mips: Add N64 machine type

Add support for the Nintendo 64.

Signed-off-by: Lauri Kasanen <[e-mail]>
Signed-off-by: Thomas Bogendoerfer <[e-mail]>

arch/mips/Kbuild.platforms

···
 platform-$(CONFIG_MACH_LOONGSON32)	+= loongson32/
 platform-$(CONFIG_MACH_LOONGSON64)	+= loongson64/
 platform-$(CONFIG_MIPS_MALTA)		+= mti-malta/
+platform-$(CONFIG_MACH_NINTENDO64)	+= n64/
 platform-$(CONFIG_NLM_COMMON)		+= netlogic/
 platform-$(CONFIG_PIC32MZDA)		+= pic32/
 platform-$(CONFIG_MACH_PISTACHIO)	+= pistachio/

arch/mips/Kconfig

···
 	select SYS_SUPPORTS_MIPS16
 	select GPIOLIB
 
+config MACH_NINTENDO64
+	bool "Nintendo 64 console"
+	select CEVT_R4K
+	select CSRC_R4K
+	select SYS_HAS_CPU_R4300
+	select SYS_SUPPORTS_BIG_ENDIAN
+	select SYS_SUPPORTS_ZBOOT
+	select SYS_SUPPORTS_32BIT_KERNEL
+	select SYS_SUPPORTS_64BIT_KERNEL
+	select DMA_NONCOHERENT
+	select IRQ_MIPS_CPU
+
 config RALINK
 	bool "Ralink based machines"
 	select CEVT_R4K

arch/mips/include/asm/mach-n64/irq.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_MACH_N64_IRQ_H
+#define __ASM_MACH_N64_IRQ_H
+
+#define NR_IRQS 8
+
+#include <asm/mach-generic/irq.h>
+
+#endif /* __ASM_MACH_N64_IRQ_H */

arch/mips/include/asm/mach-n64/kmalloc.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_MACH_N64_KMALLOC_H
+#define __ASM_MACH_N64_KMALLOC_H
+
+/* The default of 128 bytes wastes too much, use 32 (the largest cacheline, I) */
+#define ARCH_DMA_MINALIGN L1_CACHE_BYTES
+
+#endif /* __ASM_MACH_N64_KMALLOC_H */

arch/mips/n64/Makefile

···
+# SPDX-License-Identifier: GPL-2.0
+#
+# Nintendo 64
+#
+
+obj-y := init.o irq.o

arch/mips/n64/Platform

···
+# SPDX-License-Identifier: GPL-2.0
+#
+# Nintendo 64
+#
+
+cflags-$(CONFIG_MACH_NINTENDO64)    += -I$(srctree)/arch/mips/include/asm/mach-n64
+load-$(CONFIG_MACH_NINTENDO64)      += 0xffffffff80101000

