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// 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>
#include <dt-bindings/reset/raspberrypi,firmware-reset.h>
struct rpi_reset {
struct reset_controller_dev rcdev;
struct rpi_firmware *fw;
};
static inline struct rpi_reset *to_rpi(struct reset_controller_dev *rcdev)
{
return container_of(rcdev, struct rpi_reset, rcdev);
}
static int rpi_reset_reset(struct reset_controller_dev *rcdev, unsigned long id)
{
struct rpi_reset *priv = to_rpi(rcdev);
u32 dev_addr;
int ret;
switch (id) {
case RASPBERRYPI_FIRMWARE_RESET_ID_USB:
/*
* 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 triggers the
* aforementioned process.
*
* The pci device address is expected is expected by the
* firmware encoded like this:
*
* PCI_BUS << 20 | PCI_SLOT << 15 | PCI_FUNC << 12
*
* But since rpi's PCIe 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);
break;
default:
return -EINVAL;
}
return 0;
}
static const struct reset_control_ops rpi_reset_ops = {
.reset = rpi_reset_reset,
};
static int rpi_reset_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct rpi_firmware *fw;
struct device_node *np;
struct rpi_reset *priv;
np = of_get_parent(dev->of_node);
if (!np) {
dev_err(dev, "Missing firmware node\n");
return -ENOENT;
}
fw = rpi_firmware_get(np);
of_node_put(np);
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 = RASPBERRYPI_FIRMWARE_RESET_NUM_IDS;
priv->rcdev.ops = &rpi_reset_ops;
priv->rcdev.of_node = dev->of_node;
return devm_reset_controller_register(dev, &priv->rcdev);
}
static const struct of_device_id rpi_reset_of_match[] = {
{ .compatible = "raspberrypi,firmware-reset" },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, rpi_reset_of_match);
static struct platform_driver rpi_reset_driver = {
.probe = rpi_reset_probe,
.driver = {
.name = "raspberrypi-reset",
.of_match_table = rpi_reset_of_match,
},
};
module_platform_driver(rpi_reset_driver);
MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
MODULE_DESCRIPTION("Raspberry Pi 4 firmware reset driver");
MODULE_LICENSE("GPL");
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