ARM: riscpc: use GENERIC_IRQ_MULTI_HANDLER

This is one of the last platforms using the old entry path.
While this code path is spread over a few files, it is fairly
straightforward to convert it into an equivalent C version,
leaving the existing algorithm and all the priority handling
the same.

Unlike most irqchip drivers, this means reading the status
register(s) in a loop and always handling the highest-priority
irq first.

The IOMD_IRQREQC and IOMD_IRQREQD registers are not actaully
used here, but I left the code in place for the time being,
to keep the conversion as direct as possible. It could be
removed in a cleanup on top.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
[ardb: drop obsolete IOMD_IRQREQC/IOMD_IRQREQD handling]
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M

3 files changed, 98 insertions, 15 deletions

diff --git a/arch/arm/mach-rpc/fiq.S b/arch/arm/mach-rpc/fiq.S
index 0de83e9b0b39..087bdf4bc093 100644
--- a/arch/arm/mach-rpc/fiq.S
+++ b/arch/arm/mach-rpc/fiq.S
@@ -2,10 +2,11 @@
 #include <linux/linkage.h>
 #include <asm/assembler.h>
 #include <mach/hardware.h>
-#include <mach/entry-macro.S>
 
-	.text
+	.equ	ioc_base_high, IOC_BASE & 0xff000000
+	.equ	ioc_base_low, IOC_BASE & 0x00ff0000
 
+	.text
 	.global	rpc_default_fiq_end
 ENTRY(rpc_default_fiq_start)
 	mov	r12, #ioc_base_high
diff --git a/arch/arm/mach-rpc/include/mach/entry-macro.S b/arch/arm/mach-rpc/include/mach/entry-macro.S
deleted file mode 100644
index a6d1a9f4bb79..000000000000
--- a/arch/arm/mach-rpc/include/mach/entry-macro.S
+++ /dev/null
@@ -1,13 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#include <mach/hardware.h>
-#include <asm/hardware/entry-macro-iomd.S>
-
-	.equ	ioc_base_high, IOC_BASE & 0xff000000
-	.equ	ioc_base_low, IOC_BASE & 0x00ff0000
-
-	.macro  get_irqnr_preamble, base, tmp
-	mov	\base, #ioc_base_high		@ point at IOC
-	.if	ioc_base_low
-	orr	\base, \base, #ioc_base_low
-	.endif
-	.endm
diff --git a/arch/arm/mach-rpc/irq.c b/arch/arm/mach-rpc/irq.c
index 803aeb126f0e..dc29384b6ef8 100644
--- a/arch/arm/mach-rpc/irq.c
+++ b/arch/arm/mach-rpc/irq.c
@@ -14,6 +14,99 @@
 #define CLR	0x04
 #define MASK	0x08
 
+static const u8 irq_prio_h[256] = {
+	 0, 8, 9, 8,10,10,10,10,11,11,11,11,10,10,10,10,
+	12, 8, 9, 8,10,10,10,10,11,11,11,11,10,10,10,10,
+	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
+	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
+	14,14,14,14,10,10,10,10,11,11,11,11,10,10,10,10,
+	14,14,14,14,10,10,10,10,11,11,11,11,10,10,10,10,
+	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
+	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
+	15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10,
+	15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10,
+	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
+	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
+	15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10,
+	15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10,
+	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
+	13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
+};
+
+static const u8 irq_prio_d[256] = {
+	 0,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	20,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	22,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	22,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	23,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	23,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	22,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	22,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+	21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
+};
+
+static const u8 irq_prio_l[256] = {
+	 0, 0, 1, 0, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3,
+	 4, 0, 1, 0, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3,
+	 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
+	 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
+	 6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3, 3, 3, 3,
+	 6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3, 3, 3, 3,
+	 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
+	 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
+	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+	 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+};
+
+static int iomd_get_irq_nr(void)
+{
+	int irq;
+	u8 reg;
+
+	/* get highest priority first */
+	reg = readb(IOC_BASE + IOMD_IRQREQB);
+	irq = irq_prio_h[reg];
+	if (irq)
+		return irq;
+
+	/* get DMA  */
+	reg = readb(IOC_BASE + IOMD_DMAREQ);
+	irq = irq_prio_d[reg];
+	if (irq)
+		return irq;
+
+	/* get low priority */
+	reg = readb(IOC_BASE + IOMD_IRQREQA);
+	irq = irq_prio_l[reg];
+	if (irq)
+		return irq;
+	return 0;
+}
+
+static void iomd_handle_irq(struct pt_regs *regs)
+{
+	int irq;
+
+	do {
+		irq = iomd_get_irq_nr();
+		if (irq)
+			generic_handle_irq(irq);
+	} while (irq);
+}
+
 static void __iomem *iomd_get_base(struct irq_data *d)
 {
 	void *cd = irq_data_get_irq_chip_data(d);
@@ -82,6 +175,8 @@ void __init rpc_init_irq(void)
 	set_fiq_handler(&rpc_default_fiq_start,
 		&rpc_default_fiq_end - &rpc_default_fiq_start);
 
+	set_handle_irq(iomd_handle_irq);
+
 	for (irq = 0; irq < NR_IRQS; irq++) {
 		clr = IRQ_NOREQUEST;
 		set = 0;