Message-ID: <87pmmky2tw.wl-maz@kernel.org>
Date:   Thu, 17 Mar 2022 16:13:31 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        Prabhakar <prabhakar.csengg@...il.com>,
        Biju Das <biju.das.jz@...renesas.com>
Subject: Re: [RFC PATCH v4 2/5] irqchip: Add RZ/G2L IA55 Interrupt Controller driver

On Thu, 17 Mar 2022 01:24:01 +0000,
Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com> wrote:
> 
> Add a driver for the Renesas RZ/G2L Interrupt Controller.
> 
> This supports external pins being used as interrupts. It supports
> one line for NMI, 8 external pins and 32 GPIO pins (out of 123)
> to be used as IRQ lines.
> 
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> ---
>  drivers/irqchip/Kconfig             |   8 +
>  drivers/irqchip/Makefile            |   1 +
>  drivers/irqchip/irq-renesas-rzg2l.c | 462 ++++++++++++++++++++++++++++
>  3 files changed, 471 insertions(+)
>  create mode 100644 drivers/irqchip/irq-renesas-rzg2l.c
> 
> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> index 7038957f4a77..afc5999f4955 100644
> --- a/drivers/irqchip/Kconfig
> +++ b/drivers/irqchip/Kconfig
> @@ -242,6 +242,14 @@ config RENESAS_RZA1_IRQC
>  	  Enable support for the Renesas RZ/A1 Interrupt Controller, to use up
>  	  to 8 external interrupts with configurable sense select.
>  
> +config RENESAS_RZG2L_IRQC
> +	bool "Renesas RZ/G2L (and alike SoC) IRQC support" if COMPILE_TEST
> +	select GENERIC_IRQ_CHIP
> +	select IRQ_DOMAIN_HIERARCHY
> +	help
> +	  Enable support for the Renesas RZ/G2L (and alike SoC) Interrupt Controller
> +	  for external devices.
> +
>  config SL28CPLD_INTC
>  	bool "Kontron sl28cpld IRQ controller"
>  	depends on MFD_SL28CPLD=y || COMPILE_TEST
> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> index c1f611cbfbf8..b536e514a7c9 100644
> --- a/drivers/irqchip/Makefile
> +++ b/drivers/irqchip/Makefile
> @@ -51,6 +51,7 @@ obj-$(CONFIG_RDA_INTC)			+= irq-rda-intc.o
>  obj-$(CONFIG_RENESAS_INTC_IRQPIN)	+= irq-renesas-intc-irqpin.o
>  obj-$(CONFIG_RENESAS_IRQC)		+= irq-renesas-irqc.o
>  obj-$(CONFIG_RENESAS_RZA1_IRQC)		+= irq-renesas-rza1.o
> +obj-$(CONFIG_RENESAS_RZG2L_IRQC)	+= irq-renesas-rzg2l.o
>  obj-$(CONFIG_VERSATILE_FPGA_IRQ)	+= irq-versatile-fpga.o
>  obj-$(CONFIG_ARCH_NSPIRE)		+= irq-zevio.o
>  obj-$(CONFIG_ARCH_VT8500)		+= irq-vt8500.o
> diff --git a/drivers/irqchip/irq-renesas-rzg2l.c b/drivers/irqchip/irq-renesas-rzg2l.c
> new file mode 100644
> index 000000000000..be9741e88bd7
> --- /dev/null
> +++ b/drivers/irqchip/irq-renesas-rzg2l.c
> @@ -0,0 +1,462 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Renesas RZ/G2L IRQC Driver
> + *
> + * Copyright (C) 2022 Renesas Electronics Corporation.
> + *
> + * Author: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/irqchip.h>
> +#include <linux/irqdomain.h>
> +#include <linux/of_address.h>
> +#include <linux/reset.h>
> +#include <linux/spinlock.h>
> +
> +#define IRQC_IRQ_START			1
> +#define IRQC_IRQ_COUNT			8
> +#define IRQC_TINT_START			9
> +#define IRQC_TINT_COUNT			32
> +#define IRQC_NUM_IRQ			41
> +
> +#define ISCR				0x10
> +#define IITSR				0x14
> +#define TSCR				0x20
> +#define TITSR0				0x24
> +#define TITSR1				0x28
> +#define TITSR0_MAX_INT			16
> +#define TITSEL_WIDTH			0x2
> +#define TSSR(n)				(0x30 + ((n) * 4))
> +#define TIEN				BIT(7)
> +#define TSSEL_SHIFT(n)			(8 * (n))
> +#define TSSEL_MASK			GENMASK(7, 0)
> +#define IRQ_MASK			0x3
> +
> +#define TSSR_OFFSET(n)			((n) % 4)
> +#define TSSR_INDEX(n)			((n) / 4)
> +
> +#define TITSR_TITSEL_EDGE_RISING	0
> +#define TITSR_TITSEL_EDGE_FALLING	1
> +#define TITSR_TITSEL_LEVEL_HIGH		2
> +#define TITSR_TITSEL_LEVEL_LOW		3
> +
> +#define IITSR_IITSEL(n, sense)		((sense) << ((n) * 2))
> +#define IITSR_IITSEL_LEVEL_LOW		0
> +#define IITSR_IITSEL_EDGE_FALLING	1
> +#define IITSR_IITSEL_EDGE_RISING	2
> +#define IITSR_IITSEL_EDGE_BOTH		3
> +#define IITSR_IITSEL_MASK(n)		IITSR_IITSEL((n), 3)
> +
> +#define TINT_EXTRACT_HWIRQ(x)		((x) & ~GENMASK(31, 16))
> +#define TINT_EXTRACT_GPIOINT(x)		((x) >> 16)
> +
> +struct rzg2l_irqc_priv {
> +	void __iomem *base;
> +	struct of_phandle_args map[IRQC_NUM_IRQ];
> +	raw_spinlock_t lock;
> +};
> +
> +struct rzg2l_irqc_chip_data {
> +	int tint;
> +};
> +
> +static struct rzg2l_irqc_priv *irq_data_to_priv(struct irq_data *data)
> +{
> +	return data->domain->host_data;
> +}
> +
> +static void rzg2l_irq_eoi(struct irq_data *d)
> +{
> +	struct rzg2l_irqc_priv *priv = irq_data_to_priv(d);
> +	unsigned int hw_irq = irqd_to_hwirq(d) - IRQC_IRQ_START;
> +	u16 bit = BIT(hw_irq);
> +	unsigned long flags;
> +	u32 reg;
> +
> +	raw_spin_lock_irqsave(&priv->lock, flags);

