On Mon, 2015-08-17 at 16:52 -0700, Srinivas Pandruvada wrote:
> The only method to read temperature of a thermal zone is by reading sysfs
> entry "temp". This works well when kernel is primarily doing thermal
> control and user mode tools/applications are reading temperature for
> display or debug purposes. But when user mode is doing primary thermal
> control using a "user space" governor, this model causes performance
> issues and have limitations. For example Linux thermal daemon or Intel®
> Dynamic Platform and Thermal Framework (DPTF) for Chromium/Chrome OS are
> currently used as user space thermal controllers in several products.
> We have platforms with 10+ thermal sensors and thermal conditions are not
> an isolated cases, so it is important to manage thermal conditions without
> significantly degrading user experience. So we need an efficient way to
> read temperature and events, by
> - Not using polling from user space
> - Avoid sysfs string read for temperature and convert to decimal
> - Push model, so that driver can push changes when some temperature
> change event occurs, which needs attention
> - Let user space registers for some thresholds without using some
> passive trips
> - Avoid string based kobject uevent notifications
> - Able to use different external trigger (data ready indications) and push
> temperature samples
>
> There are some ways to achieve this using thermal sysfs 2.0, but still
> doesn't meet all requirements and will introduce backward compatibility
> issues. Other option is to enhance thermal sysfs by adding a sensor
> abstractions and providing a dev interface for poll/select. But since
> since Linux IIO already provides above capabilities, it is better we
> reuse IIO temperature sensor device. This change proposes use of IIO
> temperature sensor device for a thermal zone. Here IIO capabilities
> of triggered buffer and events are utilized.
>
> The iio device created during call to thermal_zone_device_register.
> Samples are pushed to iio buffers when thermal_zone_device_update is
> called from client drivers and user space governor is selected for the
> thermal zone. Only two additional callbacks for client driver to get/set
> thermal temperature thresholds.
>
> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx>
> ---
> drivers/thermal/Kconfig | 11 ++
> drivers/thermal/Makefile | 1 +
> drivers/thermal/thermal_core.c | 9 +-
> drivers/thermal/thermal_iio.c | 333 +++++++++++++++++++++++++++++++++++++++++
> drivers/thermal/user_space.c | 1 +
> include/linux/thermal.h | 46 ++++++
> 6 files changed, 399 insertions(+), 2 deletions(-)
> create mode 100644 drivers/thermal/thermal_iio.c
>
> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
> index 118938e..0ea9d8b 100644
> --- a/drivers/thermal/Kconfig
> +++ b/drivers/thermal/Kconfig
> @@ -29,6 +29,17 @@ config THERMAL_HWMON
> Say 'Y' here if you want all thermal sensors to
> have hwmon sysfs interface too.
>
> +config THERMAL_IIO
> + tristate "Thermal sensor from a zone as IIO device"
> + select IIO
> + select IIO_BUFFER
> + select IIO_TRIGGERED_BUFFER
> + help
> + This will register thermal sensor in a zone as an IIO temperature
> + sensor device.
> + This will help user space thermal controllers to use IIO ABI to
> + get events and buffered acces to temperature samples.
