| Nicolas Saenz Julienne | abffc82 | 2020-06-29 18:18:38 +0200 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | /* |
| 3 | * Raspberry Pi 4 firmware reset driver |
| 4 | * |
| 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 | |
| 16 | struct rpi_reset { |
| 17 | struct reset_controller_dev rcdev; |
| 18 | struct rpi_firmware *fw; |
| 19 | }; |
| 20 | |
| 21 | static inline struct rpi_reset *to_rpi(struct reset_controller_dev *rcdev) |
| 22 | { |
| 23 | return container_of(rcdev, struct rpi_reset, rcdev); |
| 24 | } |
| 25 | |
| 26 | static 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, a |
| 36 | * PCIe chip that implements xHCI. After a PCI reset, VL805's |
| 37 | * firmware may either be loaded directly from an EEPROM or, if |
| 38 | * not present, by the SoC's co-processor, VideoCore. rpi's |
| 39 | * VideoCore OS contains both the non public firmware load |
| 40 | * logic and the VL805 firmware blob. This triggers the |
| 41 | * aforementioned process. |
| 42 | * |
| 43 | * The pci device address is expected is expected by the |
| 44 | * firmware encoded like this: |
| 45 | * |
| 46 | * PCI_BUS << 20 | PCI_SLOT << 15 | PCI_FUNC << 12 |
| 47 | * |
| 48 | * But since rpi's PCIe is hardwired, we know the address in |
| 49 | * 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 | |
| 68 | static const struct reset_control_ops rpi_reset_ops = { |
| 69 | .reset = rpi_reset_reset, |
| 70 | }; |
| 71 | |
| 72 | static 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 = rpi_firmware_get(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 | |
| 105 | static const struct of_device_id rpi_reset_of_match[] = { |
| 106 | { .compatible = "raspberrypi,firmware-reset" }, |
| 107 | { /* sentinel */ } |
| 108 | }; |
| 109 | MODULE_DEVICE_TABLE(of, rpi_reset_of_match); |
| 110 | |
| 111 | static 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 | }; |
| 118 | module_platform_driver(rpi_reset_driver); |
| 119 | |
| 120 | MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>"); |
| 121 | MODULE_DESCRIPTION("Raspberry Pi 4 firmware reset driver"); |
| 122 | MODULE_LICENSE("GPL"); |
