Message-ID: <87bkvf56wg.wl-maz@kernel.org>
Date:   Mon, 30 May 2022 17:20:31 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Jianmin Lv <lvjianmin@...ngson.cn>
Cc:     Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
        Xuefeng Li <lixuefeng@...ngson.cn>,
        Huacai Chen <chenhuacai@...il.com>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Huacai Chen <chenhuacai@...ngson.cn>
Subject: Re: [PATCH RFC V2 02/10] irqchip: Add LoongArch CPU interrupt controller support

On Fri, 27 May 2022 12:02:12 +0100,
Jianmin Lv <lvjianmin@...ngson.cn> wrote:
> 
> We are preparing to add new Loongson (based on LoongArch, not compatible
> with old MIPS-based Loongson) support. This patch add the LoongArch CPU
> interrupt controller support.

Please drop this paragraph, as it doesn't help at all.

> 
> LoongArch CPUINTC stands for CSR.ECFG/CSR.ESTAT and related interrupt
> controller that described in Section 7.4 of "LoongArch Reference Manual,
> Vol 1". For more information please refer Documentation/loongarch/irq-
> chip-model.rst.

Where is this the patch adding this document?

> 
> LoongArch CPUINTC has 13 interrupt sources: SWI0~1, HWI0~7, IPI, TI
> (Timer) and PCOV (PMC). IRQ mappings of HWI0~7 are configurable (can be
> created from DT/ACPI), but IPI, TI (Timer) and PCOV (PMC) are hardcoded
> bits, so we define get_xxx_irq() for them.

Where are these functions? How are they used?

> 
> Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
> Signed-off-by: Jianmin Lv <lvjianmin@...ngson.cn>
> ---
>  drivers/irqchip/Kconfig                    |  10 ++
>  drivers/irqchip/Makefile                   |   1 +
>  drivers/irqchip/irq-loongarch-cpu.c        | 115 +++++++++++++++++
>  drivers/irqchip/irq-loongarch-pic-common.c | 201 +++++++++++++++++++++++++++++

One patch per driver, please.

