reset: Add Raspberry Pi 4 firmware reset controller

Raspberry Pi 4's co-processor controls some of the board's HW
initialization process, but it's up to Linux to trigger it when
relevant. Introduce a reset controller capable of interfacing with
RPi4's co-processor that models these firmware initialization routines as
reset lines.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: Matthias Brugger <mbrugger@suse.com>

1 files changed, 60 insertions, 0 deletions

diff --git a/drivers/reset/reset-raspberrypi.c b/drivers/reset/reset-raspberrypi.c
new file mode 100644
index 0000000000..e2d284e5ac
--- /dev/null
+++ b/drivers/reset/reset-raspberrypi.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Raspberry Pi 4 firmware reset driver
+ *
+ * Copyright (C) 2020 Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
+ */
+#include <common.h>
+#include <dm.h>
+#include <reset-uclass.h>
+#include <asm/arch/msg.h>
+#include <dt-bindings/reset/raspberrypi,firmware-reset.h>
+
+static int raspberrypi_reset_request(struct reset_ctl *reset_ctl)
+{
+	if (reset_ctl->id >= RASPBERRYPI_FIRMWARE_RESET_NUM_IDS)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int raspberrypi_reset_free(struct reset_ctl *reset_ctl)
+{
+	return 0;
+}
+
+static int raspberrypi_reset_assert(struct reset_ctl *reset_ctl)
+{
+	switch (reset_ctl->id) {
+	case RASPBERRYPI_FIRMWARE_RESET_ID_USB:
+		bcm2711_notify_vl805_reset();
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int raspberrypi_reset_deassert(struct reset_ctl *reset_ctl)
+{
+	return 0;
+}
+
+struct reset_ops raspberrypi_reset_ops = {
+	.request = raspberrypi_reset_request,
+	.rfree = raspberrypi_reset_free,
+	.rst_assert = raspberrypi_reset_assert,
+	.rst_deassert = raspberrypi_reset_deassert,
+};
+
+static const struct udevice_id raspberrypi_reset_ids[] = {
+	{ .compatible = "raspberrypi,firmware-reset" },
+	{ }
+};
+
+U_BOOT_DRIVER(raspberrypi_reset) = {
+	.name = "raspberrypi-reset",
+	.id = UCLASS_RESET,
+	.of_match = raspberrypi_reset_ids,
+	.ops = &raspberrypi_reset_ops,
+};
+