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Date:   Tue, 18 Aug 2020 20:42:41 +0300
From:   Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
To:     Marc Zyngier <maz@kernel.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Jason Cooper <jason@lakedaemon.net>,
        Rob Herring <robh+dt@kernel.org>,
        Andreas =?iso-8859-1?Q?F=E4rber?= <afaerber@suse.de>,
        Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-actions@lists.infradead.org,
        Saravanan Sekar <sravanhome@gmail.com>
Subject: Re: [PATCH v4 2/3] irqchip: Add Actions Semi Owl SIRQ controller
Message-ID: <20200818174241.GA2020288@BV030612LT>
References: <cover.1597571397.git.cristian.ciocaltea@gmail.com>
 <addb413d192d88c076c6ed7f453aa693095bdd15.1597571397.git.cristian.ciocaltea@gmail.com>
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Hi Marc,

Thanks for your quick and detailed review!

On Mon, Aug 17, 2020 at 02:52:06PM +0100, Marc Zyngier wrote:
> On 2020-08-16 12:33, Cristian Ciocaltea wrote:
> > This controller appears on Actions Semi Owl family SoC's S500, S700 and
> > S900 and provides support for 3 external interrupt controllers through
> 
> Is that really 3 interrupt controllers? Or merely 3 interrupt lines?

This is mostly a leftover statement from the previous patch revision.
I will change it to something like:

"This interrupt controller is found in the Actions Semi Owl SoCs (S500,
S700 and S900) and provides support for handling up to 3 external
interrupt lines."

> > dedicated SIRQ pins.
> > 
> > Each line can be independently configured as interrupt and triggers
> > on either of the edges (raising or falling) or either of the levels
> > (high or low). Each line can also be masked independently.
> > 
> > This is based on the patch series submitted by Parthiban Nallathambi:
> > https://lore.kernel.org/lkml/20181126100356.2840578-1-pn@denx.de/
> > 
> > Signed-off-by: Parthiban Nallathambi <pn@denx.de>
> > Signed-off-by: Saravanan Sekar <sravanhome@gmail.com>
> > [cristi: optimized DT, various fixes/cleanups/improvements]
> > Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
> > ---
> >  drivers/irqchip/Makefile       |   1 +
> >  drivers/irqchip/irq-owl-sirq.c | 318 +++++++++++++++++++++++++++++++++
> >  2 files changed, 319 insertions(+)
> >  create mode 100644 drivers/irqchip/irq-owl-sirq.c
> > 
> > diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> > index 133f9c45744a..b8eb5b8b766d 100644
> > --- a/drivers/irqchip/Makefile
> > +++ b/drivers/irqchip/Makefile
> > @@ -7,6 +7,7 @@ obj-$(CONFIG_ATH79)			+= irq-ath79-cpu.o
> >  obj-$(CONFIG_ATH79)			+= irq-ath79-misc.o
> >  obj-$(CONFIG_ARCH_BCM2835)		+= irq-bcm2835.o
> >  obj-$(CONFIG_ARCH_BCM2835)		+= irq-bcm2836.o
> > +obj-$(CONFIG_ARCH_ACTIONS)		+= irq-owl-sirq.o
> >  obj-$(CONFIG_DAVINCI_AINTC)		+= irq-davinci-aintc.o
> >  obj-$(CONFIG_DAVINCI_CP_INTC)		+= irq-davinci-cp-intc.o
> >  obj-$(CONFIG_EXYNOS_IRQ_COMBINER)	+= exynos-combiner.o
> > diff --git a/drivers/irqchip/irq-owl-sirq.c
> > b/drivers/irqchip/irq-owl-sirq.c
> > new file mode 100644
> > index 000000000000..29b7ffc40ac7
> > --- /dev/null
> > +++ b/drivers/irqchip/irq-owl-sirq.c
> > @@ -0,0 +1,318 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Actions Semi Owl SoCs SIRQ interrupt controller driver
> > + *
> > + * Copyright (C) 2014 Actions Semi Inc.
> > + * David Liu <liuwei@actions-semi.com>
> > + *
> > + * Author: Parthiban Nallathambi <pn@denx.de>
> > + * Author: Saravanan Sekar <sravanhome@gmail.com>
> > + * Author: Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
> > + */
> > +
> > +#include <linux/interrupt.h>
> > +#include <linux/irqchip.h>
> > +#include <linux/of_address.h>
> > +#include <linux/of_irq.h>
> > +
> > +#define NUM_SIRQ			3
> > +
> > +#define INTC_EXTCTL_PENDING		BIT(0)
> > +#define INTC_EXTCTL_CLK_SEL		BIT(4)
> > +#define INTC_EXTCTL_EN			BIT(5)
> > +#define INTC_EXTCTL_TYPE_MASK		GENMASK(7, 6)
> > +#define INTC_EXTCTL_TYPE_HIGH		0
> > +#define INTC_EXTCTL_TYPE_LOW		BIT(6)
> > +#define INTC_EXTCTL_TYPE_RISING		BIT(7)
> > +#define INTC_EXTCTL_TYPE_FALLING	(BIT(6) | BIT(7))
> > +
> > +/* S900 SIRQ1 & SIRQ2 control register offsets, relative to SIRQ0 */
> > +#define INTC_EXTCTL1			0x0328
> > +#define INTC_EXTCTL2			0x032c
> > +
> > +struct owl_sirq_params {
> > +	/* INTC_EXTCTL reg shared for all three SIRQ lines */
> > +	bool reg_shared;
> > +	/* INTC_EXTCTL reg offsets relative to controller base address */
> > +	u16 reg_offset[NUM_SIRQ];
> > +};
> > +
> > +struct owl_sirq_chip_data {
> > +	const struct owl_sirq_params *params;
> > +	void __iomem *base;
> > +	raw_spinlock_t lock;
> > +	u32 ext_irqs[NUM_SIRQ];
> > +	u8 trigger;
> 
> Nit: Please align data structure members vertically:
> 
> struct owl_sirq_chip_data {
> 	const struct owl_sirq_params *params;
> 	void __iomem                 *base;
> 	raw_spinlock_t               lock;
> 	u32                          ext_irqs[NUM_SIRQ];
> 	u8                           trigger;
> };

