Re: [PATCH v3 2/2] irqchip: Add support for Realtek RTL838x/RTL839x interrupt controller

[Marc Zyngier <maz@kernel.org>]

On Wed, 20 Jan 2021 10:10:18 +0000,
Bert Vermeulen <bert@biot.com> wrote:
> 
> Signed-off-by: Bert Vermeulen <bert@biot.com>

Please write a decent commit message.

> ---
>  drivers/irqchip/Makefile          |   1 +
>  drivers/irqchip/irq-realtek-rtl.c | 180 ++++++++++++++++++++++++++++++
>  2 files changed, 181 insertions(+)
>  create mode 100644 drivers/irqchip/irq-realtek-rtl.c
> 
> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> index 0ac93bfaec61..4fc1086bed7e 100644
> --- a/drivers/irqchip/Makefile
> +++ b/drivers/irqchip/Makefile
> @@ -113,3 +113,4 @@ obj-$(CONFIG_LOONGSON_PCH_PIC)		+= irq-loongson-pch-pic.o
>  obj-$(CONFIG_LOONGSON_PCH_MSI)		+= irq-loongson-pch-msi.o
>  obj-$(CONFIG_MST_IRQ)			+= irq-mst-intc.o
>  obj-$(CONFIG_SL28CPLD_INTC)		+= irq-sl28cpld.o
> +obj-$(CONFIG_MACH_REALTEK_RTL)		+= irq-realtek-rtl.o
> diff --git a/drivers/irqchip/irq-realtek-rtl.c b/drivers/irqchip/irq-realtek-rtl.c
> new file mode 100644
> index 000000000000..bafe9ee4a85a
> --- /dev/null
> +++ b/drivers/irqchip/irq-realtek-rtl.c
> @@ -0,0 +1,180 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2006-2012 Tony Wu <tonywu@realtek.com>
> + * Copyright (C) 2020 Birger Koblitz <mail@birger-koblitz.de>
> + * Copyright (C) 2020 Bert Vermeulen <bert@biot.com>
> + * Copyright (C) 2020 John Crispin <john@phrozen.org>

Given the list of copyright owners, shouldn't this be reflected in the
SoB chain one way or another?

