Input: add support for polling to input devices

Separating "normal" and "polled" input devices was a mistake, as often we
want to allow the very same device work on both interrupt-driven and
polled mode, depending on the board on which the device is used.

This introduces new APIs:

- input_setup_polling
- input_set_poll_interval
- input_set_min_poll_interval
- input_set_max_poll_interval

These new APIs allow switching an input device into polled mode with sysfs
attributes matching drivers using input_polled_dev APIs that will be
eventually removed.

Tested-by: Michal Vokáč <michal.vokac@ysoft.com>
Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/drivers/input/Makefile b/drivers/input/Makefile
index 40de6a7..e356509 100644 (file)
--- a/drivers/input/Makefile
+++ b/drivers/input/Makefile
@@ -6,7 +6,7 @@
 # Each configuration option enables a list of files.
 
 obj-$(CONFIG_INPUT)            += input-core.o
-input-core-y := input.o input-compat.o input-mt.o ff-core.o
+input-core-y := input.o input-compat.o input-mt.o input-poller.o ff-core.o
 
 obj-$(CONFIG_INPUT_FF_MEMLESS) += ff-memless.o
 obj-$(CONFIG_INPUT_POLLDEV)    += input-polldev.o

diff --git a/drivers/input/input-poller.c b/drivers/input/input-poller.c
new file mode 100644 (file)
index 0000000..1b3d289
--- /dev/null
+++ b/drivers/input/input-poller.c
@@ -0,0 +1,213 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Support for polling mode for input devices.
+ */
+
+#include <linux/device.h>
+#include <linux/input.h>
+#include <linux/jiffies.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/workqueue.h>
+#include "input-poller.h"
+
+struct input_dev_poller {
+       void (*poll)(struct input_dev *dev);
+
+       unsigned int poll_interval; /* msec */
+       unsigned int poll_interval_max; /* msec */
+       unsigned int poll_interval_min; /* msec */
+
+       struct input_dev *input;
+       struct delayed_work work;
+};
+
+static void input_dev_poller_queue_work(struct input_dev_poller *poller)
+{
+       unsigned long delay;
+
+       delay = msecs_to_jiffies(poller->poll_interval);
+       if (delay >= HZ)
+               delay = round_jiffies_relative(delay);
+
+       queue_delayed_work(system_freezable_wq, &poller->work, delay);
+}
+
+static void input_dev_poller_work(struct work_struct *work)
+{
+       struct input_dev_poller *poller =
+               container_of(work, struct input_dev_poller, work.work);
+
+       poller->poll(poller->input);
+       input_dev_poller_queue_work(poller);
+}
+
+void input_dev_poller_finalize(struct input_dev_poller *poller)
+{
+       if (!poller->poll_interval)
+               poller->poll_interval = 500;
+       if (!poller->poll_interval_max)
+               poller->poll_interval_max = poller->poll_interval;
+}
+
+void input_dev_poller_start(struct input_dev_poller *poller)
+{
+       /* Only start polling if polling is enabled */
+       if (poller->poll_interval > 0) {
+               poller->poll(poller->input);
+               input_dev_poller_queue_work(poller);
+       }
+}
+
+void input_dev_poller_stop(struct input_dev_poller *poller)
+{
+       cancel_delayed_work_sync(&poller->work);
+}
+
+int input_setup_polling(struct input_dev *dev,
+                       void (*poll_fn)(struct input_dev *dev))
+{
+       struct input_dev_poller *poller;
+
+       poller = kzalloc(sizeof(*poller), GFP_KERNEL);
+       if (!poller) {
+               /*
+                * We want to show message even though kzalloc() may have
+                * printed backtrace as knowing what instance of input
+                * device we were dealing with is helpful.
+                */
+               dev_err(dev->dev.parent ?: &dev->dev,
+                       "%s: unable to allocate poller structure\n", __func__);
+               return -ENOMEM;
+       }
+
+       INIT_DELAYED_WORK(&poller->work, input_dev_poller_work);
+       poller->input = dev;
+       poller->poll = poll_fn;
+
+       dev->poller = poller;
+       return 0;
+}
+EXPORT_SYMBOL(input_setup_polling);
+
+static bool input_dev_ensure_poller(struct input_dev *dev)
+{
+       if (!dev->poller) {
+               dev_err(dev->dev.parent ?: &dev->dev,
+                       "poller structure has not been set up\n");
+               return false;
+       }
+
+       return true;
+}
+
