Re: [PATCH v4 2/3] irqchip: Add Actions Semi Owl SIRQ controller

From: Marc Zyngier <maz@kernel.org>
To: Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
Cc: "Thomas Gleixner" <tglx@linutronix.de>,
	"Jason Cooper" <jason@lakedaemon.net>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Andreas Färber" <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
Date: Tue, 18 Aug 2020 21:48:41 +0100	[thread overview]
Message-ID: <87lfibn0ie.wl-maz@kernel.org> (raw)
In-Reply-To: <20200818174241.GA2020288@BV030612LT>

On Tue, 18 Aug 2020 18:42:41 +0100,
Cristian Ciocaltea <cristian.ciocaltea@gmail.com> wrote:
> 
> 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."

Looks good.

> 
> > > 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

Bah. Turning the whole thing into compile-time values would actually
be more readable, so how about this:

diff --git a/drivers/irqchip/irq-owl-sirq.c b/drivers/irqchip/irq-owl-sirq.c
index 29b7ffc40ac7..b771acbda7d5 100644
--- a/drivers/irqchip/irq-owl-sirq.c
+++ b/drivers/irqchip/irq-owl-sirq.c
@@ -57,13 +57,39 @@ static const struct owl_sirq_params owl_sirq_s900_params = {
 	.reg_offset = { 0, INTC_EXTCTL1, INTC_EXTCTL2 },
 };
 
+static u32 owl_field_get(u32 val, int index)
+{
+	switch(index) {
+	case 0:
+		return FIELD_GET(GENMASK(23, 16), val);
+	case 1:
+		return FIELD_GET(GENMASK(15, 8), val);
+	case 2:
+	default:
+		return FIELD_GET(GENMASK(7, 0), val);
+	}
+}
+
+static u32 owl_field_prep(u32 val, int index)
+{
+	switch(index) {
+	case 0:
+		return FIELD_PREP(GENMASK(23, 16), val);
+	case 1:
+		return FIELD_PREP(GENMASK(15, 8), val);
+	case 2:
+	default:
+		return FIELD_PREP(GENMASK(7, 0), val);
+	}
+}
+
 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;
+		val = owl_field_get(val, index);
 
 	return val;
 }
@@ -75,9 +101,8 @@ static void owl_sirq_write_extctl(struct owl_sirq_chip_data *data,
 
 	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;
+		val &= ~owl_field_prep(0xff, index);
+		extctl = owl_field_prep(extctl, index) | val;
 	}
 
 	writel_relaxed(extctl, data->base + data->params->reg_offset[index]);

Yes, this is a bit more code, but it *is* readable. Bonus points if
you add proper defines for the masks.

> 
> > > +
> > > +	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.

See above.

> 
> > > +	}
> > > +
> > > +	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))

Yup.

> 
> > > +		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

Looks OK.

Cheers,

	M.

-- 
Without deviation from the norm, progress is not possible.
