Commit 69edf28d authored Apr 23, 2022 by Jason A. Donenfeld Committed by Greg Kroah-Hartman Jun 14, 2022

openrisc: start CPU timer early in boot



[ Upstream commit 516dd4aacd67a0f27da94f3fe63fe0f4dbab6e2b ]

In order to measure the boot process, the timer should be switched on as
early in boot as possible. As well, the commit defines the get_cycles
macro, like the previous patches in this series, so that generic code is
aware that it's implemented by the platform, as is done on other archs.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Acked-by: Stafford Horne <shorne@gmail.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 67fb4943

arch/openrisc/include/asm/timex.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -23,6 +23,7 @@ static inline cycles_t get_cycles(void)
		{
		return mfspr(SPR_TTCR);
		}
		#define get_cycles get_cycles

		/* This isn't really used any more */
		#define CLOCK_TICK_RATE 1000

arch/openrisc/kernel/head.S

+9 −0

Original line number	Diff line number	Diff line
		@@ -521,6 +521,15 @@ _start:
		l.ori r3,r0,0x1
		l.mtspr r0,r3,SPR_SR

		/*
		* Start the TTCR as early as possible, so that the RNG can make use of
		* measurements of boot time from the earliest opportunity. Especially
		* important is that the TTCR does not return zero by the time we reach
		* rand_initialize().
		*/
		l.movhi r3,hi(SPR_TTMR_CR)
		l.mtspr r0,r3,SPR_TTMR

		CLEAR_GPR(r1)
		CLEAR_GPR(r2)
		CLEAR_GPR(r3)