HID: roccat: propagate special events of roccat hardware to userspace

Module roccat is a char device used to report special events of roccat hardware
to userland. These events include requests for on-screen-display of profile or
dpi settings or requests for execution of macro sequences that are not stored
in device. The information in these events depends on hid device implementation
and contains data that is not available in a single hid event or else hidraw
could have been used.

It is inspired by hidraw, but uses only one circular buffer for all readers.
The device is as generic as possible so that the functionality is usable by all
(kone and upcomming) roccat device drivers.

Signed-off-by: Stefan Achatz <erazor_de@users.sourceforge.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 428 insertions, 0 deletions

diff --git a/drivers/hid/hid-roccat.c b/drivers/hid/hid-roccat.c
new file mode 100644
index 000000000000..e05d48edb66f
--- /dev/null
+++ b/drivers/hid/hid-roccat.c
@@ -0,0 +1,428 @@
+/*
+ * Roccat driver for Linux
+ *
+ * Copyright (c) 2010 Stefan Achatz <erazor_de@users.sourceforge.net>
+ */
+
+/*
+ * 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.
+ */
+
+/*
+ * Module roccat is a char device used to report special events of roccat
+ * hardware to userland. These events include requests for on-screen-display of
+ * profile or dpi settings or requests for execution of macro sequences that are
+ * not stored in device. The information in these events depends on hid device
+ * implementation and contains data that is not available in a single hid event
+ * or else hidraw could have been used.
+ * It is inspired by hidraw, but uses only one circular buffer for all readers.
+ */
+
+#include <linux/cdev.h>
+#include <linux/poll.h>
+#include <linux/sched.h>
+
+#include "hid-roccat.h"
+
+#define ROCCAT_FIRST_MINOR 0
+#define ROCCAT_MAX_DEVICES 8
+
+/* should be a power of 2 for performance reason */
+#define ROCCAT_CBUF_SIZE 16
+
+struct roccat_report {
+        uint8_t *value;
+        int len;
+};
+
+struct roccat_device {
+        unsigned int minor;
+        int open;
+        int exist;
+        wait_queue_head_t wait;
+        struct device *dev;
+        struct hid_device *hid;
+        struct list_head readers;
+        /* protects modifications of readers list */
+        struct mutex readers_lock;
+
+        /*
+         * circular_buffer has one writer and multiple readers with their own
+         * read pointers
+         */
+        struct roccat_report cbuf[ROCCAT_CBUF_SIZE];
+        int cbuf_end;
+        struct mutex cbuf_lock;
+};
+
+struct roccat_reader {
+        struct list_head node;
+        struct roccat_device *device;
+        int cbuf_start;
+};
+
+static int roccat_major;
+static struct class *roccat_class;
+static struct cdev roccat_cdev;
+
+static struct roccat_device *devices[ROCCAT_MAX_DEVICES];
+/* protects modifications of devices array */
+static DEFINE_MUTEX(devices_lock);
+
+static ssize_t roccat_read(struct file *file, char __user *buffer,
+                size_t count, loff_t *ppos)
+{
+        struct roccat_reader *reader = file->private_data;
+        struct roccat_device *device = reader->device;
+        struct roccat_report *report;
+        ssize_t retval = 0, len;
+        DECLARE_WAITQUEUE(wait, current);
+
+        mutex_lock(&device->cbuf_lock);
+
+        /* no data? */
+        if (reader->cbuf_start == device->cbuf_end) {
+                add_wait_queue(&device->wait, &wait);
+                set_current_state(TASK_INTERRUPTIBLE);
+
+                /* wait for data */
+                while (reader->cbuf_start == device->cbuf_end) {
+                        if (file->f_flags & O_NONBLOCK) {
+                                retval = -EAGAIN;
+                                break;
+                        }
+                        if (signal_pending(current)) {
+                                retval = -ERESTARTSYS;
+                                break;
+                        }
+                        if (!device->exist) {
+                                retval = -EIO;
+                                break;
+                        }
+
+                        mutex_unlock(&device->cbuf_lock);
+                        schedule();
+                        mutex_lock(&device->cbuf_lock);
+                        set_current_state(TASK_INTERRUPTIBLE);
+                }
+
+                set_current_state(TASK_RUNNING);
+                remove_wait_queue(&device->wait, &wait);
+        }
+
+        /* here we either have data or a reason to return if retval is set */
+        if (retval)
+                goto exit_unlock;
+
+        report = &device->cbuf[reader->cbuf_start];
+        /*
+         * If report is larger than requested amount of data, rest of report
+         * is lost!
