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
+
#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__ */
--
2.4.3
--
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