drivers/rtc/rtc-m48t35.c

Source file repositories/reference/linux-study-clean/drivers/rtc/rtc-m48t35.c

File Facts

System
Linux kernel
Corpus path
drivers/rtc/rtc-m48t35.c
Extension
.c
Size
4481 bytes
Lines
194
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

struct m48t35_rtc {
	u8	pad[0x7ff8];    /* starts at 0x7ff8 */
#ifdef CONFIG_SGI_IP27
	u8	hour;
	u8	min;
	u8	sec;
	u8	control;
	u8	year;
	u8	month;
	u8	date;
	u8	day;
#else
	u8	control;
	u8	sec;
	u8	min;
	u8	hour;
	u8	day;
	u8	date;
	u8	month;
	u8	year;
#endif
};

#define M48T35_RTC_SET		0x80
#define M48T35_RTC_READ		0x40

struct m48t35_priv {
	struct rtc_device *rtc;
	struct m48t35_rtc __iomem *reg;
	size_t size;
	unsigned long baseaddr;
	spinlock_t lock;
};

static int m48t35_read_time(struct device *dev, struct rtc_time *tm)
{
	struct m48t35_priv *priv = dev_get_drvdata(dev);
	u8 control;

	/*
	 * Only the values that we read from the RTC are set. We leave
	 * tm_wday, tm_yday and tm_isdst untouched. Even though the
	 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
	 * by the RTC when initially set to a non-zero value.
	 */
	spin_lock_irq(&priv->lock);
	control = readb(&priv->reg->control);
	writeb(control | M48T35_RTC_READ, &priv->reg->control);
	tm->tm_sec = readb(&priv->reg->sec);
	tm->tm_min = readb(&priv->reg->min);
	tm->tm_hour = readb(&priv->reg->hour);
	tm->tm_mday = readb(&priv->reg->date);
	tm->tm_mon = readb(&priv->reg->month);
	tm->tm_year = readb(&priv->reg->year);
	writeb(control, &priv->reg->control);
	spin_unlock_irq(&priv->lock);

	tm->tm_sec = bcd2bin(tm->tm_sec);
	tm->tm_min = bcd2bin(tm->tm_min);
	tm->tm_hour = bcd2bin(tm->tm_hour);
	tm->tm_mday = bcd2bin(tm->tm_mday);
	tm->tm_mon = bcd2bin(tm->tm_mon);
	tm->tm_year = bcd2bin(tm->tm_year);

	/*
	 * Account for differences between how the RTC uses the values
	 * and how they are defined in a struct rtc_time;
	 */
	tm->tm_year += 70;
	if (tm->tm_year <= 69)
		tm->tm_year += 100;

	tm->tm_mon--;
	return 0;
}

static int m48t35_set_time(struct device *dev, struct rtc_time *tm)
{
	struct m48t35_priv *priv = dev_get_drvdata(dev);
	unsigned char mon, day, hrs, min, sec;
	unsigned int yrs;
	u8 control;

	yrs = tm->tm_year + 1900;
	mon = tm->tm_mon + 1;   /* tm_mon starts at zero */
	day = tm->tm_mday;
	hrs = tm->tm_hour;
	min = tm->tm_min;
	sec = tm->tm_sec;

Annotation

Implementation Notes