Done.

> > +};
> > +
> > +/* S500 and S700 SoCs */
> > +static const struct owl_sirq_params owl_sirq_s500_params = {
> > +	.reg_shared = true,
> > +	.reg_offset = { 0, 0, 0 },
> > +};
> > +
> > +/* S900 SoC */
> > +static const struct owl_sirq_params owl_sirq_s900_params = {
> > +	.reg_shared = false,
> > +	.reg_offset = { 0, INTC_EXTCTL1, INTC_EXTCTL2 },
> 
> 0 *is* an offset, right? Why doesn't it have a name too?

Right, I updated the defines section:

/* S900 SIRQ control register offsets, relative to controller base address */
#define INTC_EXTCTL0			0x0000
#define INTC_EXTCTL1			0x0328
[...]

The controller base address points to SIRQ0 control register, so this
offset is always 0, but I totally agree we should have a name for it.

> > +};
> > +
> > +static u32 owl_sirq_read_extctl(struct owl_sirq_chip_data *data, u32
> > index)
> > +{
> > +	u32 val;
> > +
> > +	val = readl_relaxed(data->base + data->params->reg_offset[index]);
> > +	if (data->params->reg_shared)
> > +		val = (val >> (2 - index) * 8) & 0xff;
> 
>         base = (2 - index) * 8;
>         val = FIELD_GET(GENMASK(base + 7, base), val);

Unfortunately the context doesn't allow using FIELD_GET:

./include/linux/compiler.h:392:38: error: call to ‘__compiletime_assert_159’ 
 declared with attribute error: FIELD_GET: mask is not constant

> > +
> > +	return val;
> > +}
> > +
> > +static void owl_sirq_write_extctl(struct owl_sirq_chip_data *data,
> > +				  u32 extctl, u32 index)
> > +{
> > +	u32 val;
> > +
> > +	if (data->params->reg_shared) {
> > +		val = readl_relaxed(data->base + data->params->reg_offset[index]);
> > +		val &= ~(0xff << (2 - index) * 8);
> > +		extctl &= 0xff;
> > +		extctl = (extctl << (2 - index) * 8) | val;
> 
> Please make use of FIELD_PREP, FIELD_GET and GENMASK.

