Hi Nicolas,
Thanks for your proposal, however, I have some trouble with it.
That would look lovely:
#include <linux/linkage.h>
#include <asm/assembler.h>
/*
* cpu_kinetis_do_idle()
*
* Idle the processor (wait for interrupt).
*
* IRQs are already disabled.
*/
ENTRY(cpu_kinetis_do_idle)
wfi
movw r3, #:lower16:0xe0082000
movt r3, #:upper16:0xe0082000
ldr r0, [r3, #0]
orr r2, r0, #0x85000000
str r2, [r3, #0]
ret lr
ENDPROC(cpu_kinetis_do_idle)
But... what about the rest of this hypothetical proc_kinetis.S file?
It would be a lot of code duplication with proc-v7m.S I think.
I could define CPU_KINETIS as such:
config CPU_KINETIS
bool
select CPU_V7M
But there's no such thing like customize_processor_functions that would be
called after proc-v7m.S define_processor_functions specified things like
idle routine.
Finally, while I was searching for suitable arm_pm_idle-based solution, I
found idle.c in mach-gemini that encouraged me to write my own idle.c for
Kinetis:
/*
* arch/arm/mach-kinetis/idle.c
*/
#include <linux/init.h>
#include <linux/io.h>
#include <asm/system_misc.h>
#include <asm/proc-fns.h>
static void kinetis_idle(void)
{
asm volatile ("wfi");
/*
* This is a dirty hack that invalidates the I/D bus cache
* on Kinetis K70. This must be done after idle.
*/
writel(readl(IOMEM(0xe0082000)) | 0x85000000, IOMEM(0xe0082000));
}
static int __init kinetis_idle_init(void)
{
arm_pm_idle = kinetis_idle;
return 0;
}
arch_initcall(kinetis_idle_init);
Et voila:
(gdb) c
Continuing.
^C
Program received signal SIGTRAP, Trace/breakpoint trap.
kinetis_idle () at ../arch/arm/mach-kinetis/idle.c:18
18 writel(readl(IOMEM(0xe0082000)) | 0x85000000,
IOMEM(0xe0082000));
(gdb) bt
#0 kinetis_idle () at ../arch/arm/mach-kinetis/idle.c:18
#1 0x0800a91e in arch_cpu_idle () at ../arch/arm/kernel/process.c:70
#2 0x08025402 in cpuidle_idle_call (state=<value optimized out>)
at ../kernel/sched/idle.c:157
#3 cpu_idle_loop (state=<value optimized out>) at
../kernel/sched/idle.c:253
#4 cpu_startup_entry (state=<value optimized out>) at
../kernel/sched/idle.c:301
#5 0x081bf816 in start_kernel () at ../init/main.c:683
#6 0x08008024 in stext () at ../arch/arm/kernel/head-nommu.S:85
(gdb)
On Thu, 25 Jun 2015, Nicolas Pitre wrote:
On Tue, 23 Jun 2015, Arnd Bergmann wrote:
On Tuesday 23 June 2015 23:19:41 Paul Osmialowski wrote:
Some SoCs need additional actions to be performed after arch idle,
e.g. Kinetis requires invalidation of the I/D bus cache.
Such handler could be held in provided <mach/idle.h> header file.
Signed-off-by: Paul Osmialowski <pawelo@xxxxxxxxxxx>
---
arch/arm/Kconfig | 7 +++++++
arch/arm/kernel/process.c | 7 +++++++
2 files changed, 14 insertions(+)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 8e3a833..8ef8f8f 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -98,6 +98,13 @@ config ARM_HAS_SG_CHAIN
config NEED_SG_DMA_LENGTH
bool
+config NEED_MACH_IDLE_H
+ bool
+
+config ARM_CPU_IDLE_QUIRKS
+ bool
+ select NEED_MACH_IDLE_H
+
We're not adding header files like this, please come up
with another solution. How about a cpuidle driver, or
possibly just overriding arm_pm_idle()?
If the WFI instruction always requires I and D flushing, then it might
be a better idea to provide a replacement for the corresponding
cpu_*_do_idle function. Plenty of examples exist for other cpu_*
functions.
Nicolas
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