[coreboot-gerrit] New patch to review for coreboot: 9545045 libpayload: Add a timer_us() function.

[Isaac Christensen (isaac.christensen@se-eng.com)]

Isaac Christensen (isaac.christensen at se-eng.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/6897

-gerrit

commit 95450457945f3b6713bb6f73353ebda7e7b4fe1d
Author: Gabe Black <gabeblack at google.com>
Date:   Fri Dec 6 23:30:10 2013 -0800

    libpayload: Add a timer_us() function.
    
    This function returns the number of microseconds scaled from the number of raw
    timer ticks. It accepts a base parameter which is subtracted from the current
    time, which makes it easy to keep track of relative times.
    
    Change-Id: I55f2f9e90c0e12cda430bbe88b044f12b0b563c8
    Signed-off-by: Gabe Black <gabeblack at google.com>
    Reviewed-on: https://chromium-review.googlesource.com/179600
    Reviewed-by: Ronald Minnich <rminnich at chromium.org>
    Commit-Queue: Gabe Black <gabeblack at chromium.org>
    Tested-by: Gabe Black <gabeblack at chromium.org>
    (cherry picked from commit 4dd549e18d170dbf918c5b4b11bbe1f4e99b6695)
    Signed-off-by: Isaac Christensen <isaac.christensen at se-eng.com>
---
 payloads/libpayload/include/libpayload.h |  1 +
 payloads/libpayload/libc/time.c          | 17 +++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/payloads/libpayload/include/libpayload.h b/payloads/libpayload/include/libpayload.h
index 48a034b..15ffefb 100644
--- a/payloads/libpayload/include/libpayload.h
+++ b/payloads/libpayload/include/libpayload.h
@@ -422,6 +422,7 @@ int lib_get_sysinfo(void);
 unsigned int get_cpu_speed(void);
 uint64_t timer_hz(void);
 uint64_t timer_raw_value(void);
+uint64_t timer_us(uint64_t base);
 /* Generic. */
 void ndelay(unsigned int n);
 void udelay(unsigned int n);
diff --git a/payloads/libpayload/libc/time.c b/payloads/libpayload/libc/time.c
index ec1c85c..0d81634 100644
--- a/payloads/libpayload/libc/time.c
+++ b/payloads/libpayload/libc/time.c
@@ -189,3 +189,20 @@ void delay(unsigned int s)
 {
 	_delay((uint64_t)s * timer_hz());
 }
+
+u64 timer_us(u64 base)
+{
+	static u64 hz;
+
+	// Only check timer_hz once. Assume it doesn't change.
+	if (hz == 0) {
+		hz = timer_hz();
+		if (hz < 1000000) {
+			printf("Timer frequency %lld is too low, "
+			       "must be at least 1MHz.\n", hz);
+			halt();
+		}
+	}
+
+	return timer_raw_value() / (hz / 1000000) - base;
+}