cpu: add basic cpu driver for MediaTek ARM chips

Add basic CPU driver used to retrieve CPU model information.

Tested-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/cpu/Makefile

@@ -9,6 +9,7 @@ obj-$(CONFIG_CPU) += cpu-uclass.o
 obj-$(CONFIG_ARCH_BMIPS) += bmips_cpu.o
 obj-$(CONFIG_ARCH_IMX8) += imx8_cpu.o
 obj-$(CONFIG_ARCH_AT91) += at91_cpu.o
+obj-$(CONFIG_ARCH_MEDIATEK) += mtk_cpu.o
 obj-$(CONFIG_CPU_MPC83XX) += mpc83xx_cpu.o
 obj-$(CONFIG_CPU_RISCV) += riscv_cpu.o
 obj-$(CONFIG_CPU_MICROBLAZE) += microblaze_cpu.o

drivers/cpu/mtk_cpu.c

@@ -0,0 +1,86 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022 MediaTek Inc. All rights reserved.
+ *
+ * Author: Weijie Gao <weijie.gao@mediatek.com>
+ */
+
+#include <linux/types.h>
+#include <cpu.h>
+#include <dm.h>
+#include <regmap.h>
+#include <syscon.h>
+#include <asm/global_data.h>
+#include <linux/err.h>
+#include <linux/io.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct mtk_cpu_plat {
+	struct regmap *hwver;
+};
+
+static int mtk_cpu_get_desc(const struct udevice *dev, char *buf, int size)
+{
+	struct mtk_cpu_plat *plat = dev_get_plat(dev);
+	uint val;
+
+	regmap_read(plat->hwver, 0, &val);
+
+	snprintf(buf, size, "MediaTek MT%04X", val);
+
+	return 0;
+}
+
+static int mtk_cpu_get_count(const struct udevice *dev)
+{
+	return 1;
+}
+
+static int mtk_cpu_get_vendor(const struct udevice *dev, char *buf, int size)
+{
+	snprintf(buf, size, "MediaTek");
+
+	return 0;
+}
+
+static int mtk_cpu_probe(struct udevice *dev)
+{
+	struct mtk_cpu_plat *plat = dev_get_plat(dev);
+	struct ofnode_phandle_args args;
+	int ret;
+
+	ret = dev_read_phandle_with_args(dev, "mediatek,hwver", NULL, 0, 0,
+					 &args);
+	if (ret)
+		return ret;
+
+	plat->hwver = syscon_node_to_regmap(args.node);
+	if (IS_ERR(plat->hwver))
+		return PTR_ERR(plat->hwver);
+
+	return 0;
+}
+
+static const struct cpu_ops mtk_cpu_ops = {
+	.get_desc	= mtk_cpu_get_desc,
+	.get_count	= mtk_cpu_get_count,
+	.get_vendor	= mtk_cpu_get_vendor,
+};
+
+static const struct udevice_id mtk_cpu_ids[] = {
+	{ .compatible = "arm,cortex-a7" },
+	{ .compatible = "arm,cortex-a53" },
+	{ .compatible = "arm,cortex-a73" },
+	{ /* sentinel */ }
+};
+
+U_BOOT_DRIVER(cpu_mtk) = {
+	.name		= "mtk-cpu",
+	.id		= UCLASS_CPU,
+	.of_match	= mtk_cpu_ids,
+	.ops		= &mtk_cpu_ops,
+	.probe		= mtk_cpu_probe,
+	.plat_auto	= sizeof(struct mtk_cpu_plat),
+	.flags		= DM_FLAG_PRE_RELOC,
+};