Why the irqsave flavour? Is there any case where EOI isn't performed
in a context that has interrupts already disabled?

> +	reg = readl_relaxed(priv->base + ISCR);
> +	if (reg & bit)
> +		writel_relaxed(GENMASK(IRQC_IRQ_COUNT - 1, 0) & ~bit,
> +			       priv->base + ISCR);
> +	raw_spin_unlock_irqrestore(&priv->lock, flags);
> +	irq_chip_eoi_parent(d);
> +}
> +
> +static void rzg2l_tint_eoi(struct irq_data *d)
> +{
> +	struct rzg2l_irqc_priv *priv = irq_data_to_priv(d);
> +	unsigned int hw_irq = irqd_to_hwirq(d);
> +	u32 bit = BIT(hw_irq - IRQC_TINT_START);
> +	unsigned long flags;
> +	u32 reg;
> +
> +	raw_spin_lock_irqsave(&priv->lock, flags);
> +	reg = readl_relaxed(priv->base + TSCR);
> +	if (reg & bit)
> +		writel_relaxed(GENMASK(IRQC_TINT_COUNT - 1, 0) & ~bit,
> +			       priv->base + TSCR);
> +	raw_spin_unlock_irqrestore(&priv->lock, flags);
> +	irq_chip_eoi_parent(d);
> +}
> +
> +static void rzg2l_irqc_eoi(struct irq_data *d)
> +{
> +	unsigned int hw_irq = irqd_to_hwirq(d);
> +
> +	if (hw_irq >= IRQC_IRQ_START && hw_irq <= IRQC_IRQ_COUNT)
> +		return rzg2l_irq_eoi(d);

return function_returning_void()? No, please.

