svn commit: r327971 - in head/sys: kern sys
Ian Lepore
ian at FreeBSD.org
Sun Jan 14 17:01:39 UTC 2018
Author: ian
Date: Sun Jan 14 17:01:37 2018
New Revision: 327971
URL: https://svnweb.freebsd.org/changeset/base/327971
Log:
Add RTC clock conversions for BCD values, with non-panic validation.
RTC clock hardware frequently uses BCD numbers. Currently the low-level
bcd2bin() and bin2bcd() functions will KASSERT if given out-of-range BCD
values. Every RTC driver must implement its own code for validating the
unreliable data coming from the hardware to avoid a potential kernel panic.
This change introduces two new functions, clock_bcd_to_ts() and
clock_ts_to_bcd(). The former validates its inputs and returns EINVAL if any
values are out of range. The latter guarantees the returned data will be
valid BCD in a known format (4-digit years, etc).
A new bcd_clocktime structure is used with the new functions. It is similar
to the original clocktime structure, but defines the fields holding BCD
values as uint8_t (uint16_t for year), and adds a PM flag for handling hours
using AM/PM mode.
PR: 224813
Differential Revision: https://reviews.freebsd.org/D13730 (no reviewers)
Modified:
head/sys/kern/subr_clock.c
head/sys/sys/clock.h
Modified: head/sys/kern/subr_clock.c
==============================================================================
--- head/sys/kern/subr_clock.c Sun Jan 14 16:55:14 2018 (r327970)
+++ head/sys/kern/subr_clock.c Sun Jan 14 17:01:37 2018 (r327971)
@@ -199,6 +199,55 @@ clock_ct_to_ts(struct clocktime *ct, struct timespec *
return (0);
}
+int
+clock_bcd_to_ts(struct bcd_clocktime *bct, struct timespec *ts, bool ampm)
+{
+ struct clocktime ct;
+ int bcent, byear;
+
+ /*
+ * Year may come in as 2-digit or 4-digit BCD. Split the value into
+ * separate BCD century and year values for validation and conversion.
+ */
+ bcent = bct->year >> 8;
+ byear = bct->year & 0xff;
+
+ /*
+ * Ensure that all values are valid BCD numbers, to avoid assertions in
+ * the BCD-to-binary conversion routines. clock_ct_to_ts() will further
+ * validate the field ranges (such as 0 <= min <= 59) during conversion.
+ */
+ if (!validbcd(bcent) || !validbcd(byear) || !validbcd(bct->mon) ||
+ !validbcd(bct->day) || !validbcd(bct->hour) ||
+ !validbcd(bct->min) || !validbcd(bct->sec)) {
+ if (ct_debug)
+ printf("clock_bcd_to_ts: bad BCD: "
+ "[%04x-%02x-%02x %02x:%02x:%02x]\n",
+ bct->year, bct->mon, bct->day,
+ bct->hour, bct->min, bct->sec);
+ return (EINVAL);
+ }
+
+ ct.year = FROMBCD(byear) + FROMBCD(bcent) * 100;
+ ct.mon = FROMBCD(bct->mon);
+ ct.day = FROMBCD(bct->day);
+ ct.hour = FROMBCD(bct->hour);
+ ct.min = FROMBCD(bct->min);
+ ct.sec = FROMBCD(bct->sec);
+ ct.dow = bct->dow;
+ ct.nsec = bct->nsec;
+
+ /* If asked to handle am/pm, convert from 12hr+pmflag to 24hr. */
+ if (ampm) {
+ if (ct.hour == 12)
+ ct.hour = 0;
+ if (bct->ispm)
+ ct.hour += 12;
+ }
+
+ return (clock_ct_to_ts(&ct, ts));
+}
+
void
clock_ts_to_ct(struct timespec *ts, struct clocktime *ct)
{
@@ -258,6 +307,34 @@ clock_ts_to_ct(struct timespec *ts, struct clocktime *
/* Not sure if this interface needs to handle leapseconds or not. */
KASSERT(ct->sec >= 0 && ct->sec <= 60,
("seconds %d not in 0-60", ct->sec));
+}
+
+void
+clock_ts_to_bcd(struct timespec *ts, struct bcd_clocktime *bct, bool ampm)
+{
+ struct clocktime ct;
+
+ clock_ts_to_ct(ts, &ct);
+
+ /* If asked to handle am/pm, convert from 24hr to 12hr+pmflag. */
+ bct->ispm = false;
+ if (ampm) {
+ if (ct.hour >= 12) {
+ ct.hour -= 12;
+ bct->ispm = true;
+ }
+ if (ct.hour == 0)
+ ct.hour = 12;
+ }
+
+ bct->year = TOBCD(ct.year % 100) | (TOBCD(ct.year / 100) << 8);
+ bct->mon = TOBCD(ct.mon);
+ bct->day = TOBCD(ct.day);
+ bct->hour = TOBCD(ct.hour);
+ bct->min = TOBCD(ct.min);
+ bct->sec = TOBCD(ct.sec);
+ bct->dow = ct.dow;
+ bct->nsec = ct.nsec;
}
int
Modified: head/sys/sys/clock.h
==============================================================================
--- head/sys/sys/clock.h Sun Jan 14 16:55:14 2018 (r327970)
+++ head/sys/sys/clock.h Sun Jan 14 17:01:37 2018 (r327971)
@@ -60,9 +60,22 @@ extern int tz_dsttime;
int utc_offset(void);
/*
- * Structure to hold the values typically reported by time-of-day clocks.
