[2/9] reset: Add Raspberry Pi 4 firmware USB reset controller
diff mbox series

Message ID 20200608192701.18355-3-nsaenzjulienne@suse.de
State New, archived
Headers show
Series
  • Raspberry Pi 4 USB firmware initialization rework
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Commit Message

Nicolas Saenz Julienne June 8, 2020, 7:26 p.m. UTC
The Raspberry Pi 4 gets its USB functionality from VL805, a PCIe chip
that implements the xHCI. After a PCI fundamental reset, VL805's
firmware may either be loaded directly from an EEPROM or, if not
present, by the SoC's co-processor, VideoCore. RPi4's VideoCore OS
contains both the non public firmware load logic and the VL805 firmware
blob.

We control this trough a reset controller device that's able to trigger
the aforementioned process when relevant.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 drivers/reset/Kconfig                 |   9 ++
 drivers/reset/Makefile                |   1 +
 drivers/reset/reset-raspberrypi-usb.c | 122 ++++++++++++++++++++++++++
 3 files changed, 132 insertions(+)
 create mode 100644 drivers/reset/reset-raspberrypi-usb.c

Comments

Florian Fainelli June 8, 2020, 8:13 p.m. UTC | #1
On 6/8/2020 12:26 PM, Nicolas Saenz Julienne wrote:
> The Raspberry Pi 4 gets its USB functionality from VL805, a PCIe chip
> that implements the xHCI. After a PCI fundamental reset, VL805's
> firmware may either be loaded directly from an EEPROM or, if not
> present, by the SoC's co-processor, VideoCore. RPi4's VideoCore OS
> contains both the non public firmware load logic and the VL805 firmware
> blob.
> 
> We control this trough a reset controller device that's able to trigger
> the aforementioned process when relevant.
> 
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> ---

[snip]

> +static int rpi_usb_reset_reset(struct reset_controller_dev *rcdev,
> +				unsigned long id)
> +{
> +	struct rpi_usb_reset *priv = to_rpi_usb(rcdev);
> +	u32 dev_addr;
> +	int ret;
> +
> +	/*
> +	 * The pci device address is expected like this:
> +	 *
> +	 * PCI_BUS << 20 | PCI_SLOT << 15 | PCI_FUNC << 12
> +	 *
> +	 * But since rpi's PCIe setup is hardwired, we know the address in
> +	 * advance.
> +	 */
> +	dev_addr = 0x100000;

You could encode the device address as part of the reset identifier,
such that if we ever have more devices to reset, then we only need to
define new identifiers for them, and internally within your reset
controller provide you can resolve that reset identifier 0 is PCI_BUS <<
20 | PCI_SLOT << 15 | PCI_FUN << 12 for instance.

This would make your reset controller define a "#reset-cells" property
to 1 now, such that no further DT ABI breakage would occur if you were
to extend it later on.

Patch
diff mbox series

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index d9efbfd29646..80e07190cd04 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -140,6 +140,15 @@  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_USB
+	tristate "Raspberry Pi 4 USB Reset Driver"
+	depends on RASPBERRYPI_FIRMWARE || (RASPBERRYPI_FIRMWARE=n && COMPILE_TEST)
+	default USB_XHCI_PCI
+	help
+	  This driver provides support for resetting the USB HW available in
+	  the Raspberry Pi 4. This reset process is controlled by firmware
+	  through a custom interface (see drivers/firmware/raspberrypi.c).
+
 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..49cd2868c7ab 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-$(CONFIG_RESET_RASPBERRYPI_USB) += reset-raspberrypi-usb.o
 obj-$(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-usb.c b/drivers/reset/reset-raspberrypi-usb.c
new file mode 100644
index 000000000000..e9a6e7018c6d
--- /dev/null
+++ b/drivers/reset/reset-raspberrypi-usb.c
@@ -0,0 +1,122 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Raspberry Pi 4 USB reset driver
+ *
+ * The Raspberry Pi 4 gets its USB functionality from VL805, a PCIe chip that
+ * implements xHCI. After a PCI reset, VL805's firmware may either be loaded
+ * directly from an EEPROM or, if not present, by the SoC's co-processor,
+ * VideoCore. rpi's VideoCore OS contains both the non public firmware load
+ * logic and the VL805 firmware blob. This driver triggers the aforementioned
+ * process.
+ *
+ * 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_usb_reset {
+	struct reset_controller_dev rcdev;
+	struct rpi_firmware *fw;
+};
+
+static inline
+struct rpi_usb_reset *to_rpi_usb(struct reset_controller_dev *rcdev)
+{
+	return container_of(rcdev, struct rpi_usb_reset, rcdev);
+}
+
+static int rpi_usb_reset_reset(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	struct rpi_usb_reset *priv = to_rpi_usb(rcdev);
+	u32 dev_addr;
+	int ret;
+
+	/*
+	 * The pci device address is expected like this:
+	 *
+	 * PCI_BUS << 20 | PCI_SLOT << 15 | PCI_FUNC << 12
+	 *
+	 * But since rpi's PCIe setup is hardwired, we know the address in
+	 * advance.
+	 */
+	dev_addr = 0x100000;
+	ret = rpi_firmware_property(priv->fw, RPI_FIRMWARE_NOTIFY_XHCI_RESET,
+				    &dev_addr, sizeof(dev_addr));
+	if (ret)
+		return ret;
+
+	/* Wait for vl805 to startup */
+	usleep_range(200, 1000);
+
+	return 0;
+}
+
+static const struct reset_control_ops rpi_usb_reset_ops = {
+	.reset	= rpi_usb_reset_reset,
+};
+
+static int rpi_usb_reset_xlate(struct reset_controller_dev *rcdev,
+			       const struct of_phandle_args *reset_spec)
+{
+	/* This is needed if #reset-cells == 0. */
+	return 0;
+}
+
+static int rpi_usb_reset_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *fw_node;
+	struct rpi_usb_reset *priv;
+	struct rpi_firmware *fw;
+
+	fw_node = of_get_parent(dev->of_node);
+	if (!fw_node) {
+		dev_err(dev, "Missing firmware node\n");
+		return -ENOENT;
+	}
+
+	fw = rpi_firmware_get(fw_node);
+	of_node_put(fw_node);
+	if (!fw)
+		return -EPROBE_DEFER;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	dev_set_drvdata(dev, priv);
+
+	priv->fw = fw;
+	priv->rcdev.owner = THIS_MODULE;
+	priv->rcdev.nr_resets = 1;
+	priv->rcdev.ops = &rpi_usb_reset_ops;
+	priv->rcdev.of_node = dev->of_node;
+	priv->rcdev.of_xlate = rpi_usb_reset_xlate;
+
+	return devm_reset_controller_register(dev, &priv->rcdev);
+}
+
+static const struct of_device_id rpi_usb_reset_of_match[] = {
+	{ .compatible = "raspberrypi,firmware-usb-reset" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, rpi_usb_reset_of_match);
+
+static struct platform_driver rpi_usb_reset_driver = {
+	.probe	= rpi_usb_reset_probe,
+	.driver	= {
+		.name = "raspberrypi-usb-reset",
+		.of_match_table = rpi_usb_reset_of_match,
+	},
+};
+module_platform_driver(rpi_usb_reset_driver);
+
+MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
+MODULE_DESCRIPTION("Raspberry Pi 4 USB reset driver");
+MODULE_LICENSE("GPL");