On Wed, May 16, 2018 at 03:37:04PM +0200, Stefan Wahren wrote:
> Currently there is no easy way to detect under-voltage conditions on a remote
> Raspberry Pi. This hwmon driver retrieves the state of the under-voltage sensor
> via mailbox interface. The handling based on Noralf's modifications to the
> downstream firmware driver. In case of an under-voltage condition only an entry
> is written to the kernel log.
>
My major concern is how this is displayed with the 'sensors' command.
Can you test and report ?
Of course, it would be much better if the firmware would also report
the actual voltage, but I guess we can't have everything.
More comments inline.
Thanks,
Guenter
> CC: "Noralf Trønnes" <noralf@xxxxxxxxxxx>
> Signed-off-by: Stefan Wahren <stefan.wahren@xxxxxxxx>
> ---
> drivers/hwmon/Kconfig | 10 ++
> drivers/hwmon/Makefile | 1 +
> drivers/hwmon/raspberrypi-hwmon.c | 207 ++++++++++++++++++++++++++++++++++++++
Please also provide Documentation/hwmon/raspberrypi-hwmon.
> 3 files changed, 218 insertions(+)
> create mode 100644 drivers/hwmon/raspberrypi-hwmon.c
>
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 768aed5..7f935cf 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -1298,6 +1298,16 @@ config SENSORS_PWM_FAN
> This driver can also be built as a module. If so, the module
> will be called pwm-fan.
>
> +config SENSORS_RASPBERRYPI_HWMON
> + tristate "Raspberry Pi voltage monitor"
> + depends on (ARCH_BCM2835 && RASPBERRYPI_FIRMWARE) || (COMPILE_TEST && !RASPBERRYPI_FIRMWARE)
> + help
> + If you say yes here you get support for voltage sensor on the
> + Raspberry Pi.
> +
> + This driver can also be built as a module. If so, the module
> + will be called raspberrypi-hwmon.
> +
> config SENSORS_SHT15
> tristate "Sensiron humidity and temperature sensors. SHT15 and compat."
> depends on GPIOLIB || COMPILE_TEST
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index e7d52a3..a929770 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -141,6 +141,7 @@ obj-$(CONFIG_SENSORS_PC87427) += pc87427.o
> obj-$(CONFIG_SENSORS_PCF8591) += pcf8591.o
> obj-$(CONFIG_SENSORS_POWR1220) += powr1220.o
> obj-$(CONFIG_SENSORS_PWM_FAN) += pwm-fan.o
> +obj-$(CONFIG_SENSORS_RASPBERRYPI_HWMON) += raspberrypi-hwmon.o
> obj-$(CONFIG_SENSORS_S3C) += s3c-hwmon.o
> obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o
> obj-$(CONFIG_SENSORS_SCH5627) += sch5627.o
> diff --git a/drivers/hwmon/raspberrypi-hwmon.c b/drivers/hwmon/raspberrypi-hwmon.c
> new file mode 100644
> index 0000000..2003f6c
> --- /dev/null
> +++ b/drivers/hwmon/raspberrypi-hwmon.c
> @@ -0,0 +1,207 @@
> +// 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@xxxxxxxx>
> + */
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
Unnecessary include
> +#include <linux/module.h>
> +#include <linux/of_device.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;
> +
> + /* Clear sticky bits */
Please make more explicit that this is a request/command sent to the firmware.
> + value = 0xffff;
> +
> + ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_THROTTLED,
> + &value, sizeof(value));
> + if (ret) {
> + dev_err_once(data->hwmon_dev, "%s: Failed to get throttled (%d)\n",
> + __func__, ret);
The function name seems unnecessary.
> + 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, "Under-voltage detected! (0x%08x)\n",
> + value);
> + else
> + dev_info(data->hwmon_dev, "Voltage normalised (0x%08x)\n",
> + value);
What value do those hex values provide to the user ?
> +
> + 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);
> +
> + if (type != hwmon_in)
> + return -EOPNOTSUPP;
> +
> + if (attr != hwmon_in_lcrit_alarm)
> + return -EOPNOTSUPP;
> +
> + if (channel)
> + return -EOPNOTSUPP;
> +
There is only one channel, one attribute, and one type supported.
As such, the checks are unnecessary.
> + *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)
> +{
> + if (type != hwmon_in)
> + return 0;
> +
> + if (attr != hwmon_in_lcrit_alarm)
> + return 0;
> +
> + if (channel)
> + return 0;
Same as above. In the list below, there is not a single conditional attribute.
Given that, the checks should be unnecessary, and it should be sufficient to
just return 0444.
> +
> + 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 device_node *fw_node;
> + struct rpi_hwmon_data *data;
> + int ret;
> +
> + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> + if (!data)
> + return -ENOMEM;
> +
> + fw_node = of_get_parent(dev->of_node);
> + if (!fw_node) {
> + dev_err(dev, "Missing firmware node\n");
> + return -ENOENT;
> + }
> +
> + data->fw = rpi_firmware_get(fw_node);
> + of_node_put(fw_node);
> + if (!data->fw)
> + return -EPROBE_DEFER;
> +
> + ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_THROTTLED,
> + &data->last_throttled,
> + sizeof(data->last_throttled));
> + if (ret) {
> + dev_info(dev, "Firmware doesn't support GET_THROTTLED\n");
If this is an error -> dev_err().
> + return -EOPNOTSUPP;
or return -ENODEV.
> + }
> +
> + 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 const struct of_device_id rpi_hwmon_of_match[] = {
> + { .compatible = "raspberrypi,bcm2835-hwmon", },
> + { /* sentinel */},
> +};
> +MODULE_DEVICE_TABLE(of, rpi_hwmon_of_match);
> +
> +static struct platform_driver rpi_hwmon_driver = {
> + .probe = rpi_hwmon_probe,
> + .remove = rpi_hwmon_remove,
> + .driver = {
> + .name = "raspberrypi-hwmon",
> + .of_match_table = rpi_hwmon_of_match,
> + },
> +};
> +module_platform_driver(rpi_hwmon_driver);
> +
> +MODULE_AUTHOR("Stefan Wahren <stefan.wahren@xxxxxxxx>");
> +MODULE_DESCRIPTION("Raspberry Pi voltage sensor driver");
> +MODULE_LICENSE("GPL v2");
> --
> 2.7.4
>
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