[PATCH v3 12/19] cpu: Add loongarch_cpu driver

From: Jiaxun Yang <[email protected]>

Implement a driver for LoongArch CPU solely for gathering
some information bits from FDT and CPU level config registers.

Signed-off-by: Jiaxun Yang <[email protected]>
Signed-off-by: Yao Zi <[email protected]>
---

Changed from v2
- Fall through to devicetree path in loongarch_cpu_get_desc() when
  probing with CPUCFG gets no meaningful results, instead of handling
  such cases with goto
- Replace open-coded copying loop with memcpy() in
  loongarch_cpu_get_desc()
- Correctly return -ENOSPC when snprintf() truncates the string in
  loongarch_cpu_get_desc()

Changed from v1
- Drop unnecessary check against -ENOTSUPP clk_enable()'s return value
  in loongarch_cpu_probe()

 drivers/cpu/Kconfig         |   6 ++
 drivers/cpu/Makefile        |   1 +
 drivers/cpu/loongarch_cpu.c | 142 ++++++++++++++++++++++++++++++++++++
 3 files changed, 149 insertions(+)
 create mode 100644 drivers/cpu/loongarch_cpu.c

diff --git a/drivers/cpu/Kconfig b/drivers/cpu/Kconfig
index c805c0bbfa19..9fd43ff88fde 100644
--- a/drivers/cpu/Kconfig
+++ b/drivers/cpu/Kconfig
@@ -13,6 +13,12 @@ config CPU_IMX
 	help
 	  Support CPU cores for SoCs of the i.MX series.
 
