linux-kernel - Re: [PATCH v5 04/11] irqchip: Add driver for Loongson-3 HyperTransport PIC controller

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Date:   Sat, 21 Mar 2020 14:14:39 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     Jiaxun Yang <jiaxun.yang@...goat.com>
Cc:     linux-mips@...r.kernel.org, Huacai Chen <chenhc@...ote.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Paul Burton <paulburton@...nel.org>,
        Allison Randal <allison@...utok.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v5 04/11] irqchip: Add driver for Loongson-3
 HyperTransport PIC controller

On 2020-03-18 06:20, Jiaxun Yang wrote:
> This controller appeared on Loongson-3 family of chips to receive 
> interrupts
> from PCH PIC.
> It is a I8259 with optimized interrupt polling flow. We can poll
> interrupt number
> from HT vector directly but still have to follow standard I8259
> routines to mask,
> unmask and EOI.
> 
> Co-developed-by: Huacai Chen <chenhc@...ote.com>
> Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
> 
> ---
> v4-v5:
> 	Enhancements according to maz's suggestions:
> 		- Add static for private struct
> 		- Drop pointless rename
> 		- Fix DT parse bug
> 		- Clarifications in comments and commit message
> ---
>  arch/mips/include/asm/i8259.h        |   1 +
>  drivers/irqchip/Kconfig              |  10 ++
>  drivers/irqchip/Makefile             |   1 +
>  drivers/irqchip/irq-loongson-htpic.c | 149 +++++++++++++++++++++++++++
>  4 files changed, 161 insertions(+)
>  create mode 100644 drivers/irqchip/irq-loongson-htpic.c

[...]

> +int __init htpic_of_init(struct device_node *node, struct device_node 
> *parent)
> +{
> +	unsigned int parent_irq[4];
> +	int i, err;
> +	int num_parents = 0;
> +
> +	if (htpic) {
> +		pr_err("loongson-htpic: Only one HTPIC is allowed in the system\n");
> +		return -ENODEV;
> +	}
> +
> +	htpic = kzalloc(sizeof(*htpic), GFP_KERNEL);
> +	if (!htpic) {
> +		err = -ENOMEM;
> +		goto out_free;
> +	}
> +
> +	htpic->base = of_iomap(node, 0);
> +	if (!htpic->base) {
> +		err = -ENODEV;
> +		goto out_free;
> +	}
> +
> +	htpic->domain = __init_i8259_irqs(node);
> +	if (!htpic->domain) {
> +		pr_err("loongson-htpic: Failed to initialize i8259 IRQs\n");
> +		err = -ENOMEM;
> +		goto out_iounmap;
> +	}
> +
> +	/* Interrupt may come from any of the 4 interrupt line */
> +	for (i = 0; i < HTPIC_MAX_PARENT_IRQ; i++) {
> +		parent_irq[i] = irq_of_parse_and_map(node, i);
> +		if (parent_irq[i] < 0)

irq_of_parse_and_map() returns 0 when there is no interrupt to be
mapped. You should probably test for that too.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...