drivers/reset/reset-raspberrypi.c

   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 = 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
 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");