MIPS: PS2: Identify the machine by model name

ROM version 1.00 is always SCPH-10000. Later machines with ROM version
1.0x have the machine name in the ROM0 file OSDSYS at offset 0x8c808.
These are late SCPH-10000 and all SCPH-15000. Even later machines have
a system command (SCMD) to read the machine name.

The machine name is shown in the /proc/cpuinfo file.

Signed-off-by: Fredrik Noring <noring@nocrew.org>

arch/mips/ps2/Makefile

@@ -1,4 +1,5 @@
 obj-y		+= dmac-irq.o
+obj-y		+= identify.o
 obj-y		+= intc-irq.o
 obj-y		+= irq.o
 obj-y		+= memory.o

arch/mips/ps2/identify.c

@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * PlayStation 2 identification
+ *
+ * Copyright (C) 2019 Fredrik Noring
+ */
+
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/printk.h>
+
+#include <asm/prom.h>
+
+#include <asm/mach-ps2/rom.h>
+#include <asm/mach-ps2/scmd.h>
+
+static int __init set_machine_name_by_scmd(void)
+{
+	const struct scmd_machine_name machine = scmd_read_machine_name();
+
+	if (machine.name[0] == '\0') {
+		pr_err("identify: %s: Reading failed\n", __func__);
+		return -EIO;
+	}
+
+	mips_set_machine_name(machine.name);
+
+	return 0;
+}
+
+static int __init set_machine_name_by_osdsys(void)
+{
+	char name[12] = { };
+	int err = rom_read_file(rom0_dir, "OSDSYS",
+		name, sizeof(name) - 1, 0x8c808);
+
+	if (err) {
+		pr_err("identify: %s: Reading failed with %d\n", __func__, err);
+		return err;
+	}
+
+	mips_set_machine_name(name);
+
+	return 0;
+}
+
+static void __init set_machine_name(void)
+{
+	const int rom_version_number = rom_version().number;
+	int err = 0;
+
+	/*
+	 * ROM version 1.00 is always SCPH-10000. Later machines with
+	 * ROM version 1.0x have the machine name in the ROM0 file OSDSYS
+	 * at offset 0x8c808. These are late SCPH-10000 and all SCPH-15000.
+	 * Even later machines have a system command (SCMD) to read the
+	 * machine name.
+	 */
+
+	if (rom_version_number >= 0x110)
+		err = set_machine_name_by_scmd();	/* ver >= 1.10 */
+	else if (rom_version_number > 0x100)
+		err = set_machine_name_by_osdsys();	/* 1.10 > ver > 1.00 */
+	else if (rom_version_number == 0x100)
+		mips_set_machine_name("SCPH-10000");	/* ver = 1.00 */
+	else
+		err = -ENODEV;
+
+	if (err)
+		pr_err("identify: Determining machine name for ROM %04x failed with %d\n",
+			rom_version_number, err);
+}
+
+static int __init ps2_identify_init(void)
+{
+	set_machine_name();
+
+	return 0;
+}
+subsys_initcall(ps2_identify_init);