+         */
+        len = report->len > count ? count : report->len;
+
+        if (copy_to_user(buffer, report->value, len)) {
+                retval = -EFAULT;
+                goto exit_unlock;
+        }
+        retval += len;
+        reader->cbuf_start = (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE;
+
+exit_unlock:
+        mutex_unlock(&device->cbuf_lock);
+        return retval;
+}
+
+static unsigned int roccat_poll(struct file *file, poll_table *wait)
+{
+        struct roccat_reader *reader = file->private_data;
+        poll_wait(file, &reader->device->wait, wait);
+        if (reader->cbuf_start != reader->device->cbuf_end)
+                return POLLIN | POLLRDNORM;
+        if (!reader->device->exist)
+                return POLLERR | POLLHUP;
+        return 0;
+}
+
+static int roccat_open(struct inode *inode, struct file *file)
+{
+        unsigned int minor = iminor(inode);
+        struct roccat_reader *reader;
+        struct roccat_device *device;
+        int error = 0;
+
+        reader = kzalloc(sizeof(struct roccat_reader), GFP_KERNEL);
+        if (!reader)
+                return -ENOMEM;
+
+        mutex_lock(&devices_lock);
+
+        device = devices[minor];
+
+        mutex_lock(&device->readers_lock);
+
+        if (!device) {
+                printk(KERN_EMERG "roccat device with minor %d doesn't exist\n",
+                                minor);
+                error = -ENODEV;
+                goto exit_unlock;
+        }
+
+        if (!device->open++) {
+                /* power on device on adding first reader */
+                if (device->hid->ll_driver->power) {
+                        error = device->hid->ll_driver->power(device->hid,
+                                        PM_HINT_FULLON);
+                        if (error < 0) {
+                                --device->open;
+                                goto exit_unlock;
+                        }
+                }
+                error = device->hid->ll_driver->open(device->hid);
+                if (error < 0) {
+                        if (device->hid->ll_driver->power)
+                                device->hid->ll_driver->power(device->hid,
+                                                PM_HINT_NORMAL);
+                        --device->open;
+                        goto exit_unlock;
+                }
+        }
+
+        reader->device = device;
+        /* new reader doesn't get old events */
+        reader->cbuf_start = device->cbuf_end;
+
+        list_add_tail(&reader->node, &device->readers);
+        file->private_data = reader;
+
+exit_unlock:
+        mutex_unlock(&device->readers_lock);
+        mutex_unlock(&devices_lock);
+        return error;
+}
+
+static int roccat_release(struct inode *inode, struct file *file)
+{
+        unsigned int minor = iminor(inode);
+        struct roccat_reader *reader = file->private_data;
+        struct roccat_device *device;
+
+        mutex_lock(&devices_lock);
+
+        device = devices[minor];
+        if (!device) {
+                mutex_unlock(&devices_lock);
+                printk(KERN_EMERG "roccat device with minor %d doesn't exist\n",
+                                minor);
+                return -ENODEV;
+        }
+
+        mutex_lock(&device->readers_lock);
+        list_del(&reader->node);
+        mutex_unlock(&device->readers_lock);
+        kfree(reader);
+
+        if (!--device->open) {
+                /* removing last reader */
+                if (device->exist) {
+                        if (device->hid->ll_driver->power)
+                                device->hid->ll_driver->power(device->hid,
+                                                PM_HINT_NORMAL);
+                        device->hid->ll_driver->close(device->hid);
+                } else {
+                        kfree(device);
+                }
+        }
+
+        mutex_unlock(&devices_lock);
+
+        return 0;
+}
+
+/*
+ * roccat_report_event() - output data to readers
+ * @minor: minor device number returned by roccat_connect()
+ * @data: pointer to data
+ * @len: size of data
+ *
+ * Return value is zero on success, a negative error code on failure.
+ *
+ * This is called from interrupt handler.
+ */
+int roccat_report_event(int minor, u8 const *data, int len)
+{
+        struct roccat_device *device;
+        struct roccat_reader *reader;
+        struct roccat_report *report;
+        uint8_t *new_value;
+
+        new_value = kmemdup(data, len, GFP_ATOMIC);
+        if (!new_value)
+                return -ENOMEM;
+
+        device = devices[minor];
+
+        report = &device->cbuf[device->cbuf_end];
+
+        /* passing NULL is safe */
+        kfree(report->value);
+
+        report->value = new_value;
+        report->len = len;
+        device->cbuf_end = (device->cbuf_end + 1) % ROCCAT_CBUF_SIZE;
+
+        list_for_each_entry(reader, &device->readers, node) {
+                /*
+                 * As we already inserted one element, the buffer can't be
+                 * empty. If start and end are equal, buffer is full and we
+                 * increase start, so that slow reader misses one event, but
+                 * gets the newer ones in the right order.