> +
> config THERMAL_OF
> bool
> prompt "APIs to parse thermal data out of device tree"
> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
> index 535dfee..4b42734 100644
> --- a/drivers/thermal/Makefile
> +++ b/drivers/thermal/Makefile
> @@ -7,6 +7,7 @@ thermal_sys-y += thermal_core.o
>
> # interface to/from other layers providing sensors
> thermal_sys-$(CONFIG_THERMAL_HWMON) += thermal_hwmon.o
> +thermal_sys-$(CONFIG_THERMAL_IIO) += thermal_iio.o
> thermal_sys-$(CONFIG_THERMAL_OF) += of-thermal.o
>
> # governors
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index 04659bf..483a4a1 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -1833,10 +1833,15 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
>
> mutex_unlock(&thermal_governor_lock);
>
> + if (thermal_iio_sensor_register(tz))
> + goto unregister;
> +
> if (!tz->tzp || !tz->tzp->no_hwmon) {
> result = thermal_add_hwmon_sysfs(tz);
> - if (result)
> + if (result) {
> + thermal_iio_sensor_unregister(tz);
> goto unregister;
> + }
> }
>
> mutex_lock(&thermal_list_lock);
> @@ -1919,7 +1924,7 @@ void thermal_zone_device_unregister(struct thermal_zone_device *tz)
> device_remove_file(&tz->device, &dev_attr_policy);
> remove_trip_attrs(tz);
> thermal_set_governor(tz, NULL);
> -
> + thermal_iio_sensor_unregister(tz);
> thermal_remove_hwmon_sysfs(tz);
> release_idr(&thermal_tz_idr, &thermal_idr_lock, tz->id);
> idr_destroy(&tz->idr);
> diff --git a/drivers/thermal/thermal_iio.c b/drivers/thermal/thermal_iio.c
> new file mode 100644
> index 0000000..e36ad90
> --- /dev/null
> +++ b/drivers/thermal/thermal_iio.c
> @@ -0,0 +1,333 @@
> +/*
> + * thermal iio interface driver
> + * Copyright (c) 2015, Intel Corporation.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + */
> +
> +#include <linux/thermal.h>
> +
> +struct thermal_iio_data {
> + struct thermal_zone_device *tz;
> + struct iio_trigger *dready_trig;
> + s16 buffer[8];
> + bool enable;
> + long temp_thres;
> + bool ev_enable_state;
> + struct mutex mutex;
> +
> +};
> +
> +static const struct iio_event_spec thermal_event = {
> + .type = IIO_EV_TYPE_THRESH,
> + .dir = IIO_EV_DIR_EITHER,
> + .mask_separate = BIT(IIO_EV_INFO_VALUE) |
> + BIT(IIO_EV_INFO_ENABLE)
> +};
> +
> +#define THERMAL_TEMP_CHANNELS { \
> + { \
> + .type = IIO_TEMP, \
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> + .scan_index = 0, \
> + .scan_type = { \
> + .sign = 'u', \
> + .realbits = 32, \
> + .storagebits = 32, \
> + .shift = 0, \
> + .endianness = IIO_CPU, \
> + }, \
> + .event_spec = &thermal_event, \
> + .num_event_specs = 1 \
> + }, \
> +}
> +
> +static const struct iio_chan_spec thermal_iio_channels[] =
> + THERMAL_TEMP_CHANNELS;
> +
> +static int thermal_iio_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long mask)
> +{
> + struct thermal_iio_data *iio_data = iio_priv(indio_dev);
> + long temp;
> + int ret;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + ret = thermal_zone_get_temp(iio_data->tz, &temp);
> + if (ret)
> + return ret;
> + *val = (int) temp;
> + return IIO_VAL_INT;
> + default:
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +static irqreturn_t thermal_trigger_handler(int irq, void *p)
> +{
> + struct iio_poll_func *pf = p;
> + struct iio_dev *indio_dev = pf->indio_dev;
