| Message ID | 1526988112-4021-3-git-send-email-stefan.wahren@i2se.com |
|---|---|
| State | New |
| Headers | show |
| Series | hwmon: Add support for Raspberry Pi voltage sensor | expand |
On 05/22/2018 04:21 AM, Stefan Wahren wrote: > Currently there is no easy way to detect undervoltage conditions on a > remote Raspberry Pi. This hwmon driver retrieves the state of the > undervoltage sensor via mailbox interface. The handling based on > Noralf's modifications to the downstream firmware driver. In case of > an undervoltage condition only an entry is written to the kernel log. > > CC: "Noralf Trønnes" <noralf@tronnes.org> > Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com> > --- > Documentation/hwmon/raspberrypi-hwmon | 22 +++++ > drivers/hwmon/Kconfig | 10 ++ > drivers/hwmon/Makefile | 1 + > drivers/hwmon/raspberrypi-hwmon.c | 168 ++++++++++++++++++++++++++++++++++ > 4 files changed, 201 insertions(+) > create mode 100644 Documentation/hwmon/raspberrypi-hwmon > create mode 100644 drivers/hwmon/raspberrypi-hwmon.c > > diff --git a/Documentation/hwmon/raspberrypi-hwmon b/Documentation/hwmon/raspberrypi-hwmon > new file mode 100644 > index 0000000..3c92e2c > --- /dev/null > +++ b/Documentation/hwmon/raspberrypi-hwmon > @@ -0,0 +1,22 @@ > +Kernel driver raspberrypi-hwmon > +=============================== > + > +Supported boards: > + * Raspberry Pi A+ (via GPIO on SoC) > + * Raspberry Pi B+ (via GPIO on SoC) > + * Raspberry Pi 2 B (via GPIO on SoC) > + * Raspberry Pi 3 B (via GPIO on port expander) > + * Raspberry Pi 3 B+ (via PMIC) > + > +Author: Stefan Wahren <stefan.wahren@i2se.com> > + > +Description > +----------- > + > +This driver periodically polls a mailbox property of the VC4 firmware to detect > +undervoltage conditions. > + > +Sysfs entries > +------------- > + > +in0_lcrit_alarm Undervoltage alarm > diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig > index 768aed5..9a5bdb0 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 RASPBERRYPI_FIRMWARE || COMPILE_TEST > + 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..6233e84 > --- /dev/null > +++ b/drivers/hwmon/raspberrypi-hwmon.c > @@ -0,0 +1,168 @@ > +// 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; > + > + data->fw = platform_get_drvdata(to_platform_device(dev->parent)); > + if (!data->fw) > + return -EPROBE_DEFER; > + I am a bit at loss here (and sorry I didn't bring this up before). How would this ever be possible, given that the driver is registered from the firmware driver ? > + ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_THROTTLED, > + &data->last_throttled, > + sizeof(data->last_throttled)); > + if (ret) > + 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 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"); >
Hi Guenter, > Guenter Roeck <linux@roeck-us.net> hat am 22. Mai 2018 um 15:41 geschrieben: > > > On 05/22/2018 04:21 AM, Stefan Wahren wrote: > > Currently there is no easy way to detect undervoltage conditions on a > > remote Raspberry Pi. This hwmon driver retrieves the state of the > > undervoltage sensor via mailbox interface. The handling based on > > Noralf's modifications to the downstream firmware driver. In case of > > an undervoltage condition only an entry is written to the kernel log. > > > > CC: "Noralf Trønnes" <noralf@tronnes.org> > > Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com> > > --- > > Documentation/hwmon/raspberrypi-hwmon | 22 +++++ > > drivers/hwmon/Kconfig | 10 ++ > > drivers/hwmon/Makefile | 1 + > > drivers/hwmon/raspberrypi-hwmon.c | 168 ++++++++++++++++++++++++++++++++++ > > 4 files changed, 201 insertions(+) > > create mode 100644 Documentation/hwmon/raspberrypi-hwmon > > create mode 100644 drivers/hwmon/raspberrypi-hwmon.c > > > > diff --git a/Documentation/hwmon/raspberrypi-hwmon b/Documentation/hwmon/raspberrypi-hwmon > > new file mode 100644 > > index 0000000..3c92e2c > > --- /dev/null > > +++ b/Documentation/hwmon/raspberrypi-hwmon > > @@ -0,0 +1,22 @@ > > +Kernel driver raspberrypi-hwmon > > +=============================== > > + > > +Supported boards: > > + * Raspberry Pi A+ (via GPIO on SoC) > > + * Raspberry Pi B+ (via GPIO on SoC) > > + * Raspberry Pi 2 B (via GPIO on SoC) > > + * Raspberry Pi 3 B (via GPIO on port expander) > > + * Raspberry Pi 3 B+ (via PMIC) > > + > > +Author: Stefan Wahren <stefan.wahren@i2se.com> > > + > > +Description > > +----------- > > + > > +This driver periodically polls a mailbox property of the VC4 firmware to detect > > +undervoltage conditions. > > + > > +Sysfs entries > > +------------- > > + > > +in0_lcrit_alarm Undervoltage alarm > > diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig > > index 768aed5..9a5bdb0 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 RASPBERRYPI_FIRMWARE || COMPILE_TEST > > + 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..6233e84 > > --- /dev/null > > +++ b/drivers/hwmon/raspberrypi-hwmon.c > > @@ -0,0 +1,168 @@ > > +// 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; > > + > > + data->fw = platform_get_drvdata(to_platform_device(dev->parent)); > > + if (!data->fw) > > + return -EPROBE_DEFER; > > + > > I am a bit at loss here (and sorry I didn't bring this up before). > How would this ever be possible, given that the driver is registered > from the firmware driver ? Do you refer to the (wrong) return code, the assumption that the parent must be a platform driver or a possible race? > > > + ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_THROTTLED, > > + &data->last_throttled, > > + sizeof(data->last_throttled)); > > + if (ret) > > + 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 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"); > > >
On 05/22/2018 06:51 AM, Stefan Wahren wrote: > Hi Guenter, > >> Guenter Roeck <linux@roeck-us.net> hat am 22. Mai 2018 um 15:41 geschrieben: >> >> >> On 05/22/2018 04:21 AM, Stefan Wahren wrote: >>> Currently there is no easy way to detect undervoltage conditions on a >>> remote Raspberry Pi. This hwmon driver retrieves the state of the >>> undervoltage sensor via mailbox interface. The handling based on >>> Noralf's modifications to the downstream firmware driver. In case of >>> an undervoltage condition only an entry is written to the kernel log. >>> >>> CC: "Noralf Trønnes" <noralf@tronnes.org> >>> Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com> >>> --- >>> Documentation/hwmon/raspberrypi-hwmon | 22 +++++ >>> drivers/hwmon/Kconfig | 10 ++ >>> drivers/hwmon/Makefile | 1 + >>> drivers/hwmon/raspberrypi-hwmon.c | 168 ++++++++++++++++++++++++++++++++++ >>> 4 files changed, 201 insertions(+) >>> create mode 100644 Documentation/hwmon/raspberrypi-hwmon >>> create mode 100644 drivers/hwmon/raspberrypi-hwmon.c >>> >>> diff --git a/Documentation/hwmon/raspberrypi-hwmon b/Documentation/hwmon/raspberrypi-hwmon >>> new file mode 100644 >>> index 0000000..3c92e2c >>> --- /dev/null >>> +++ b/Documentation/hwmon/raspberrypi-hwmon >>> @@ -0,0 +1,22 @@ >>> +Kernel driver raspberrypi-hwmon >>> +=============================== >>> + >>> +Supported boards: >>> + * Raspberry Pi A+ (via GPIO on SoC) >>> + * Raspberry Pi B+ (via GPIO on SoC) >>> + * Raspberry Pi 2 B (via GPIO on SoC) >>> + * Raspberry Pi 3 B (via GPIO on port expander) >>> + * Raspberry Pi 3 B+ (via PMIC) >>> + >>> +Author: Stefan Wahren <stefan.wahren@i2se.com> >>> + >>> +Description >>> +----------- >>> + >>> +This driver periodically polls a mailbox property of the VC4 firmware to detect >>> +undervoltage