I'm not sure how to deal with the mask constness restriction, except
using static defines and if/else statements, which is not quite elegant.

> > +	}
> > +
> > +	writel_relaxed(extctl, data->base + data->params->reg_offset[index]);
> > +}
> > +
> > +static void owl_sirq_clear_set_extctl(struct owl_sirq_chip_data *d,
> > +				      u32 clear, u32 set, u32 index)
> > +{
> > +	unsigned long flags;
> > +	u32 val;
> > +
> > +	raw_spin_lock_irqsave(&d->lock, flags);
> > +	val = owl_sirq_read_extctl(d, index);
> > +	val &= ~clear;
> > +	val |= set;
> > +	owl_sirq_write_extctl(d, val, index);
> > +	raw_spin_unlock_irqrestore(&d->lock, flags);
> > +}
> > +
> > +static void owl_sirq_eoi(struct irq_data *data)
> > +{
> > +	struct owl_sirq_chip_data *chip_data =
> > irq_data_get_irq_chip_data(data);
> > +
> > +	/*
> > +	 * Software must clear external interrupt pending, when interrupt type
> > +	 * is edge triggered, so we need per SIRQ based clearing.
> > +	 */
> > +	if (chip_data->trigger & (1 << data->hwirq))
> 
> BIT(d->hwirq)
> 
> But it also begs the question: we already have all the trigger information
> in the irqdesc. Why do you need some additional bookkeeping?

That's another leftover from the original work. Thanks for pointing
this out, I missed it. I dropped the redundant handling of the IRQ
trigger information and just replaced this with:

  if (!irqd_is_level_type(data))

> > +		owl_sirq_clear_set_extctl(chip_data, 0, INTC_EXTCTL_PENDING,
> > +					  data->hwirq);
> > +
> > +	irq_chip_eoi_parent(data);
> > +}
> > +
> > +static void owl_sirq_mask(struct irq_data *data)
> > +{
> > +	struct owl_sirq_chip_data *chip_data =
> > irq_data_get_irq_chip_data(data);
> > +
> > +	owl_sirq_clear_set_extctl(chip_data, INTC_EXTCTL_EN, 0, data->hwirq);
> > +	irq_chip_mask_parent(data);
> > +}
> > +
> > +static void owl_sirq_unmask(struct irq_data *data)
> > +{
> > +	struct owl_sirq_chip_data *chip_data =
> > irq_data_get_irq_chip_data(data);
> > +
> > +	owl_sirq_clear_set_extctl(chip_data, 0, INTC_EXTCTL_EN, data->hwirq);
> > +	irq_chip_unmask_parent(data);
> > +}
> > +
> > +/*
> > + * GIC does not handle falling edge or active low, hence SIRQ shall be
> > + * programmed to convert falling edge to rising edge signal and active
> > + * low to active high signal.
> > + */
> > +static int owl_sirq_set_type(struct irq_data *data, unsigned int type)
> > +{
> > +	struct owl_sirq_chip_data *chip_data =
> > irq_data_get_irq_chip_data(data);
> > +	u32 sirq_type;
> > +
> > +	switch (type) {
> > +	case IRQ_TYPE_LEVEL_LOW:
> > +		sirq_type = INTC_EXTCTL_TYPE_LOW;
> > +		chip_data->trigger &= ~(1 << data->hwirq);
> > +		type = IRQ_TYPE_LEVEL_HIGH;
> > +		break;
> > +	case IRQ_TYPE_LEVEL_HIGH:
> > +		sirq_type = INTC_EXTCTL_TYPE_HIGH;
> > +		chip_data->trigger &= ~(1 << data->hwirq);
> > +		break;
> > +	case IRQ_TYPE_EDGE_FALLING:
> > +		sirq_type = INTC_EXTCTL_TYPE_FALLING;
> > +		chip_data->trigger |= 1 << data->hwirq;
> > +		type = IRQ_TYPE_EDGE_RISING;
> > +		break;
> > +	case IRQ_TYPE_EDGE_RISING:
> > +		sirq_type = INTC_EXTCTL_TYPE_RISING;
> > +		chip_data->trigger |= 1 << data->hwirq;
> > +		break;
> > +	default:
> > +		WARN_ON(1);
> 
> No need for this WARN_ON(), the core kernel is loud enough.

