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 <apatel@ventanamicro.com>

include/sbi_utils/mailbox/fdt_mailbox.h

@@ -0,0 +1,35 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2024 Ventana Micro Systems Inc.
+ *
+ * Authors:
+ *   Anup Patel <apatel@ventanamicro.com>
+ */
+
+#ifndef __FDT_MAILBOX_H__
+#define __FDT_MAILBOX_H__
+
+#include <sbi_utils/fdt/fdt_driver.h>
+#include <sbi_utils/mailbox/mailbox.h>
+
+struct fdt_phandle_args;
+
+/** FDT based mailbox driver */
+struct fdt_mailbox {
+	struct fdt_driver driver;
+	int (*xlate)(struct mbox_controller *mbox,
+		     const struct fdt_phandle_args *pargs,
+		     u32 *out_chan_args);
+};
+
+/** Request a mailbox channel using "mboxes" DT property of client DT node */
+int fdt_mailbox_request_chan(const void *fdt, int nodeoff, int index,
+			     struct mbox_chan **out_chan);
+
+/** Simple xlate function to convert one mailbox FDT cell into channel args */
+int fdt_mailbox_simple_xlate(struct mbox_controller *mbox,
+			     const struct fdt_phandle_args *pargs,
+			     u32 *out_chan_args);
+
+#endif

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

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 <apatel@ventanamicro.com>
+ */
+
+#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;
+}

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

lib/utils/mailbox/objects.mk

@@ -7,4 +7,7 @@
 #   Anup Patel <apatel@ventanamicro.com>
 #
 
+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