Input: implement new force feedback interface

Implement a new force feedback interface, in which all non-driver-specific
operations are separated to a common module. This includes handling effect
type validations, locking, etc.

The effects are now file descriptor specific instead of the previous strange
half-process half-fd specific behaviour. The effect memory of devices is not
emptied if the root user opens and closes the device while another user is
using effects. This is a minor change and most likely no force feedback
aware programs are affected by this negatively.

Otherwise the userspace interface is left unaltered.

Signed-off-by: Anssi Hannula <anssi.hannula@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

4 files changed, 389 insertions, 18 deletions

diff --git a/drivers/input/Makefile b/drivers/input/Makefile
index e539a309df8a..abdc9d435705 100644
--- a/drivers/input/Makefile
+++ b/drivers/input/Makefile
@@ -5,7 +5,7 @@
 # Each configuration option enables a list of files.
 
 obj-$(CONFIG_INPUT)             += input-core.o
-input-core-objs := input.o
+input-core-objs := input.o ff-core.o
 
 obj-$(CONFIG_INPUT_MOUSEDEV)    += mousedev.o
 obj-$(CONFIG_INPUT_JOYDEV)      += joydev.o
diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index 4bf48188cc91..12c7ab876c34 100644
--- a/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -391,8 +391,10 @@ static long evdev_ioctl_handler(struct file *file, unsigned int cmd,
         struct evdev *evdev = list->evdev;
         struct input_dev *dev = evdev->handle.dev;
         struct input_absinfo abs;
+        struct ff_effect effect;
         int __user *ip = (int __user *)p;
         int i, t, u, v;
+        int error;
 
         if (!evdev->exist)
                 return -ENODEV;
@@ -460,27 +462,22 @@ static long evdev_ioctl_handler(struct file *file, unsigned int cmd,
                         return 0;
 
                 case EVIOCSFF:
-                        if (dev->upload_effect) {
-                                struct ff_effect effect;
-                                int err;
-
-                                if (copy_from_user(&effect, p, sizeof(effect)))
-                                        return -EFAULT;
-                                err = dev->upload_effect(dev, &effect);
-                                if (put_user(effect.id, &(((struct ff_effect __user *)p)->id)))
-                                        return -EFAULT;
-                                return err;
-                        } else
-                                return -ENOSYS;
+                        if (copy_from_user(&effect, p, sizeof(effect)))
+                                return -EFAULT;
 
-                case EVIOCRMFF:
-                        if (!dev->erase_effect)
-                                return -ENOSYS;
+                        error = input_ff_upload(dev, &effect, file);
 
-                        return dev->erase_effect(dev, (int)(unsigned long) p);
+                        if (put_user(effect.id, &(((struct ff_effect __user *)p)->id)))
+                                return -EFAULT;
+
+                        return error;
+
+                case EVIOCRMFF:
+                        return input_ff_erase(dev, (int)(unsigned long) p, file);
 
                 case EVIOCGEFFECTS:
-                        if (put_user(dev->ff_effects_max, ip))
+                        i = test_bit(EV_FF, dev->evbit) ? dev->ff->max_effects : 0;
+                        if (put_user(i, ip))
                                 return -EFAULT;
                         return 0;
 
@@ -669,6 +666,7 @@ static void evdev_disconnect(struct input_handle *handle)
         evdev->exist = 0;
 