Done.

> > +		return -EINVAL;
> > +	}
> > +
> > +	owl_sirq_clear_set_extctl(chip_data, INTC_EXTCTL_TYPE_MASK, sirq_type,
> > +				  data->hwirq);
> > +
> > +	return irq_chip_set_type_parent(data, type);
> > +}
> > +
> > +static struct irq_chip owl_sirq_chip = {
> > +	.name		= "owl-sirq",
> > +	.irq_mask	= owl_sirq_mask,
> > +	.irq_unmask	= owl_sirq_unmask,
> > +	.irq_eoi	= owl_sirq_eoi,
> > +	.irq_set_type	= owl_sirq_set_type,
> > +	.irq_retrigger	= irq_chip_retrigger_hierarchy,
> 
> How about irq_set_affinity? Or does it only exist on UP systems?

I have just added:

#ifdef CONFIG_SMP
	.irq_set_affinity = irq_chip_set_affinity_parent,
#endif

> > +};
> > +
> > +static int owl_sirq_domain_translate(struct irq_domain *d,
> > +				     struct irq_fwspec *fwspec,
> > +				     unsigned long *hwirq,
> > +				     unsigned int *type)
> > +{
> > +	if (!is_of_node(fwspec->fwnode))
> > +		return -EINVAL;
> > +
> > +	if (fwspec->param_count != 2 || fwspec->param[0] >= NUM_SIRQ)
> > +		return -EINVAL;
> > +
> > +	*hwirq = fwspec->param[0];
> > +	*type = fwspec->param[1];
> > +
> > +	return 0;
> > +}
> > +
> > +static int owl_sirq_domain_alloc(struct irq_domain *domain, unsigned
> > int virq,
> > +				 unsigned int nr_irqs, void *data)
> > +{
> > +	struct owl_sirq_chip_data *chip_data = domain->host_data;
> > +	struct irq_fwspec *fwspec = data;
> > +	struct irq_fwspec parent_fwspec;
> > +	irq_hw_number_t hwirq;
> > +	unsigned int type;
> > +	int ret;
> > +
> > +	if (WARN_ON(nr_irqs != 1))
> > +		return -EINVAL;
> > +
> > +	ret = owl_sirq_domain_translate(domain, fwspec, &hwirq, &type);
> > +	if (ret)
> > +		return ret;
> > +
> > +	switch (type) {
> > +	case IRQ_TYPE_EDGE_RISING:
> > +	case IRQ_TYPE_LEVEL_HIGH:
> > +		break;
> > +	case IRQ_TYPE_EDGE_FALLING:
> > +		type = IRQ_TYPE_EDGE_RISING;
> > +		break;
> > +	case IRQ_TYPE_LEVEL_LOW:
> > +		type = IRQ_TYPE_LEVEL_HIGH;
> > +		break;
> > +	default:
> > +		return -EINVAL;
> > +	}
> > +
> > +	irq_domain_set_hwirq_and_chip(domain, virq, hwirq, &owl_sirq_chip,
> > +				      chip_data);
> > +
> > +	parent_fwspec.fwnode = domain->parent->fwnode;
> > +	parent_fwspec.param_count = 3;
> > +	parent_fwspec.param[0] = 0;	/* SPI */
> > +	parent_fwspec.param[1] = chip_data->ext_irqs[hwirq];
> > +	parent_fwspec.param[2] = type;
> > +
> > +	return irq_domain_alloc_irqs_parent(domain, virq, 1, &parent_fwspec);
> > +}
> > +
> > +static const struct irq_domain_ops owl_sirq_domain_ops = {
> > +	.translate	= owl_sirq_domain_translate,