>  drivers/irqchip/irq-loongarch-pic-common.h |  44 +++++++
>  5 files changed, 371 insertions(+)
>  create mode 100644 drivers/irqchip/irq-loongarch-cpu.c
>  create mode 100644 drivers/irqchip/irq-loongarch-pic-common.c
>  create mode 100644 drivers/irqchip/irq-loongarch-pic-common.h
> 
> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> index 39d6be2..a596ee7 100644
> --- a/drivers/irqchip/Kconfig
> +++ b/drivers/irqchip/Kconfig
> @@ -545,6 +545,16 @@ config EXYNOS_IRQ_COMBINER
>  	  Say yes here to add support for the IRQ combiner devices embedded
>  	  in Samsung Exynos chips.
>  
> +config IRQ_LOONGARCH_CPU
> +	bool
> +	select GENERIC_IRQ_CHIP
> +	select IRQ_DOMAIN
> +	select GENERIC_IRQ_EFFECTIVE_AFF_MASK
> +	help
> +	  Support for the LoongArch CPU Interrupt Controller. For details of
> +	  irq chip hierarchy on LoongArch platforms please read the document
> +	  Documentation/loongarch/irq-chip-model.rst.
> +
>  config LOONGSON_LIOINTC
>  	bool "Loongson Local I/O Interrupt Controller"
>  	depends on MACH_LOONGSON64
> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> index 160a1d8..736f030 100644
> --- a/drivers/irqchip/Makefile
> +++ b/drivers/irqchip/Makefile
> @@ -105,6 +105,7 @@ obj-$(CONFIG_LS1X_IRQ)			+= irq-ls1x.o
>  obj-$(CONFIG_TI_SCI_INTR_IRQCHIP)	+= irq-ti-sci-intr.o
>  obj-$(CONFIG_TI_SCI_INTA_IRQCHIP)	+= irq-ti-sci-inta.o
>  obj-$(CONFIG_TI_PRUSS_INTC)		+= irq-pruss-intc.o
> +obj-$(CONFIG_IRQ_LOONGARCH_CPU)		+= irq-loongarch-cpu.o irq-loongarch-pic-common.o
>  obj-$(CONFIG_LOONGSON_LIOINTC)		+= irq-loongson-liointc.o
>  obj-$(CONFIG_LOONGSON_HTPIC)		+= irq-loongson-htpic.o
>  obj-$(CONFIG_LOONGSON_HTVEC)		+= irq-loongson-htvec.o
> diff --git a/drivers/irqchip/irq-loongarch-cpu.c b/drivers/irqchip/irq-loongarch-cpu.c
> new file mode 100644
> index 0000000..26f948f
> --- /dev/null
> +++ b/drivers/irqchip/irq-loongarch-cpu.c
> @@ -0,0 +1,115 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
> + */
> +
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/irqchip.h>
> +#include <linux/irqdomain.h>
> +
> +#include <asm/loongarch.h>
> +#include <asm/setup.h>
> +#include "irq-loongarch-pic-common.h"
> +
> +static struct irq_domain *irq_domain;
> +
> +static void mask_loongarch_irq(struct irq_data *d)
> +{
> +	clear_csr_ecfg(ECFGF(d->hwirq));
> +}
> +
> +static void unmask_loongarch_irq(struct irq_data *d)
> +{
> +	set_csr_ecfg(ECFGF(d->hwirq));
> +}
> +
> +static struct irq_chip cpu_irq_controller = {
> +	.name		= "LoongArch",
> +	.irq_mask	= mask_loongarch_irq,
> +	.irq_unmask	= unmask_loongarch_irq,
> +};
> +
> +static void handle_cpu_irq(struct pt_regs *regs)
> +{
> +	int hwirq;
> +	unsigned int estat = read_csr_estat() & CSR_ESTAT_IS;
> +
> +	while ((hwirq = ffs(estat))) {
> +		estat &= ~BIT(hwirq - 1);
> +		generic_handle_domain_irq(irq_domain, hwirq - 1);
> +	}
> +}
> +
> +static int loongarch_cpu_intc_map(struct irq_domain *d, unsigned int irq,
> +			     irq_hw_number_t hwirq)
> +{
> +	irq_set_noprobe(irq);
> +	irq_set_chip_and_handler(irq, &cpu_irq_controller, handle_percpu_irq);
> +
> +	return 0;
> +}
> +
> +static const struct irq_domain_ops loongarch_cpu_intc_irq_domain_ops = {
> +	.map = loongarch_cpu_intc_map,
> +	.xlate = irq_domain_xlate_onecell,
> +};
> +
> +struct irq_domain * __init loongarch_cpu_irq_init(void)
> +{
> +	/* Mask interrupts. */
> +	clear_csr_ecfg(ECFG0_IM);
> +	clear_csr_estat(ESTATF_IP);
> +
> +	irq_domain = irq_domain_add_legacy(NULL, EXCCODE_INT_NUM, 0, 0,
> +						&loongarch_cpu_intc_irq_domain_ops, NULL);

I already commented on this in the past, and my position is still the
same: this isn't a legacy architecture, you are not converting
anything from a board file, so there is no reason why you get to use a
legacy domain.

Since you are using ACPI, irq_domain_add_*() really is the wrong API,
as they take an of_node. Use irq_domain_create_linear(), and pass an
actual fwnode there (there are plenty of examples in the tree).

> +	if (!irq_domain)
> +		panic("Failed to add irqdomain for LoongArch CPU");
> +
> +	set_handle_irq(&handle_cpu_irq);
> +
> +	return irq_domain;

What uses this irq_domain in the arch code?

> +}
> +#ifdef CONFIG_ACPI

Why the #ifdef? Isn't this system supposed to be ACPI only? There is
no DT support anyway, so you should make the driver depend on ACPI and
that's about it.

