Re: [PATCH 1/2] irqchip: irq-mt58xx: Add mt58xx interrupt controller support

quoted

From: Marc Zyngier <maz@kernel.org>

On 2020-08-03 07:22, Mark-PK Tsai wrote:
Add mt58xx interrupt controller support using hierarchy irq
domain.

Signed-off-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
---
 drivers/irqchip/Kconfig      |   7 ++
 drivers/irqchip/Makefile     |   1 +
 drivers/irqchip/irq-mt58xx.c | 196 +++++++++++++++++++++++++++++++++++
 3 files changed, 204 insertions(+)
 create mode 100644 drivers/irqchip/irq-mt58xx.c

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 216b3b8392b5..00453af78be0 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -572,4 +572,11 @@ config LOONGSON_PCH_MSI
 	help
 	  Support for the Loongson PCH MSI Controller.

+config MT58XX_IRQ
+	bool "MT58XX IRQ"
+	select IRQ_DOMAIN
+	select IRQ_DOMAIN_HIERARCHY
+	help
+	  Support Mediatek MT58XX Interrupt Controller.
+
 endmenu
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 133f9c45744a..5062e9bfa92d 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -111,3 +111,4 @@ obj-$(CONFIG_LOONGSON_HTPIC)		+= 
irq-loongson-htpic.o
 obj-$(CONFIG_LOONGSON_HTVEC)		+= irq-loongson-htvec.o
 obj-$(CONFIG_LOONGSON_PCH_PIC)		+= irq-loongson-pch-pic.o
 obj-$(CONFIG_LOONGSON_PCH_MSI)		+= irq-loongson-pch-msi.o
+obj-$(CONFIG_MT58XX_IRQ)		+= irq-mt58xx.o
diff --git a/drivers/irqchip/irq-mt58xx.c 
b/drivers/irqchip/irq-mt58xx.c
new file mode 100644
index 000000000000..e45ad023afa6
--- /dev/null
+++ b/drivers/irqchip/irq-mt58xx.c
@@ -0,0 +1,196 @@
+// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
+/*
+ * Copyright (c) 2020 MediaTek Inc.
+ * Author Mark-PK Tsai <mark-pk.tsai@mediatek.com>
+ */
+
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/irqchip.h>
+#include <linux/irqdomain.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/slab.h>
+
+#define INTC_MASK	0x0
+#define INTC_EOI	0x20
+
+struct mtk_intc_chip_data {
+	char *name;
+	struct irq_chip chip;
There is no need to embed a full struct irqchip per controller, see 
below.
We want to distinguish which controller the device interrupts are belong to
by "cat /proc/interrupts".
And if all the controller share the same struct, the name field will be the
same.
Do you have suggestion for this?


+	unsigned int irq_start, nr_irqs;
+	void __iomem *base;
+
};
+
+static void mtk_poke_irq(struct irq_data *d, u32 offset)
	> +{
+	struct mtk_intc_chip_data *cd = irq_data_get_irq_chip_data(d);
+	void __iomem *base = cd->base;
+	u8 index = (u8)irqd_to_hwirq(d);
Why the restrictive type? Why isn't unsigned int good enough?
You're right, unsigned int is ok.
I'll fix it in patch v2.


+	u16 val, mask;
+
+	mask = 1 << (index % 16);
+	val = readw_relaxed(base + offset + (index / 16) * 4) | mask;
+	writew_relaxed(val, base + offset + (index / 16) * 4);
RMW without locking, you will end-up with corruption.
Please store the address calculation in a temporaty variable to make it
more readable
Thanks for the comment, I will fix it in pacth v2.

+
	}
+
+static void mtk_clear_irq(struct irq_data *d, u32 offset)
	> +{
+	struct mtk_intc_chip_data *cd = irq_data_get_irq_chip_data(d);
+	void __iomem *base = cd->base;
+	u8 index = (u8)irqd_to_hwirq(d);
+	u16 val, mask;
+
+	mask = 1 << (index % 16);
+	val = readw_relaxed(base + offset + (index / 16) * 4) & ~mask;
+	writew_relaxed(val, base + offset + (index / 16) * 4);
Same comments.
You're right, unsigned int is ok.
I'll fix it in patch v2.

+
	}
+
+static void mtk_intc_mask_irq(struct irq_data *d)
	> +{
+	mtk_poke_irq(d, INTC_MASK);
+	irq_chip_mask_parent(d);
+
	}
+
+static void mtk_intc_unmask_irq(struct irq_data *d)
	> +{
+	mtk_clear_irq(d, INTC_MASK);
+	irq_chip_unmask_parent(d);
+
	}
+
+static void mtk_intc_eoi_irq(struct irq_data *d)
	> +{
+	mtk_poke_irq(d, INTC_EOI);
+	irq_chip_eoi_parent(d);
+
	}
+
+static struct irq_chip mtk_intc_chip = {
+	.irq_mask		= mtk_intc_mask_irq,
+	.irq_unmask		= mtk_intc_unmask_irq,
+	.irq_eoi		= mtk_intc_eoi_irq,
+	.irq_get_irqchip_state	= irq_chip_get_parent_state,
+	.irq_set_irqchip_state	= irq_chip_set_parent_state,
+	.irq_set_affinity	= irq_chip_set_affinity_parent,
+	.irq_set_vcpu_affinity	= irq_chip_set_vcpu_affinity_parent,
How about retrigger?
What is retrigger means?
To be honest, I just try to direct all the irqchip ops implemented in 
/drivers/irqchip/irq-gic.c to gic driver.
But "irq_set_vcpu_affinity" is not used in our projects now.
Should I remove ".irq_set_vcpu_affinity" here?