conditions. >>> + >>> +Sysfs entries >>> +------------- >>> + >>> +in0_lcrit_alarm Undervoltage alarm >>> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig >>> index 768aed5..9a5bdb0 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 RASPBERRYPI_FIRMWARE || COMPILE_TEST >>> + 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..6233e84 >>> --- /dev/null >>> +++ b/drivers/hwmon/raspberrypi-hwmon.c >>> @@ -0,0 +1,168 @@ >>> +// 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; >>> + >>> + data->fw = platform_get_drvdata(to_platform_device(dev->parent)); >>> + if (!data->fw) >>> + return -EPROBE_DEFER; >>> + >> >> I am a bit at loss here (and sorry I didn't bring this up before). >> How would this ever be possible, given that the driver is registered >> from the firmware driver ? > > Do you refer to the (wrong) return code, the assumption that the parent must be a platform driver or a possible race? > The return code is one thing. My question was how the driver would ever be instantiated with platform_get_drvdata(to_platform_device(dev->parent)) == NULL (but dev->parent != NULL), so I referred to the race. But, sure, a second question would be how that would indicate that the parent is not instantiated yet (which by itself seems like an odd question). Yet another question, as you point out, is why to use platform_get_drvdata(to_platform_device(dev->parent)) instead of dev_get_drvdata(dev->parent). Guenter >> >>> + ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_THROTTLED, >>> + &data->last_throttled, >>> + sizeof(data->last_throttled)); >>> + if (ret) >>> + 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 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"); >>> >> >
> Guenter Roeck <linux@roeck-us.net> hat am 22. Mai 2018 um 16:10 geschrieben: > > > On 05/22/2018 06:51 AM, Stefan Wahren wrote: > > Hi Guenter, > > > >> Guenter Roeck <linux@roeck-us.net> hat am 22. Mai 2018 um 15:41 geschrieben: > >> > >> > >> On 05/22/2018 04:21 AM, Stefan Wahren wrote: > >>> Currently there is no easy way to detect undervoltage conditions on a > >>> remote Raspberry Pi. This hwmon driver retrieves the state of the > >>> undervoltage sensor via mailbox interface. The handling based on > >>> Noralf's modifications to the downstream firmware driver. In case of > >>> an undervoltage condition only an entry is written to the kernel log. > >>> > >>> CC: "Noralf Trønnes" <noralf@tronnes.org> > >>> Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com> > >>> --- > >>> Documentation/hwmon/raspberrypi-hwmon | 22 +++++ > >>> drivers/hwmon/Kconfig | 10 ++ > >>> drivers/hwmon/Makefile | 1 + > >>> drivers/hwmon/raspberrypi-hwmon.c | 168 ++++++++++++++++++++++++++++++++++ > >>> 4 files changed, 201 insertions(+) > >>> create mode 100644 Documentation/hwmon/raspberrypi-hwmon > >>> create mode 100644 drivers/hwmon/raspberrypi-hwmon.c > >>> > >>> diff --git a/Documentation/hwmon/raspberrypi-hwmon b/Documentation/hwmon/raspberrypi-hwmon > >>> new file mode 100644 > >>> index 0000000..3c92e2c > >>> --- /dev/null > >>> +++ b/Documentation/hwmon/raspberrypi-hwmon > >>> @@ -0,0 +1,22 @@ > >>> +Kernel driver raspberrypi-hwmon > >>> +=============================== > >>> + > >>> +Supported boards: > >>> + * Raspberry Pi A+ (via GPIO on SoC) > >>> + * Raspberry Pi B+ (via GPIO on SoC) > >>> + * Raspberry Pi 2 B (via GPIO on SoC) > >>> + * Raspberry Pi 3 B (via GPIO on port expander) > >>> + * Raspberry Pi 3 B+ (via PMIC) > >>> + > >>> +Author: Stefan Wahren <stefan.wahren@i2se.com> > >>> + > >>> +Description > >>> +----------- > >>> + > >>> +This driver periodically polls a mailbox property of the VC4 firmware to detect > >>> +undervoltage conditions. > >>> + > >>> +Sysfs entries > >>> +------------- > >>> + > >>> +in0_lcrit_alarm Undervoltage alarm > >>> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig > >>> index 768aed5..9a5bdb0 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 RASPBERRYPI_FIRMWARE || COMPILE_TEST > >>> + 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..6233e84 > >>> --- /dev/null > >>> +++ b/drivers/hwmon/raspberrypi-hwmon.c > >>> @@ -0,0 +1,168 @@ > >>> +// 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; > >>> + > >>> + data->fw = platform_get_drvdata(to_platform_device(dev->parent)); > >>> + if (!data->fw) > >>> + return -EPROBE_DEFER; > >>> + > >> > >> I am a bit at loss here (and sorry I didn't bring this up before). > >> How would this ever be possible, given that the driver is registered > >> from the firmware driver ? > > > > Do you refer to the (wrong) return code, the assumption that the parent must be a platform driver or a possible race? > > > > The return code is one thing. My question was how the driver would ever be instantiated > with platform_get_drvdata(to_platform_device(dev->parent)) == NULL (but dev->parent != NULL), > so I referred to the race. But, sure, a second question would be how that would indicate > that the parent is not instantiated yet (which by itself seems like an odd question). This shouldn't happen and worth a log error. In patch #3 the registration is called after the complete private data of the firmware driver is initialized. Did i missed something? But i must confess that i didn't test all builtin/module combinations. > > Yet another question, as you point out, is why to use platform_get_drvdata(to_platform_device(dev->parent)) > instead of dev_get_drvdata(dev->parent). Sure this is much simpler Thanks Stefan
On 22/05/18 20:31, Stefan Wahren wrote: [...] >>>>> +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; >>>>> + >>>>> + data->fw = platform_get_drvdata(to_platform_device(dev->parent)); >>>>> + if (!data->fw) >>>>> + return -EPROBE_DEFER; >>>>> + >>>> >>>> I am a bit at loss here (and sorry I didn't bring this up before). >>>> How would this ever be possible, given that the driver is registered >>>> from the firmware driver ? >>> >>> Do you refer to the (wrong) return code, the assumption that the parent must be a platform driver or a possible race? >>> >> >> The return code is one thing. My question was how the driver would ever be instantiated >> with platform_get_drvdata(to_platform_device(dev->parent)) == NULL (but dev->parent != NULL), >> so I referred to the race. But, sure, a second question would be how that would indicate >> that the parent is not instantiated yet (which by itself seems like an odd question). > > This shouldn't happen and worth a log error. In patch #3 the registration is called after the complete private data of the firmware driver is initialized. Did i missed something? > > But i must confess that i didn't test all builtin/module combinations. The point is that, by construction, a "raspberrypi-hwmon" device will only ever be created for this driver to bind to if the firmware device is both fully initialised and known to support the GET_THROTTLED call already. Thus trying to check those again from the hwmon driver is at best pointless, and at worst misleading. If somebody *does* manage to bind this driver to some random inappropriate device, you've still got no guarantee that dev->parent is valid or that dev_get_drvdata(dev->parent)) won't return something non-NULL that isn't a struct rpi_firmware pointer, at which point you're liable to pass the paranoid check yet still crash anyway. IOW, you can't reasonably defend against incorrect operation, and under correct operation there's nothing to defend against, so either way it's pretty futile to waste effort trying. Robin.
