drivers/rtc/rtc-ds1347.c

Source file repositories/reference/linux-study-clean/drivers/rtc/rtc-ds1347.c

File Facts

System
Linux kernel
Corpus path
drivers/rtc/rtc-ds1347.c
Extension
.c
Size
4331 bytes
Lines
184
Domain
Driver Families
Bucket
drivers/rtc
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-only
/* rtc-ds1347.c
 *
 * Driver for Dallas Semiconductor DS1347 Low Current, SPI Compatible
 * Real Time Clock
 *
 * Author : Raghavendra Chandra Ganiga <ravi23ganiga@gmail.com>
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/spi/spi.h>
#include <linux/bcd.h>
#include <linux/regmap.h>

/* Registers in ds1347 rtc */

#define DS1347_SECONDS_REG	0x01
#define DS1347_MINUTES_REG	0x03
#define DS1347_HOURS_REG	0x05
#define DS1347_DATE_REG		0x07
#define DS1347_MONTH_REG	0x09
#define DS1347_DAY_REG		0x0B
#define DS1347_YEAR_REG		0x0D
#define DS1347_CONTROL_REG	0x0F
#define DS1347_CENTURY_REG	0x13
#define DS1347_STATUS_REG	0x17
#define DS1347_CLOCK_BURST	0x3F

#define DS1347_WP_BIT		BIT(7)

#define DS1347_NEOSC_BIT	BIT(7)
#define DS1347_OSF_BIT		BIT(2)

static const struct regmap_range ds1347_ranges[] = {
	{
		.range_min = DS1347_SECONDS_REG,
		.range_max = DS1347_STATUS_REG,
	},
};

static const struct regmap_access_table ds1347_access_table = {
	.yes_ranges = ds1347_ranges,
	.n_yes_ranges = ARRAY_SIZE(ds1347_ranges),
};

static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
{
	struct regmap *map = dev_get_drvdata(dev);
	unsigned int status, century, secs;
	unsigned char buf[8];
	int err;

	err = regmap_read(map, DS1347_STATUS_REG, &status);
	if (err)
		return err;

	if (status & DS1347_OSF_BIT)
		return -EINVAL;

	do {
		err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8);
		if (err)
			return err;

		err = regmap_read(map, DS1347_CENTURY_REG, &century);
		if (err)
			return err;

		err = regmap_read(map, DS1347_SECONDS_REG, &secs);
		if (err)
			return err;
	} while (buf[0] != secs);

	dt->tm_sec = bcd2bin(buf[0]);
	dt->tm_min = bcd2bin(buf[1] & 0x7f);
	dt->tm_hour = bcd2bin(buf[2] & 0x3F);
	dt->tm_mday = bcd2bin(buf[3]);
	dt->tm_mon = bcd2bin(buf[4]) - 1;
	dt->tm_wday = bcd2bin(buf[5]) - 1;
	dt->tm_year = (bcd2bin(century) * 100) + bcd2bin(buf[6]) - 1900;

	return 0;
}

static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
{

Annotation

Implementation Notes