> +static int __init
> +liointc_parse_madt(union acpi_subtable_headers *header,
> +		       const unsigned long end)
> +{
> +	struct acpi_madt_lio_pic *liointc_entry = (struct acpi_madt_lio_pic *)header;
> +
> +	return liointc_acpi_init(irq_domain, liointc_entry);
> +}
> +
> +static int __init
> +eiointc_parse_madt(union acpi_subtable_headers *header,
> +		       const unsigned long end)
> +{
> +	struct acpi_madt_eio_pic *eiointc_entry = (struct acpi_madt_eio_pic *)header;
> +
> +	return eiointc_acpi_init(irq_domain, eiointc_entry);
> +}
> +static int __init acpi_cascade_irqdomain_init(void)
> +{
> +	acpi_table_parse_madt(ACPI_MADT_TYPE_LIO_PIC,
> +			      liointc_parse_madt, 0);
> +	acpi_table_parse_madt(ACPI_MADT_TYPE_EIO_PIC,
> +			      eiointc_parse_madt, 0);
> +	return 0;
> +}
> +static int __init coreintc_acpi_init_v1(union acpi_subtable_headers *header,
> +				   const unsigned long end)
> +{
> +	if (irq_domain)
> +		return 0;
> +
> +	init_vector_parent_group();
> +	loongarch_cpu_irq_init();
> +	acpi_cascade_irqdomain_init();
> +	return 0;
> +}
> +IRQCHIP_ACPI_DECLARE(coreintc_v1, ACPI_MADT_TYPE_CORE_PIC,
> +		NULL, ACPI_MADT_CORE_PIC_VERSION_V1,
> +		coreintc_acpi_init_v1);
> +#endif
> diff --git a/drivers/irqchip/irq-loongarch-pic-common.c b/drivers/irqchip/irq-loongarch-pic-common.c
> new file mode 100644
> index 0000000..94437e4
> --- /dev/null
> +++ b/drivers/irqchip/irq-loongarch-pic-common.c
> @@ -0,0 +1,201 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2022 Loongson Limited, All Rights Reserved.
> + */
> +
> +#include <linux/irq.h>
> +#include <linux/acpi.h>
> +#include <linux/pci.h>
> +#include "irq-loongarch-pic-common.h"
> +
> +static struct acpi_vector_group vector_group[MAX_IO_PICS];
> +struct acpi_madt_bio_pic *acpi_pchpic[MAX_IO_PICS];
> +
> +struct irq_domain *liointc_domain;
> +struct irq_domain *pch_lpc_domain;
> +struct irq_domain *pch_msi_domain[MAX_IO_PICS];
> +struct irq_domain *pch_pic_domain[MAX_IO_PICS];

Why isn't this static? If someone needs to know, why isn't there an
accessor?


> +
> +static int find_pch_pic(u32 gsi)
> +{
> +	int i, start, end;
> +
> +	/* Find the PCH_PIC that manages this GSI. */
> +	for (i = 0; i < MAX_IO_PICS; i++) {
> +		struct acpi_madt_bio_pic *irq_cfg = acpi_pchpic[i];
> +
> +		if (!irq_cfg)
> +			return -1;
> +
> +		start = irq_cfg->gsi_base;
> +		end   = irq_cfg->gsi_base + irq_cfg->size;
> +		if (gsi >= start && gsi < end)
> +			return i;
> +	}
> +
> +	pr_err("ERROR: Unable to locate PCH_PIC for GSI %d\n", gsi);
> +	return -1;
> +}
> +
> +int pcibios_device_add(struct pci_dev *dev)
> +{
> +	int id = pci_domain_nr(dev->bus);
> +
> +	dev_set_msi_domain(&dev->dev, pch_msi_domain[id]);
> +
> +	return 0;
> +}

This doesn't belong here at all. Please move it to the PCI code.