- * This can be passed to the generic conversion functions to be converted
- * to a struct timespec.
+ * Structure to hold the values typically reported by time-of-day clocks,
+ * expressed as binary integers (see below for a BCD version). This can be
+ * passed to the conversion functions to be converted to/from a struct timespec.
+ *
+ * On input, the year is interpreted as follows:
+ * 0 - 69 = 2000 - 2069
+ * 70 - 99 = 1970 - 1999
+ * 100 - 199 = 2000 - 2099 (Supports hardware "century bit".)
+ * 200 - 1969 = Invalid.
+ * 1970 - 9999 = Full 4-digit century+year.
+ *
+ * The dow field is ignored (not even validated) on input, but is always
+ * populated with day-of-week on output.
+ *
+ * clock_ct_to_ts() returns EINVAL if any values are out of range. The year
+ * field will always be 4-digit on output.
*/
struct clocktime {
int year; /* year (4 digit year) */
@@ -77,6 +90,43 @@ struct clocktime {
int clock_ct_to_ts(struct clocktime *, struct timespec *);
void clock_ts_to_ct(struct timespec *, struct clocktime *);
+
+/*
+ * Structure to hold the values typically reported by time-of-day clocks,
+ * expressed as BCD. This can be passed to the conversion functions to be
+ * converted to/from a struct timespec.
+ *
+ * The clock_bcd_to_ts() function interprets the values in the year through sec
+ * fields as BCD numbers, and returns EINVAL if any BCD values are out of range.
+ * After conversion to binary, the values are passed to clock_ct_to_ts() and
+ * undergo further validation as described above. Year may be 2 or 4-digit BCD,
+ * interpreted as described above. The nsec field is binary. If the ampm arg
+ * is true, the incoming hour and ispm values are interpreted as 12-hour am/pm
+ * representation of the hour, otherwise hour is interpreted as 24-hour and ispm
+ * is ignored.
+ *
+ * The clock_ts_to_bcd() function converts the timespec to BCD values stored
+ * into year through sec. The value in year will be 4-digit BCD (e.g.,
+ * 0x2017). The mon through sec values will be 2-digit BCD. The nsec field will
+ * be binary, and the range of dow makes its binary and BCD values identical.
+ * If the ampm arg is true, the hour and ispm fields are set to the 12-hour
+ * time plus a pm flag, otherwise the hour is set to 24-hour time and ispm is
+ * set to false.
+ */
+struct bcd_clocktime {
+ uint16_t year; /* year (2 or 4 digit year) */
+ uint8_t mon; /* month (1 - 12) */
+ uint8_t day; /* day (1 - 31) */
+ uint8_t hour; /* hour (0 - 23 or 1 - 12) */
+ uint8_t min; /* minute (0 - 59) */
+ uint8_t sec; /* second (0 - 59) */
+ uint8_t dow; /* day of week (0 - 6; 0 = Sunday) */
+ long nsec; /* nanoseconds */
+ bool ispm; /* true if hour represents pm time */
+};
+
+int clock_bcd_to_ts(struct bcd_clocktime *, struct timespec *, bool ampm);
+void clock_ts_to_bcd(struct timespec *, struct bcd_clocktime *, bool ampm);
/*
* Time-of-day clock functions and flags. These functions might sleep.
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