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| author | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-04-23 21:11:41 +0200 |
|---|---|---|
| committer | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-05-13 23:59:23 +0200 |
| commit | 516dd4aacd67a0f27da94f3fe63fe0f4dbab6e2b (patch) | |
| tree | d4b39700ff5ff1ae2968d3a2c3b05b5ddfc4b3a5 /arch/openrisc/kernel | |
| parent | 408835832158df0357e18e96da7f2d1ed6b80e7f (diff) | |
| download | linux-516dd4aacd67a0f27da94f3fe63fe0f4dbab6e2b.tar.bz2 | |
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 <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>
Diffstat (limited to 'arch/openrisc/kernel')
| -rw-r--r-- | arch/openrisc/kernel/head.S | 9 |
1 files changed, 9 insertions, 0 deletions
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) |