         if (evdev->open) {
+                input_flush_device(handle, NULL);
                 input_close_device(handle);
                 wake_up_interruptible(&evdev->wait);
                 list_for_each_entry(list, &evdev->list, node)
diff --git a/drivers/input/ff-core.c b/drivers/input/ff-core.c
new file mode 100644
index 000000000000..35656cadc914
--- /dev/null
+++ b/drivers/input/ff-core.c
@@ -0,0 +1,367 @@
+/*
+ *  Force feedback support for Linux input subsystem
+ *
+ *  Copyright (c) 2006 Anssi Hannula <anssi.hannula@gmail.com>
+ *  Copyright (c) 2006 Dmitry Torokhov <dtor@mail.ru>
+ */
+
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+/* #define DEBUG */
+
+#define debug(format, arg...) pr_debug("ff-core: " format "\n", ## arg)
+
+#include <linux/input.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+
+/*
+ * Check that the effect_id is a valid effect and whether the user
+ * is the owner
+ */
+static int check_effect_access(struct ff_device *ff, int effect_id,
+                                struct file *file)
+{
+        if (effect_id < 0 || effect_id >= ff->max_effects ||
+            !ff->effect_owners[effect_id])
+                return -EINVAL;
+
+        if (file && ff->effect_owners[effect_id] != file)
+                return -EACCES;
+
+        return 0;
+}
+
+/*
+ * Checks whether 2 effects can be combined together
+ */
+static inline int check_effects_compatible(struct ff_effect *e1,
+                                           struct ff_effect *e2)
+{
+        return e1->type == e2->type &&
+               (e1->type != FF_PERIODIC ||
+                e1->u.periodic.waveform == e2->u.periodic.waveform);
+}
+
+/*
+ * Convert an effect into compatible one
+ */
+static int compat_effect(struct ff_device *ff, struct ff_effect *effect)
+{
+        int magnitude;
+
+        switch (effect->type) {
+        case FF_RUMBLE:
+                if (!test_bit(FF_PERIODIC, ff->ffbit))
+                        return -EINVAL;
+
+                /*
+                 * calculate manginude of sine wave as average of rumble's
+                 * 2/3 of strong magnitude and 1/3 of weak magnitude
+                 */
+                magnitude = effect->u.rumble.strong_magnitude / 3 +
+                            effect->u.rumble.weak_magnitude / 6;
+
+                effect->type = FF_PERIODIC;
+                effect->u.periodic.waveform = FF_SINE;
+                effect->u.periodic.period = 50;
+                effect->u.periodic.magnitude = max(magnitude, 0x7fff);
+                effect->u.periodic.offset = 0;
+                effect->u.periodic.phase = 0;
+                effect->u.periodic.envelope.attack_length = 0;
+                effect->u.periodic.envelope.attack_level = 0;
+                effect->u.periodic.envelope.fade_length = 0;
+                effect->u.periodic.envelope.fade_level = 0;
+
+                return 0;
+
+        default:
+                /* Let driver handle conversion */
+                return 0;
+        }
+}
+
+/**
+ * input_ff_upload() - upload effect into force-feedback device
+ * @dev: input device
+ * @effect: effect to be uploaded
+ * @file: owner of the effect
+ */
+int input_ff_upload(struct input_dev *dev, struct ff_effect *effect,
+                    struct file *file)
+{
+        struct ff_device *ff = dev->ff;
+        struct ff_effect *old;
+        int ret = 0;
+        int id;
+
+        if (!test_bit(EV_FF, dev->evbit))
+                return -ENOSYS;
+
+        if (effect->type < FF_EFFECT_MIN || effect->type > FF_EFFECT_MAX ||
+            !test_bit(effect->type, dev->ffbit)) {
+                debug("invalid or not supported effect type in upload");
+                return -EINVAL;
+        }
+
+        if (effect->type == FF_PERIODIC &&
+            (effect->u.periodic.waveform < FF_WAVEFORM_MIN ||
+             effect->u.periodic.waveform > FF_WAVEFORM_MAX ||
+             !test_bit(effect->u.periodic.waveform, dev->ffbit))) {
+                debug("invalid or not supported wave form in upload");
+                return -EINVAL;
+        }
+
+        if (!test_bit(effect->type, ff->ffbit)) {
+                ret = compat_effect(ff, effect);
+                if (ret)
+                        return ret;
+        }
+
+        mutex_lock(&ff->mutex);
+
+        if (effect->id == -1) {
+                for (id = 0; id < ff->max_effects; id++)
+                     if (!ff->effect_owners[id])
+                        break;
+
+                if (id >= ff->max_effects) {
+                        ret = -ENOSPC;
+                        goto out;
+                }
+
+                effect->id = id;
+                old = NULL;
+
+        } else {
+                id = effect->id;
+
+                ret = check_effect_access(ff, id, file);
+                if (ret)
+                        goto out;
+
+                old = &ff->effects[id];
+
+                if (!check_effects_compatible(effect, old)) {
+                        ret = -EINVAL;
+                        goto out;
+                }
+        }
+
+        ret = ff->upload(dev, effect, old);
+        if (ret)
+                goto out;
+
+        ff->effects[id] = *effect;
+        ff->effect_owners[id] = file;
+
+ out:
+        mutex_unlock(&ff->mutex);
+        return ret;
+}
+EXPORT_SYMBOL_GPL(input_ff_upload);
+
+/*
+ * Erases the effect if the requester is also the effect owner. The mutex
+ * should already be locked before calling this function.
+ */
+static int erase_effect(struct input_dev *dev, int effect_id,
+                        struct file *file)
+{
+        struct ff_device *ff = dev->ff;
+        int error;
+
+        error = check_effect_access(ff, effect_id, file);
+        if (error)
+                return error;
+
+        ff->playback(dev, effect_id, 0);
