linux-kernel - Re: [PATCH] clk: at91: clk-main: update key before writing AT91_CKGR

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20200804160028.GD10725@piout.net>
Date:   Tue, 4 Aug 2020 18:00:28 +0200
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Claudiu Beznea <claudiu.beznea@...rochip.com>
Cc:     mturquette@...libre.com, sboyd@...nel.org,
        nicolas.ferre@...rochip.com, ludovic.desroches@...rochip.com,
        mturquette@...aro.org, bbrezillon@...nel.org,
        linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: at91: clk-main: update key before writing
 AT91_CKGR_MOR

On 30/07/2020 12:03:23+0300, Claudiu Beznea wrote:
> SAMA5D2 datasheet specifies on chapter 33.22.8 (PMC Clock Generator
> Main Oscillator Register) that writing any value other than
> 0x37 on KEY field aborts the write operation. Use the key when
> selecting main clock parent.
> 
> Fixes: 27cb1c2083373 ("clk: at91: rework main clk implementation")
> Signed-off-by: Claudiu Beznea <claudiu.beznea@...rochip.com>

Reviewed-by: Alexandre Belloni <alexandre.belloni@...tlin.com>

> ---
>  drivers/clk/at91/clk-main.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clk/at91/clk-main.c b/drivers/clk/at91/clk-main.c
> index 5c83e899084f..cfae2f59df66 100644
> --- a/drivers/clk/at91/clk-main.c
> +++ b/drivers/clk/at91/clk-main.c
> @@ -437,12 +437,17 @@ static int clk_sam9x5_main_set_parent(struct clk_hw *hw, u8 index)
>  		return -EINVAL;
>  
>  	regmap_read(regmap, AT91_CKGR_MOR, &tmp);
> -	tmp &= ~MOR_KEY_MASK;
>  
>  	if (index && !(tmp & AT91_PMC_MOSCSEL))
> -		regmap_write(regmap, AT91_CKGR_MOR, tmp | AT91_PMC_MOSCSEL);
> +		tmp = AT91_PMC_MOSCSEL;
>  	else if (!index && (tmp & AT91_PMC_MOSCSEL))
> -		regmap_write(regmap, AT91_CKGR_MOR, tmp & ~AT91_PMC_MOSCSEL);
> +		tmp = 0;
> +	else
> +		return 0;
> +
> +	regmap_update_bits(regmap, AT91_CKGR_MOR,
> +			   AT91_PMC_MOSCSEL | MOR_KEY_MASK,
> +			   tmp | AT91_PMC_KEY);
>  
>  	while (!clk_sam9x5_main_ready(regmap))
>  		cpu_relax();
> -- 
> 2.7.4
> 

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com