Commit b3a50169 authored by Alexandre Belloni's avatar Alexandre Belloni
Browse files

rtc: ds1307: properly handle oscillator failure flags 



Stop enabling the oscillator and removing the oscillator failure flags in
probe. Instead, return -EINVAL in .read_time when the oscillaotr is not
start or when it failed at some point. The oscillator gets enabled on the
first .set_time after failure and the failure flags are cleared.

This also removes the possibility of an infinite loop at probe where a
failing RTC will make the goto read_rtc to be taken every time.

Tested on mcp79411.

Reported-by: default avatarMastro Gippo <gipmad@gmail.com>
Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@bootlin.com>
parent 097aa24b

drivers/rtc/rtc-ds1307.c

+58 −71
Original line number Diff line number Diff line
@@ -225,6 +225,45 @@ static int ds1307_get_time(struct device *dev, struct rtc_time *t) 
		return -EINVAL;

	}



	tmp = regs[DS1307_REG_SECS];

	switch (ds1307->type) {

	case ds_1307:

	case m41t0:

	case m41t00:

	case m41t11:

		if (tmp & DS1307_BIT_CH)

			return -EINVAL;

		break;

	case ds_1308:

	case ds_1338:

		if (tmp & DS1307_BIT_CH)

			return -EINVAL;



		ret = regmap_read(ds1307->regmap, DS1307_REG_CONTROL, &tmp);

		if (ret)

			return ret;

		if (tmp & DS1338_BIT_OSF)

			return -EINVAL;

		break;

	case ds_1340:

		if (tmp & DS1340_BIT_nEOSC)

			return -EINVAL;



		ret = regmap_read(ds1307->regmap, DS1340_REG_FLAG, &tmp);

		if (ret)

			return ret;

		if (tmp & DS1340_BIT_OSF)

			return -EINVAL;

		break;

	case mcp794xx:

		if (!(tmp & MCP794XX_BIT_ST))

			return -EINVAL;



		break;

	default:

		break;

	}



	t->tm_sec = bcd2bin(regs[DS1307_REG_SECS] & 0x7f);

	t->tm_min = bcd2bin(regs[DS1307_REG_MIN] & 0x7f);

	tmp = regs[DS1307_REG_HOUR] & 0x3f;
@@ -289,7 +328,17 @@ static int ds1307_set_time(struct device *dev, struct rtc_time *t) 
	if (t->tm_year > 199 && chip->century_bit)

		regs[chip->century_reg] |= chip->century_bit;



	if (ds1307->type == mcp794xx) {

	switch (ds1307->type) {

	case ds_1308:

	case ds_1338:

		regmap_update_bits(ds1307->regmap, DS1307_REG_CONTROL,

				   DS1338_BIT_OSF, 0);

		break;

	case ds_1340:

		regmap_update_bits(ds1307->regmap, DS1340_REG_FLAG,

				   DS1340_BIT_OSF, 0);

		break;

	case mcp794xx:

		/*

		 * these bits were cleared when preparing the date/time

		 * values and need to be set again before writing the
@@ -297,6 +346,9 @@ static int ds1307_set_time(struct device *dev, struct rtc_time *t) 
		 */

		regs[DS1307_REG_SECS] |= MCP794XX_BIT_ST;

		regs[DS1307_REG_WDAY] |= MCP794XX_BIT_VBATEN;

		break;

	default:

		break;

	}



	dev_dbg(dev, "%s: %7ph\n", "write", regs);
@@ -1705,7 +1757,6 @@ static int ds1307_probe(struct i2c_client *client, 
		break;

	}



read_rtc:

	/* read RTC registers */

	err = regmap_bulk_read(ds1307->regmap, chip->offset, regs,

			       sizeof(regs));
@@ -1714,77 +1765,13 @@ read_rtc: 
		goto exit;

	}



	/*

	 * minimal sanity checking; some chips (like DS1340) don't

	 * specify the extra bits as must-be-zero, but there are

	 * still a few values that are clearly out-of-range.

	 */

	tmp = regs[DS1307_REG_SECS];

	switch (ds1307->type) {

	case ds_1307:

	case m41t0:

	case m41t00:

	case m41t11:

		/* clock halted?  turn it on, so clock can tick. */

		if (tmp & DS1307_BIT_CH) {

			regmap_write(ds1307->regmap, DS1307_REG_SECS, 0);

			dev_warn(ds1307->dev, "SET TIME!\n");

			goto read_rtc;

		}

		break;

	case ds_1308:

	case ds_1338:

		/* clock halted?  turn it on, so clock can tick. */

		if (tmp & DS1307_BIT_CH)

			regmap_write(ds1307->regmap, DS1307_REG_SECS, 0);



		/* oscillator fault?  clear flag, and warn */

		if (regs[DS1307_REG_CONTROL] & DS1338_BIT_OSF) {

			regmap_write(ds1307->regmap, DS1307_REG_CONTROL,

				     regs[DS1307_REG_CONTROL] &

				     ~DS1338_BIT_OSF);

			dev_warn(ds1307->dev, "SET TIME!\n");

			goto read_rtc;

		}

		break;

	case ds_1340:

		/* clock halted?  turn it on, so clock can tick. */

		if (tmp & DS1340_BIT_nEOSC)

			regmap_write(ds1307->regmap, DS1307_REG_SECS, 0);



		err = regmap_read(ds1307->regmap, DS1340_REG_FLAG, &tmp);

		if (err) {

			dev_dbg(ds1307->dev, "read error %d\n", err);

			goto exit;

		}



		/* oscillator fault?  clear flag, and warn */

		if (tmp & DS1340_BIT_OSF) {

			regmap_write(ds1307->regmap, DS1340_REG_FLAG, 0);

			dev_warn(ds1307->dev, "SET TIME!\n");

		}

		break;

	case mcp794xx:

		/* make sure that the backup battery is enabled */

		if (!(regs[DS1307_REG_WDAY] & MCP794XX_BIT_VBATEN)) {

	if (ds1307->type == mcp794xx &&

	    !(regs[DS1307_REG_WDAY] & MCP794XX_BIT_VBATEN)) {

		regmap_write(ds1307->regmap, DS1307_REG_WDAY,

			     regs[DS1307_REG_WDAY] |

			     MCP794XX_BIT_VBATEN);

	}



		/* clock halted?  turn it on, so clock can tick. */

		if (!(tmp & MCP794XX_BIT_ST)) {

			regmap_write(ds1307->regmap, DS1307_REG_SECS,

				     MCP794XX_BIT_ST);

			dev_warn(ds1307->dev, "SET TIME!\n");

			goto read_rtc;

		}



		break;

	default:

		break;

	}



	tmp = regs[DS1307_REG_HOUR];

	switch (ds1307->type) {

	case ds_1340:

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