> + struct thermal_iio_data *iio_data = iio_priv(indio_dev);
> + long temp;
> + int ret;
> +
> + ret = thermal_zone_get_temp(iio_data->tz, &temp);
> + if (ret)
> + goto err_read;
> +
> + *(s32 *)iio_data->buffer = (s32)temp;
> + iio_push_to_buffers(indio_dev, iio_data->buffer);
> +err_read:
> + iio_trigger_notify_done(indio_dev->trig);
> + return IRQ_HANDLED;
> +}
> +
> +static int thermal_data_rdy_trigger_set_state(struct iio_trigger *trig,
> + bool state)
> +{
> + struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
> + struct thermal_iio_data *iio_data = iio_priv(indio_dev);
> +
> + mutex_lock(&iio_data->mutex);
> + iio_data->enable = state;
> + mutex_unlock(&iio_data->mutex);
> +
> + return 0;
> +}
> +
> +static const struct iio_trigger_ops thermal_trigger_ops = {
> + .set_trigger_state = thermal_data_rdy_trigger_set_state,
> + .owner = THIS_MODULE,
> +};
> +
> +static int thermal_iio_read_event(struct iio_dev *indio_dev,
> + const struct iio_chan_spec *chan,
> + enum iio_event_type type,
> + enum iio_event_direction dir,
> + enum iio_event_info info,
> + int *val, int *val2)
> +{
> + struct thermal_iio_data *iio_data = iio_priv(indio_dev);
> + int ret;
> +
> + mutex_lock(&iio_data->mutex);
> + *val2 = 0;
> + switch (info) {
> + case IIO_EV_INFO_VALUE:
> + *val = iio_data->temp_thres;
> + ret = IIO_VAL_INT;
> + break;
> + default:
> + ret = -EINVAL;
> + break;
> + }
> + mutex_unlock(&iio_data->mutex);
> +
> + return ret;
> +}
> +
> +static int thermal_iio_write_event(struct iio_dev *indio_dev,
> + const struct iio_chan_spec *chan,
> + enum iio_event_type type,
> + enum iio_event_direction dir,
> + enum iio_event_info info,
> + int val, int val2)
> +{
> + struct thermal_iio_data *iio_data = iio_priv(indio_dev);
> + int ret = 0;
> +
> + mutex_lock(&iio_data->mutex);
> + if (iio_data->ev_enable_state) {
> + ret = -EBUSY;
> + goto done_write_event;
> + }
> + switch (info) {
> + case IIO_EV_INFO_VALUE:
> + iio_data->temp_thres = val;
> + break;
> + default:
> + ret = -EINVAL;
> + break;
> + }
> +done_write_event:
> + mutex_unlock(&iio_data->mutex);
> +
> + return ret;
> +}
> +
> +static int thermal_iio_read_event_config(struct iio_dev *indio_dev,
> + const struct iio_chan_spec *chan,
> + enum iio_event_type type,
> + enum iio_event_direction dir)
> +{
> +
> + struct thermal_iio_data *iio_data = iio_priv(indio_dev);
> + bool state;
> +
> + mutex_lock(&iio_data->mutex);
> + state = iio_data->ev_enable_state;
> + mutex_unlock(&iio_data->mutex);
> +
> + return state;
> +}
> +
> +static int thermal_iio_write_event_config(struct iio_dev *indio_dev,
> + const struct iio_chan_spec *chan,
> + enum iio_event_type type,
> + enum iio_event_direction dir,
> + int state)
> +{
> + struct thermal_iio_data *iio_data = iio_priv(indio_dev);
> + int ret = 0;
> +
> + mutex_lock(&iio_data->mutex);
> + if (state && iio_data->ev_enable_state)
> + goto done_write_event;
> +
> + if (iio_data->tz->ops->set_threshold_temp)
> + ret = iio_data->tz->ops->set_threshold_temp(iio_data->tz, 0,
> + iio_data->temp_thres);
> + iio_data->ev_enable_state = state;
> +
> +done_write_event:
> + mutex_unlock(&iio_data->mutex);
> +
> + return ret;
> +}
> +
> +static const struct iio_info thermal_iio_info = {
> + .read_raw = thermal_iio_read_raw,
