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1 | // SPDX-License-Identifier: GPL-2.0+ |
2 | /* | |
3 | * Raspberry Pi voltage sensor driver | |
4 | * | |
5 | * Based on firmware/raspberrypi.c by Noralf Trønnes | |
6 | * | |
7 | * Copyright (C) 2018 Stefan Wahren <stefan.wahren@i2se.com> | |
8 | */ | |
9 | #include <linux/device.h> | |
96dc2b31 | 10 | #include <linux/devm-helpers.h> |
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11 | #include <linux/err.h> |
12 | #include <linux/hwmon.h> | |
13 | #include <linux/module.h> | |
14 | #include <linux/platform_device.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/workqueue.h> | |
17 | #include <soc/bcm2835/raspberrypi-firmware.h> | |
18 | ||
19 | #define UNDERVOLTAGE_STICKY_BIT BIT(16) | |
20 | ||
21 | struct rpi_hwmon_data { | |
22 | struct device *hwmon_dev; | |
23 | struct rpi_firmware *fw; | |
24 | u32 last_throttled; | |
25 | struct delayed_work get_values_poll_work; | |
26 | }; | |
27 | ||
28 | static void rpi_firmware_get_throttled(struct rpi_hwmon_data *data) | |
29 | { | |
30 | u32 new_uv, old_uv, value; | |
31 | int ret; | |
32 | ||
33 | /* Request firmware to clear sticky bits */ | |
34 | value = 0xffff; | |
35 | ||
36 | ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_THROTTLED, | |
37 | &value, sizeof(value)); | |
38 | if (ret) { | |
39 | dev_err_once(data->hwmon_dev, "Failed to get throttled (%d)\n", | |
40 | ret); | |
41 | return; | |
42 | } | |
43 | ||
44 | new_uv = value & UNDERVOLTAGE_STICKY_BIT; | |
45 | old_uv = data->last_throttled & UNDERVOLTAGE_STICKY_BIT; | |
46 | data->last_throttled = value; | |
47 | ||
48 | if (new_uv == old_uv) | |
49 | return; | |
50 | ||
51 | if (new_uv) | |
52 | dev_crit(data->hwmon_dev, "Undervoltage detected!\n"); | |
53 | else | |
54 | dev_info(data->hwmon_dev, "Voltage normalised\n"); | |
55 | ||
d73287ee | 56 | hwmon_notify_event(data->hwmon_dev, hwmon_in, hwmon_in_lcrit_alarm, 0); |
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57 | } |
58 | ||
59 | static void get_values_poll(struct work_struct *work) | |
60 | { | |
61 | struct rpi_hwmon_data *data; | |
62 | ||
63 | data = container_of(work, struct rpi_hwmon_data, | |
64 | get_values_poll_work.work); | |
65 | ||
66 | rpi_firmware_get_throttled(data); | |
67 | ||
68 | /* | |
69 | * We can't run faster than the sticky shift (100ms) since we get | |
70 | * flipping in the sticky bits that are cleared. | |
71 | */ | |
72 | schedule_delayed_work(&data->get_values_poll_work, 2 * HZ); | |
73 | } | |
74 | ||
75 | static int rpi_read(struct device *dev, enum hwmon_sensor_types type, | |
76 | u32 attr, int channel, long *val) | |
77 | { | |
78 | struct rpi_hwmon_data *data = dev_get_drvdata(dev); | |
79 | ||
80 | *val = !!(data->last_throttled & UNDERVOLTAGE_STICKY_BIT); | |
81 | return 0; | |
82 | } | |
83 | ||
84 | static umode_t rpi_is_visible(const void *_data, enum hwmon_sensor_types type, | |
85 | u32 attr, int channel) | |
86 | { | |
87 | return 0444; | |
88 | } | |
89 | ||
70df9a55 | 90 | static const struct hwmon_channel_info * const rpi_info[] = { |
0c42186e GR |
91 | HWMON_CHANNEL_INFO(in, |
92 | HWMON_I_LCRIT_ALARM), | |
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93 | NULL |
94 | }; | |
95 | ||
96 | static const struct hwmon_ops rpi_hwmon_ops = { | |
97 | .is_visible = rpi_is_visible, | |
98 | .read = rpi_read, | |
99 | }; | |
100 | ||
101 | static const struct hwmon_chip_info rpi_chip_info = { | |
102 | .ops = &rpi_hwmon_ops, | |
103 | .info = rpi_info, | |
104 | }; | |
105 | ||
106 | static int rpi_hwmon_probe(struct platform_device *pdev) | |
107 | { | |
108 | struct device *dev = &pdev->dev; | |
109 | struct rpi_hwmon_data *data; | |
96dc2b31 | 110 | int ret; |
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111 | |
112 | data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); | |
113 | if (!data) | |
114 | return -ENOMEM; | |
115 | ||
116 | /* Parent driver assure that firmware is correct */ | |
117 | data->fw = dev_get_drvdata(dev->parent); | |
118 | ||
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119 | data->hwmon_dev = devm_hwmon_device_register_with_info(dev, "rpi_volt", |
120 | data, | |
121 | &rpi_chip_info, | |
122 | NULL); | |
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123 | if (IS_ERR(data->hwmon_dev)) |
124 | return PTR_ERR(data->hwmon_dev); | |
74d1e007 | 125 | |
96dc2b31 MV |
126 | ret = devm_delayed_work_autocancel(dev, &data->get_values_poll_work, |
127 | get_values_poll); | |
128 | if (ret) | |
129 | return ret; | |
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130 | platform_set_drvdata(pdev, data); |
131 | ||
9c6d5551 | 132 | schedule_delayed_work(&data->get_values_poll_work, 2 * HZ); |
74d1e007 | 133 | |
9c6d5551 | 134 | return 0; |
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135 | } |
136 | ||
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137 | static struct platform_driver rpi_hwmon_driver = { |
138 | .probe = rpi_hwmon_probe, | |
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139 | .driver = { |
140 | .name = "raspberrypi-hwmon", | |
141 | }, | |
142 | }; | |
143 | module_platform_driver(rpi_hwmon_driver); | |
144 | ||
10b1f2a9 | 145 | MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx.net>"); |
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146 | MODULE_DESCRIPTION("Raspberry Pi voltage sensor driver"); |
147 | MODULE_LICENSE("GPL v2"); | |
d07f05fb | 148 | MODULE_ALIAS("platform:raspberrypi-hwmon"); |