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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>
10#include <linux/devm-helpers.h>
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
21struct 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
28static 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
56 hwmon_notify_event(data->hwmon_dev, hwmon_in, hwmon_in_lcrit_alarm, 0);
57}
58
59static 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
75static 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
84static umode_t rpi_is_visible(const void *_data, enum hwmon_sensor_types type,
85 u32 attr, int channel)
86{
87 return 0444;
88}
89
90static const struct hwmon_channel_info * const rpi_info[] = {
91 HWMON_CHANNEL_INFO(in,
92 HWMON_I_LCRIT_ALARM),
93 NULL
94};
95
96static const struct hwmon_ops rpi_hwmon_ops = {
97 .is_visible = rpi_is_visible,
98 .read = rpi_read,
99};
100
101static const struct hwmon_chip_info rpi_chip_info = {
102 .ops = &rpi_hwmon_ops,
103 .info = rpi_info,
104};
105
106static int rpi_hwmon_probe(struct platform_device *pdev)
107{
108 struct device *dev = &pdev->dev;
109 struct rpi_hwmon_data *data;
110 int ret;
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
119 data->hwmon_dev = devm_hwmon_device_register_with_info(dev, "rpi_volt",
120 data,
121 &rpi_chip_info,
122 NULL);
123 if (IS_ERR(data->hwmon_dev))
124 return PTR_ERR(data->hwmon_dev);
125
126 ret = devm_delayed_work_autocancel(dev, &data->get_values_poll_work,
127 get_values_poll);
128 if (ret)
129 return ret;
130 platform_set_drvdata(pdev, data);
131
132 schedule_delayed_work(&data->get_values_poll_work, 2 * HZ);
133
134 return 0;
135}
136
137static struct platform_driver rpi_hwmon_driver = {
138 .probe = rpi_hwmon_probe,
139 .driver = {
140 .name = "raspberrypi-hwmon",
141 },
142};
143module_platform_driver(rpi_hwmon_driver);
144
145MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx.net>");
146MODULE_DESCRIPTION("Raspberry Pi voltage sensor driver");
147MODULE_LICENSE("GPL v2");
148MODULE_ALIAS("platform:raspberrypi-hwmon");
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>
10#include <linux/err.h>
11#include <linux/hwmon.h>
12#include <linux/module.h>
13#include <linux/platform_device.h>
14#include <linux/slab.h>
15#include <linux/workqueue.h>
16#include <soc/bcm2835/raspberrypi-firmware.h>
17
18#define UNDERVOLTAGE_STICKY_BIT BIT(16)
19
20struct rpi_hwmon_data {
21 struct device *hwmon_dev;
22 struct rpi_firmware *fw;
23 u32 last_throttled;
24 struct delayed_work get_values_poll_work;
25};
26
27static void rpi_firmware_get_throttled(struct rpi_hwmon_data *data)
28{
29 u32 new_uv, old_uv, value;
30 int ret;
31
32 /* Request firmware to clear sticky bits */
33 value = 0xffff;
34
35 ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_THROTTLED,
36 &value, sizeof(value));
37 if (ret) {
38 dev_err_once(data->hwmon_dev, "Failed to get throttled (%d)\n",
39 ret);
40 return;
41 }
42
43 new_uv = value & UNDERVOLTAGE_STICKY_BIT;
44 old_uv = data->last_throttled & UNDERVOLTAGE_STICKY_BIT;
45 data->last_throttled = value;
46
47 if (new_uv == old_uv)
48 return;
49
50 if (new_uv)
51 dev_crit(data->hwmon_dev, "Undervoltage detected!\n");
52 else
53 dev_info(data->hwmon_dev, "Voltage normalised\n");
54
55 sysfs_notify(&data->hwmon_dev->kobj, NULL, "in0_lcrit_alarm");
56}
57
58static void get_values_poll(struct work_struct *work)
59{
60 struct rpi_hwmon_data *data;
61
62 data = container_of(work, struct rpi_hwmon_data,
63 get_values_poll_work.work);
64
65 rpi_firmware_get_throttled(data);
66
67 /*
68 * We can't run faster than the sticky shift (100ms) since we get
69 * flipping in the sticky bits that are cleared.
70 */
71 schedule_delayed_work(&data->get_values_poll_work, 2 * HZ);
72}
73
74static int rpi_read(struct device *dev, enum hwmon_sensor_types type,
75 u32 attr, int channel, long *val)
76{
77 struct rpi_hwmon_data *data = dev_get_drvdata(dev);
78
79 *val = !!(data->last_throttled & UNDERVOLTAGE_STICKY_BIT);
80 return 0;
81}
82
83static umode_t rpi_is_visible(const void *_data, enum hwmon_sensor_types type,
84 u32 attr, int channel)
85{
86 return 0444;
87}
88
89static const struct hwmon_channel_info *rpi_info[] = {
90 HWMON_CHANNEL_INFO(in,
91 HWMON_I_LCRIT_ALARM),
92 NULL
93};
94
95static const struct hwmon_ops rpi_hwmon_ops = {
96 .is_visible = rpi_is_visible,
97 .read = rpi_read,
98};
99
100static const struct hwmon_chip_info rpi_chip_info = {
101 .ops = &rpi_hwmon_ops,
102 .info = rpi_info,
103};
104
105static int rpi_hwmon_probe(struct platform_device *pdev)
106{
107 struct device *dev = &pdev->dev;
108 struct rpi_hwmon_data *data;
109
110 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
111 if (!data)
112 return -ENOMEM;
113
114 /* Parent driver assure that firmware is correct */
115 data->fw = dev_get_drvdata(dev->parent);
116
117 data->hwmon_dev = devm_hwmon_device_register_with_info(dev, "rpi_volt",
118 data,
119 &rpi_chip_info,
120 NULL);
121
122 INIT_DELAYED_WORK(&data->get_values_poll_work, get_values_poll);
123 platform_set_drvdata(pdev, data);
124
125 if (!PTR_ERR_OR_ZERO(data->hwmon_dev))
126 schedule_delayed_work(&data->get_values_poll_work, 2 * HZ);
127
128 return PTR_ERR_OR_ZERO(data->hwmon_dev);
129}
130
131static int rpi_hwmon_remove(struct platform_device *pdev)
132{
133 struct rpi_hwmon_data *data = platform_get_drvdata(pdev);
134
135 cancel_delayed_work_sync(&data->get_values_poll_work);
136
137 return 0;
138}
139
140static struct platform_driver rpi_hwmon_driver = {
141 .probe = rpi_hwmon_probe,
142 .remove = rpi_hwmon_remove,
143 .driver = {
144 .name = "raspberrypi-hwmon",
145 },
146};
147module_platform_driver(rpi_hwmon_driver);
148
149MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx.net>");
150MODULE_DESCRIPTION("Raspberry Pi voltage sensor driver");
151MODULE_LICENSE("GPL v2");
152MODULE_ALIAS("platform:raspberrypi-hwmon");