> + .read_event_value = thermal_iio_read_event,
> + .write_event_value = thermal_iio_write_event,
> + .write_event_config = thermal_iio_write_event_config,
> + .read_event_config = thermal_iio_read_event_config,
> + .driver_module = THIS_MODULE,
> +};
> +
> +int thermal_iio_sensor_register(struct thermal_zone_device *tz)
> +{
> + struct thermal_iio_data *iio_data;
> + int ret;
> +
> + tz->indio_dev = devm_iio_device_alloc(&tz->device, sizeof(*iio_data));
> + if (!tz->indio_dev)
> + return -ENOMEM;
> +
> + iio_data = iio_priv(tz->indio_dev);
> + iio_data->tz = tz;
> + mutex_init(&iio_data->mutex);
> +
> + tz->indio_dev->dev.parent = &tz->device;
> + tz->indio_dev->channels = thermal_iio_channels;
> + tz->indio_dev->num_channels = ARRAY_SIZE(thermal_iio_channels);
> + tz->indio_dev->name = tz->type;
> + tz->indio_dev->info = &thermal_iio_info;
> + tz->indio_dev->modes = INDIO_DIRECT_MODE;
> +
> + iio_data->dready_trig = devm_iio_trigger_alloc(&tz->device, "%s-dev%d",
> + tz->type,
> + tz->indio_dev->id);
> + if (iio_data->dready_trig == NULL) {
> + dev_err(&tz->device, "Trigger Allocate Failed\n");
> + return -ENOMEM;
> + }
> +
> + iio_data->dready_trig->dev.parent = &tz->device;
> + iio_data->dready_trig->ops = &thermal_trigger_ops;
> + iio_trigger_set_drvdata(iio_data->dready_trig, tz->indio_dev);
> + tz->indio_dev->trig = iio_data->dready_trig;
> + iio_trigger_get(tz->indio_dev->trig);
> + ret = iio_trigger_register(iio_data->dready_trig);
> + if (ret) {
> + dev_err(&tz->device, "Trigger Allocate Failed\n");
> + return ret;
> + }
> +
> + ret = iio_triggered_buffer_setup(tz->indio_dev,
> + &iio_pollfunc_store_time,
> + thermal_trigger_handler, NULL);
> + if (ret) {
> + dev_err(&tz->device, "failed to initialize trigger buffer\n");
> + goto err_unreg_trig;
> + }
> +
> + ret = iio_device_register(tz->indio_dev);
> + if (ret < 0) {
> + dev_err(&tz->device, "unable to register iio device\n");
> + goto err_cleanup_trig;
> + }
> +
> + return 0;
> +
> +err_cleanup_trig:
> + iio_triggered_buffer_cleanup(tz->indio_dev);
> +err_unreg_trig:
> + iio_device_unregister(tz->indio_dev);
> +
> + return ret;
> +}
> +
> +int thermal_iio_sensor_unregister(struct thermal_zone_device *tz)
> +{
> + struct thermal_iio_data *iio_data = iio_priv(tz->indio_dev);
> +
> + iio_device_unregister(tz->indio_dev);
> + iio_triggered_buffer_cleanup(tz->indio_dev);
> + iio_trigger_unregister(iio_data->dready_trig);
> +
> + return 0;
> +}
> +
> +#define IIO_EVENT_CODE_THERMAL_THRES IIO_UNMOD_EVENT_CODE(IIO_TEMP, 0,\
> + IIO_EV_TYPE_THRESH,\
> + IIO_EV_DIR_EITHER)
> +
> +#define IIO_EVENT_CODE_TRIP_UPDATE IIO_UNMOD_EVENT_CODE(IIO_TEMP, 0,\
> + IIO_EV_TYPE_CHANGE,\
> + IIO_EV_DIR_NONE)
> +
> +int thermal_iio_sensor_notify(struct thermal_zone_device *tz,
> + enum thermal_zone_event_type event)
> +{
> + struct thermal_iio_data *iio_data = iio_priv(tz->indio_dev);
> + long temp = 0;
> + int ret;
> +
> + mutex_lock(&iio_data->mutex);
> + if (iio_data->ev_enable_state) {
> + if (event == THERMAL_TEMP_THRESHOLD)
> + iio_push_event(tz->indio_dev,
> + IIO_EVENT_CODE_THERMAL_THRES,
> + iio_get_time_ns());
> + else if (event == THERMAL_TRIP_UPDATE)
> + iio_push_event(tz->indio_dev,
> + IIO_EVENT_CODE_TRIP_UPDATE,
> + iio_get_time_ns());
> + else
