| 1 | |
| 2 | |
| 3 | * Raspberry Pi 4 firmware reset driver
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| 4 | *
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| 5 | * Copyright (C) 2020 Nicolas Saenz Julienne <[email protected]>
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| 6 |
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| 7 | #include <linux/delay.h>
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| 8 | #include <linux/device.h>
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| 9 | #include <linux/module.h>
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| 10 | #include <linux/of.h>
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| 11 | #include <linux/platform_device.h>
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| 12 | #include <linux/reset-controller.h>
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| 13 | #include <soc/bcm2835/raspberrypi-firmware.h>
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| 14 | #include <dt-bindings/reset/raspberrypi,firmware-reset.h>
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| 15 |
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| 16 | struct rpi_reset {
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| 17 | struct reset_controller_dev rcdev;
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| 18 | struct rpi_firmware *fw;
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| 19 | };
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| 20 |
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| 21 | static inline struct rpi_reset *to_rpi(struct reset_controller_dev *rcdev)
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| 22 | {
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| 23 | return container_of(rcdev, struct rpi_reset, rcdev);
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| 24 | }
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| 25 |
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| 26 | static int rpi_reset_reset(struct reset_controller_dev *rcdev, unsigned long id)
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| 27 | {
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| 28 | struct rpi_reset *priv = to_rpi(rcdev);
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| 29 | u32 dev_addr;
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| 30 | int ret;
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| 31 |
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| 32 | switch (id) {
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| 33 | case RASPBERRYPI_FIRMWARE_RESET_ID_USB:
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| 34 | |
| 35 | * The Raspberry Pi 4 gets its USB functionality from VL805, a
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| 36 | * PCIe chip that implements xHCI. After a PCI reset, VL805's
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| 37 | * firmware may either be loaded directly from an EEPROM or, if
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| 38 | * not present, by the SoC's co-processor, VideoCore. rpi's
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| 39 | * VideoCore OS contains both the non public firmware load
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| 40 | * logic and the VL805 firmware blob. This triggers the
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| 41 | * aforementioned process.
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| 42 | *
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| 43 | * The pci device address is expected is expected by the
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| 44 | * firmware encoded like this:
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| 45 | *
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| 46 | * PCI_BUS << 20 | PCI_SLOT << 15 | PCI_FUNC << 12
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| 47 | *
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| 48 | * But since rpi's PCIe is hardwired, we know the address in
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| 49 | * advance.
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| 50 |
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| 51 | dev_addr = 0x100000;
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| 52 | ret = rpi_firmware_property(priv->fw, RPI_FIRMWARE_NOTIFY_XHCI_RESET,
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| 53 | &dev_addr, sizeof(dev_addr));
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| 54 | if (ret)
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| 55 | return ret;
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| 56 |
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| 57 |
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| 58 | usleep_range(200, 1000);
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| 59 | break;
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| 60 |
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| 61 | default:
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| 62 | return -EINVAL;
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| 63 | }
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| 64 |
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| 65 | return 0;
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| 66 | }
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| 67 |
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| 68 | static const struct reset_control_ops rpi_reset_ops = {
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| 69 | .reset = rpi_reset_reset,
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| 70 | };
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| 71 |
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| 72 | static int rpi_reset_probe(struct platform_device *pdev)
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| 73 | {
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| 74 | struct device *dev = &pdev->dev;
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| 75 | struct rpi_firmware *fw;
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| 76 | struct device_node *np;
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| 77 | struct rpi_reset *priv;
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| 78 |
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| 79 | np = of_get_parent(dev->of_node);
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| 80 | if (!np) {
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| 81 | dev_err(dev, "Missing firmware node\n");
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| 82 | return -ENOENT;
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| 83 | }
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| 84 |
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| 85 | fw = devm_rpi_firmware_get(&pdev->dev, np);
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| 86 | of_node_put(np);
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| 87 | if (!fw)
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| 88 | return -EPROBE_DEFER;
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| 89 |
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| 90 | priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
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| 91 | if (!priv)
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| 92 | return -ENOMEM;
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| 93 |
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| 94 | dev_set_drvdata(dev, priv);
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| 95 |
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| 96 | priv->fw = fw;
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| 97 | priv->rcdev.owner = THIS_MODULE;
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| 98 | priv->rcdev.nr_resets = RASPBERRYPI_FIRMWARE_RESET_NUM_IDS;
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| 99 | priv->rcdev.ops = &rpi_reset_ops;
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| 100 | priv->rcdev.of_node = dev->of_node;
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| 101 |
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| 102 | return devm_reset_controller_register(dev, &priv->rcdev);
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| 103 | }
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| 104 |
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| 105 | static const struct of_device_id rpi_reset_of_match[] = {
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| 106 | { .compatible = "raspberrypi,firmware-reset" },
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| 107 | { }
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| 108 | };
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| 109 | MODULE_DEVICE_TABLE(of, rpi_reset_of_match);
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| 110 |
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| 111 | static struct platform_driver rpi_reset_driver = {
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| 112 | .probe = rpi_reset_probe,
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| 113 | .driver = {
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| 114 | .name = "raspberrypi-reset",
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| 115 | .of_match_table = rpi_reset_of_match,
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| 116 | },
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| 117 | };
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| 118 | module_platform_driver(rpi_reset_driver);
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| 119 |
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| 120 | MODULE_AUTHOR("Nicolas Saenz Julienne <[email protected]>");
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| 121 | MODULE_DESCRIPTION("Raspberry Pi 4 firmware reset driver");
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| 122 | MODULE_LICENSE("GPL");
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