+
+        if (ff->erase) {
+                error = ff->erase(dev, effect_id);
+                if (error)
+                        return error;
+        }
+
+        ff->effect_owners[effect_id] = NULL;
+
+        return 0;
+}
+
+/**
+ * input_ff_erase - erase an effect from device
+ * @dev: input device to erase effect from
+ * @effect_id: id of the ffect to be erased
+ * @file: purported owner of the request
+ *
+ * This function erases a force-feedback effect from specified device.
+ * The effect will only be erased if it was uploaded through the same
+ * file handle that is requesting erase.
+ */
+int input_ff_erase(struct input_dev *dev, int effect_id, struct file *file)
+{
+        struct ff_device *ff = dev->ff;
+        int ret;
+
+        if (!test_bit(EV_FF, dev->evbit))
+                return -ENOSYS;
+
+        mutex_lock(&ff->mutex);
+        ret = erase_effect(dev, effect_id, file);
+        mutex_unlock(&ff->mutex);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(input_ff_erase);
+
+/*
+ * flush_effects - erase all effects owned by a file handle
+ */
+static int flush_effects(struct input_dev *dev, struct file *file)
+{
+        struct ff_device *ff = dev->ff;
+        int i;
+
+        debug("flushing now");
+
+        mutex_lock(&ff->mutex);
+
+        for (i = 0; i < ff->max_effects; i++)
+                erase_effect(dev, i, file);
+
+        mutex_unlock(&ff->mutex);
+
+        return 0;
+}
+
+/**
+ * input_ff_event() - generic handler for force-feedback events
+ * @dev: input device to send the effect to
+ * @type: event type (anything but EV_FF is ignored)
+ * @code: event code
+ * @value: event value
+ */
+int input_ff_event(struct input_dev *dev, unsigned int type,
+                   unsigned int code, int value)
+{
+        struct ff_device *ff = dev->ff;
+
+        if (type != EV_FF)
+                return 0;
+
+        mutex_lock(&ff->mutex);
+
+        switch (code) {
+        case FF_GAIN:
+                if (!test_bit(FF_GAIN, dev->ffbit) || value > 0xffff)
+                        break;
+
+                ff->set_gain(dev, value);
+                break;
+
+        case FF_AUTOCENTER:
+                if (!test_bit(FF_AUTOCENTER, dev->ffbit) || value > 0xffff)
+                        break;
+
+                ff->set_autocenter(dev, value);
+                break;
+
+        default:
+                ff->playback(dev, code, value);
+                break;
+        }
+
+        mutex_unlock(&ff->mutex);
+        return 0;
+}
+EXPORT_SYMBOL_GPL(input_ff_event);
+
+/**
+ * input_ff_create() - create force-feedback device
+ * @dev: input device supporting force-feedback
+ * @max_effects: maximum number of effects supported by the device
+ *
+ * This function allocates all necessary memory for a force feedback
+ * portion of an input device and installs all default handlers.
+ * @dev->ffbit should be already set up before calling this function.
+ * Once ff device is created you need to setup its upload, erase,
+ * playback and other handlers before registering input device
+ */
+int input_ff_create(struct input_dev *dev, int max_effects)
+{
+        struct ff_device *ff;
+        int i;
+
+        if (!max_effects) {
+                printk(KERN_ERR
+                       "ff-core: cannot allocate device without any effects\n");
+                return -EINVAL;
+        }
+
+        ff = kzalloc(sizeof(struct ff_device) +
+                     max_effects * sizeof(struct file *), GFP_KERNEL);
+        if (!ff)
+                return -ENOMEM;
+
+        ff->effects = kcalloc(max_effects, sizeof(struct ff_effect),
+                              GFP_KERNEL);
+        if (!ff->effects) {
+                kfree(ff);
+                return -ENOMEM;
+        }
+
+        ff->max_effects = max_effects;
+        mutex_init(&ff->mutex);
+
+        dev->ff = ff;
+        dev->flush = flush_effects;
+        dev->event = input_ff_event;
+        set_bit(EV_FF, dev->evbit);
+
+        /* Copy "true" bits into ff device bitmap */
+        for (i = 0; i <= FF_MAX; i++)
+                if (test_bit(i, dev->ffbit))
+                        set_bit(i, ff->ffbit);
+
+        /* we can emulate RUMBLE with periodic effects */
+        if (test_bit(FF_PERIODIC, ff->ffbit))
+                set_bit(FF_RUMBLE, dev->ffbit);
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(input_ff_create);
+
+/**
+ * input_ff_free() - frees force feedback portion of input device
+ * @dev: input device supporintg force feedback
+ *
+ * This function is only needed in error path as input core will
+ * automatically free force feedback structures when device is
+ * destroyed.
+ */
+void input_ff_destroy(struct input_dev *dev)
+{
+        clear_bit(EV_FF, dev->evbit);
+        if (dev->ff) {
+                if (dev->ff->destroy)
+                        dev->ff->destroy(dev->ff);
+                kfree(dev->ff->private);
+                kfree(dev->ff);
+                dev->ff = NULL;
+        }
+}
+EXPORT_SYMBOL_GPL(input_ff_destroy);
diff --git a/drivers/input/input.c b/drivers/input/input.c
index 9cb4b9a54f01..1fc0517e9428 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -176,6 +176,10 @@ void input_event(struct input_dev *dev, unsigned int type, unsigned int code, in
                         break;
 
                 case EV_FF:
+
+                        if (value < 0)
+                                return;
+
                         if (dev->event)
                                 dev->event(dev, type, code, value);
                         break;
@@ -762,7 +766,9 @@ static void input_dev_release(struct class_device *class_dev)
 {
         struct input_dev *dev = to_input_dev(class_dev);
 
+        input_ff_destroy(dev);
         kfree(dev);
+
         module_put(THIS_MODULE);
 }