MIPS: Loongson 3: Add IRQ init and dispatch support

IRQ routing path of Loongson-3:
Devices(most) --> I8259 --> HT Controller --> IRQ Routing Table --> CPU
                                                  ^
                                                  |
Device(legacy devices such as UART) --> Bonito ---|

IRQ Routing Table route 32 INTs to CPU's INT0~INT3(IP2~IP5 of CP0), 32
INTs include 16 HT INTs(mostly), 4 PCI INTs, 1 LPC INT, etc. IP6 is used
for IPI and IP7 is used for internal MIPS timer. LOONGSON_INT_ROUTER_*
are IRQ Routing Table registers.

I8259 IRQs are 1:1 mapped to HT1 INTs. LOONGSON_HT1_* are configuration
registers of HT1 controller.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Hongliang Tao <taohl@lemote.com>
Signed-off-by: Hua Yan <yanh@lemote.com>
Tested-by: Alex Smith <alex.smith@imgtec.com>
Reviewed-by: Alex Smith <alex.smith@imgtec.com>
Cc: John Crispin <john@phrozen.org>
Cc: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: linux-mips@linux-mips.org
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/6634
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

3 files changed, 106 insertions, 0 deletions

diff --git a/arch/mips/loongson/Makefile b/arch/mips/loongson/Makefile
index 0dc0055754cd..7429994e7604 100644
--- a/arch/mips/loongson/Makefile
+++ b/arch/mips/loongson/Makefile
@@ -15,3 +15,9 @@ obj-$(CONFIG_LEMOTE_FULOONG2E)	+= fuloong-2e/
 #
 
 obj-$(CONFIG_LEMOTE_MACH2F)  += lemote-2f/
+
+#
+# All Loongson-3 family machines
+#
+
+obj-$(CONFIG_CPU_LOONGSON3)  += loongson-3/
diff --git a/arch/mips/loongson/loongson-3/Makefile b/arch/mips/loongson/loongson-3/Makefile
new file mode 100644
index 000000000000..b9968cd1602e
--- /dev/null
+++ b/arch/mips/loongson/loongson-3/Makefile
@@ -0,0 +1,4 @@
+#
+# Makefile for Loongson-3 family machines
+#
+obj-y			+= irq.o
diff --git a/arch/mips/loongson/loongson-3/irq.c b/arch/mips/loongson/loongson-3/irq.c
new file mode 100644
index 000000000000..b2dc62b97a0f
--- /dev/null
+++ b/arch/mips/loongson/loongson-3/irq.c
@@ -0,0 +1,96 @@
+#include <loongson.h>
+#include <irq.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+
+#include <asm/irq_cpu.h>
+#include <asm/i8259.h>
+#include <asm/mipsregs.h>
+
+unsigned int ht_irq[] = {1, 3, 4, 5, 6, 7, 8, 12, 14, 15};
+
+static void ht_irqdispatch(void)
+{
+	unsigned int i, irq;
+
+	irq = LOONGSON_HT1_INT_VECTOR(0);
+	LOONGSON_HT1_INT_VECTOR(0) = irq; /* Acknowledge the IRQs */
+
+	for (i = 0; i < ARRAY_SIZE(ht_irq); i++) {
+		if (irq & (0x1 << ht_irq[i]))
+			do_IRQ(ht_irq[i]);
+	}
+}
+
+void mach_irq_dispatch(unsigned int pending)
+{
+	if (pending & CAUSEF_IP7)
+		do_IRQ(LOONGSON_TIMER_IRQ);
+	else if (pending & CAUSEF_IP3)
+		ht_irqdispatch();
+	else if (pending & CAUSEF_IP2)
+		do_IRQ(LOONGSON_UART_IRQ);
+	else {
+		pr_err("%s : spurious interrupt\n", __func__);
+		spurious_interrupt();
+	}
+}
+
+static struct irqaction cascade_irqaction = {
+	.handler = no_action,
+	.name = "cascade",
+};
+
+static inline void mask_loongson_irq(struct irq_data *d)
+{
+	clear_c0_status(0x100 << (d->irq - MIPS_CPU_IRQ_BASE));
+	irq_disable_hazard();
+}
+
+static inline void unmask_loongson_irq(struct irq_data *d)
+{
+	set_c0_status(0x100 << (d->irq - MIPS_CPU_IRQ_BASE));
+	irq_enable_hazard();
+}
+
+ /* For MIPS IRQs which shared by all cores */
+static struct irq_chip loongson_irq_chip = {
+	.name		= "Loongson",
+	.irq_ack	= mask_loongson_irq,
+	.irq_mask	= mask_loongson_irq,
+	.irq_mask_ack	= mask_loongson_irq,
+	.irq_unmask	= unmask_loongson_irq,
+	.irq_eoi	= unmask_loongson_irq,
+};
+
+void irq_router_init(void)
+{
+	int i;
+
+	/* route LPC int to cpu core0 int 0 */
+	LOONGSON_INT_ROUTER_LPC = LOONGSON_INT_CORE0_INT0;
+	/* route HT1 int0 ~ int7 to cpu core0 INT1*/
+	for (i = 0; i < 8; i++)
+		LOONGSON_INT_ROUTER_HT1(i) = LOONGSON_INT_CORE0_INT1;
+	/* enable HT1 interrupt */
+	LOONGSON_HT1_INTN_EN(0) = 0xffffffff;
+	/* enable router interrupt intenset */
+	LOONGSON_INT_ROUTER_INTENSET =
+		LOONGSON_INT_ROUTER_INTEN | (0xffff << 16) | 0x1 << 10;
+}
+
+void __init mach_init_irq(void)
+{
+	clear_c0_status(ST0_IM | ST0_BEV);
+
+	irq_router_init();
+	mips_cpu_irq_init();
+	init_i8259_irqs();
+	irq_set_chip_and_handler(LOONGSON_UART_IRQ,
+			&loongson_irq_chip, handle_level_irq);
+
+	/* setup HT1 irq */
+	setup_irq(LOONGSON_HT1_IRQ, &cascade_irqaction);
+
+	set_c0_status(STATUSF_IP2 | STATUSF_IP6);
+}