> +	else if (hw_irq >= IRQC_TINT_START && hw_irq <= IRQC_TINT_COUNT)
> +		return rzg2l_tint_eoi(d);

Move the locking and the call to irq_chip_eoi_parent() here, as there
is no need to duplicate any of this.

> +}
> +
> +static void rzg2l_irqc_irq_disable(struct irq_data *d)
> +{
> +	unsigned int hw_irq = irqd_to_hwirq(d);
> +
> +	if (hw_irq >= IRQC_TINT_START && hw_irq <= IRQC_TINT_COUNT) {
> +		struct rzg2l_irqc_priv *priv = irq_data_to_priv(d);
> +		u32 offset = hw_irq - IRQC_TINT_START;
> +		u32 tssr_offset = TSSR_OFFSET(offset);
> +		u8 tssr_index = TSSR_INDEX(offset);
> +		unsigned long flags;
> +		u32 reg;
> +
> +		raw_spin_lock_irqsave(&priv->lock, flags);
> +		reg = readl_relaxed(priv->base + TSSR(tssr_index));
> +		reg &= ~(TSSEL_MASK << tssr_offset);
> +		writel_relaxed(reg, priv->base + TSSR(tssr_index));
> +		raw_spin_unlock_irqrestore(&priv->lock, flags);
> +	}
> +	irq_chip_disable_parent(d);
> +}
> +
> +static void rzg2l_irqc_irq_enable(struct irq_data *d)
> +{
> +	unsigned int hw_irq = irqd_to_hwirq(d);
> +
> +	if (hw_irq >= IRQC_TINT_START && hw_irq <= IRQC_TINT_COUNT) {
> +		struct rzg2l_irqc_priv *priv = irq_data_to_priv(d);
> +		struct rzg2l_irqc_chip_data *chip_data = d->chip_data;
> +		u32 offset = hw_irq - IRQC_TINT_START;
> +		u32 tssr_offset = TSSR_OFFSET(offset);
> +		u8 tssr_index = TSSR_INDEX(offset);
> +		unsigned long flags;
> +		u32 reg;
> +
> +		raw_spin_lock_irqsave(&priv->lock, flags);
> +		reg = readl_relaxed(priv->base + TSSR(tssr_index));
> +		reg |= (TIEN | chip_data->tint) << TSSEL_SHIFT(tssr_offset);
> +		writel_relaxed(reg, priv->base + TSSR(tssr_index));
> +		raw_spin_unlock_irqrestore(&priv->lock, flags);
> +	}
> +	irq_chip_enable_parent(d);
> +}
> +
> +static int rzg2l_irq_set_type(struct irq_data *d, unsigned int type)
> +{
> +	unsigned int hw_irq = irqd_to_hwirq(d) - IRQC_IRQ_START;
> +	struct rzg2l_irqc_priv *priv = irq_data_to_priv(d);
> +	unsigned long flags;
> +	u16 sense, tmp;
> +
> +	switch (type & IRQ_TYPE_SENSE_MASK) {
> +	case IRQ_TYPE_LEVEL_LOW:
> +		sense = IITSR_IITSEL_LEVEL_LOW;
> +		break;
> +
> +	case IRQ_TYPE_EDGE_FALLING:
> +		sense = IITSR_IITSEL_EDGE_FALLING;
> +		break;
> +
> +	case IRQ_TYPE_EDGE_RISING:
> +		sense = IITSR_IITSEL_EDGE_RISING;
> +		break;
> +
> +	case IRQ_TYPE_EDGE_BOTH:
> +		sense = IITSR_IITSEL_EDGE_BOTH;
> +		break;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	raw_spin_lock_irqsave(&priv->lock, flags);

This already happens in an irq disabled context.

