
+}
+
+static const struct rtc_driver_api ds1307_driver_api = {
+	.set_time = ds1307_set_time,
+	.get_time = ds1307_get_time,
+};
+
+static int ds1307_init(const struct device *dev)
+{
+	int err;
+	uint8_t tx_buf[2];
+	const struct ds1307_config *config = dev->config;
+
+	if (!i2c_is_ready_dt(&config->i2c_bus)) {
+		LOG_ERR("I2C bus not ready");
+		return -ENODEV;
+	}
+
+	tx_buf[0] = DS1307_REG_CTRL;
+	tx_buf[1] = 0x00;
+
+	/* Disable squarewave output */
+	err = i2c_write_dt(&config->i2c_bus, tx_buf, sizeof(tx_buf));
+	if (err < 0) {
+                LOG_ERR("Error: SQW:%d\n", err);
+        }
+
+	tx_buf[0] = DS1307_REG_SECONDS;
+
+	/* Make clock halt = 0 */
+	err = i2c_write_dt(&config->i2c_bus, tx_buf, sizeof(tx_buf));
+	if (err < 0) {
+		LOG_ERR("Error: Set clock halt bit:%d\n", err);
+	}
+
+	return 0;
+}
+
+#define DS1307_INIT(inst)                                                                          \
+	static struct ds1307_data ds1307_data_##inst;                                              \
+	static const struct ds1307_config ds1307_config_##inst = {                                 \
+		.i2c_bus = I2C_DT_SPEC_INST_GET(inst),                                             \
+	};                                                                                         \
+	DEVICE_DT_INST_DEFINE(inst, &ds1307_init, NULL, &ds1307_data_##inst,                       \
+			      &ds1307_config_##inst, POST_KERNEL, CONFIG_RTC_INIT_PRIORITY,        \
+			      &ds1307_driver_api);
+
+DT_INST_FOREACH_STATUS_OKAY(DS1307_INIT)

dts/bindings/rtc/maxim,ds1307.yaml

@@ -0,0 +1,11 @@
+# SPDX-License-Identifier: Apache-2.0
+# Copyright (c) 2023 Arunmani Alagarsamy
+# Author: Arunmani Alagarsamy <[email protected]>
+
+description: MAXIM DS1307 RTC
+
+compatible: "maxim,ds1307"
+
+include:
+  - name: rtc-device.yaml
+  - name: i2c-device.yaml