hwtimer: add support for tracking time since cold boot

Pinweaver needs a timer that counts through deep sleep. This change
keeps track of the time since cold boot in PWRDN_SCRATCH23. Before the
low speed timer is cleared during init add the value to PWRDN_SCRATCH23.

BUG=b:262036852,b:279759625
TEST=manual

	After hard reset the cold reset time and system time should be
	the same.
	> sysinfo
	Reset flags: 0x00000800 (hard)
	Reset count: 0
	> get
	Time: 0x0000000006628dd7 = 107.122135 s
	since cold_reset: 107 s

	Verify the cold reset timer keeps counting during deep sleep.
	dut-control cold_reset:on
	[138.415843 AP off]

	[Reset cause: hibernate wake-pin]
	[Image: RW, ...
	[0.003864 Inits done]
	[0.009647 init_jittery_clock_locking_o...
	[0.039134 init took 22838]

	> get
	Time: 0x0000000000bf3e3a = 12.533306 s
	since cold_reset: 150 s
	> sysi
	Reset flags: 0x00000140 (hibernate wake-pin)

	Verify cold reset and system time are the same after H1_RST_L
	is pulsed
	dut-control gsc_reset:on gsc_reset:off

	> get
	Time: 0x00000000001cdea9 = 1.892009 s
	since cold_reset: 1 s
	> sysi
	Reset flags: 0x00000008 (power-on)
	Reset count: 1

Change-Id: Ie57324880c8b8068ddff62760848e161b2df903d
Signed-off-by: Mary Ruthven <mruthven@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/4093120
Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-by: Andrey Pronin <apronin@chromium.org>

4 files changed, 34 insertions, 1 deletions

diff --git a/chip/g/hwtimer.c b/chip/g/hwtimer.c
index fe5db33858..e7e0b0b84e 100644
--- a/chip/g/hwtimer.c
+++ b/chip/g/hwtimer.c
@@ -4,10 +4,12 @@
  */
 
 #include "common.h"
+#include "ec_commands.h"
 #include "hooks.h"
 #include "hwtimer.h"
 #include "init_chip.h"
 #include "registers.h"
+#include "system.h"
 #include "task.h"
 #include "timer.h"
 #include "util.h"
@@ -33,6 +35,11 @@
  */
 #define MAX_TIME_USEC 0xffffffff
 #define TIMELS_MAX (usecs_to_ticks(MAX_TIME_USEC))
+/*
+ * Seconds to add when the timer wraps. Round up to ensure cr50 doesn't lose
+ * time during the wrap around.
+ */
+#define OVERFLOW_TIME_S ((MAX_TIME_USEC + SECOND - 1) / SECOND)
 
 /*
  * The below calculation is lightweight and can be implemented using
@@ -62,6 +69,19 @@ uint32_t __hw_clock_event_get(void)
 		ticks_to_usecs(GREG32(TIMELS, EVENT(VALUE)));
 }
 
+uint32_t get_seconds_since_cold_boot(void)
+{
+	uint32_t overflow_s = GREAD_FIELD(TIMELS, SOURCE(STATUS), WRAPPED) ?
+			      OVERFLOW_TIME_S : 0;
+	return (GREG32(PMU, PWRDN_SCRATCH23) + overflow_s +
+		(__hw_clock_source_read() / SECOND));
+}
+
+static void save_seconds_since_cold_boot(void)
+{
+	GREG32(PMU, PWRDN_SCRATCH23) = get_seconds_since_cold_boot();
+}
+
 void __hw_clock_event_clear(void)
 {
 	/* one-shot, 32-bit, timer & interrupts disabled, 1:1 prescale */
@@ -125,6 +145,8 @@ void __hw_clock_source_irq(void)
 	GWRITE(TIMELS, SOURCE(WAKEUP_ACK), 1);
 	GWRITE(TIMELS, SOURCE(IAR), 1);
 
+	save_seconds_since_cold_boot();
+
 	/* Reset the load value */
 	GREG32(TIMELS, SOURCE(LOAD)) = TIMELS_MAX;
 
@@ -151,6 +173,11 @@ int __hw_clock_source_init(uint32_t start_t)
 	GWRITE_FIELD(TIMELS, EVENT(CONTROL), RELOAD, 0);
 	GWRITE_FIELD(TIMELS, EVENT(CONTROL), ENABLE, 0);
 
+
+	/* Save time since deep sleep before resetting the SOURCE timer. */
+	if (system_get_reset_flags() & EC_RESET_FLAG_HIBERNATE)
+		save_seconds_since_cold_boot();
+
 	/* Configure timer0 */
 	GREG32(TIMELS, SOURCE(RELOADVAL)) = TIMELS_MAX;
 	GWRITE_FIELD(TIMELS, SOURCE(CONTROL), WRAP, 1);
diff --git a/chip/g/init_chip.h b/chip/g/init_chip.h
index 7421b996f3..5414399bb4 100644
--- a/chip/g/init_chip.h
+++ b/chip/g/init_chip.h
@@ -26,6 +26,7 @@
  *	SCRATCH20 - Preserving EC-EFS context
  *	SCRATCH21 - Preserving TPM_BOARD_CFG register
  *	SCRATCH22 - Preserve FIPS power-up test status on Cr50
+ *	SCRATCH23 - Preserve time since cold boot
  *
  * PWRDN_SCRATCH 28 - 31 - Reserved for boot rom
  */
diff --git a/common/timer.c b/common/timer.c
index e08fe88056..a43da30861 100644
--- a/common/timer.c
+++ b/common/timer.c
@@ -323,7 +323,7 @@ static int command_get_time(int argc, char **argv)
 {
 	timestamp_t ts = get_time();
 	ccprintf("Time: 0x%016llx = %.6lld s\n", ts.val, ts.val);
-
+	ccprintf("since cold_reset: %u s\n", get_seconds_since_cold_boot());
 	return EC_SUCCESS;
 }
 DECLARE_SAFE_CONSOLE_COMMAND(gettime, command_get_time,
diff --git a/include/timer.h b/include/timer.h
index 7c107d2185..bbdf3c3435 100644
--- a/include/timer.h
+++ b/include/timer.h
@@ -117,6 +117,11 @@ static inline void sleep(unsigned sec)
 timestamp_t get_time(void);
 
 /**
+ * Get the time in seconds since cold boot.
+ */
+uint32_t get_seconds_since_cold_boot(void);
+
+/**
  * Force the current value of the system timer.
  *
  * This function is for the power management implementation which wants to fix