From: slash.tmp@free•fr (Mason)
To: linux-arm-kernel@lists•infradead.org
Subject: Reading twd_base at run-time
Date: Fri, 27 Mar 2015 17:16:33 +0100 [thread overview]
Message-ID: <55158261.9010108@free.fr> (raw)
Hello everyone,
In arch/arm/kernel/smp_twd.c, twd_local_timer_register() receives a
struct twd_local_timer argument, which specifies
1) the physical address of twd_base
2) the twd interrupt number
There's a helper to fill out the static struct: DEFINE_TWD_LOCAL_TIMER()
But it seems to me (please correct me if I'm wrong) that the address
of twd_base can be read at run-time, making it one less parameter to
specify by hand at compile-time (with the risk that a HW engineer
change the address in the next chip with no warning).
Here's an incomplete patch to express my intent:
diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
index 6591e26..5177db8 100644
--- a/arch/arm/kernel/smp_twd.c
+++ b/arch/arm/kernel/smp_twd.c
@@ -369,14 +369,14 @@ out_free:
return err;
}
-int __init twd_local_timer_register(struct twd_local_timer *tlt)
+int __init twd_local_timer_register(void)
{
if (twd_base || twd_evt)
return -EBUSY;
- twd_ppi = tlt->res[1].start;
+ twd_ppi = 29;
- twd_base = ioremap(tlt->res[0].start, resource_size(&tlt->res[0]));
+ twd_base = ioremap(scu_a9_get_base() + 0x600, 0x10);
if (!twd_base)
return -ENOMEM;
As far as I can tell, all platforms use 29 for twd_ppi, but I can make
sure if people agree this patch is indeed an improvement.
Regards.
next reply other threads:[~2015-03-27 16:16 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-27 16:16 Mason [this message]
2015-03-27 16:35 ` Reading twd_base at run-time Marc Zyngier
2015-03-27 20:33 ` Mason
2015-03-27 20:53 ` Russell King - ARM Linux
2015-04-01 12:07 ` Mason
2015-04-01 12:12 ` Russell King - ARM Linux
2015-04-01 12:47 ` Mason
2015-04-01 12:28 ` Marc Zyngier
2015-04-01 12:47 ` Mason
2015-04-01 13:01 ` Mason
2015-04-01 13:14 ` Marc Zyngier
2015-04-01 14:39 ` Mason
2015-04-01 14:56 ` Marc Zyngier
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