diff options
| author | Nicolas Boichat <drinkcat@chromium.org> | 2019-06-22 21:02:35 +0800 |
|---|---|---|
| committer | Commit Bot <commit-bot@chromium.org> | 2019-06-24 06:45:16 +0000 |
| commit | 5d4f631acf5ef95a8893d3f91512ed549f105ec0 (patch) | |
| tree | 29095a2766ce5e9fa832936962a4e1becae1f224 /chip/mt_scp | |
| parent | 406fb2c7181f0dcf25d4a8d0626af2fca8c01f93 (diff) | |
| download | chrome-ec-5d4f631acf5ef95a8893d3f91512ed549f105ec0.tar.gz | |
chip/mt_scp/clock: Fix frequency meter divider (1024, not 1000)
The frequency meter measures at 26 Mhz / 1024, not 26 Mhz / 1000,
and use DIV_ROUND_CLOSEST to get a closer frequency meter target.
Also, print the frequencies in kHz, not Mhz.
BRANCH=none
BUG=b:120176040
TEST=Add new timer sourced from (precise) 32.768 kHz to tick
every second, see that the interval is close to a second.
Change-Id: I32a9265187ed2936a928f2c09da8f544d814b5ae
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1672650
Reviewed-by: Yilun Lin <yllin@chromium.org>
Diffstat (limited to 'chip/mt_scp')
| -rw-r--r-- | chip/mt_scp/clock.c | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/chip/mt_scp/clock.c b/chip/mt_scp/clock.c index 579db68dd3..8214f5ae15 100644 --- a/chip/mt_scp/clock.c +++ b/chip/mt_scp/clock.c @@ -127,8 +127,8 @@ static unsigned int scp_measure_ulposc_freq(int osc) AP_SCP_CFG_0 |= CFG_FREQ_METER_RUN; /* - * Frequency meter counts cycles in 1 / (26 * 1000) second period. - * freq_in_hz = freq_counter * 26 * 1000 + * Frequency meter counts cycles in 1 / (26 * 1024) second period. + * freq_in_hz = freq_counter * 26 * 1024 * * The hardware takes 38us to count cycles. Delay up to 100us, * as busy_udelay may not be accurate when sysclk is not 26Mhz @@ -163,9 +163,9 @@ static int scp_ulposc_config_measure(int osc, int div, int cali) scp_ulposc_config(osc, div, cali); freq = scp_measure_ulposc_freq(osc); - CPRINTF("ULPOSC%d: %d %d %d (%dMHz)\n", + CPRINTF("ULPOSC%d: %d %d %d (%dkHz)\n", osc + 1, div, cali, freq, - freq * 26 / 1000); + freq * 26 * 1000 / 1024); return freq; } @@ -180,7 +180,7 @@ static int scp_ulposc_config_measure(int osc, int div, int cali) */ static int scp_calibrate_ulposc(int osc, int target_mhz) { - int target_freq = target_mhz * 1000 / 26; + int target_freq = DIV_ROUND_NEAREST(target_mhz * 1024, 26); struct ulposc { int div; /* frequency divisor/multiplier */ int cali; /* variable resistor calibrator */ @@ -338,11 +338,11 @@ int command_ulposc(int argc, char *argv[]) scp_calibrate_ulposc(1, ULPOSC2_CLOCK_MHZ); } - /* SCP clock meter counts every (26MHz / 1000) tick */ - ccprintf("ULPOSC1 frequency: %u MHz\n", - scp_measure_ulposc_freq(0) * 26 / 1000); - ccprintf("ULPOSC2 frequency: %u MHz\n", - scp_measure_ulposc_freq(1) * 26 / 1000); + /* SCP clock meter counts every (26MHz / 1024) tick */ + ccprintf("ULPOSC1 frequency: %u kHz\n", + scp_measure_ulposc_freq(0) * 26 * 1000 / 1024); + ccprintf("ULPOSC2 frequency: %u kHz\n", + scp_measure_ulposc_freq(1) * 26 * 1000 / 1024); return EC_SUCCESS; } |