linux-kernel - Re: [PATCH] OMAP3 ROM Random Number Generator support

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Date:	Sun, 31 Mar 2013 14:43:11 +0200
From:	Pali Rohár <pali.rohar@...il.com>
To:	Ивайло Димитров 
	<freemangordon@....bg>
Cc:	tony@...mide.com, juha.yrjola@...idboot.com,
	linux@....linux.org.uk, mpm@...enic.com,
	herbert@...dor.apana.org.au, linux-omap@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] OMAP3 ROM Random Number Generator support

On Sunday 31 March 2013 14:05:42 Ивайло Димитров wrote:
> Hi Pali,
> 
> Yep, the code looks almost identical, I guess with some tweaks
> all SMC code from that patch could be removed and instead
> used the one from SMC PPA API.
> 
> What I don't get, is why one needs to disable/enable
> fiqs/irqs:
> 
> +static int call_sec_rom(u32 appl_id, u32 proc_id, u32 flag,
> ...) +{
> +	va_list ap;
> +	u32 ret;
> +	u32 val;
> +
> +	va_start(ap, flag);
> +	val = *(u32 *) &ap;
> +	local_irq_disable();
> +	local_fiq_disable();
> +	ret = omap3_rom_rng_call(appl_id, proc_id, flag,
> +				 (u32) virt_to_phys((void *) val));
> +	local_fiq_enable();
> +	local_irq_enable();
> +	va_end(ap);
> +
> +	return ret;
> +}
> 
> Do you have any idea why is that needed? Any other code I've
> ever seen to call SM, does not disable fiqs/irqs, is RNG SMC
> somehow special? I know this is Nokia's code, but still, if
> we can get some understanding...
> 
> Regards,
> Ivo

This driver is written by Juha Yrjola and is part of maemo 2.6.28 kernel.

Juha Yrjola, are you still around?

-- 
Pali Rohár
pali.rohar@...il.com

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