Re: [PATCH v2 2/9] 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 <redacted>

---

Changes since v1:
  - Make the whole driver less USB centric as per Florian's comments

 drivers/reset/Kconfig             |  11 +++
 drivers/reset/Makefile            |   1 +
 drivers/reset/reset-raspberrypi.c | 126 ++++++++++++++++++++++++++++++
 3 files changed, 138 insertions(+)
 create mode 100644 drivers/reset/reset-raspberrypi.c

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index d9efbfd29646..97e848740e13 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig

@@ -140,6 +140,17 @@ config RESET_QCOM_PDC
 	  to control reset signals provided by PDC for Modem, Compute,
 	  Display, GPU, Debug, AOP, Sensors, Audio, SP and APPS.
 
+config RESET_RASPBERRYPI
+	tristate "Raspberry Pi 4 Firmware Reset Driver"
+	depends on RASPBERRYPI_FIRMWARE || (RASPBERRYPI_FIRMWARE=n && COMPILE_TEST)
+	default USB_XHCI_PCI
+	help
+	  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. This driver provides a reset controller capable of
+	  interfacing with RPi4's co-processor and model these firmware
+	  initialization routines as reset lines.
+
 config RESET_SCMI
 	tristate "Reset driver controlled via ARM SCMI interface"
 	depends on ARM_SCMI_PROTOCOL || COMPILE_TEST

diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 249ed357c997..16947610cc3b 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile

@@ -21,6 +21,7 @@ obj-$(CONFIG_RESET_OXNAS) += reset-oxnas.o
 obj-$(CONFIG_RESET_PISTACHIO) += reset-pistachio.o
 obj-$(CONFIG_RESET_QCOM_AOSS) += reset-qcom-aoss.o
 obj-$(CONFIG_RESET_QCOM_PDC) += reset-qcom-pdc.o
+obj-$(CONFIG_RESET_RASPBERRYPI) += reset-raspberrypi.o
 obj-$(CONFIG_RESET_SCMI) += reset-scmi.o
 obj-$(CONFIG_RESET_SIMPLE) += reset-simple.o
 obj-$(CONFIG_RESET_STM32MP157) += reset-stm32mp1.o

diff --git a/drivers/reset/reset-raspberrypi.c b/drivers/reset/reset-raspberrypi.c
new file mode 100644
index 000000000000..5fc8c6319a20
--- /dev/null
+++ b/drivers/reset/reset-raspberrypi.c

@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Raspberry Pi 4 firmware reset driver
+ *
+ * Copyright (C) 2020 Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
+ */
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <soc/bcm2835/raspberrypi-firmware.h>
+
+struct rpi_reset {
+	struct reset_controller_dev rcdev;
+	struct rpi_firmware *fw;
+};
+
+enum rpi_reset_ids {
+	RASPBERRYPI_FIRMWARE_RESET_ID_USB,