mfd: db8500-prcmu: Support U8420-sysclk firmware

There is a distinct version of the Ux500 U8420 variant
with "sysclk", as can be seen from the vendor code that
didn't make it upstream, this firmware lacks the
ULPPLL (ultra-low power phase locked loop) which in
effect means that the timer clock is instead wired to
the 32768 Hz always-on clock.

This has some repercussions when enabling the timer
clock as the code as it stands will disable the timer
clock on these platforms (lacking the so-called
"doze mode") and obtaining the wrong rate of the timer
clock.

The timer frequency is of course needed very early in
the boot, and as a consequence, we need to shuffle
around the early PRCMU init code: whereas in the past
we did not need to look up the PRCMU firmware version
in the early init, but now we need to know the version
before the core system timers are registered so we
restructure the platform callbacks to the PRCMU so as
not to take any arguments and instead look up the
resources it needs directly from the device tree
when initializing.

As we do not yet support any platforms using this
firmware it is not a regression, but as PostmarketOS
is starting to support products with this firmware we
need to fix this up.

The low rate of 32kHz also makes the MTU timer unsuitable
as delay timer but this needs to be fixed in a separate
patch.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Stephan Gerhold <stephan@gerhold.net>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/arm/mach-ux500/cpu-db8500.c b/arch/arm/mach-ux500/cpu-db8500.c
index 3875027ef8fc..e929aaa744c0 100644
--- a/arch/arm/mach-ux500/cpu-db8500.c
+++ b/arch/arm/mach-ux500/cpu-db8500.c
@@ -84,6 +84,7 @@ static void __init ux500_init_irq(void)
 	struct resource r;
 
 	irqchip_init();
+	prcmu_early_init();
 	np = of_find_compatible_node(NULL, NULL, "stericsson,db8500-prcmu");
 	of_address_to_resource(np, 0, &r);
 	of_node_put(np);
@@ -91,7 +92,6 @@ static void __init ux500_init_irq(void)
 		pr_err("could not find PRCMU base resource\n");
 		return;
 	}
-	prcmu_early_init(r.start, r.end-r.start);
 	ux500_pm_init(r.start, r.end-r.start);
 
 	/* Unlock before init */