> +	tmp = readl_relaxed(priv->base + IITSR);
> +	tmp &= ~IITSR_IITSEL_MASK(hw_irq);
> +	tmp |= IITSR_IITSEL(hw_irq, sense);
> +	writel_relaxed(tmp, priv->base + IITSR);
> +	raw_spin_unlock_irqrestore(&priv->lock, flags);

What about the parent irqchip? If this is a hierarchical setup, it
definitely should be told.

> +
> +	return 0;
> +}
> +
> +static int rzg2l_tint_set_edge(struct irq_data *d, unsigned int type)
> +{
> +	struct rzg2l_irqc_priv *priv = irq_data_to_priv(d);
> +	unsigned int hwirq = irqd_to_hwirq(d);
> +	u32 titseln = hwirq - IRQC_TINT_START;
> +	unsigned long flags;
> +	u32 offset;
> +	u8 sense;
> +	u32 reg;
> +
> +	switch (type & IRQ_TYPE_SENSE_MASK) {
> +	case IRQ_TYPE_EDGE_RISING:
> +		sense = TITSR_TITSEL_EDGE_RISING;
> +		break;
> +
> +	case IRQ_TYPE_EDGE_FALLING:
> +		sense = TITSR_TITSEL_EDGE_FALLING;
> +		break;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	if (titseln < TITSR0_MAX_INT) {
> +		offset = TITSR0;
> +	} else {
> +		titseln /= TITSEL_WIDTH;
> +		offset  = TITSR1;
> +	}
> +
> +	raw_spin_lock_irqsave(&priv->lock, flags);
> +	reg = readl_relaxed(priv->base + offset);
> +	reg &= ~(IRQ_MASK << (titseln * TITSEL_WIDTH));
> +	reg |= sense << (titseln * TITSEL_WIDTH);
> +	writel_relaxed(reg, priv->base + offset);
> +	raw_spin_unlock_irqrestore(&priv->lock, flags);
> +
> +	return 0;
> +}
> +
> +static int rzg2l_irqc_set_type(struct irq_data *d, unsigned int type)
> +{
> +	unsigned int hw_irq = irqd_to_hwirq(d);
> +
> +	if (hw_irq >= IRQC_IRQ_START && hw_irq <= IRQC_IRQ_COUNT)
> +		return rzg2l_irq_set_type(d, type);
> +	else if (hw_irq >= IRQC_TINT_START && hw_irq <= IRQC_TINT_COUNT)
> +		return rzg2l_tint_set_edge(d, type);
> +
> +	return -EINVAL;
> +}
> +
> +static struct irq_chip irqc_chip = {
> +	.name			= "rzg2l-irqc",
> +	.irq_eoi		= rzg2l_irqc_eoi,
> +	.irq_mask		= irq_chip_mask_parent,
> +	.irq_unmask		= irq_chip_unmask_parent,
> +	.irq_disable		= rzg2l_irqc_irq_disable,
> +	.irq_enable		= rzg2l_irqc_irq_enable,

So this looks a bit odd. irq_mask only calls the parent and does nothing
locally, while irq_disable does something locally and calls into the
parent. If the parent is a GIC, this is turned into a mask (GIC has no
notion of disabled).

If that's the flow you expect, good. But please check this is the case.

