Date:	Fri, 20 May 2016 09:15:56 +0100
From:	Marc Zyngier <marc.zyngier@....com>
To:	Rich Felker <dalias@...c.org>, linux-kernel@...r.kernel.org,
	linux-sh@...r.kernel.org
Cc:	Jason Cooper <jason@...edaemon.net>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v2 08/12] irqchip: add J-Core AIC driver

On 20/05/16 03:53, Rich Felker wrote:
> Signed-off-by: Rich Felker <dalias@...c.org>
> ---
> My previous post of the patch series accidentally omitted omitted
> Cc'ing of subsystem maintainers for the necessary clocksource,
> irqchip, and spi drivers. Please ack if this looks ok because I want
> to get it merged as part of the arch/sh pull request for 4.7.

For a start, a decent commit message wouldn't hurt.

> 
>  drivers/irqchip/Kconfig         |  6 +++
>  drivers/irqchip/Makefile        |  1 +
>  drivers/irqchip/irq-jcore-aic.c | 95 +++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 102 insertions(+)
>  create mode 100644 drivers/irqchip/irq-jcore-aic.c
> 
> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> index 3e12479..3cb37d6 100644
> --- a/drivers/irqchip/Kconfig
> +++ b/drivers/irqchip/Kconfig
> @@ -149,6 +149,12 @@ config PIC32_EVIC
>  	select GENERIC_IRQ_CHIP
>  	select IRQ_DOMAIN
>  
> +config JCORE_AIC
> +	bool "J-Core integrated AIC"
> +	select IRQ_DOMAIN
> +	help
> +	  Support for the J-Core integrated AIC.
> +
>  config RENESAS_INTC_IRQPIN
>  	bool
>  	select IRQ_DOMAIN
> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> index b03cfcb..5a1f1bf 100644
> --- a/drivers/irqchip/Makefile
> +++ b/drivers/irqchip/Makefile
> @@ -37,6 +37,7 @@ obj-$(CONFIG_I8259)			+= irq-i8259.o
>  obj-$(CONFIG_IMGPDC_IRQ)		+= irq-imgpdc.o
>  obj-$(CONFIG_IRQ_MIPS_CPU)		+= irq-mips-cpu.o
>  obj-$(CONFIG_SIRF_IRQ)			+= irq-sirfsoc.o
> +obj-$(CONFIG_JCORE_AIC)			+= irq-jcore-aic.o
>  obj-$(CONFIG_RENESAS_INTC_IRQPIN)	+= irq-renesas-intc-irqpin.o
>  obj-$(CONFIG_RENESAS_IRQC)		+= irq-renesas-irqc.o
>  obj-$(CONFIG_VERSATILE_FPGA_IRQ)	+= irq-versatile-fpga.o
> diff --git a/drivers/irqchip/irq-jcore-aic.c b/drivers/irqchip/irq-jcore-aic.c
> new file mode 100644
> index 0000000..68178fb
> --- /dev/null
> +++ b/drivers/irqchip/irq-jcore-aic.c
> @@ -0,0 +1,95 @@
> +/*
> + * J-Core SoC AIC driver
> + *
> + * Copyright (C) 2015-2016 Smart Energy Instruments, Inc.
> + *
> + * This file is subject to the terms and conditions of the GNU General Public
> + * License.  See the file "COPYING" in the main directory of this archive
> + * for more details.
> + */
> +
> +#include <linux/irq.h>
> +#include <linux/io.h>
> +#include <linux/irqchip.h>
> +#include <linux/irqdomain.h>
> +#include <linux/module.h>
> +#include <linux/cpu.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +
> +#define AIC1_INTPRI 8
> +
> +struct aic_data {
> +	unsigned char __iomem *base;
> +	u32 cpu_offset;
> +	struct irq_chip chip;
> +	struct irq_domain *domain;
> +	struct notifier_block nb;
> +} aic_data;
> +
> +static int aic_irqdomain_map(struct irq_domain *d, unsigned int irq, irq_hw_number_t hwirq)
> +{
> +	struct aic_data *aic = d->host_data;
> +
> +	irq_set_chip_data(irq, aic);
> +	irq_set_chip_and_handler(irq, &aic->chip, handle_simple_irq);
> +	irq_set_probe(irq);
> +
> +	return 0;
> +}
> +
> +static const struct irq_domain_ops aic_irqdomain_ops = {
> +	.map = aic_irqdomain_map,
> +	.xlate = irq_domain_xlate_onecell,
> +};
> +
> +static void noop(struct irq_data *data)
> +{
> +}
> +
> +static void aic1_localenable(struct aic_data *aic)
> +{
> +	unsigned cpu = smp_processor_id();
> +	pr_info("Local AIC enable on cpu %u\n", cpu);
> +	writel(0xffffffff, aic->base + cpu * aic->cpu_offset + AIC1_INTPRI);
> +}
> +
> +static int aic1_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)
> +{
> +	switch (action & ~CPU_TASKS_FROZEN) {
> +	case CPU_STARTING:
> +		aic1_localenable(container_of(self, struct aic_data, nb));
> +		break;
> +	}

And nothing happens when the CPU goes down?

> +	return NOTIFY_OK;
> +}
> +
> +int __init aic_irq_of_init(struct device_node *node, struct device_node *parent)
> +{
> +	struct aic_data *aic = &aic_data;
> +
> +	aic->base = of_iomap(node, 0);
> +	of_property_read_u32(node, "cpu-offset", &aic->cpu_offset);
> +
> +	pr_info("Initializing J-Core AIC at %p\n", aic->base);
> +
> +	if (of_device_is_compatible(node, "jcore,aic1")) {
> +		/* For aic1, need to enabled zero-priority-by-default irqs */
> +		aic->nb.notifier_call = aic1_cpu_notify;
> +		register_cpu_notifier(&aic->nb);
> +		aic1_localenable(aic);
> +	}
> +
> +	aic->chip.name = node->name;
> +	aic->chip.irq_mask = noop;
> +	aic->chip.irq_unmask = noop;

So this driver is doing exactly nothing. Not even an EOI. How does it
work? How is this driver involved in the interrupt flow?

> +
> +	aic->domain = irq_domain_add_linear(node, 128, &aic_irqdomain_ops, aic);

The DT binding says that aic1 has 8 interrupts, and aic2 has 64. Why are
you allocating 128 of them?

> +	irq_create_strict_mappings(aic->domain, 16, 16, 112);

What are the first 16 interrupts for? By the look of it, this is a
legacy domain in disguise.

> +
> +	return 0;
> +}
> +
> +IRQCHIP_DECLARE(jcore_aic2, "jcore,aic2", aic_irq_of_init);
> +IRQCHIP_DECLARE(jcore_aic1, "jcore,aic1", aic_irq_of_init);
> 

To be honest, this doesn't look like an irqchip driver. More like a
glorified probe function. Maybe this is a property of the architecture,
but I'd really like at least a comment explaining this.

Thanks,

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

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