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devices: cmos: Populate Update in Progress bit (UIP)

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This bit should be set for the last 224us of each second. To be able to
fill this bit we need to use clock_gettime() to get the nanoseconds.
Also set the frequency bit to indicate we update at 32kHz.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>
This commit is contained in:
Rob Bradford 2020-07-21 16:30:14 +01:00 committed by Sebastien Boeuf
parent f03afea0d6
commit 08288305ef
1 changed files with 17 additions and 7 deletions
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24
devices/src/legacy/cmos.rs
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@ -2,7 +2,7 @@
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
use libc::{gmtime_r, time, time_t, tm};
use libc::{clock_gettime, gmtime_r, time_t, timespec, tm, CLOCK_REALTIME};
use std::cmp::min;
use std::mem;
@ -77,14 +77,17 @@ impl BusDevice for Cmos {
let day;
let month;
let year;
// The time and gmtime_r calls are safe as long as the structs they are given are
// large enough, and neither of them fail. It is safe to zero initialize the tm
// struct because it contains only plain data.
unsafe {
// The clock_gettime and gmtime_r calls are safe as long as the structs they are
// given are large enough, and neither of them fail. It is safe to zero initialize
// the tm and timespec struct because it contains only plain data.
let update_in_progress = unsafe {
let mut timespec: timespec = mem::zeroed();
clock_gettime(CLOCK_REALTIME, &mut timespec as *mut _);
let now: time_t = timespec.tv_sec;
let mut tm: tm = mem::zeroed();
let mut now: time_t = 0;
time(&mut now as *mut _);
gmtime_r(&now, &mut tm as *mut _);
// The following lines of code are safe but depend on tm being in scope.
seconds = tm.tm_sec;
minutes = tm.tm_min;
@ -93,6 +96,11 @@ impl BusDevice for Cmos {
day = tm.tm_mday;
month = tm.tm_mon + 1;
year = tm.tm_year;
// Update in Progress bit held for last 224us of each second
const NANOSECONDS_PER_SECOND: i64 = 1_000_000_000;
const UIP_HOLD_LENGTH: i64 = 8 * NANOSECONDS_PER_SECOND / 32768;
timespec.tv_nsec >= (NANOSECONDS_PER_SECOND - UIP_HOLD_LENGTH)
};
match self.index {
0x00 => to_bcd(seconds as u8),
@ -102,6 +110,8 @@ impl BusDevice for Cmos {
0x07 => to_bcd(day as u8),
0x08 => to_bcd(month as u8),
0x09 => to_bcd((year % 100) as u8),
// Bit 5 for 32kHz clock. Bit 7 for Update in Progress
0x0a => 1 << 5 | (update_in_progress as u8) << 7,
0x32 => to_bcd(((year + 1900) / 100) as u8),
_ => {
// self.index is always guaranteed to be in range via INDEX_MASK.