> + dev_err(&tz->device, "invalid event\n");
> + }
> + if (iio_data->enable) {
> + ret = thermal_zone_get_temp(iio_data->tz, &temp);
> + if (ret)
> + goto err_read;
> + *(u32 *)iio_data->buffer = (u32)temp;
> + iio_push_to_buffers(tz->indio_dev, iio_data->buffer);
> + }
> + mutex_unlock(&iio_data->mutex);
> +
> + return 0;
> +err_read:
> + mutex_unlock(&iio_data->mutex);
> + return ret;
> +}
> diff --git a/drivers/thermal/user_space.c b/drivers/thermal/user_space.c
> index 10adcdd..742adec 100644
> --- a/drivers/thermal/user_space.c
> +++ b/drivers/thermal/user_space.c
> @@ -34,6 +34,7 @@
> */
> static int notify_user_space(struct thermal_zone_device *tz, int trip)
> {
> + thermal_iio_sensor_notify(tz, THERMAL_TEMP_THRESHOLD);
> mutex_lock(&tz->lock);
> kobject_uevent(&tz->device.kobj, KOBJ_CHANGE);
> mutex_unlock(&tz->lock);
> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> index 037e9df..4c4c487 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -31,6 +31,16 @@
> #include <linux/workqueue.h>
> #include <uapi/linux/thermal.h>
>
> +#if IS_ENABLED(CONFIG_THERMAL_IIO)
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/trigger.h>
> +#include <linux/iio/events.h>
> +#include <linux/iio/trigger_consumer.h>
> +#include <linux/iio/triggered_buffer.h>
> +#endif
> +
IMO, we only need to reference linux/iio/iio.h in this header, all the
others should be moved to drivers/thermal/thermal_iio.c.
Plus, I'm curious why iio subsystem has so many different external
headers for driver to reference.
thanks,
rui
> #define THERMAL_TRIPS_NONE -1
> #define THERMAL_MAX_TRIPS 12
>
> @@ -111,6 +121,10 @@ struct thermal_zone_device_ops {
> int (*set_emul_temp) (struct thermal_zone_device *, unsigned long);
> int (*get_trend) (struct thermal_zone_device *, int,
> enum thermal_trend *);
> + int (*get_threshold_temp)(struct thermal_zone_device *, int,
> + unsigned long *);
> + int (*set_threshold_temp)(struct thermal_zone_device *, int,
> + unsigned long);
> int (*notify) (struct thermal_zone_device *, int,
> enum thermal_trip_type);
> };
> @@ -205,6 +219,9 @@ struct thermal_zone_device {
> struct mutex lock;
> struct list_head node;
> struct delayed_work poll_queue;
> +#ifdef CONFIG_THERMAL_IIO
> + struct iio_dev *indio_dev;
> +#endif
> };
>
> /**
> @@ -483,4 +500,33 @@ static inline int thermal_generate_netlink_event(struct thermal_zone_device *tz,
> }
> #endif
>
> +enum thermal_zone_event_type {
> + THERMAL_TEMP_THRESHOLD,
> + THERMAL_TRIP_UPDATE,
> + THERMAL_EVENT_TYPE_MAX,
> +};
> +
> +#if IS_ENABLED(CONFIG_THERMAL) && IS_ENABLED(CONFIG_THERMAL_IIO)
> +int thermal_iio_sensor_register(struct thermal_zone_device *tz);
> +int thermal_iio_sensor_unregister(struct thermal_zone_device *tz);
> +int thermal_iio_sensor_notify(struct thermal_zone_device *tz,
> + enum thermal_zone_event_type event);
> +#else
> +static int thermal_iio_sensor_register(struct thermal_zone_device *tz)
> +{
> + return 0;
> +}
> +
> +static int thermal_iio_sensor_unregister(struct thermal_zone_device *tz)
> +{
> + return 0;
> +}
> +
> +static int thermal_iio_sensor_notify(struct thermal_zone_device *tz
> + enum thermal_zone_event_type event)
> +{
> + return 0;
> +}
> +#endif
> +
> #endif /* __THERMAL_H__ */
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