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(fw: priv->fw, tag: RPI_FIRMWARE_NOTIFY_XHCI_RESET, |
53 | data: &dev_addr, len: sizeof(dev_addr)); |
54 | if (ret) |
55 | return ret; |
56 | |
57 | /* Wait for vl805 to startup */ |
58 | usleep_range(min: 200, max: 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(node: 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(dev: &pdev->dev, firmware_node: np); |
86 | of_node_put(node: np); |
87 | if (!fw) |
88 | return -EPROBE_DEFER; |
89 | |
90 | priv = devm_kzalloc(dev, size: sizeof(*priv), GFP_KERNEL); |
91 | if (!priv) |
92 | return -ENOMEM; |
93 | |
94 | dev_set_drvdata(dev, data: 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, rcdev: &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" ); |
123 | |