> +
> +int acpi_gsi_to_irq(u32 gsi, unsigned int *irqp)
> +{
> +	if (irqp != NULL)
> +		*irqp = acpi_register_gsi(NULL, gsi, -1, -1);
> +	return (*irqp >= 0) ? 0 : -EINVAL;
> +}
> +EXPORT_SYMBOL_GPL(acpi_gsi_to_irq);
> +
> +int acpi_isa_irq_to_gsi(unsigned int isa_irq, u32 *gsi)
> +{
> +	if (gsi)
> +		*gsi = isa_irq;
> +	return 0;
> +}
> +
> +/*
> + * success: return IRQ number (>=0)
> + * failure: return < 0
> + */
> +int acpi_register_gsi(struct device *dev, u32 gsi, int trigger, int polarity)
> +{
> +	int id;
> +	struct irq_fwspec fwspec;
> +
> +	switch (gsi) {
> +	case GSI_MIN_CPU_IRQ ... GSI_MAX_CPU_IRQ:
> +		fwspec.fwnode = liointc_domain->fwnode;
> +		fwspec.param[0] = gsi - GSI_MIN_CPU_IRQ;
> +		fwspec.param_count = 1;
> +
> +		return irq_create_fwspec_mapping(&fwspec);
> +
> +	case GSI_MIN_LPC_IRQ ... GSI_MAX_LPC_IRQ:
> +		if (!pch_lpc_domain)
> +			return -EINVAL;
> +
> +		fwspec.fwnode = pch_lpc_domain->fwnode;
> +		fwspec.param[0] = gsi - GSI_MIN_LPC_IRQ;
> +		fwspec.param[1] = acpi_dev_get_irq_type(trigger, polarity);
> +		fwspec.param_count = 2;
> +
> +		return irq_create_fwspec_mapping(&fwspec);
> +
> +	case GSI_MIN_PCH_IRQ ... GSI_MAX_PCH_IRQ:
> +		id = find_pch_pic(gsi);
> +		if (id < 0)
> +			return -EINVAL;
> +
> +		fwspec.fwnode = pch_pic_domain[id]->fwnode;
> +		fwspec.param[0] = gsi - acpi_pchpic[id]->gsi_base;
> +		fwspec.param[1] = IRQ_TYPE_LEVEL_HIGH;
> +		fwspec.param_count = 2;
> +
> +		return irq_create_fwspec_mapping(&fwspec);
> +	}

So all the complexity here seems to stem from the fact that you deal
with three ranges of interrupts, managed by three different pieces of
code?

Other architectures have similar requirements, and don't require to
re-implement a private version of the ACPI API. Instead, they expose a
single irqdomain, and deal with the various ranges internally.

Clearly, not being able to reuse drivers/acpi/irq.c *is* an issue.

> +
> +	return -EINVAL;
> +}
> +EXPORT_SYMBOL_GPL(acpi_register_gsi);
> +
> +void acpi_unregister_gsi(u32 gsi)
> +{
> +	int id, irq, hw_irq;
> +	struct irq_domain *d;
> +
> +	switch (gsi) {
> +	case GSI_MIN_CPU_IRQ ... GSI_MAX_CPU_IRQ:
> +		if (!liointc_domain)
> +			return;
> +		d = liointc_domain;
> +		hw_irq = gsi - GSI_MIN_CPU_IRQ;
> +		break;
> +
> +	case GSI_MIN_LPC_IRQ ... GSI_MAX_LPC_IRQ:
> +		if (!pch_lpc_domain)
> +			return;
> +		d = pch_lpc_domain;
> +		hw_irq = gsi - GSI_MIN_LPC_IRQ;
> +		break;
> +
> +	case GSI_MIN_PCH_IRQ ... GSI_MAX_PCH_IRQ:
> +		id = find_pch_pic(gsi);
> +		if (id < 0)
> +			return;
> +		if (!pch_pic_domain[id])
> +			return;
> +		d = pch_pic_domain[id];
> +
> +		hw_irq = gsi - acpi_pchpic[id]->gsi_base;
> +		break;
> +	}
> +	irq = irq_find_mapping(d, hw_irq);
> +	irq_dispose_mapping(irq);
> +
> +	return;
> +}
> +EXPORT_SYMBOL_GPL(acpi_unregister_gsi);
> +
> +static int pci_mcfg_parse(struct acpi_table_header *header)
> +{
> +	struct acpi_table_mcfg *mcfg;
> +	struct acpi_mcfg_allocation *mptr;
> +	int i, n;
> +
> +	if (header->length < sizeof(struct acpi_table_mcfg))
> +		return -EINVAL;
> +
> +	n = (header->length - sizeof(struct acpi_table_mcfg)) /
> +					sizeof(struct acpi_mcfg_allocation);
> +	mcfg = (struct acpi_table_mcfg *)header;
> +	mptr = (struct acpi_mcfg_allocation *) &mcfg[1];
> +
> +	for (i = 0; i < n; i++, mptr++)
> +		vector_group[mptr->pci_segment].node = (mptr->address >> 44) & 0xf;
> +
> +	return 0;
> +}

Again, why can't you reuse drivers/acpi/pci_mcfg.c?