+void input_set_poll_interval(struct input_dev *dev, unsigned int interval)
+{
+       if (input_dev_ensure_poller(dev))
+               dev->poller->poll_interval = interval;
+}
+EXPORT_SYMBOL(input_set_poll_interval);
+
+void input_set_min_poll_interval(struct input_dev *dev, unsigned int interval)
+{
+       if (input_dev_ensure_poller(dev))
+               dev->poller->poll_interval_min = interval;
+}
+EXPORT_SYMBOL(input_set_min_poll_interval);
+
+void input_set_max_poll_interval(struct input_dev *dev, unsigned int interval)
+{
+       if (input_dev_ensure_poller(dev))
+               dev->poller->poll_interval_max = interval;
+}
+EXPORT_SYMBOL(input_set_max_poll_interval);
+
+/* SYSFS interface */
+
+static ssize_t input_dev_get_poll_interval(struct device *dev,
+                                          struct device_attribute *attr,
+                                          char *buf)
+{
+       struct input_dev *input = to_input_dev(dev);
+
+       return sprintf(buf, "%d\n", input->poller->poll_interval);
+}
+
+static ssize_t input_dev_set_poll_interval(struct device *dev,
+                                          struct device_attribute *attr,
+                                          const char *buf, size_t count)
+{
+       struct input_dev *input = to_input_dev(dev);
+       struct input_dev_poller *poller = input->poller;
+       unsigned int interval;
+       int err;
+
+       err = kstrtouint(buf, 0, &interval);
+       if (err)
+               return err;
+
+       if (interval < poller->poll_interval_min)
+               return -EINVAL;
+
+       if (interval > poller->poll_interval_max)
+               return -EINVAL;
+
+       mutex_lock(&input->mutex);
+
+       poller->poll_interval = interval;
+
+       if (input->users) {
+               cancel_delayed_work_sync(&poller->work);
+               if (poller->poll_interval > 0)
+                       input_dev_poller_queue_work(poller);
+       }
+
+       mutex_unlock(&input->mutex);
+
+       return count;
+}
+
+static DEVICE_ATTR(poll, 0644,
+                  input_dev_get_poll_interval, input_dev_set_poll_interval);
+
+static ssize_t input_dev_get_poll_max(struct device *dev,
+                                     struct device_attribute *attr, char *buf)
+{
+       struct input_dev *input = to_input_dev(dev);
+
+       return sprintf(buf, "%d\n", input->poller->poll_interval_max);
+}
+
+static DEVICE_ATTR(max, 0444, input_dev_get_poll_max, NULL);
+
+static ssize_t input_dev_get_poll_min(struct device *dev,
+                                    struct device_attribute *attr, char *buf)
+{
+       struct input_dev *input = to_input_dev(dev);
+
+       return sprintf(buf, "%d\n", input->poller->poll_interval_min);
+}
+
+static DEVICE_ATTR(min, 0444, input_dev_get_poll_min, NULL);
+
+static umode_t input_poller_attrs_visible(struct kobject *kobj,
+                                         struct attribute *attr, int n)
+{
+       struct device *dev = kobj_to_dev(kobj);
+       struct input_dev *input = to_input_dev(dev);
+
+       return input->poller ? attr->mode : 0;
+}
+
+static struct attribute *input_poller_attrs[] = {
+       &dev_attr_poll.attr,
+       &dev_attr_max.attr,
+       &dev_attr_min.attr,
+       NULL
+};
+
+struct attribute_group input_poller_attribute_group = {
+       .is_visible     = input_poller_attrs_visible,
+       .attrs          = input_poller_attrs,
+};

diff --git a/drivers/input/input-poller.h b/drivers/input/input-poller.h
new file mode 100644 (file)
index 0000000..e3fca0b
--- /dev/null
+++ b/drivers/input/input-poller.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _INPUT_POLLER_H
+#define _INPUT_POLLER_H
+
+/*
+ * Support for polling mode for input devices.
+ */
+#include <linux/sysfs.h>
+
+struct input_dev_poller;
+
+void input_dev_poller_finalize(struct input_dev_poller *poller);
+void input_dev_poller_start(struct input_dev_poller *poller);
+void input_dev_poller_stop(struct input_dev_poller *poller);
+
+extern struct attribute_group input_poller_attribute_group;
+
+#endif /* _INPUT_POLLER_H */

diff --git a/drivers/input/input.c b/drivers/input/input.c
index 7494a0d..c08aa35 100644 (file)
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -24,6 +24,7 @@
 #include <linux/mutex.h>
 #include <linux/rcupdate.h>
 #include "input-compat.h"
+#include "input-poller.h"
 
