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

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Message-Id: <201303272303.44420@pali>
Date:	Wed, 27 Mar 2013 23:03:44 +0100
From:	Pali Rohár <pali.rohar@...il.com>
To:	Tony Lindgren <tony@...mide.com>
Cc:	Juha Yrjola <juha.yrjola@...idboot.com>,
	Russell King <linux@....linux.org.uk>,
	Matt Mackall <mpm@...enic.com>,
	Herbert Xu <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 Wednesday 27 March 2013 22:09:18 Tony Lindgren wrote:
> * Pali Rohár <pali.rohar@...il.com> [130228 10:09]:
> > --- /dev/null
> > +++ b/drivers/char/hw_random/omap3-rom-asm.S
> > @@ -0,0 +1,27 @@
> > +/*
> > + * Copyright (C) 2009 Nokia Corporation
> > + *
> > + * This program is free software; you can redistribute it
> > and/or modify + * it under the terms of the GNU General
> > Public License version 2 as + * published by the Free
> > Software Foundation.
> > + *
> > + */
> > +
> > +#include <linux/linkage.h>
> > +#include <asm/assembler.h>
> > +
> > +ENTRY(omap3_rng_call_rom_asm)
> > +	.arch_extension sec
> > +	stmfd	sp!, {r4-r12, lr}
> > +	stmfd	sp!, {r0-r3}
> > +	bl	v7_flush_dcache_all
> > +	ldmfd	sp!, {r0-r3}
> > +	mov	r6, #0xff
> > +	mov	r12, r0
> > +	smc	#1
> > +	mov	r12, r0
> > +	bl	v7_flush_dcache_all
> > +	mov	r0, #0
> > +	mcr	p15, 0, r0, c7, c5, 0
> > +	mov	r0, r12
> > +	ldmfd	sp!, {r4-r12, pc}
> 
> This part should be in arch/arm/mach-omap2 because of the
> direct calls to v7_flush_dcache_all. Then you can pass a
> pointer to this function in platform_data for now, and set it
> up based on the compatible flag with device tree from driver
> later on.
> 

Ok, I will move this file to arch/arm/mach-omap2/omap3-rom-rng.S 
and pass function via platform_data to driver.

> > --- /dev/null
> > +++ b/drivers/char/hw_random/omap3-rom-drv.c
> > @@ -0,0 +1,167 @@
> > +/*
> > + * omap3-rom-drv.c - RNG driver for TI OMAP3 CPU family
> > + *
> > + * Copyright (C) 2009 Nokia Corporation
> > + * Author: Juha Yrjola <juha.yrjola@...idboot.com>
> > + *
> > + * This file is licensed under  the terms of the GNU
> > General Public + * License version 2. This program is
> > licensed "as is" without any + * warranty of any kind,
> > whether express or implied. + */
> > +
> > +#include <linux/module.h>
> > +#include <linux/init.h>
> > +#include <linux/random.h>
> > +#include <linux/hw_random.h>
> > +#include <linux/timer.h>
> > +#include <linux/clk.h>
> > +#include <linux/err.h>
> > +#include <linux/platform_device.h>
> > +
> > +#include "../../../arch/arm/mach-omap2/soc.h"
> 
> NAK for this, this must be private to arch/arm/mach-omap2.
> 
> Instead, just create a minimal
> include/linux/platform_data/omap3-rom.h, and pass the
> function pointer in the pdata if passed.
> 
> > +static int omap3_rom_rng_probe(struct platform_device
> > *pdev) +{
> > +	printk(KERN_INFO "%s: initializing\n",
> > omap3_rom_rng_name); +	if (!cpu_is_omap34xx()) {
> > +		printk(KERN_ERR "%s: currently supports only OMAP34xx
> > CPUs\n", +		       omap3_rom_rng_name);
> > +		return -ENODEV;
> > +	}
> > +	if (omap_type() == OMAP2_DEVICE_TYPE_GP) {
> > +		printk(KERN_ERR "%s: GP OMAPs not supported\n",
> > +		       omap3_rom_rng_name);
> > +		return -ENODEV;
> > +	}
> > +
> > +	setup_timer(&idle_timer, omap3_rom_idle_rng, 0);
> > +	rng_clk = clk_get_sys("omap_rng", "ick");
> > +	if (IS_ERR(rng_clk)) {
> > +		printk(KERN_ERR "%s: unable to get RNG clock\n",
> > +		       omap3_rom_rng_name);
> > +		return IS_ERR(rng_clk);
> > +	}
> > +
> > +	/* Leave the RNG in reset state. */
> > +	clk_prepare_enable(rng_clk);
> > +	omap3_rom_idle_rng(0);
> > +
> > +	return hwrng_register(&omap3_rom_rng_ops);
> > +}
> 
> You should replace the cpu_is_omap34xx() and omap_type() with
> some flags that you pass in the pdata. These too can be then
> deciphered based on the DT compatible flag later on. And then
> you don't need to include soc.h.
> 
> Regards,
> 
> Tony

I will remove above code for checking omap type from hw rand 
driver, because same code is in omap part which creating 
platform_device for this driver. So soc.h is not needed.

-- 
Pali Rohár
pali.rohar@...il.com

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