linux-kernel - Re: [PATCH v15 08/10] irqchip/riscv-aplic: Add support for MSI-mode

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Message-ID: <87y1avbboj.fsf@all.your.base.are.belong.to.us>
Date: Wed, 06 Mar 2024 16:51:56 +0100
From: Björn Töpel <bjorn@...nel.org>
To: Anup Patel <apatel@...tanamicro.com>, Palmer Dabbelt
 <palmer@...belt.com>, Paul Walmsley <paul.walmsley@...ive.com>, Thomas
 Gleixner <tglx@...utronix.de>, Rob Herring <robh+dt@...nel.org>, Krzysztof
 Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Frank Rowand
 <frowand.list@...il.com>, Conor Dooley <conor+dt@...nel.org>
Cc: Anup Patel <apatel@...tanamicro.com>, devicetree@...r.kernel.org,
 Saravana Kannan <saravanak@...gle.com>, Marc Zyngier <maz@...nel.org>,
 Anup Patel <anup@...infault.org>, linux-kernel@...r.kernel.org, Atish
 Patra <atishp@...shpatra.org>, linux-riscv@...ts.infradead.org,
 linux-arm-kernel@...ts.infradead.org, Andrew Jones
 <ajones@...tanamicro.com>
Subject: Re: [PATCH v15 08/10] irqchip/riscv-aplic: Add support for MSI-mode

Anup Patel <apatel@...tanamicro.com> writes:

> diff --git a/drivers/irqchip/irq-riscv-aplic-msi.c b/drivers/irqchip/irq-riscv-aplic-msi.c
> new file mode 100644
> index 000000000000..b2a25e011bb2
> --- /dev/null
> +++ b/drivers/irqchip/irq-riscv-aplic-msi.c
> +static void aplic_msi_write_msg(struct irq_data *d, struct msi_msg *msg)
> +{
> +	unsigned int group_index, hart_index, guest_index, val;
> +	struct aplic_priv *priv = irq_data_get_irq_chip_data(d);
> +	struct aplic_msicfg *mc = &priv->msicfg;
> +	phys_addr_t tppn, tbppn, msg_addr;
> +	void __iomem *target;
> +
> +	/* For zeroed MSI, simply write zero into the target register */
> +	if (!msg->address_hi && !msg->address_lo && !msg->data) {
> +		target = priv->regs + APLIC_TARGET_BASE;
> +		target += (d->hwirq - 1) * sizeof(u32);
> +		writel(0, target);

Is the fence needed here (writel_relaxed())...

> +		return;
> +	}
> +
> +	/* Sanity check on message data */
> +	WARN_ON(msg->data > APLIC_TARGET_EIID_MASK);
> +
> +	/* Compute target MSI address */
> +	msg_addr = (((u64)msg->address_hi) << 32) | msg->address_lo;
> +	tppn = msg_addr >> APLIC_xMSICFGADDR_PPN_SHIFT;
> +
> +	/* Compute target HART Base PPN */
> +	tbppn = tppn;
> +	tbppn &= ~APLIC_xMSICFGADDR_PPN_HART(mc->lhxs);
> +	tbppn &= ~APLIC_xMSICFGADDR_PPN_LHX(mc->lhxw, mc->lhxs);
> +	tbppn &= ~APLIC_xMSICFGADDR_PPN_HHX(mc->hhxw, mc->hhxs);
> +	WARN_ON(tbppn != mc->base_ppn);
> +
> +	/* Compute target group and hart indexes */
> +	group_index = (tppn >> APLIC_xMSICFGADDR_PPN_HHX_SHIFT(mc->hhxs)) &
> +		     APLIC_xMSICFGADDR_PPN_HHX_MASK(mc->hhxw);
> +	hart_index = (tppn >> APLIC_xMSICFGADDR_PPN_LHX_SHIFT(mc->lhxs)) &
> +		     APLIC_xMSICFGADDR_PPN_LHX_MASK(mc->lhxw);
> +	hart_index |= (group_index << mc->lhxw);
> +	WARN_ON(hart_index > APLIC_TARGET_HART_IDX_MASK);
> +
> +	/* Compute target guest index */
> +	guest_index = tppn & APLIC_xMSICFGADDR_PPN_HART(mc->lhxs);
> +	WARN_ON(guest_index > APLIC_TARGET_GUEST_IDX_MASK);
> +
> +	/* Update IRQ TARGET register */
> +	target = priv->regs + APLIC_TARGET_BASE;
> +	target += (d->hwirq - 1) * sizeof(u32);
> +	val = FIELD_PREP(APLIC_TARGET_HART_IDX, hart_index);
> +	val |= FIELD_PREP(APLIC_TARGET_GUEST_IDX, guest_index);
> +	val |= FIELD_PREP(APLIC_TARGET_EIID, msg->data);
> +	writel(val, target);

..and here?


Björn