 MODULE_AUTHOR("Vojtech Pavlik <vojtech@suse.cz>");
 MODULE_DESCRIPTION("Input core");
@@ -603,20 +604,31 @@ int input_open_device(struct input_handle *handle)
 
        handle->open++;
 
-       if (!dev->users++ && dev->open)
-               retval = dev->open(dev);
+       if (dev->users++) {
+               /*
+                * Device is already opened, so we can exit immediately and
+                * report success.
+                */
+               goto out;
+       }
 
-       if (retval) {
-               dev->users--;
-               if (!--handle->open) {
+       if (dev->open) {
+               retval = dev->open(dev);
+               if (retval) {
+                       dev->users--;
+                       handle->open--;
                        /*
                         * Make sure we are not delivering any more events
                         * through this handle
                         */
                        synchronize_rcu();
+                       goto out;
                }
        }
 
+       if (dev->poller)
+               input_dev_poller_start(dev->poller);
+
  out:
        mutex_unlock(&dev->mutex);
        return retval;
@@ -655,8 +667,13 @@ void input_close_device(struct input_handle *handle)
 
        __input_release_device(handle);
 
-       if (!--dev->users && dev->close)
-               dev->close(dev);
+       if (!--dev->users) {
+               if (dev->poller)
+                       input_dev_poller_stop(dev->poller);
+
+               if (dev->close)
+                       dev->close(dev);
+       }
 
        if (!--handle->open) {
                /*
@@ -1502,6 +1519,7 @@ static const struct attribute_group *input_dev_attr_groups[] = {
        &input_dev_attr_group,
        &input_dev_id_attr_group,
        &input_dev_caps_attr_group,
+       &input_poller_attribute_group,
        NULL
 };
 
@@ -1511,6 +1529,7 @@ static void input_dev_release(struct device *device)
 
        input_ff_destroy(dev);
        input_mt_destroy_slots(dev);
+       kfree(dev->poller);
        kfree(dev->absinfo);
        kfree(dev->vals);
        kfree(dev);
@@ -2175,6 +2194,9 @@ int input_register_device(struct input_dev *dev)
        if (!dev->setkeycode)
                dev->setkeycode = input_default_setkeycode;
 
+       if (dev->poller)
+               input_dev_poller_finalize(dev->poller);
+
        error = device_add(&dev->dev);
        if (error)
                goto err_free_vals;

diff --git a/include/linux/input.h b/include/linux/input.h
index e95a439..94f277c 100644 (file)
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -21,6 +21,8 @@
 #include <linux/timer.h>
 #include <linux/mod_devicetable.h>
 
+struct input_dev_poller;
+
 /**
  * struct input_value - input value representation
  * @type: type of value (EV_KEY, EV_ABS, etc)
@@ -71,6 +73,8 @@ enum input_clock_type {
  *     not sleep
  * @ff: force feedback structure associated with the device if device
  *     supports force feedback effects
+ * @poller: poller structure associated with the device if device is
+ *     set up to use polling mode
  * @repeat_key: stores key code of the last key pressed; used to implement
  *     software autorepeat
  * @timer: timer for software autorepeat
@@ -156,6 +160,8 @@ struct input_dev {
 
        struct ff_device *ff;
 
+       struct input_dev_poller *poller;
+
        unsigned int repeat_key;
        struct timer_list timer;
 
@@ -372,6 +378,12 @@ void input_unregister_device(struct input_dev *);
 
 void input_reset_device(struct input_dev *);
 
+int input_setup_polling(struct input_dev *dev,
+                       void (*poll_fn)(struct input_dev *dev));
+void input_set_poll_interval(struct input_dev *dev, unsigned int interval);
+void input_set_min_poll_interval(struct input_dev *dev, unsigned int interval);
+void input_set_max_poll_interval(struct input_dev *dev, unsigned int interval);
+
 int __must_check input_register_handler(struct input_handler *);
 void input_unregister_handler(struct input_handler *);