irqchip: RISC-V per-HART local interrupt controller driver

The RISC-V per-HART local interrupt controller manages software
interrupts, timer interrupts, external interrupts (which are routed
via the platform level interrupt controller) and other per-HART
local interrupts.

We add a driver for the RISC-V local interrupt controller, which
eventually replaces the RISC-V architecture code, allowing for a
better split between arch code and drivers.

The driver is compliant with RISC-V Hart-Level Interrupt Controller
DT bindings located at:
Documentation/devicetree/bindings/interrupt-controller/riscv,cpu-intc.txt

Co-developed-by: Palmer Dabbelt <palmer@dabbelt.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
[Palmer: Cleaned up warnings]
Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>

4 files changed, 4 insertions, 34 deletions

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 8244b8f7e7c3..4f5bff0e7ab2 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -40,6 +40,7 @@ config RISCV
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_STRNCPY_FROM_USER if MMU
 	select GENERIC_STRNLEN_USER if MMU
+	select HANDLE_DOMAIN_IRQ
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_KASAN if MMU && 64BIT
 	select HAVE_ARCH_KGDB
diff --git a/arch/riscv/include/asm/irq.h b/arch/riscv/include/asm/irq.h
index 0183e15ace66..a9e5f07a7e9c 100644
--- a/arch/riscv/include/asm/irq.h
+++ b/arch/riscv/include/asm/irq.h
@@ -10,8 +10,6 @@
 #include <linux/interrupt.h>
 #include <linux/linkage.h>
 
-#define NR_IRQS         0
-
 void riscv_timer_interrupt(void);
 
 #include <asm-generic/irq.h>
diff --git a/arch/riscv/kernel/irq.c b/arch/riscv/kernel/irq.c
index bb0bfcd537e7..eb8777642ce6 100644
--- a/arch/riscv/kernel/irq.c
+++ b/arch/riscv/kernel/irq.c
@@ -7,7 +7,6 @@
 
 #include <linux/interrupt.h>
 #include <linux/irqchip.h>
-#include <linux/irqdomain.h>
 #include <linux/seq_file.h>
 #include <asm/smp.h>
 
@@ -19,39 +18,13 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 
 asmlinkage __visible void __irq_entry do_IRQ(struct pt_regs *regs)
 {
-	struct pt_regs *old_regs;
-
-	switch (regs->cause & ~CAUSE_IRQ_FLAG) {
-	case RV_IRQ_TIMER:
-		old_regs = set_irq_regs(regs);
-		irq_enter();
-		riscv_timer_interrupt();
-		irq_exit();
-		set_irq_regs(old_regs);
-		break;
-#ifdef CONFIG_SMP
-	case RV_IRQ_SOFT:
-		/*
-		 * We only use software interrupts to pass IPIs, so if a non-SMP
-		 * system gets one, then we don't know what to do.
-		 */
-		handle_IPI(regs);
-		break;
-#endif
-	case RV_IRQ_EXT:
-		old_regs = set_irq_regs(regs);
-		irq_enter();
+	if (handle_arch_irq)
 		handle_arch_irq(regs);
-		irq_exit();
-		set_irq_regs(old_regs);
-		break;
-	default:
-		pr_alert("unexpected interrupt cause 0x%lx", regs->cause);
-		BUG();
-	}
 }
 
 void __init init_IRQ(void)
 {
 	irqchip_init();
+	if (!handle_arch_irq)
+		panic("No interrupt controller found.");
 }
diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index 5080fdf8c296..ecec1778e3a4 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -183,6 +183,4 @@ void trap_init(void)
 	csr_write(CSR_SCRATCH, 0);
 	/* Set the exception vector address */
 	csr_write(CSR_TVEC, &handle_exception);
-	/* Enable interrupts */
-	csr_write(CSR_IE, IE_SIE);
 }