// 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");