Re: [PATCH v4 01/13] ARM: PJ4B: Add cpu_suspend/cpu_resume hooks for PJ4B

[Gregory CLEMENT <gregory.clement@free-electrons.com>]

On 14/02/2014 17:06, Lorenzo Pieralisi wrote:
> Hi Gregory,
> 
> On Thu, Feb 13, 2014 at 05:33:24PM +0000, Gregory CLEMENT wrote:
>> PJ4B needs extra instructions for suspend and resume, so instead of
>> using the armv7 version, this commit introduces specific versions for
>> PJ4B.
>>
>> Cc: Russell King <linux@arm.linux.org.uk>
>> Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
>> ---
>>  arch/arm/mm/proc-v7.S | 64 ++++++++++++++++++++++++++++++++++++++++++++++++---
>>  1 file changed, 61 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
>> index bd1781979a39..11117423a9b4 100644
>> --- a/arch/arm/mm/proc-v7.S
>> +++ b/arch/arm/mm/proc-v7.S
>> @@ -169,9 +169,67 @@ ENDPROC(cpu_pj4b_do_idle)
>>  	globl_equ	cpu_pj4b_do_idle,  	cpu_v7_do_idle
>>  #endif
>>  	globl_equ	cpu_pj4b_dcache_clean_area,	cpu_v7_dcache_clean_area
>> -	globl_equ	cpu_pj4b_do_suspend,	cpu_v7_do_suspend
>> -	globl_equ	cpu_pj4b_do_resume,	cpu_v7_do_resume
>> -	globl_equ	cpu_pj4b_suspend_size,	cpu_v7_suspend_size
>> +#ifdef CONFIG_ARM_CPU_SUSPEND
>> +ENTRY(cpu_pj4b_do_suspend)
>> +	stmfd	sp!, {r4 - r10, lr}
>> +	mrc	p15, 0, r4, c13, c0, 0	@ FCSE/PID
>> +	mrc	p15, 0, r5, c13, c0, 3	@ User r/o thread ID
>> +	stmia	r0!, {r4 - r5}
>> +	mrc	p15, 1, r6, c15, c1, 0  @ save CP15 - extra features
>> +	mrc	p15, 1, r7, c15, c2, 0	@ save CP15 - Aux Func Modes Ctrl 0
>> +	mrc	p15, 1, r8, c15, c1, 2	@ save CP15 - Aux Debug Modes Ctrl 2
>> +	mrc	p15, 1, r9, c15, c1, 1  @ save CP15 - Aux Debug Modes Ctrl 1
>> +	mrc	p15, 0, r10, c9, c14, 0  @ save CP15 - PMC
>> +	stmia	r0!, {r6 - r10}
>> +	mrc	p15, 0, r6, c3, c0, 0	@ Domain ID
>> +	mrc	p15, 0, r7, c2, c0, 1	@ TTB 1
>> +	mrc	p15, 0, r11, c2, c0, 2	@ TTB control register
>> +	mrc	p15, 0, r8, c1, c0, 0	@ Control register
>> +	mrc	p15, 0, r9, c1, c0, 1	@ Auxiliary control register
>> +	mrc	p15, 0, r10, c1, c0, 2	@ Co-processor access control
>> +	stmia	r0, {r6 - r11}
>> +	ldmfd	sp!, {r4 - r10, pc}
>> +ENDPROC(cpu_pj4b_do_suspend)
>> +
>> +ENTRY(cpu_pj4b_do_resume)
>> +	mov	ip, #0
>> +	mcr	p15, 0, ip, c7, c5, 0	@ invalidate I cache
>> +	mcr	p15, 0, ip, c13, c0, 1	@ set reserved context ID
>> +	ldmia	r0!, {r4 - r5}
>> +	mcr	p15, 0, r4, c13, c0, 0	@ FCSE/PID
>> +	mcr	p15, 0, r5, c13, c0, 3	@ User r/o thread ID
>> +	ldmia	r0!, {r6 - r10}
>> +	mcr	p15, 1, r6, c15, c1, 0  @ save CP15 - extra features
>> +	mcr	p15, 1, r7, c15, c2, 0	@ save CP15 - Aux Func Modes Ctrl 0
>> +	mcr	p15, 1, r8, c15, c1, 2	@ save CP15 - Aux Debug Modes Ctrl 2
>> +	mcr	p15, 1, r9, c15, c1, 1  @ save CP15 - Aux Debug Modes Ctrl 1
>> +	mcr	p15, 0, r10, c9, c14, 0  @ save CP15 - PMC
>> +	ldmia	r0, {r6 - r11}
>> +	mcr	p15, 0, ip, c8, c7, 0	@ invalidate TLBs
>> +	mcr	p15, 0, r6, c3, c0, 0	@ Domain ID
>> +#ifndef CONFIG_ARM_LPAE
>> +	ALT_SMP(orr	r1, r1, #TTB_FLAGS_SMP)
>> +	ALT_UP(orr	r1, r1, #TTB_FLAGS_UP)
>> +#endif
>> +	mcr	p15, 0, r1, c2, c0, 0	@ TTB 0
>> +	mcr	p15, 0, r7, c2, c0, 1	@ TTB 1
>> +	mcr	p15, 0, r11, c2, c0, 2	@ TTB control register
>> +	ldr	r4, =PRRR		@ PRRR
>> +	ldr	r5, =NMRR		@ NMRR
>> +	mcr	p15, 0, r4, c10, c2, 0	@ write PRRR
>> +	mcr	p15, 0, r5, c10, c2, 1	@ write NMRR
>> +	mrc	p15, 0, r4, c1, c0, 1	@ Read Auxiliary control register
>> +	teq	r4, r9			@ Is it already set?
>> +	mcrne	p15, 0, r9, c1, c0, 1	@ No, so write it
>> +	mcr	p15, 0, r10, c1, c0, 2	@ Co-processor access control
>> +	isb
>> +	dsb
>> +	mov	r0, r8			@ control register
>> +	b	cpu_resume_mmu
>> +ENDPROC(cpu_pj4b_do_resume)
>> +#endif
>> +.globl	cpu_pj4b_suspend_size
>> +.equ	cpu_pj4b_suspend_size, 4 * 13
>>  
>>  #endif
> 
> A couple of questions:
> 
> 1) Do the extra registers ever change after coldboot ?
> 2) Do you need to restore them before turning the MMU and caches on ?

yes we need it.

> 3) Most of the code is copy'n'paste from v7, is not it possible to reuse
>    that code by doing processor specific save/restore and then jump to
>    the v7 functions ?

Yes it was possible and I have done it in the 5th version I have just sent.

> 
> Thanks,
> Lorenzo
> 


-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com