From 516dd4aacd67a0f27da94f3fe63fe0f4dbab6e2b Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Sat, 23 Apr 2022 21:11:41 +0200 Subject: openrisc: start CPU timer early in boot 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 Cc: Arnd Bergmann Cc: Jonas Bonn Cc: Stefan Kristiansson Acked-by: Stafford Horne Reported-by: Guenter Roeck Signed-off-by: Jason A. Donenfeld --- arch/openrisc/kernel/head.S | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'arch/openrisc/kernel') diff --git a/arch/openrisc/kernel/head.S b/arch/openrisc/kernel/head.S index 15f1b38dfe03..871f4c858859 100644 --- a/arch/openrisc/kernel/head.S +++ b/arch/openrisc/kernel/head.S @@ -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) -- cgit v1.2.3