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1// SPDX-License-Identifier: GPL-2.02/*3 * Raspberry Pi 4 firmware reset driver4 *5 * Copyright (C) 2020 Nicolas Saenz Julienne <nsaenzjulienne@suse.de>6 */7#include <linux/delay.h>8#include <linux/device.h>9#include <linux/module.h>10#include <linux/of.h>11#include <linux/platform_device.h>12#include <linux/reset-controller.h>13#include <soc/bcm2835/raspberrypi-firmware.h>14#include <dt-bindings/reset/raspberrypi,firmware-reset.h>15 16struct rpi_reset {17 struct reset_controller_dev rcdev;18 struct rpi_firmware *fw;19};20 21static inline struct rpi_reset *to_rpi(struct reset_controller_dev *rcdev)22{23 return container_of(rcdev, struct rpi_reset, rcdev);24}25 26static int rpi_reset_reset(struct reset_controller_dev *rcdev, unsigned long id)27{28 struct rpi_reset *priv = to_rpi(rcdev);29 u32 dev_addr;30 int ret;31 32 switch (id) {33 case RASPBERRYPI_FIRMWARE_RESET_ID_USB:34 /*35 * The Raspberry Pi 4 gets its USB functionality from VL805, a36 * PCIe chip that implements xHCI. After a PCI reset, VL805's37 * firmware may either be loaded directly from an EEPROM or, if38 * not present, by the SoC's co-processor, VideoCore. rpi's39 * VideoCore OS contains both the non public firmware load40 * logic and the VL805 firmware blob. This triggers the41 * aforementioned process.42 *43 * The pci device address is expected is expected by the44 * firmware encoded like this:45 *46 * PCI_BUS << 20 | PCI_SLOT << 15 | PCI_FUNC << 1247 *48 * But since rpi's PCIe is hardwired, we know the address in49 * advance.50 */51 dev_addr = 0x100000;52 ret = rpi_firmware_property(priv->fw, RPI_FIRMWARE_NOTIFY_XHCI_RESET,53 &dev_addr, sizeof(dev_addr));54 if (ret)55 return ret;56 57 /* Wait for vl805 to startup */58 usleep_range(200, 1000);59 break;60 61 default:62 return -EINVAL;63 }64 65 return 0;66}67 68static const struct reset_control_ops rpi_reset_ops = {69 .reset = rpi_reset_reset,70};71 72static int rpi_reset_probe(struct platform_device *pdev)73{74 struct device *dev = &pdev->dev;75 struct rpi_firmware *fw;76 struct device_node *np;77 struct rpi_reset *priv;78 79 np = of_get_parent(dev->of_node);80 if (!np) {81 dev_err(dev, "Missing firmware node\n");82 return -ENOENT;83 }84 85 fw = devm_rpi_firmware_get(&pdev->dev, np);86 of_node_put(np);87 if (!fw)88 return -EPROBE_DEFER;89 90 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);91 if (!priv)92 return -ENOMEM;93 94 dev_set_drvdata(dev, priv);95 96 priv->fw = fw;97 priv->rcdev.owner = THIS_MODULE;98 priv->rcdev.nr_resets = RASPBERRYPI_FIRMWARE_RESET_NUM_IDS;99 priv->rcdev.ops = &rpi_reset_ops;100 priv->rcdev.of_node = dev->of_node;101 102 return devm_reset_controller_register(dev, &priv->rcdev);103}104 105static const struct of_device_id rpi_reset_of_match[] = {106 { .compatible = "raspberrypi,firmware-reset" },107 { /* sentinel */ }108};109MODULE_DEVICE_TABLE(of, rpi_reset_of_match);110 111static struct platform_driver rpi_reset_driver = {112 .probe = rpi_reset_probe,113 .driver = {114 .name = "raspberrypi-reset",115 .of_match_table = rpi_reset_of_match,116 },117};118module_platform_driver(rpi_reset_driver);119 120MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");121MODULE_DESCRIPTION("Raspberry Pi 4 firmware reset driver");122MODULE_LICENSE("GPL");123