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Subject[PATCH v5 04/11] irqchip: Add driver for Loongson-3 HyperTransport PIC controller
Date
This controller appeared on Loongson-3 family of chips to receive interrupts
from PCH PIC.
It is a I8259 with optimized interrupt polling flow. We can poll interrupt number
from HT vector directly but still have to follow standard I8259 routines to mask,
unmask and EOI.

Co-developed-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>

---
v4-v5:
Enhancements according to maz's suggestions:
- Add static for private struct
- Drop pointless rename
- Fix DT parse bug
- Clarifications in comments and commit message
---
arch/mips/include/asm/i8259.h | 1 +
drivers/irqchip/Kconfig | 10 ++
drivers/irqchip/Makefile | 1 +
drivers/irqchip/irq-loongson-htpic.c | 149 +++++++++++++++++++++++++++
4 files changed, 161 insertions(+)
create mode 100644 drivers/irqchip/irq-loongson-htpic.c

diff --git a/arch/mips/include/asm/i8259.h b/arch/mips/include/asm/i8259.h
index 97a5e41ed1ab..a54b9649de22 100644
--- a/arch/mips/include/asm/i8259.h
+++ b/arch/mips/include/asm/i8259.h
@@ -36,6 +36,7 @@ extern raw_spinlock_t i8259A_lock;
extern void make_8259A_irq(unsigned int irq);

extern void init_i8259_irqs(void);
+extern struct irq_domain *__init_i8259_irqs(struct device_node *node);

/**
* i8159_set_poll() - Override the i8259 polling function
diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index c609eaa319d2..cae6f480c987 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -522,4 +522,14 @@ config LOONGSON_LIOINTC
help
Support for the Loongson Local I/O Interrupt Controller.

+config LOONGSON_HTPIC
+ bool "Loongson3 HyperTransport PIC Controller"
+ depends on MACH_LOONGSON64
+ default y
+ select IRQ_DOMAIN
+ select GENERIC_IRQ_CHIP
+ select I8259
+ help
+ Support for the Loongson-3 HyperTransport PIC Controller.
+
endmenu
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 5e7678efdfe6..37bbe39bf909 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -106,3 +106,4 @@ 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_LOONGSON_LIOINTC) += irq-loongson-liointc.o
+obj-$(CONFIG_LOONGSON_HTPIC) += irq-loongson-htpic.o
diff --git a/drivers/irqchip/irq-loongson-htpic.c b/drivers/irqchip/irq-loongson-htpic.c
new file mode 100644
index 000000000000..3391e472766d
--- /dev/null
+++ b/drivers/irqchip/irq-loongson-htpic.c
@@ -0,0 +1,149 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020, Jiaxun Yang <jiaxun.yang@flygoat.com>
+ * Loongson HTPIC IRQ support
+ */
+
+#include <linux/init.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/irq.h>
+#include <linux/io.h>
+#include <linux/syscore_ops.h>
+
+#include <asm/i8259.h>
+
+#define HTPIC_MAX_PARENT_IRQ 4
+#define HTINT_NUM_VECTORS 8
+#define HTINT_EN_OFF 0x20
+
+struct loongson_htpic {
+ void __iomem *base;
+ struct irq_domain *domain;
+};
+
+static struct loongson_htpic *htpic;
+
+static void htpic_irq_dispatch(struct irq_desc *desc)
+{
+ struct loongson_htpic *priv = irq_desc_get_handler_data(desc);
+ struct irq_chip *chip = irq_desc_get_chip(desc);
+ uint32_t pending;
+
+ chained_irq_enter(chip, desc);
+ pending = readl(priv->base);
+ /* Ack all IRQs at once, otherwise IRQ flood might happen */
+ writel(pending, priv->base);
+
+ if (!pending)
+ spurious_interrupt();
+
+ while (pending) {
+ int bit = __ffs(pending);
+
+ if (unlikely(bit > 15)) {
+ spurious_interrupt();
+ break;
+ }
+
+ generic_handle_irq(irq_linear_revmap(priv->domain, bit));
+ pending &= ~BIT(bit);
+ }
+ chained_irq_exit(chip, desc);
+}
+
+static void htpic_reg_init(void)
+{
+ int i;
+
+ for (i = 0; i < HTINT_NUM_VECTORS; i++) {
+ uint32_t val;
+
+ /* Disable all HT Vectors */
+ writel(0x0, htpic->base + HTINT_EN_OFF + i * 0x4);
+ val = readl(htpic->base + i * 0x4);
+ /* Ack all possible pending IRQs */
+ writel(GENMASK(31, 0), htpic->base + i * 0x4);
+ }
+
+ /* Enable 16 vectors for PIC */
+ writel(0xffff, htpic->base + HTINT_EN_OFF);
+}
+
+static void htpic_resume(void)
+{
+ htpic_reg_init();
+}
+
+struct syscore_ops htpic_syscore_ops = {
+ .resume = htpic_resume,
+};
+
+int __init htpic_of_init(struct device_node *node, struct device_node *parent)
+{
+ unsigned int parent_irq[4];
+ int i, err;
+ int num_parents = 0;
+
+ if (htpic) {
+ pr_err("loongson-htpic: Only one HTPIC is allowed in the system\n");
+ return -ENODEV;
+ }
+
+ htpic = kzalloc(sizeof(*htpic), GFP_KERNEL);
+ if (!htpic) {
+ err = -ENOMEM;
+ goto out_free;
+ }
+
+ htpic->base = of_iomap(node, 0);
+ if (!htpic->base) {
+ err = -ENODEV;
+ goto out_free;
+ }
+
+ htpic->domain = __init_i8259_irqs(node);
+ if (!htpic->domain) {
+ pr_err("loongson-htpic: Failed to initialize i8259 IRQs\n");
+ err = -ENOMEM;
+ goto out_iounmap;
+ }
+
+ /* Interrupt may come from any of the 4 interrupt line */
+ for (i = 0; i < HTPIC_MAX_PARENT_IRQ; i++) {
+ parent_irq[i] = irq_of_parse_and_map(node, i);
+ if (parent_irq[i] < 0)
+ break;
+
+ num_parents++;
+ }
+
+ if (!num_parents) {
+ pr_err("loongson-htpic: Failed to get parent irqs\n");
+ err = -ENODEV;
+ goto out_remove_domain;
+ }
+
+ htpic_reg_init();
+
+ for (i = 0; i < num_parents; i++) {
+ irq_set_chained_handler_and_data(parent_irq[i],
+ htpic_irq_dispatch, htpic);
+ }
+
+ register_syscore_ops(&htpic_syscore_ops);
+
+ return 0;
+
+out_remove_domain:
+ irq_domain_remove(htpic->domain);
+out_iounmap:
+ iounmap(htpic->base);
+out_free:
+ kfree(htpic);
+ return err;
+}
+
+IRQCHIP_DECLARE(loongson_htpic, "loongson,htpic-1.0", htpic_of_init);
--
2.26.0.rc2

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