> > +	.alloc		= owl_sirq_domain_alloc,
> > +	.free		= irq_domain_free_irqs_common,
> > +};
> > +
> > +static const struct of_device_id owl_sirq_of_match[] = {
> > +	{ .compatible = "actions,s500-sirq", .data = &owl_sirq_s500_params },
> > +	{ .compatible = "actions,s700-sirq", .data = &owl_sirq_s500_params },
> > +	{ .compatible = "actions,s900-sirq", .data = &owl_sirq_s900_params },
> > +	{ /* sentinel */ }
> > +};
> > +
> > +static int __init owl_sirq_of_init(struct device_node *node,
> > +				   struct device_node *parent)
> > +{
> > +	const struct of_device_id *match;
> > +	struct irq_domain *domain, *parent_domain;
> > +	struct owl_sirq_chip_data *chip_data;
> > +	int ret, i;
> > +
> > +	parent_domain = irq_find_host(parent);
> > +	if (!parent_domain) {
> > +		pr_err("%pOF: failed to find sirq parent domain\n", node);
> > +		return -ENXIO;
> > +	}
> > +
> > +	chip_data = kzalloc(sizeof(*chip_data), GFP_KERNEL);
> > +	if (!chip_data)
> > +		return -ENOMEM;
> > +
> > +	match = of_match_node(owl_sirq_of_match, node);
> > +	if (!match) {
> > +		pr_warn("owl-sirq: assuming S500/S700 compatible controller\n");
> > +		chip_data->params = &owl_sirq_s500_params;
> > +	} else {
> > +		chip_data->params = match->data;
> > +	}
> > +
> > +	raw_spin_lock_init(&chip_data->lock);
> > +
> > +	chip_data->base = of_iomap(node, 0);
> > +	if (!chip_data->base) {
> > +		pr_err("%pOF: failed to map sirq registers\n", node);
> > +		ret = -ENXIO;
> > +		goto out_free;
> > +	}
> > +
> > +	ret = of_property_read_variable_u32_array(node,
> > "actions,ext-interrupts",
> > +						  chip_data->ext_irqs,
> > +						  NUM_SIRQ, NUM_SIRQ);
> > +	if (ret < NUM_SIRQ) {
> > +		pr_err("%pOF: failed to read sirq interrupts\n", node);
> > +		goto out_unmap;
> > +	}
> > +
> > +	/* Set 24MHz external interrupt clock freq */
> > +	for (i = 0; i < NUM_SIRQ; i++)
> > +		owl_sirq_clear_set_extctl(chip_data, 0, INTC_EXTCTL_CLK_SEL, i);
> > +
> > +	domain = irq_domain_add_hierarchy(parent_domain, 0, NUM_SIRQ, node,
> > +					  &owl_sirq_domain_ops, chip_data);
> > +	if (!domain) {
> > +		pr_err("%pOF: failed to add domain\n", node);
> > +		ret = -ENOMEM;
> > +		goto out_unmap;
> > +	}
> > +
> > +	return 0;
> > +
> > +out_unmap:
> > +	iounmap(chip_data->base);
> > +out_free:
> > +	kfree(chip_data);
> > +
> > +	return ret;
> > +}
> > +
> > +IRQCHIP_DECLARE(owl_sirq, "actions,owl-sirq", owl_sirq_of_init);
> 
> Thanks,
> 
>         M.
> -- 
> Jazz is not dead. It just smells funny...

Thanks again,
Cristi