+config CPU_LOONGARCH
+	bool "Enable LoongArch CPU driver"
+	depends on CPU && LOONGARCH
+	help
+	  Support CPU cores for LoongArch processors.
+
 config CPU_MPC83XX
 	bool "Enable MPC83xx CPU driver"
 	depends on CPU && MPC83xx
diff --git a/drivers/cpu/Makefile b/drivers/cpu/Makefile
index eaf494706e2c..d9c0db74dd5a 100644
--- a/drivers/cpu/Makefile
+++ b/drivers/cpu/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_ARCH_AT91) += at91_cpu.o
 obj-$(CONFIG_ARCH_MEDIATEK) += mtk_cpu.o
 obj-$(CONFIG_CPU_ARMV8) += armv8_cpu.o
 obj-$(CONFIG_CPU_IMX) += imx8_cpu.o
+obj-$(CONFIG_CPU_LOONGARCH) += loongarch_cpu.o
 obj-$(CONFIG_CPU_MPC83XX) += mpc83xx_cpu.o
 obj-$(CONFIG_CPU_RISCV) += riscv_cpu.o
 obj-$(CONFIG_CPU_MICROBLAZE) += microblaze_cpu.o
diff --git a/drivers/cpu/loongarch_cpu.c b/drivers/cpu/loongarch_cpu.c
new file mode 100644
index 000000000000..74a80f9e79a4
--- /dev/null
+++ b/drivers/cpu/loongarch_cpu.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2024 Jiaxun Yang <[email protected]>
+ */
+
+#include <clk.h>
+#include <cpu.h>
+#include <dm.h>
+#include <errno.h>
+#include <log.h>
+#include <asm/loongarch.h>
+#include <dm/device-internal.h>
+#include <dm/lists.h>
+#include <linux/bitops.h>
+#include <linux/err.h>
+
+static int loongarch_cpu_get_desc(const struct udevice *dev, char *buf, int size)
+{
+	const char *cpu;
+
+	/* We try to get CPU name from IOCSR first */
+	if ((read_cpucfg(LOONGARCH_CPUCFG1) & CPUCFG1_IOCSR)) {
+		char vendor_buf[9] = { 0 };
+		char name_buf[9] = { 0 };
+		u64 vendor = iocsr_read64(LOONGARCH_IOCSR_VENDOR);
+		u64 name = iocsr_read64(LOONGARCH_IOCSR_CPUNAME);
+
+		if (vendor && name) {
+			int ret;
+
+			memcpy(vendor_buf, &vendor, sizeof(vendor));
+			memcpy(name_buf, &name, sizeof(name));
+
+			ret = snprintf(buf, size, "%s-%s", vendor_buf, name_buf);
+			return ret >= size ? -ENOSPC : 0;
+		}
+	}
+
+	cpu = dev_read_string(dev, "compatible");
+	if (!cpu || size < (strlen(cpu) + 1))
+		return -ENOSPC;
+
+	strcpy(buf, cpu);
+
+	return 0;
+}
+
+static int loongarch_cpu_get_info(const struct udevice *dev, struct cpu_info *info)
+{
+	int ret;
+	struct clk clk;
+
+	/* First try getting the frequency from the assigned clock */
+	ret = clk_get_by_index((struct udevice *)dev, 0, &clk);
+	if (!ret) {
+		ret = clk_get_rate(&clk);
+		if (!IS_ERR_VALUE(ret))
+			info->cpu_freq = ret;
+	}
+
+	if (!info->cpu_freq)
+		dev_read_u32(dev, "clock-frequency", (u32 *)&info->cpu_freq);
+
+	if (read_cpucfg(LOONGARCH_CPUCFG1) & CPUCFG1_PAGING)
+		info->features |= BIT(CPU_FEAT_MMU);
+
+	if (read_cpucfg(LOONGARCH_CPUCFG16) & CPUCFG16_L1_IUPRE)
+		info->features |= BIT(CPU_FEAT_L1_CACHE);
+
+	return 0;
+}
+
+static int loongarch_cpu_get_count(const struct udevice *dev)
+{
+	ofnode node;
+	int num = 0;
+
+	ofnode_for_each_subnode(node, dev_ofnode(dev->parent)) {
+		const char *device_type;
+
+		/* skip if core is marked as not available in the device tree */
+		if (!ofnode_is_enabled(node))
+			continue;
+
+		device_type = ofnode_read_string(node, "device_type");
+		if (!device_type)
+			continue;
+		if (strcmp(device_type, "cpu") == 0)
+			num++;
+	}
+
+	return num;
+}
+
+static int loongarch_cpu_bind(struct udevice *dev)
+{
+	struct cpu_plat *plat = dev_get_parent_plat(dev);
+
+	plat->cpu_id = dev_read_addr(dev);
+
+	return 0;
+}
+
+static int loongarch_cpu_probe(struct udevice *dev)
+{
+	int ret = 0;
+	struct clk clk;
+
+	/* Get a clock if it exists */
+	ret = clk_get_by_index(dev, 0, &clk);
+	if (ret)
+		return 0;
+
+	ret = clk_enable(&clk);
+	if (ret == -ENOSYS)
+		return 0;
+	else
+		return ret;
+}
+
+static const struct cpu_ops loongarch_cpu_ops = {
+	.get_desc	= loongarch_cpu_get_desc,
+	.get_info	= loongarch_cpu_get_info,
+	.get_count	= loongarch_cpu_get_count,
+};
+
+static const struct udevice_id loongarch_cpu_ids[] = {
+	{ .compatible = "loongarch,Loongson-3A5000" }, /* From QEMU, undocumented */
+	{ .compatible = "loongson,la264" },
+	{ .compatible = "loongson,la364" },
+	{ }
+};
+
+U_BOOT_DRIVER(loongarch_cpu) = {
+	.name = "loongarch_cpu",
+	.id = UCLASS_CPU,
+	.of_match = loongarch_cpu_ids,
+	.bind = loongarch_cpu_bind,
+	.probe = loongarch_cpu_probe,
+	.ops = &loongarch_cpu_ops,
+	.flags = DM_FLAG_PRE_RELOC,
+};
-- 
2.55.0