+	.irq_set_type		= irq_chip_set_type_parent,
+	.flags			= IRQCHIP_SET_TYPE_MASKED |
+				  IRQCHIP_SKIP_SET_WAKE |
+				  IRQCHIP_MASK_ON_SUSPEND,
+
};
+
+static int mt58xx_intc_domain_translate(struct irq_domain *d,
+					struct irq_fwspec *fwspec,
+					unsigned long *hwirq,
+					unsigned int *type)
	> +{
		> +	if (is_of_node(fwspec->fwnode)) {
+		if (fwspec->param_count != 3)
+			return -EINVAL;
+
+		/* No PPI should point to this domain */
+		if (fwspec->param[0] != 0)
+			return -EINVAL;
+
+		*hwirq = fwspec->param[1];
+		*type = fwspec->param[2] & IRQ_TYPE_SENSE_MASK;
+		return 0;
+	
		}
+
+	return -EINVAL;
+
	}
+
+static int mt58xx_intc_domain_alloc(struct irq_domain *domain,
unsigned int virq,
+				    unsigned int nr_irqs, void *data)
	> +{
+	int i;
+	irq_hw_number_t hwirq;
+	struct irq_fwspec parent_fwspec, *fwspec = data;
+	struct mtk_intc_chip_data *cd = (struct mtk_intc_chip_data
*)domain->host_data;
+
+	/* Not GIC compliant */
+	if (fwspec->param_count != 3)
+		return -EINVAL;
+
+	/* No PPI should point to this domain */
+	if (fwspec->param[0])
+		return -EINVAL;
+
+	if (fwspec->param[1] >= cd->nr_irqs)
+		return -EINVAL;
+
+	hwirq = fwspec->param[1];
+	for (i = 0; i < nr_irqs; i++)
+		irq_domain_set_hwirq_and_chip(domain, virq + i, hwirq + i,
+					      &cd->chip,
+					      domain->host_data);
+
+	parent_fwspec = *fwspec;
+	parent_fwspec.fwnode = domain->parent->fwnode;
+	parent_fwspec.param[1] = cd->irq_start + hwirq;
+	return irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, 
&parent_fwspec);
+
	}
+
+static const struct irq_domain_ops mt58xx_intc_domain_ops = {
+	.translate	= mt58xx_intc_domain_translate,
+	.alloc		= mt58xx_intc_domain_alloc,
+	.free		= irq_domain_free_irqs_common,
+
};
+
+int __init
+mt58xx_intc_of_init(struct device_node *dn, struct device_node 
*parent)
+{
+	static int nr_intc;
+	struct irq_domain *domain, *domain_parent;
+	struct mtk_intc_chip_data *cd;
+	unsigned int irq_start, irq_end;
+
+	domain_parent = irq_find_host(parent);
+	if (!domain_parent) {
+		pr_err("mt58xx-intc: interrupt-parent not found\n");
+		return -EINVAL;
+	
}
+
+	cd = kzalloc(sizeof(*cd), GFP_KERNEL);
+	if (!cd)
+		return -ENOMEM;
+
+	cd->chip = mtk_intc_chip;
+	if (of_property_read_u32_index(dn, "mediatek,irqs-map-range", 0,
&irq_start) ||
+	    of_property_read_u32_index(dn, "mediatek,irqs-map-range", 1, 
	> &irq_end)) {
+		kfree(cd);
+		return -EINVAL;
+	
}
+
+	if (of_property_read_bool(dn, "mediatek,intc-no-eoi"))
+		cd->chip.irq_eoi = irq_chip_eoi_parent;
No. Just add a flag to your chip data structure, and check for this
flag in your irq_eoi callback. Or provide two distinct irq_chip
structures that will only differ by the irq_eoi method.
Thanks for the comment, I will modify it in patch v2.


+
+	cd->irq_start = irq_start;
+	cd->nr_irqs = irq_end - irq_start + 1;
+	cd->chip.name = kasprintf(GFP_KERNEL, "mt58xx-intc-%d", nr_intc++);
Neither. That's not useful, and is a waste of memory. Stick to constant
names in the irq_chip structure.
Actually we have multiple irq controller in our SoCs.
And if we use the constant names in irq_chip structure, the information in
"/proc/interrupts" will be hard to understand because all the irqchip name
is the same.
Do you have any suggestion for this?

+	if (!cd->chip.name) {
+		kfree(cd);
+		return -ENOMEM;
+	
}
+
+	cd->base = of_iomap(dn, 0);
+	if (!cd->base) {
+		kfree(cd->chip.name);
+		kfree(cd);
+		return -ENOMEM;
+	
}
+
+	domain = irq_domain_add_hierarchy(domain_parent, 0, cd->nr_irqs,
+					  dn, &mt58xx_intc_domain_ops, cd);
+	if (!domain) {
+		kfree(cd->chip.name);
+		iounmap(cd->base);
+		kfree(cd);
+		return -ENOMEM;
+	
}
+
+	return 0;
+
}
+
+IRQCHIP_DECLARE(mt58xx_intc, "mediatek,mt58xx-intc", 
mt58xx_intc_of_init);
On a side note, the merge window has just opened. Please refrain from
reposting this until -rc1.
Got it, and thanks for your comments.
I'll update the patch and post it after -rc1.
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