timer: Add AST2700 IBEX timer support

Add the driver for the AST2700 Ibex timer, which uses CPU
cycles as the timer count running at 200MHz.

Signed-off-by: Chia-Wei Wang <chiawei_wang@aspeedtech.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>

drivers/timer/Kconfig

@@ -106,6 +106,12 @@ config AST_TIMER
 	  This is mostly because they all share several registers which
 	  makes it difficult to completely separate them.
 
+config AST_IBEX_TIMER
+	bool "Aspeed ast2700 Ibex timer"
+	depends on TIMER
+	help
+	  Select this to enable a timer support for the Ibex RV32-based MCUs in AST2700.
+
 config ATCPIT100_TIMER
 	bool "ATCPIT100 timer support"
 	depends on TIMER

drivers/timer/Makefile

@@ -9,6 +9,7 @@ obj-$(CONFIG_$(SPL_)ANDES_PLMT_TIMER) += andes_plmt_timer.o
 obj-$(CONFIG_ARC_TIMER)	+= arc_timer.o
 obj-$(CONFIG_ARM_TWD_TIMER)	+= arm_twd_timer.o
 obj-$(CONFIG_AST_TIMER)	+= ast_timer.o
+obj-$(CONFIG_AST_IBEX_TIMER)	+= ast_ibex_timer.o
 obj-$(CONFIG_ATCPIT100_TIMER) += atcpit100_timer.o
 obj-$(CONFIG_$(SPL_)ATMEL_PIT_TIMER) += atmel_pit_timer.o
 obj-$(CONFIG_$(SPL_)ATMEL_TCB_TIMER) += atmel_tcb_timer.o

drivers/timer/ast_ibex_timer.c

@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2024 Aspeed Technology Inc.
+ */
+
+#include <asm/csr.h>
+#include <asm/io.h>
+#include <dm.h>
+#include <errno.h>
+#include <timer.h>
+
+#define CSR_MCYCLE	0xb00
+#define CSR_MCYCLEH	0xb80
+
+static u64 ast_ibex_timer_get_count(struct udevice *dev)
+{
+	uint32_t cnt_l, cnt_h;
+
+	cnt_l = csr_read(CSR_MCYCLE);
+	cnt_h = csr_read(CSR_MCYCLEH);
+
+	return ((uint64_t)cnt_h << 32) | cnt_l;
+}
+
+static int ast_ibex_timer_probe(struct udevice *dev)
+{
+	return 0;
+}
+
+static const struct timer_ops ast_ibex_timer_ops = {
+	.get_count = ast_ibex_timer_get_count,
+};
+
+static const struct udevice_id ast_ibex_timer_ids[] = {
+	{ .compatible = "aspeed,ast2700-ibex-timer" },
+	{ }
+};
+
+U_BOOT_DRIVER(ast_ibex_timer) = {
+	.name = "ast_ibex_timer",
+	.id = UCLASS_TIMER,
+	.of_match = ast_ibex_timer_ids,
+	.probe = ast_ibex_timer_probe,
+	.ops = &ast_ibex_timer_ops,
+};