diff options
Diffstat (limited to 'drivers/hwmon/raspberrypi-hwmon.c')
| -rw-r--r-- | drivers/hwmon/raspberrypi-hwmon.c | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/drivers/hwmon/raspberrypi-hwmon.c b/drivers/hwmon/raspberrypi-hwmon.c new file mode 100644 index 000000000000..fb4e4a6bb1f6 --- /dev/null +++ b/drivers/hwmon/raspberrypi-hwmon.c @@ -0,0 +1,166 @@ +// 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 u32 rpi_in_config[] = { + HWMON_I_LCRIT_ALARM, + 0 +}; + +static const struct hwmon_channel_info rpi_in = { + .type = hwmon_in, + .config = rpi_in_config, +}; + +static const struct hwmon_channel_info *rpi_info[] = { + &rpi_in, + 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; + int ret; + + 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); + + /* Init throttled */ + ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_THROTTLED, + &data->last_throttled, + sizeof(data->last_throttled)); + + 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"); |