> +	.irq_get_irqchip_state	= irq_chip_get_parent_state,
> +	.irq_set_irqchip_state	= irq_chip_set_parent_state,
> +	.irq_retrigger		= irq_chip_retrigger_hierarchy,
> +	.irq_set_type		= rzg2l_irqc_set_type,
> +	.flags			= IRQCHIP_MASK_ON_SUSPEND |
> +				  IRQCHIP_SET_TYPE_MASKED |
> +				  IRQCHIP_SKIP_SET_WAKE,
> +};
> +
> +static int rzg2l_irqc_alloc(struct irq_domain *domain, unsigned int virq,
> +			    unsigned int nr_irqs, void *arg)
> +{
> +	struct rzg2l_irqc_priv *priv = domain->host_data;
> +	struct rzg2l_irqc_chip_data *chip_data = NULL;
> +	struct irq_fwspec spec;
> +	irq_hw_number_t hwirq;
> +	int tint = -EINVAL;
> +	unsigned int type;
> +	unsigned int i;
> +	int ret;
> +
> +	ret = irq_domain_translate_twocell(domain, arg, &hwirq, &type);
> +	if (ret)
> +		return ret;
> +
> +	/*
> +	 * For TINIT interrupts ie where pinctrl driver is child of irqc domain
> +	 * the hwirq and TINT are encoded in fwspec->param[0].
> +	 * hwirq for TINIT range from 9-40, hwirq is embedded 0-15 bits and TINT
> +	 * from 16-31 bits. TINIT from the pinctrl driver needs to be programmed
> +	 * in IRQC registers to enable a given gpio pin as interrupt.
> +	 */
> +	if (hwirq > IRQC_IRQ_COUNT) {
> +		tint = TINT_EXTRACT_GPIOINT(hwirq);
> +		hwirq = TINT_EXTRACT_HWIRQ(hwirq);
> +	}
> +
> +	if (hwirq > (IRQC_NUM_IRQ - 1))
> +		return -EINVAL;
> +
> +	if (tint != -EINVAL && (hwirq < IRQC_TINT_START || hwirq > (IRQC_NUM_IRQ - 1)))
> +		return -EINVAL;
> +
> +	chip_data = kzalloc(sizeof(*chip_data), GFP_KERNEL);
> +	if (!chip_data)
> +		return -ENOMEM;
> +	chip_data->tint = tint;
> +
> +	ret = irq_domain_set_hwirq_and_chip(domain, virq, hwirq, &irqc_chip,
> +					    chip_data);
> +	if (ret) {
> +		kfree(chip_data);
> +		return ret;
> +	}
> +
> +	spec.fwnode = domain->parent->fwnode;
> +	spec.param_count = priv->map[hwirq].args_count;
> +	for (i = 0; i < spec.param_count; i++)
> +		spec.param[i] = priv->map[hwirq].args[i];
> +
> +	ret = irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, &spec);
> +	if (ret)
> +		kfree(chip_data);
> +
> +	return ret;
> +}
> +
> +static void rzg2l_irqc_domain_free(struct irq_domain *domain, unsigned int virq,
> +				   unsigned int nr_irqs)
> +{
> +	struct irq_data *d;
> +
> +	d = irq_domain_get_irq_data(domain, virq);
> +	if (d) {
> +		struct rzg2l_irqc_chip_data *chip_data = d->chip_data;
> +
> +		kfree(chip_data);
> +	}
> +	irq_domain_free_irqs_common(domain, virq, nr_irqs);
> +}
> +
> +static const struct irq_domain_ops rzg2l_irqc_domain_ops = {
> +	.alloc = rzg2l_irqc_alloc,
> +	.free = rzg2l_irqc_domain_free,
> +	.translate = irq_domain_translate_twocell,
> +};
> +
> +static int rzg2l_irqc_parse_map(struct rzg2l_irqc_priv *priv,
> +				struct device_node *np,
> +				struct device_node *parent)
> +{
> +	unsigned int len, j;
> +	const __be32 *range;
> +
> +	range = of_get_property(np, "interrupts", &len);
> +	if (!range)
> +		return -EINVAL;
> +
> +	for (len /= sizeof(*range), j = 0; len >= 3; len -= 3) {
> +		if (j >= IRQC_NUM_IRQ)
> +			return -EINVAL;
> +
> +		priv->map[j].args[0] = be32_to_cpu(*range++);
> +		priv->map[j].args[1] = be32_to_cpu(*range++);
> +		priv->map[j].args[2] = be32_to_cpu(*range++);
> +		priv->map[j].args_count = 3;
> +		j++;
> +	}

I'm confused. Why do you have to invent a new interrupt parser? What
is wrong with of_irq_parse_one() populating the of_phandle_args array?
I expected to see something like:

static void rzg2l_irqc_parse_map(struct rzg2l_irqc_priv *priv,
				 struct device_node *np)
{
	int i;

	for (i = 0; i < IRQC_NUM_IRQ; i++)
		of_irq_parse_one(np, i, &priv->map[i]);
}

and that's it.

Thanks,

	M.

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

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