On Wed, May 23, 2018 at 01:12:10PM +0100, Robin Murphy wrote: > On 22/05/18 20:31, Stefan Wahren wrote: > [...] > >>>>>+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; > >>>>>+ > >>>>>+ data->fw = platform_get_drvdata(to_platform_device(dev->parent)); > >>>>>+ if (!data->fw) > >>>>>+ return -EPROBE_DEFER; > >>>>>+ > >>>> > >>>>I am a bit at loss here (and sorry I didn't bring this up before). > >>>>How would this ever be possible, given that the driver is registered > >>>>from the firmware driver ? > >>> > >>>Do you refer to the (wrong) return code, the assumption that the parent must be a platform driver or a possible race? > >>> > >> > >>The return code is one thing. My question was how the driver would ever be instantiated > >>with platform_get_drvdata(to_platform_device(dev->parent)) == NULL (but dev->parent != NULL), > >>so I referred to the race. But, sure, a second question would be how that would indicate > >>that the parent is not instantiated yet (which by itself seems like an odd question). > > > >This shouldn't happen and worth a log error. In patch #3 the registration is called after the complete private data of the firmware driver is initialized. Did i missed something? > > > >But i must confess that i didn't test all builtin/module combinations. > > The point is that, by construction, a "raspberrypi-hwmon" device will only > ever be created for this driver to bind to if the firmware device is both > fully initialised and known to support the GET_THROTTLED call already. Thus > trying to check those again from the hwmon driver is at best pointless, and > at worst misleading. If somebody *does* manage to bind this driver to some > random inappropriate device, you've still got no guarantee that dev->parent > is valid or that dev_get_drvdata(dev->parent)) won't return something > non-NULL that isn't a struct rpi_firmware pointer, at which point you're > liable to pass the paranoid check yet still crash anyway. > > IOW, you can't reasonably defend against incorrect operation, and under > correct operation there's nothing to defend against, so either way it's > pretty futile to waste effort trying. > Well said. Guenter
diff --git a/Documentation/hwmon/raspberrypi-hwmon b/Documentation/hwmon/raspberrypi-hwmon new file mode 100644 index 0000000..3c92e2c --- /dev/null +++ b/Documentation/hwmon/raspberrypi-hwmon @@ -0,0 +1,22 @@ +Kernel driver raspberrypi-hwmon +=============================== + +Supported boards: + * Raspberry Pi A+ (via GPIO on SoC) + * Raspberry Pi B+ (via GPIO on SoC) + * Raspberry Pi 2 B (via GPIO on SoC) + * Raspberry Pi 3 B (via GPIO on port expander) + * Raspberry Pi 3 B+ (via PMIC) + +Author: Stefan Wahren <stefan.wahren@i2se.com> + +Description +----------- + +This driver periodically polls a mailbox property of the VC4 firmware to detect +undervoltage conditions. + +Sysfs entries +------------- + +in0_lcrit_alarm Undervoltage alarm diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig index 768aed5..9a5bdb0 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 RASPBERRYPI_FIRMWARE || COMPILE_TEST + 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..6233e84 --- /dev/null +++ b/drivers/hwmon/raspberrypi-hwmon.c @@ -0,0 +1,168 @@ +// 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; + + data->fw = platform_get_drvdata(to_platform_device(dev->parent)); + 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) + 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 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");
Currently there is no easy way to detect undervoltage conditions on a remote Raspberry Pi. This hwmon driver retrieves the state of the undervoltage sensor via mailbox interface. The handling based on Noralf's modifications to the downstream firmware driver. In case of an undervoltage condition only an entry is written to the kernel log. CC: "Noralf Trønnes" <noralf@tronnes.org> Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com> --- Documentation/hwmon/raspberrypi-hwmon | 22 +++++ drivers/hwmon/Kconfig | 10 ++ drivers/hwmon/Makefile | 1 + drivers/hwmon/raspberrypi-hwmon.c | 168 ++++++++++++++++++++++++++++++++++ 4 files changed, 201 insertions(+) create mode 100644 Documentation/hwmon/raspberrypi-hwmon create mode 100644 drivers/hwmon/raspberrypi-hwmon.c