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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 | ||
9419f7f4 | 85 | fw = devm_rpi_firmware_get(&pdev->dev, np); |
abffc82a NSJ |
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"); |