// SPDX-License-Identifier: GPL-2.0
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/*
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* Raspberry Pi 4 firmware reset driver
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*
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* Copyright (C) 2020 Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
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*/
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#include <linux/delay.h>
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#include <linux/device.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/platform_device.h>
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#include <linux/reset-controller.h>
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#include <soc/bcm2835/raspberrypi-firmware.h>
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#include <dt-bindings/reset/raspberrypi,firmware-reset.h>
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struct rpi_reset {
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struct reset_controller_dev rcdev;
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struct rpi_firmware *fw;
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};
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static inline struct rpi_reset *to_rpi(struct reset_controller_dev *rcdev)
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{
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return container_of(rcdev, struct rpi_reset, rcdev);
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}
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static int rpi_reset_reset(struct reset_controller_dev *rcdev, unsigned long id)
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{
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struct rpi_reset *priv = to_rpi(rcdev);
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u32 dev_addr;
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int ret;
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switch (id) {
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case RASPBERRYPI_FIRMWARE_RESET_ID_USB:
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/*
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* The Raspberry Pi 4 gets its USB functionality from VL805, a
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* PCIe chip that implements xHCI. After a PCI reset, VL805's
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* firmware may either be loaded directly from an EEPROM or, if
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* not present, by the SoC's co-processor, VideoCore. rpi's
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* VideoCore OS contains both the non public firmware load
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* logic and the VL805 firmware blob. This triggers the
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* aforementioned process.
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*
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* The pci device address is expected is expected by the
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* firmware encoded like this:
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*
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* PCI_BUS << 20 | PCI_SLOT << 15 | PCI_FUNC << 12
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*
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* But since rpi's PCIe is hardwired, we know the address in
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* advance.
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*/
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dev_addr = 0x100000;
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ret = rpi_firmware_property(priv->fw, RPI_FIRMWARE_NOTIFY_XHCI_RESET,
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&dev_addr, sizeof(dev_addr));
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if (ret)
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return ret;
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/* Wait for vl805 to startup */
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usleep_range(200, 1000);
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break;
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default:
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return -EINVAL;
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}
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return 0;
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}
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static const struct reset_control_ops rpi_reset_ops = {
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.reset = rpi_reset_reset,
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};
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static int rpi_reset_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct rpi_firmware *fw;
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struct device_node *np;
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struct rpi_reset *priv;
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np = of_get_parent(dev->of_node);
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if (!np) {
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dev_err(dev, "Missing firmware node\n");
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return -ENOENT;
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}
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fw = rpi_firmware_get(np);
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of_node_put(np);
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if (!fw)
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return -EPROBE_DEFER;
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priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
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if (!priv)
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return -ENOMEM;
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dev_set_drvdata(dev, priv);
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priv->fw = fw;
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priv->rcdev.owner = THIS_MODULE;
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priv->rcdev.nr_resets = RASPBERRYPI_FIRMWARE_RESET_NUM_IDS;
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priv->rcdev.ops = &rpi_reset_ops;
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priv->rcdev.of_node = dev->of_node;
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return devm_reset_controller_register(dev, &priv->rcdev);
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}
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static const struct of_device_id rpi_reset_of_match[] = {
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{ .compatible = "raspberrypi,firmware-reset" },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, rpi_reset_of_match);
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static struct platform_driver rpi_reset_driver = {
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.probe = rpi_reset_probe,
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.driver = {
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.name = "raspberrypi-reset",
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.of_match_table = rpi_reset_of_match,
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},
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};
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module_platform_driver(rpi_reset_driver);
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MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
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MODULE_DESCRIPTION("Raspberry Pi 4 firmware reset driver");
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MODULE_LICENSE("GPL");
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