Re: [PATCH v4 2/7] ARM: rpi: retrieve miniuart clock from firmware

[Roland Hieber <r.hieber@pengutronix.de>]

On Mon, Dec 17, 2018 at 09:10:40AM +0100, Rouven Czerwinski wrote:
> The miniuart uses the core clock as the clock source. This clock is fixed by the
> firmware to 250Mhz if enable_uart=1 is set in the config.txt file.
> However a user could still choose to overclock the core frequency,
> which would result in wrong baudrates computed by barebox.
> Retrieve the core clock frequency from the firmware to allow all potential
> firmware configurations to work with barebox.
> 
> Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
> ---
>  arch/arm/boards/raspberry-pi/rpi-common.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/arch/arm/boards/raspberry-pi/rpi-common.c b/arch/arm/boards/raspberry-pi/rpi-common.c
> index 490aeef..e29177d 100644
> --- a/arch/arm/boards/raspberry-pi/rpi-common.c
> +++ b/arch/arm/boards/raspberry-pi/rpi-common.c
> @@ -309,6 +309,13 @@ static int rpi_console_clock_init(void)
>  	clkdev_add_physbase(clk, 0x20201000, NULL);
>  	clkdev_add_physbase(clk, 0x3f201000, NULL);
>  
> +	clk = rpi_register_firmware_clock(BCM2835_MBOX_CLOCK_ID_CORE,
> +					  "uart1-8250");
> +	if (IS_ERR(clk))
> +		return PTR_ERR(clk);
> +
> +	clkdev_add_physbase(clk, 0x3f215040, NULL);

This magic value could probably have an explaining comment somewhere
next to it.

 - Roland

> +
>  	clk = clk_fixed("bcm2835-cs", 1 * 1000 * 1000);
>  	clk_register_clkdev(clk, NULL, "bcm2835-cs");
>  
> -- 
> git-series 0.9.1
> 
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> 

-- 
Roland Hieber                     | r.hieber@pengutronix.de     |
Pengutronix e.K.                  | https://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim | Phone: +49-5121-206917-5086 |
Amtsgericht Hildesheim, HRA 2686  | Fax:   +49-5121-206917-5555 |

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