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* [PATCH] clk: at91: clk-main: update key before writing AT91_CKGR_MOR
@ 2020-07-30  9:03 Claudiu Beznea
  2020-08-04 16:00 ` Alexandre Belloni
  0 siblings, 1 reply; 2+ messages in thread
From: Claudiu Beznea @ 2020-07-30  9:03 UTC (permalink / raw)
  To: mturquette, sboyd, nicolas.ferre, alexandre.belloni,
	ludovic.desroches, mturquette, bbrezillon
  Cc: linux-clk, linux-arm-kernel, linux-kernel, Claudiu Beznea

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@microchip.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


^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [PATCH] clk: at91: clk-main: update key before writing AT91_CKGR_MOR
  2020-07-30  9:03 [PATCH] clk: at91: clk-main: update key before writing AT91_CKGR_MOR Claudiu Beznea
@ 2020-08-04 16:00 ` Alexandre Belloni
  0 siblings, 0 replies; 2+ messages in thread
From: Alexandre Belloni @ 2020-08-04 16:00 UTC (permalink / raw)
  To: Claudiu Beznea
  Cc: mturquette, sboyd, nicolas.ferre, ludovic.desroches, mturquette,
	bbrezillon, linux-clk, linux-arm-kernel, linux-kernel

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@microchip.com>

Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.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

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2020-07-30  9:03 [PATCH] clk: at91: clk-main: update key before writing AT91_CKGR_MOR Claudiu Beznea
2020-08-04 16:00 ` Alexandre Belloni

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