lib: utils/mailbox: Add simple FDT based mailbox framework

Add a simple FDT based mailbox framework which is built on top of the generic
mailbox library. The phandle of FDT mailbox DT node is treated as the unique
mailbox controller ID which is required by the generic mailbox library. The
FDT based mailbox drivers will be probed on-demand from fdt_mailbox_request_chan()
called by the mailbox client drivers.

Signed-off-by: Anup Patel <[email protected]>

4 files changed, 110 insertions, 0 deletions

diff --git a/lib/utils/mailbox/Kconfig b/lib/utils/mailbox/Kconfig
index f91a9bb9..3957bfba 100644
--- a/lib/utils/mailbox/Kconfig
+++ b/lib/utils/mailbox/Kconfig
@@ -2,6 +2,12 @@
 
 menu "Mailbox Support"
 
+config FDT_MAILBOX
+	bool "FDT based mailbox drivers"
+	depends on FDT
+	select MAILBOX
+	default n
+
 config MAILBOX
 	bool "Mailbox support"
 	default n
diff --git a/lib/utils/mailbox/fdt_mailbox.c b/lib/utils/mailbox/fdt_mailbox.c
new file mode 100644
index 00000000..6378ab0d
--- /dev/null
+++ b/lib/utils/mailbox/fdt_mailbox.c
@@ -0,0 +1,96 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2024 Ventana Micro Systems Inc.
+ *
+ * Authors:
+ *   Anup Patel <[email protected]>
+ */
+
+#include <libfdt.h>
+#include <sbi/sbi_error.h>
+#include <sbi_utils/fdt/fdt_helper.h>
+#include <sbi_utils/mailbox/fdt_mailbox.h>
+
+/* List of FDT mailbox drivers generated at compile time */
+extern const struct fdt_driver *const fdt_mailbox_drivers[];
+
+static int fdt_mbox_controller_find(const void *fdt, int nodeoff,
+				    struct mbox_controller **out_mbox)
+{
+	int rc;
+	struct mbox_controller *mbox = mbox_controller_find(nodeoff);
+
+	if (!mbox) {
+		/* mailbox not found so initialize matching driver */
+		rc = fdt_driver_init_by_offset(fdt, nodeoff, fdt_mailbox_drivers);
+		if (rc)
+			return rc;
+
+		/* Try to find mailbox controller again */
+		mbox = mbox_controller_find(nodeoff);
+		if (!mbox)
+			return SBI_ENOSYS;
+	}
+
+	if (out_mbox)
+		*out_mbox = mbox;
+
+	return 0;
+}
+
+int fdt_mailbox_request_chan(const void *fdt, int nodeoff, int index,
+			     struct mbox_chan **out_chan)
+{
+	int rc;
+	struct mbox_chan *chan;
+	struct fdt_mailbox *drv;
+	struct fdt_phandle_args pargs;
+	struct mbox_controller *mbox = NULL;
+	u32 chan_args[MBOX_CHAN_MAX_ARGS];
+
+	if (!fdt || (nodeoff < 0) || (index < 0) || !out_chan)
+		return SBI_EINVAL;
+
+	pargs.node_offset = pargs.args_count = 0;
+	rc = fdt_parse_phandle_with_args(fdt, nodeoff,
+					 "mboxes", "#mbox-cells",
+					 index, &pargs);
+	if (rc)
+		return rc;
+
+	rc = fdt_mbox_controller_find(fdt, pargs.node_offset, &mbox);
+	if (rc)
+		return rc;
+
+	drv = mbox->driver;
+	if (!drv || !drv->xlate)
+		return SBI_ENOSYS;
+
+	rc = drv->xlate(mbox, &pargs, chan_args);
+	if (rc)
+		return rc;
+
+	chan = mbox_controller_request_chan(mbox, chan_args);
+	if (!chan)
+		return SBI_ENOENT;
+
+	*out_chan = chan;
+	return 0;
+}
+
+int fdt_mailbox_simple_xlate(struct mbox_controller *mbox,
+			     const struct fdt_phandle_args *pargs,
+			     u32 *out_chan_args)
+{
+	int i;
+
+	if (pargs->args_count < 1)
+		return SBI_EINVAL;
+
+	out_chan_args[0] = pargs->args[0];
+	for (i = 1; i < MBOX_CHAN_MAX_ARGS; i++)
+		out_chan_args[i] = 0;
+
+	return 0;
+}
diff --git a/lib/utils/mailbox/fdt_mailbox_drivers.carray b/lib/utils/mailbox/fdt_mailbox_drivers.carray
new file mode 100644
index 00000000..cf87d40c
--- /dev/null
+++ b/lib/utils/mailbox/fdt_mailbox_drivers.carray
@@ -0,0 +1,5 @@
+HEADER: sbi_utils/mailbox/fdt_mailbox.h
+TYPE: const struct fdt_mailbox
+NAME: fdt_mailbox_drivers
+MEMBER-NAME: driver
+MEMBER-TYPE: const struct fdt_driver
diff --git a/lib/utils/mailbox/objects.mk b/lib/utils/mailbox/objects.mk
index 79b27e4c..2135898c 100644
--- a/lib/utils/mailbox/objects.mk
+++ b/lib/utils/mailbox/objects.mk
@@ -7,4 +7,7 @@
 #   Anup Patel <[email protected]>
 #
 
+libsbiutils-objs-$(CONFIG_FDT_MAILBOX) += mailbox/fdt_mailbox.o
+libsbiutils-objs-$(CONFIG_FDT_MAILBOX) += mailbox/fdt_mailbox_drivers.carray.o
+
 libsbiutils-objs-$(CONFIG_MAILBOX) += mailbox/mailbox.o