arch/mips/n64/init.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Nintendo 64 init.
+ *
+ *  Copyright (C) 2021	Lauri Kasanen
+ */
+#include <linux/init.h>
+#include <linux/ioport.h>
+#include <linux/irq.h>
+#include <linux/memblock.h>
+#include <linux/platform_device.h>
+#include <linux/platform_data/simplefb.h>
+#include <linux/string.h>
+
+#include <asm/bootinfo.h>
+#include <asm/fw/fw.h>
+#include <asm/time.h>
+
+#define IO_MEM_RESOURCE_START	0UL
+#define IO_MEM_RESOURCE_END	0x1fffffffUL
+
+/*
+ * System-specifc irq names for clarity
+ */
+#define MIPS_CPU_IRQ(x)		(MIPS_CPU_IRQ_BASE + (x))
+#define MIPS_SOFTINT0_IRQ	MIPS_CPU_IRQ(0)
+#define MIPS_SOFTINT1_IRQ	MIPS_CPU_IRQ(1)
+#define RCP_IRQ			MIPS_CPU_IRQ(2)
+#define CART_IRQ		MIPS_CPU_IRQ(3)
+#define PRENMI_IRQ		MIPS_CPU_IRQ(4)
+#define RDBR_IRQ		MIPS_CPU_IRQ(5)
+#define RDBW_IRQ		MIPS_CPU_IRQ(6)
+#define TIMER_IRQ		MIPS_CPU_IRQ(7)
+
+static void __init iomem_resource_init(void)
+{
+	iomem_resource.start = IO_MEM_RESOURCE_START;
+	iomem_resource.end = IO_MEM_RESOURCE_END;
+}
+
+const char *get_system_type(void)
+{
+	return "Nintendo 64";
+}
+
+void __init prom_init(void)
+{
+	fw_init_cmdline();
+}
+
+#define W 320
+#define H 240
+#define REG_BASE ((u32 *) CKSEG1ADDR(0x4400000))
+
+static void __init n64rdp_write_reg(const u8 reg, const u32 value)
+{
+	__raw_writel(value, REG_BASE + reg);
+}
+
+#undef REG_BASE
+
+static const u32 ntsc_320[] __initconst = {
+	0x00013212, 0x00000000, 0x00000140, 0x00000200,
+	0x00000000, 0x03e52239, 0x0000020d, 0x00000c15,
+	0x0c150c15, 0x006c02ec, 0x002501ff, 0x000e0204,
+	0x00000200, 0x00000400
+};
+
+#define MI_REG_BASE 0x4300000
+#define NUM_MI_REGS 4
+#define AI_REG_BASE 0x4500000
+#define NUM_AI_REGS 6
+#define PI_REG_BASE 0x4600000
+#define NUM_PI_REGS 5
+#define SI_REG_BASE 0x4800000
+#define NUM_SI_REGS 7
+
+static int __init n64_platform_init(void)
+{
+	static const char simplefb_resname[] = "FB";
+	static const struct simplefb_platform_data mode = {
+		.width = W,
+		.height = H,
+		.stride = W * 2,
+		.format = "r5g5b5a1"
+	};
+	struct resource res[3];
+	void *orig;
+	unsigned long phys;
+	unsigned i;
+
+	memset(res, 0, sizeof(struct resource) * 3);
+	res[0].flags = IORESOURCE_MEM;
+	res[0].start = MI_REG_BASE;
+	res[0].end = MI_REG_BASE + NUM_MI_REGS * 4 - 1;
+
+	res[1].flags = IORESOURCE_MEM;
+	res[1].start = AI_REG_BASE;
+	res[1].end = AI_REG_BASE + NUM_AI_REGS * 4 - 1;
+
+	res[2].flags = IORESOURCE_IRQ;
+	res[2].start = RCP_IRQ;
+	res[2].end = RCP_IRQ;
+
+	platform_device_register_simple("n64audio", -1, res, 3);
+
+	memset(&res[0], 0, sizeof(res[0]));
+	res[0].flags = IORESOURCE_MEM;
+	res[0].start = PI_REG_BASE;
+	res[0].end = PI_REG_BASE + NUM_PI_REGS * 4 - 1;
+
+	platform_device_register_simple("n64cart", -1, res, 1);
+
+	memset(&res[0], 0, sizeof(res[0]));
+	res[0].flags = IORESOURCE_MEM;
+	res[0].start = SI_REG_BASE;
+	res[0].end = SI_REG_BASE + NUM_SI_REGS * 4 - 1;
+
+	platform_device_register_simple("n64joy", -1, res, 1);
+
+	/* The framebuffer needs 64-byte alignment */
+	orig = kzalloc(W * H * 2 + 63, GFP_DMA | GFP_KERNEL);
+	if (!orig)
+		return -ENOMEM;
+	phys = virt_to_phys(orig);
+	phys += 63;
+	phys &= ~63;
+
+	for (i = 0; i < ARRAY_SIZE(ntsc_320); i++) {
+		if (i == 1)
+			n64rdp_write_reg(i, phys);
+		else
+			n64rdp_write_reg(i, ntsc_320[i]);
+	}
+
+	/* setup IORESOURCE_MEM as framebuffer memory */
+	memset(&res[0], 0, sizeof(res[0]));
+	res[0].flags = IORESOURCE_MEM;
+	res[0].name = simplefb_resname;
+	res[0].start = phys;
+	res[0].end = phys + W * H * 2 - 1;
+
+	platform_device_register_resndata(NULL, "simple-framebuffer", 0,
+					  &res[0], 1, &mode, sizeof(mode));
+
+	return 0;
+}
+
+#undef W
+#undef H
+
+arch_initcall(n64_platform_init);
+
+void __init plat_mem_setup(void)
+{
+	iomem_resource_init();
+	memblock_add(0x0, 8 * 1024 * 1024); /* Bootloader blocks the 4mb config */
+}
+
+void __init plat_time_init(void)
+{
+	/* 93.75 MHz cpu, count register runs at half rate */
+	mips_hpt_frequency = 93750000 / 2;
+}

arch/mips/n64/irq.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  N64 IRQ
+ *
+ *  Copyright (C) 2021 Lauri Kasanen
+ */
+#include <linux/export.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+
+#include <asm/irq_cpu.h>
+
+void __init arch_init_irq(void)
+{
+	mips_cpu_irq_init();
+}