linux-kernel - Re: [PATCH 4/7] irqchip/renesas-rzg2l: implement restriction when writing ISCR register

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Message-ID: <878r7o2bbd.ffs@tglx>
Date:   Fri, 27 Oct 2023 20:02:30 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Claudiu <claudiu.beznea@...on.dev>, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        geert+renesas@...der.be, magnus.damm@...il.com,
        mturquette@...libre.com, sboyd@...nel.org,
        prabhakar.mahadev-lad.rj@...renesas.com
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org, linux-clk@...r.kernel.org,
        Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH 4/7] irqchip/renesas-rzg2l: implement restriction when
 writing ISCR register

On Mon, Oct 23 2023 at 13:22, Claudiu wrote:
> In hardware manual of RZ/G2L (r01uh0914ej0130-rzg2l-rzg2lc.pdf)

This filename is completely useless.

> is available the following statement with regards to clearing
> interrupts

The RZ/G2L manual describes the operation to clear interrupts

> though ISCR register:

through the ISCR ...

>
> [Write operation]
> When "Falling-edge detection", "Rising-edge detection" or
> "Falling/Rising-edge detection" is set in ISCR.:
> - In case ISTAT is 1
> 	0: IRQn interrupt detection status is cleared.
> 	1: Invalid to write.
> - In case ISTAT is 0
> 	Invalid to write.
> When “Low-level detection” is set in IITSR.:
> 	Invalid to write.
>
> Thus, take into account interrupt type when clearing interrupts though

take the interrupt type into account... through the ISCR ...

> ISCR register.
>
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> ---
>  drivers/irqchip/irq-renesas-rzg2l.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/irqchip/irq-renesas-rzg2l.c b/drivers/irqchip/irq-renesas-rzg2l.c
> index 9ce0d6d67486..1ed9cb7178fa 100644
> --- a/drivers/irqchip/irq-renesas-rzg2l.c
> +++ b/drivers/irqchip/irq-renesas-rzg2l.c
> @@ -73,11 +73,17 @@ static void rzg2l_irq_eoi(struct irq_data *d)
>  	unsigned int hw_irq = irqd_to_hwirq(d) - IRQC_IRQ_START;
>  	struct rzg2l_irqc_priv *priv = irq_data_to_priv(d);
>  	u32 bit = BIT(hw_irq);
> -	u32 reg;
> +	u32 iitsr, iscr;
>  
> -	reg = readl_relaxed(priv->base + ISCR);
> -	if (reg & bit)
> -		writel_relaxed(reg & ~bit, priv->base + ISCR);
> +	iscr = readl_relaxed(priv->base + ISCR);
> +	iitsr = readl_relaxed(priv->base + IITSR);
> +
> +	/*
> +	 * ISCR could be cleared only if type is falling-edge, rising-edge or

ISCR can only be cleared if the type is ...

> +	 * falling/rising-edge.
> +	 */
> +	if ((iscr & bit) && (iitsr & IITSR_IITSEL_MASK(hw_irq)))
> +		writel_relaxed(iscr & ~bit, priv->base + ISCR);
>  }
>  
>  static void rzg2l_tint_eoi(struct irq_data *d)