| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <20190410221629.18906-1-alexandre.belloni@bootlin.com>
Date: Thu, 11 Apr 2019 00:16:29 +0200
From: Alexandre Belloni <alexandre.belloni@...tlin.com>
To: linux-rtc@...r.kernel.org
Cc: Mastro Gippo <gipmad@...il.com>, linux-kernel@...r.kernel.org,
Alexandre Belloni <alexandre.belloni@...tlin.com>
Subject: [PATCH] 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: Mastro Gippo <gipmad@...il.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@...tlin.com>
---
drivers/rtc/rtc-ds1307.c | 129 ++++++++++++++++++---------------------
1 file changed, 58 insertions(+), 71 deletions(-)
diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index 07530fe1da2a..7f8b236c935c 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -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));
@@ -1714,75 +1765,11 @@ static int ds1307_probe(struct i2c_client *client,
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)) {
- 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;
+ 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);
}
tmp = regs[DS1307_REG_HOUR];
--
2.20.1
Powered by blists - more mailing lists