> + */
> +
> +#include <linux/of_irq.h>
> +#include <linux/irqchip.h>
> +#include <linux/spinlock.h>
> +#include <linux/of_address.h>
> +#include <linux/irqchip/chained_irq.h>
> +
> +/* Global Interrupt Mask Register */
> +#define RTL_ICTL_GIMR		0x00
> +/* Global Interrupt Status Register */
> +#define RTL_ICTL_GISR		0x04
> +/* Interrupt Routing Registers */
> +#define RTL_ICTL_IRR0		0x08
> +#define RTL_ICTL_IRR1		0x0c
> +#define RTL_ICTL_IRR2		0x10
> +#define RTL_ICTL_IRR3		0x14
> +
> +#define REG(x)		(realtek_ictl_base + x)
> +
> +static DEFINE_RAW_SPINLOCK(irq_lock);
> +static void __iomem *realtek_ictl_base;
> +
> +static void realtek_ictl_unmask_irq(struct irq_data *i)
> +{
> +	unsigned long flags;
> +	u32 value;
> +
> +	raw_spin_lock_irqsave(&irq_lock, flags);
> +
> +	value = readl(REG(RTL_ICTL_GIMR));
> +	value |= BIT(i->hwirq);
> +	writel(value, REG(RTL_ICTL_GIMR));
> +
> +	raw_spin_unlock_irqrestore(&irq_lock, flags);
> +}
> +
> +static void realtek_ictl_mask_irq(struct irq_data *i)
> +{
> +	unsigned long flags;
> +	u32 value;
> +
> +	raw_spin_lock_irqsave(&irq_lock, flags);
> +
> +	value = readl(REG(RTL_ICTL_GIMR));
> +	value &= ~BIT(i->hwirq);
> +	writel(value, REG(RTL_ICTL_GIMR));
> +
> +	raw_spin_unlock_irqrestore(&irq_lock, flags);
> +}
> +
> +static struct irq_chip realtek_ictl_irq = {
> +	.name = "realtek-rtl-intc",
> +	.irq_mask = realtek_ictl_mask_irq,
> +	.irq_unmask = realtek_ictl_unmask_irq,
> +};
> +
> +static int intc_map(struct irq_domain *d, unsigned int irq, irq_hw_number_t hw)
> +{
> +	irq_set_chip_and_handler(hw, &realtek_ictl_irq, handle_level_irq);
> +
> +	return 0;
> +}
> +
> +static const struct irq_domain_ops irq_domain_ops = {
> +	.map = intc_map,
> +	.xlate = irq_domain_xlate_onecell,
> +};
> +
> +static void realtek_irq_dispatch(struct irq_desc *desc)
> +{
> +	struct irq_chip *chip = irq_desc_get_chip(desc);
> +	struct irq_domain *domain;
> +	unsigned int pending;
> +
> +	chained_irq_enter(chip, desc);
> +	pending = readl(REG(RTL_ICTL_GIMR)) & readl(REG(RTL_ICTL_GISR));
> +	if (unlikely(!pending)) {
> +		spurious_interrupt();
> +		goto out;
> +	}
> +	domain = irq_desc_get_handler_data(desc);
> +	generic_handle_irq(irq_find_mapping(domain, __ffs(pending)));
> +
> +out:
> +	chained_irq_exit(chip, desc);
> +}
> +
> +/*
> + * SoC interrupts are cascaded to MIPS CPU interrupts according to the
> + * interrupt-map in the device tree. Each SoC interrupt gets 4 bits for
> + * the CPU interrupt in an Interrupt Routing Register. Max 32 SoC interrupts
> + * thus go into 4 IRRs.
> + */
> +static int __init map_interrupts(struct device_node *node)
> +{
> +	struct device_node *cpu_ictl;
> +	const __be32 *imap;
> +	u32 imaplen, soc_int, cpu_int, tmp, regs[4];
> +	int ret, i, irr_regs[] = {
> +		RTL_ICTL_IRR3,
> +		RTL_ICTL_IRR2,
> +		RTL_ICTL_IRR1,
> +		RTL_ICTL_IRR0,
> +	};
> +
> +	ret = of_property_read_u32(node, "#address-cells", &tmp);
> +	if (ret || tmp)
> +		return -EINVAL;
> +
> +	imap = of_get_property(node, "interrupt-map", &imaplen);
> +	if (!imap || imaplen % 3)
> +		return -EINVAL;
> +
> +	memset(regs, 0, sizeof(regs));
> +	for (i = 0; i < imaplen; i += 3 * sizeof(u32)) {
> +		soc_int = be32_to_cpup(imap);
> +		if (soc_int > 31)
> +			return -EINVAL;
> +
> +		cpu_ictl = of_find_node_by_phandle(be32_to_cpup(imap + 1));
> +		if (!cpu_ictl)
> +			return -EINVAL;
> +		ret = of_property_read_u32(cpu_ictl, "#interrupt-cells", &tmp);
> +		if (ret || tmp != 1)
> +			return -EINVAL;
> +		of_node_put(cpu_ictl);
> +
> +		cpu_int = be32_to_cpup(imap + 2);
> +		if (cpu_int > 7)
> +			return -EINVAL;
> +
> +		regs[(soc_int * 4) / 32] |= cpu_int << (soc_int * 4) % 32;
> +		imap += 3;
> +	}
> +
> +	for (i = 0; i < 4; i++)
> +		writel(regs[i], REG(irr_regs[i]));
> +
> +	return 0;
> +}
> +
> +static int __init realtek_rtl_of_init(struct device_node *node, struct device_node *parent)
> +{
> +	struct irq_domain *domain;
> +	int ret;
> +
> +	domain = irq_domain_add_simple(node, 32, 0,
> +				       &irq_domain_ops, NULL);
> +	irq_set_chained_handler_and_data(2, realtek_irq_dispatch, domain);
> +	irq_set_chained_handler_and_data(3, realtek_irq_dispatch, domain);
> +	irq_set_chained_handler_and_data(4, realtek_irq_dispatch, domain);
> +	irq_set_chained_handler_and_data(5, realtek_irq_dispatch, domain);

Where are these numbers coming from? Are they hard-coded? There isn't
an interrupt-parent to link this to the root controller?

> +
> +	realtek_ictl_base = of_iomap(node, 0);
> +	if (!realtek_ictl_base)
> +		return -ENXIO;
> +
> +	/* Disable all cascaded interrupts */
> +	writel(0, REG(RTL_ICTL_GIMR));

This really should happen before you enable the chained handler...

> +
> +	ret = map_interrupts(node);

Why are all mappings done ahead of time, and not at the point where
the interrupt gets mapped (in the irqdomain sense)? Not necessarily a
deal-breaker, but we usually try to do things on demand rather than
upfront.

> +	if (ret) {
> +		pr_err("invalid interrupt map\n");
> +		return ret;
> +	}
> +
> +	/* Clear timer interrupt */
> +	write_c0_compare(0);

What is the timer interrupt doing here?

> +
> +	return 0;
> +}
> +
> +IRQCHIP_DECLARE(realtek_rtl_intc, "realtek,rtl-intc", realtek_rtl_of_init);
> -- 
> 2.25.1
> 
> 

Thanks,

	M.

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