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147 lines
3.5 KiB
147 lines
3.5 KiB
// SPDX-License-Identifier: GPL-2.0+ |
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/* |
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* Raspberry Pi voltage sensor driver |
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* |
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* Based on firmware/raspberrypi.c by Noralf Trønnes |
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* |
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* Copyright (C) 2018 Stefan Wahren <[email protected]> |
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*/ |
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#include <linux/device.h> |
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#include <linux/devm-helpers.h> |
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#include <linux/err.h> |
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#include <linux/hwmon.h> |
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#include <linux/module.h> |
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#include <linux/platform_device.h> |
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#include <linux/slab.h> |
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#include <linux/workqueue.h> |
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#include <soc/bcm2835/raspberrypi-firmware.h> |
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#define UNDERVOLTAGE_STICKY_BIT BIT(16) |
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struct rpi_hwmon_data { |
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struct device *hwmon_dev; |
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struct rpi_firmware *fw; |
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u32 last_throttled; |
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struct delayed_work get_values_poll_work; |
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}; |
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static void rpi_firmware_get_throttled(struct rpi_hwmon_data *data) |
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{ |
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u32 new_uv, old_uv, value; |
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int ret; |
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/* Request firmware to clear sticky bits */ |
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value = 0xffff; |
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ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_THROTTLED, |
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&value, sizeof(value)); |
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if (ret) { |
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dev_err_once(data->hwmon_dev, "Failed to get throttled (%d)\n", |
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ret); |
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return; |
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} |
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new_uv = value & UNDERVOLTAGE_STICKY_BIT; |
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old_uv = data->last_throttled & UNDERVOLTAGE_STICKY_BIT; |
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data->last_throttled = value; |
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if (new_uv == old_uv) |
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return; |
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if (new_uv) |
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dev_crit(data->hwmon_dev, "Undervoltage detected!\n"); |
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else |
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dev_info(data->hwmon_dev, "Voltage normalised\n"); |
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sysfs_notify(&data->hwmon_dev->kobj, NULL, "in0_lcrit_alarm"); |
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} |
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static void get_values_poll(struct work_struct *work) |
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{ |
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struct rpi_hwmon_data *data; |
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data = container_of(work, struct rpi_hwmon_data, |
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get_values_poll_work.work); |
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rpi_firmware_get_throttled(data); |
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/* |
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* We can't run faster than the sticky shift (100ms) since we get |
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* flipping in the sticky bits that are cleared. |
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*/ |
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schedule_delayed_work(&data->get_values_poll_work, 2 * HZ); |
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} |
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static int rpi_read(struct device *dev, enum hwmon_sensor_types type, |
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u32 attr, int channel, long *val) |
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{ |
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struct rpi_hwmon_data *data = dev_get_drvdata(dev); |
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*val = !!(data->last_throttled & UNDERVOLTAGE_STICKY_BIT); |
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return 0; |
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} |
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static umode_t rpi_is_visible(const void *_data, enum hwmon_sensor_types type, |
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u32 attr, int channel) |
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{ |
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return 0444; |
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} |
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static const struct hwmon_channel_info *rpi_info[] = { |
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HWMON_CHANNEL_INFO(in, |
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HWMON_I_LCRIT_ALARM), |
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NULL |
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}; |
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static const struct hwmon_ops rpi_hwmon_ops = { |
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.is_visible = rpi_is_visible, |
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.read = rpi_read, |
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}; |
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static const struct hwmon_chip_info rpi_chip_info = { |
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.ops = &rpi_hwmon_ops, |
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.info = rpi_info, |
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}; |
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static int rpi_hwmon_probe(struct platform_device *pdev) |
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{ |
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struct device *dev = &pdev->dev; |
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struct rpi_hwmon_data *data; |
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int ret; |
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data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); |
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if (!data) |
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return -ENOMEM; |
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/* Parent driver assure that firmware is correct */ |
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data->fw = dev_get_drvdata(dev->parent); |
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data->hwmon_dev = devm_hwmon_device_register_with_info(dev, "rpi_volt", |
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data, |
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&rpi_chip_info, |
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NULL); |
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ret = devm_delayed_work_autocancel(dev, &data->get_values_poll_work, |
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get_values_poll); |
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if (ret) |
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return ret; |
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platform_set_drvdata(pdev, data); |
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if (!PTR_ERR_OR_ZERO(data->hwmon_dev)) |
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schedule_delayed_work(&data->get_values_poll_work, 2 * HZ); |
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return PTR_ERR_OR_ZERO(data->hwmon_dev); |
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} |
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static struct platform_driver rpi_hwmon_driver = { |
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.probe = rpi_hwmon_probe, |
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.driver = { |
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.name = "raspberrypi-hwmon", |
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}, |
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}; |
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module_platform_driver(rpi_hwmon_driver); |
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MODULE_AUTHOR("Stefan Wahren <[email protected]>"); |
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MODULE_DESCRIPTION("Raspberry Pi voltage sensor driver"); |
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MODULE_LICENSE("GPL v2"); |
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MODULE_ALIAS("platform:raspberrypi-hwmon");
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