> +
> +void __init init_vector_parent_group(void)
> +{
> +	acpi_table_parse(ACPI_SIG_MCFG, pci_mcfg_parse);
> +}
> +
> +void acpi_set_vector_parent(int node, struct irq_domain *parent)
> +{
> +	int i;
> +
> +	if (cpu_has_flatmode)
> +		node = cpu_to_node(node * CORES_PER_EIO_NODE);
> +
> +	for (i = 0; i < MAX_IO_PICS; i++) {
> +		if (node == vector_group[i].node) {
> +			vector_group[i].parent = parent;
> +			return;
> +		}
> +	}
> +}
> +
> +struct irq_domain *acpi_get_msi_parent(int index)
> +{
> +	return vector_group[index].parent;
> +}
> +
> +struct irq_domain *acpi_get_pch_parent(int node)
> +{
> +	int i;
> +
> +	for (i = 0; i < MAX_IO_PICS; i++) {
> +		if (node == vector_group[i].node)
> +			return vector_group[i].parent;
> +	}
> +	return NULL;
> +}
> diff --git a/drivers/irqchip/irq-loongarch-pic-common.h b/drivers/irqchip/irq-loongarch-pic-common.h
> new file mode 100644
> index 0000000..3815fc9
> --- /dev/null
> +++ b/drivers/irqchip/irq-loongarch-pic-common.h
> @@ -0,0 +1,44 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2022 Loongson Limited, All Rights Reserved.
> + */
> +
> +#ifndef _IRQ_LOONGARCH_PIC_COMMON_H
> +#define _IRQ_LOONGARCH_PIC_COMMON_H
> +
> +#include <linux/of.h>
> +#include <linux/irqdomain.h>
> +
> +struct acpi_vector_group {
> +	int node;
> +	struct irq_domain *parent;
> +};
> +
> +/* IRQ number definitions */
> +#define LOONGSON_LPC_IRQ_BASE		0
> +#define LOONGSON_CPU_IRQ_BASE		16
> +#define LOONGSON_PCH_IRQ_BASE		64
> +
> +#define GSI_MIN_LPC_IRQ		LOONGSON_LPC_IRQ_BASE
> +#define GSI_MAX_LPC_IRQ		(LOONGSON_LPC_IRQ_BASE + 16 - 1)
> +#define GSI_MIN_CPU_IRQ		LOONGSON_CPU_IRQ_BASE
> +#define GSI_MAX_CPU_IRQ		(LOONGSON_CPU_IRQ_BASE + 48 - 1)
> +#define GSI_MIN_PCH_IRQ		LOONGSON_PCH_IRQ_BASE
> +#define GSI_MAX_PCH_IRQ		(LOONGSON_PCH_IRQ_BASE + 256 - 1)
> +
> +extern struct acpi_madt_bio_pic *acpi_pchpic[MAX_IO_PICS];
> +extern struct irq_domain *liointc_domain;
> +extern struct irq_domain *pch_lpc_domain;
> +extern struct irq_domain *pch_msi_domain[MAX_IO_PICS];
> +extern struct irq_domain *pch_pic_domain[MAX_IO_PICS];
> +
> +int liointc_acpi_init(struct irq_domain *parent, struct acpi_madt_lio_pic *acpi_liointc);
> +int eiointc_acpi_init(struct irq_domain *parent, struct acpi_madt_eio_pic *acpi_eiointc);
> +int htvec_acpi_init(struct irq_domain *parent, struct acpi_madt_ht_pic *acpi_htvec);
> +int pch_lpc_acpi_init(struct irq_domain *parent, struct acpi_madt_lpc_pic *acpi_pchlpc);
> +void init_vector_parent_group(void);
> +void acpi_set_vector_parent(int node, struct irq_domain *parent);
> +struct irq_domain *acpi_get_msi_parent(int index);
> +struct irq_domain *acpi_get_pch_parent(int node);
> +
> +#endif /* _IRQ_LOONGARCH_PIC_COMMON_H */
> -- 
> 1.8.3.1
> 
> 

Thanks,

	M.

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

Powered by blists - more mailing lists