lib: utils: Add simple FDT timer framework

We add simple timer framework which will select and use timer driver
based on details in FDT passed by previous booting stage.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>

include/sbi_utils/timer/fdt_timer.h

@@ -0,0 +1,35 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2020 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *   Anup Patel <anup.patel@wdc.com>
+ */
+
+#ifndef __FDT_TIMER_H__
+#define __FDT_TIMER_H__
+
+#include <sbi/sbi_types.h>
+
+struct fdt_timer {
+	const struct fdt_match *match_table;
+	int (*cold_init)(void *fdt, int nodeoff, const struct fdt_match *match);
+	int (*warm_init)(void);
+	void (*exit)(void);
+	u64 (*value)(void);
+	void (*event_stop)(void);
+	void (*event_start)(u64 next_event);
+};
+
+u64 fdt_timer_value(void);
+
+void fdt_timer_event_stop(void);
+
+void fdt_timer_event_start(u64 next_event);
+
+void fdt_timer_exit(void);
+
+int fdt_timer_init(bool cold_boot);
+
+#endif

lib/utils/timer/fdt_timer.c

@@ -0,0 +1,110 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2020 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *   Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <sbi/sbi_scratch.h>
+#include <sbi_utils/fdt/fdt_helper.h>
+#include <sbi_utils/timer/fdt_timer.h>
+
+extern struct fdt_timer fdt_timer_clint;
+
+static struct fdt_timer *timer_drivers[] = {
+	&fdt_timer_clint
+};
+
+static u64 dummy_value(void)
+{
+	return 0;
+}
+
+static void dummy_event_stop(void)
+{
+}
+
+static void dummy_event_start(u64 next_event)
+{
+}
+
+static struct fdt_timer dummy = {
+	.match_table = NULL,
+	.cold_init = NULL,
+	.warm_init = NULL,
+	.exit = NULL,
+	.value = dummy_value,
+	.event_stop = dummy_event_stop,
+	.event_start = dummy_event_start
+};
+
+static struct fdt_timer *current_driver = &dummy;
+
+u64 fdt_timer_value(void)
+{
+	return current_driver->value();
+}
+
+void fdt_timer_event_stop(void)
+{
+	current_driver->event_stop();
+}
+
+void fdt_timer_event_start(u64 next_event)
+{
+	current_driver->event_start(next_event);
+}
+
+void fdt_timer_exit(void)
+{
+	if (current_driver->exit)
+		current_driver->exit();
+}
+
+static int fdt_timer_warm_init(void)
+{
+	if (current_driver->warm_init)
+		return current_driver->warm_init();
+	return 0;
+}
+
+static int fdt_timer_cold_init(void)
+{
+	int pos, noff, rc;
+	struct fdt_timer *drv;
+	const struct fdt_match *match;
+	void *fdt = sbi_scratch_thishart_arg1_ptr();
+
+	for (pos = 0; pos < array_size(timer_drivers); pos++) {
+		drv = timer_drivers[pos];
+
+		noff = fdt_find_match(fdt, drv->match_table, &match);
+		if (noff < 0)
+			continue;
+
+		if (drv->cold_init) {
+			rc = drv->cold_init(fdt, noff, match);
+			if (rc)
+				return rc;
+		}
+		current_driver = drv;
+		break;
+	}
+
+	return 0;
+}
+
+int fdt_timer_init(bool cold_boot)
+{
+	int rc;
+
+	if (cold_boot) {
+		rc = fdt_timer_cold_init();
+		if (rc)
+			return rc;
+	}
+
+	return fdt_timer_warm_init();
+}

lib/utils/timer/fdt_timer_clint.c

@@ -0,0 +1,46 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2020 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *   Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <sbi_utils/fdt/fdt_helper.h>
+#include <sbi_utils/timer/fdt_timer.h>
+#include <sbi_utils/sys/clint.h>
+
+static int timer_clint_cold_init(void *fdt, int nodeoff,
+				  const struct fdt_match *match)
+{
+	int rc;
+	u32 max_hartid;
+	unsigned long addr;
+
+	rc = fdt_parse_max_hart_id(fdt, &max_hartid);
+	if (rc)
+		return rc;
+
+	rc = fdt_get_node_addr_size(fdt, nodeoff, &addr, NULL);
+	if (rc)
+		return rc;
+
+	/* TODO: We should figure-out CLINT has_64bit_mmio from DT node */
+	return clint_cold_timer_init(addr, max_hartid + 1, TRUE);
+}
+
+static const struct fdt_match timer_clint_match[] = {
+	{ .compatible = "riscv,clint0" },
+	{ },
+};
+
+struct fdt_timer fdt_timer_clint = {
+	.match_table = timer_clint_match,
+	.cold_init = timer_clint_cold_init,
+	.warm_init = clint_warm_timer_init,
+	.exit = NULL,
+	.value = clint_timer_value,
+	.event_stop = clint_timer_event_stop,
+	.event_start = clint_timer_event_start,
+};

lib/utils/timer/objects.mk

@@ -0,0 +1,11 @@
+#
+# SPDX-License-Identifier: BSD-2-Clause
+#
+# Copyright (c) 2020 Western Digital Corporation or its affiliates.
+#
+# Authors:
+#   Anup Patel <anup.patel@wdc.com>
+#
+
+libsbiutils-objs-y += timer/fdt_timer.o
+libsbiutils-objs-y += timer/fdt_timer_clint.o