[linux-2.6-block.git] / drivers / hwmon / raspberrypi-hwmon.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Raspberry Pi voltage sensor driver
 *
 * Based on firmware/raspberrypi.c by Noralf Trønnes
 *
 * Copyright (C) 2018 Stefan Wahren <stefan.wahren@i2se.com>
 */
#include <linux/device.h>
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <soc/bcm2835/raspberrypi-firmware.h>

#define UNDERVOLTAGE_STICKY_BIT	BIT(16)

struct rpi_hwmon_data {
	struct device *hwmon_dev;
	struct rpi_firmware *fw;
	u32 last_throttled;
	struct delayed_work get_values_poll_work;
};

static void rpi_firmware_get_throttled(struct rpi_hwmon_data *data)
{
	u32 new_uv, old_uv, value;
	int ret;

	/* Request firmware to clear sticky bits */
	value = 0xffff;

	ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_THROTTLED,
				    &value, sizeof(value));
	if (ret) {
		dev_err_once(data->hwmon_dev, "Failed to get throttled (%d)\n",
			     ret);
		return;
	}

	new_uv = value & UNDERVOLTAGE_STICKY_BIT;
	old_uv = data->last_throttled & UNDERVOLTAGE_STICKY_BIT;
	data->last_throttled = value;

	if (new_uv == old_uv)
		return;

	if (new_uv)
		dev_crit(data->hwmon_dev, "Undervoltage detected!\n");
	else
		dev_info(data->hwmon_dev, "Voltage normalised\n");

	sysfs_notify(&data->hwmon_dev->kobj, NULL, "in0_lcrit_alarm");
}

static void get_values_poll(struct work_struct *work)
{
	struct rpi_hwmon_data *data;

	data = container_of(work, struct rpi_hwmon_data,
			    get_values_poll_work.work);

	rpi_firmware_get_throttled(data);

	/*
	 * We can't run faster than the sticky shift (100ms) since we get
	 * flipping in the sticky bits that are cleared.
	 */
	schedule_delayed_work(&data->get_values_poll_work, 2 * HZ);
}

static int rpi_read(struct device *dev, enum hwmon_sensor_types type,
		    u32 attr, int channel, long *val)
{
	struct rpi_hwmon_data *data = dev_get_drvdata(dev);

	*val = !!(data->last_throttled & UNDERVOLTAGE_STICKY_BIT);
	return 0;
}

static umode_t rpi_is_visible(const void *_data, enum hwmon_sensor_types type,
			      u32 attr, int channel)
{
	return 0444;
}

static const struct hwmon_channel_info *rpi_info[] = {
	HWMON_CHANNEL_INFO(in,
			   HWMON_I_LCRIT_ALARM),
	NULL
};

static const struct hwmon_ops rpi_hwmon_ops = {
	.is_visible = rpi_is_visible,
	.read = rpi_read,
};

static const struct hwmon_chip_info rpi_chip_info = {
	.ops = &rpi_hwmon_ops,
	.info = rpi_info,
};

static int rpi_hwmon_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct rpi_hwmon_data *data;

	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	/* Parent driver assure that firmware is correct */
	data->fw = dev_get_drvdata(dev->parent);

	data->hwmon_dev = devm_hwmon_device_register_with_info(dev, "rpi_volt",
							       data,
							       &rpi_chip_info,
							       NULL);

	INIT_DELAYED_WORK(&data->get_values_poll_work, get_values_poll);
	platform_set_drvdata(pdev, data);

	if (!PTR_ERR_OR_ZERO(data->hwmon_dev))
		schedule_delayed_work(&data->get_values_poll_work, 2 * HZ);

	return PTR_ERR_OR_ZERO(data->hwmon_dev);
}

static int rpi_hwmon_remove(struct platform_device *pdev)
{
	struct rpi_hwmon_data *data = platform_get_drvdata(pdev);

	cancel_delayed_work_sync(&data->get_values_poll_work);

	return 0;
}

static struct platform_driver rpi_hwmon_driver = {
	.probe = rpi_hwmon_probe,
	.remove = rpi_hwmon_remove,
	.driver = {
		.name = "raspberrypi-hwmon",
	},
};
module_platform_driver(rpi_hwmon_driver);

MODULE_AUTHOR("Stefan Wahren <stefan.wahren@i2se.com>");
MODULE_DESCRIPTION("Raspberry Pi voltage sensor driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:raspberrypi-hwmon");
Commit	Line	Data
74d1e007 SW	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
	20	struct 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
	27	static 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
	58	static 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
74	static 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
83	static umode_t rpi_is_visible(const void *_data, enum hwmon_sensor_types type,
84	u32 attr, int channel)
85	{
86	return 0444;
87	}
88
74d1e007	89	static const struct hwmon_channel_info *rpi_info[] = {
0c42186e GR	90	HWMON_CHANNEL_INFO(in,
0c42186e GR	91	HWMON_I_LCRIT_ALARM),
74d1e007 SW	92	NULL
	93	};
	94
	95	static const struct hwmon_ops rpi_hwmon_ops = {
	96	.is_visible = rpi_is_visible,
	97	.read = rpi_read,
	98	};
	99
	100	static const struct hwmon_chip_info rpi_chip_info = {
	101	.ops = &rpi_hwmon_ops,
	102	.info = rpi_info,
	103	};
	104
	105	static int rpi_hwmon_probe(struct platform_device *pdev)
	106	{
	107	struct device *dev = &pdev->dev;
	108	struct rpi_hwmon_data *data;
74d1e007 SW	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
74d1e007 SW	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
	131	static 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
	140	static struct platform_driver rpi_hwmon_driver = {
	141	.probe = rpi_hwmon_probe,
	142	.remove = rpi_hwmon_remove,
	143	.driver = {
	144	.name = "raspberrypi-hwmon",
	145	},
	146	};
	147	module_platform_driver(rpi_hwmon_driver);
	148
	149	MODULE_AUTHOR("Stefan Wahren <stefan.wahren@i2se.com>");
	150	MODULE_DESCRIPTION("Raspberry Pi voltage sensor driver");
	151	MODULE_LICENSE("GPL v2");
d07f05fb	152	MODULE_ALIAS("platform:raspberrypi-hwmon");