netdev - Re: [PATCH 6/6] can: sja1000: Add support for RZ/N1 SJA1000 CAN Controller

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Message-ID: <20220702164018.ztizq3ftto4lsabr@pengutronix.de>
Date:   Sat, 2 Jul 2022 18:40:18 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Biju Das <biju.das.jz@...renesas.com>
Cc:     Wolfgang Grandegger <wg@...ndegger.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, linux-can@...r.kernel.org,
        netdev@...r.kernel.org,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Chris Paterson <Chris.Paterson2@...esas.com>,
        Biju Das <biju.das@...renesas.com>,
        linux-renesas-soc@...r.kernel.org, ukl@...gutronix.de
Subject: Re: [PATCH 6/6] can: sja1000: Add support for RZ/N1 SJA1000 CAN
 Controller

On 02.07.2022 15:01:30, Biju Das wrote:
> The SJA1000 CAN controller on RZ/N1 SoC has some differences compared
> to others like it has no clock divider register (CDR) support and it has
> no HW loopback(HW doesn't see tx messages on rx).
> 
> This patch adds support for RZ/N1 SJA1000 CAN Controller.
> 
> Signed-off-by: Biju Das <biju.das.jz@...renesas.com>
> ---
>  drivers/net/can/sja1000/sja1000_platform.c | 34 ++++++++++++++++++----
>  1 file changed, 29 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/can/sja1000/sja1000_platform.c b/drivers/net/can/sja1000/sja1000_platform.c
> index 5f3d362e0da5..8e63af76a013 100644
> --- a/drivers/net/can/sja1000/sja1000_platform.c
> +++ b/drivers/net/can/sja1000/sja1000_platform.c
[...]
> @@ -262,6 +276,16 @@ static int sp_probe(struct platform_device *pdev)
>  	priv->reg_base = addr;
>  
>  	if (of) {
> +		clk = devm_clk_get_optional(&pdev->dev, "can_clk");
> +		if (IS_ERR(clk))
> +			return dev_err_probe(&pdev->dev, PTR_ERR(clk), "no CAN clk");
> +
> +		if (clk) {
> +			priv->can.clock.freq  = clk_get_rate(clk) / 2;
> +			if (!priv->can.clock.freq)
> +				return dev_err_probe(&pdev->dev, -EINVAL, "Zero CAN clk rate");
> +		}

There's no clk_prepare_enable in the driver. You might go the quick and
dirty way an enable the clock right here. IIRC there's a new convenience
function to get and enable a clock, managed bei devm. Uwe (Cc'ed) can
point you in the right direction.

Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |

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