+                 */
+                if (reader->cbuf_start == device->cbuf_end)
+                        reader->cbuf_start = (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE;
+        }
+
+        wake_up_interruptible(&device->wait);
+        return 0;
+}
+EXPORT_SYMBOL_GPL(roccat_report_event);
+
+/*
+ * roccat_connect() - create a char device for special event output
+ * @hid: the hid device the char device should be connected to.
+ *
+ * Return value is minor device number in Range [0, ROCCAT_MAX_DEVICES] on
+ * success, a negative error code on failure.
+ */
+int roccat_connect(struct hid_device *hid)
+{
+        unsigned int minor;
+        struct roccat_device *device;
+        int temp;
+
+        device = kzalloc(sizeof(struct roccat_device), GFP_KERNEL);
+        if (!device)
+                return -ENOMEM;
+
+        mutex_lock(&devices_lock);
+
+        for (minor = 0; minor < ROCCAT_MAX_DEVICES; ++minor) {
+                if (devices[minor])
+                        continue;
+                break;
+        }
+
+        if (minor < ROCCAT_MAX_DEVICES) {
+                devices[minor] = device;
+        } else {
+                mutex_unlock(&devices_lock);
+                kfree(device);
+                return -EINVAL;
+        }
+
+        device->dev = device_create(roccat_class, &hid->dev,
+                        MKDEV(roccat_major, minor), NULL,
+                        "%s%s%d", "roccat", hid->driver->name, minor);
+
+        if (IS_ERR(device->dev)) {
+                devices[minor] = NULL;
+                mutex_unlock(&devices_lock);
+                temp = PTR_ERR(device->dev);
+                kfree(device);
+                return temp;
+        }
+
+        mutex_unlock(&devices_lock);
+
+        init_waitqueue_head(&device->wait);
+        INIT_LIST_HEAD(&device->readers);
+        mutex_init(&device->readers_lock);
+        mutex_init(&device->cbuf_lock);
+        device->minor = minor;
+        device->hid = hid;
+        device->exist = 1;
+        device->cbuf_end = 0;
+
+        return minor;
+}
+EXPORT_SYMBOL_GPL(roccat_connect);
+
+/* roccat_disconnect() - remove char device from hid device
+ * @minor: the minor device number returned by roccat_connect()
+ */
+void roccat_disconnect(int minor)
+{
+        struct roccat_device *device;
+
+        mutex_lock(&devices_lock);
+        device = devices[minor];
+        devices[minor] = NULL;
+        mutex_unlock(&devices_lock);
+
+        device->exist = 0; /* TODO exist maybe not needed */
+
+        device_destroy(roccat_class, MKDEV(roccat_major, minor));
+
+        if (device->open) {
+                device->hid->ll_driver->close(device->hid);
+                wake_up_interruptible(&device->wait);
+        } else {
+                kfree(device);
+        }
+}
+EXPORT_SYMBOL_GPL(roccat_disconnect);
+
+static const struct file_operations roccat_ops = {
+        .owner = THIS_MODULE,
+        .read = roccat_read,
+        .poll = roccat_poll,
+        .open = roccat_open,
+        .release = roccat_release,
+};
+
+static int __init roccat_init(void)
+{
+        int retval;
+        dev_t dev_id;
+
+        retval = alloc_chrdev_region(&dev_id, ROCCAT_FIRST_MINOR,
+                        ROCCAT_MAX_DEVICES, "roccat");
+
+        roccat_major = MAJOR(dev_id);
+
+        if (retval < 0) {
+                printk(KERN_WARNING "roccat: can't get major number\n");
+                return retval;
+        }
+
+        roccat_class = class_create(THIS_MODULE, "roccat");
+        if (IS_ERR(roccat_class)) {
+                retval = PTR_ERR(roccat_class);
+                unregister_chrdev_region(dev_id, ROCCAT_MAX_DEVICES);
+                return retval;
+        }
+
+        cdev_init(&roccat_cdev, &roccat_ops);
+        cdev_add(&roccat_cdev, dev_id, ROCCAT_MAX_DEVICES);
+
+        return 0;
+}
+
+static void __exit roccat_exit(void)
+{
+        dev_t dev_id = MKDEV(roccat_major, 0);
+
+        cdev_del(&roccat_cdev);
+        class_destroy(roccat_class);
+        unregister_chrdev_region(dev_id, ROCCAT_MAX_DEVICES);
+}
+
+module_init(roccat_init);
+module_exit(roccat_exit);
+
+MODULE_AUTHOR("Stefan Achatz");
+MODULE_DESCRIPTION("USB Roccat char device");
+MODULE_LICENSE("GPL v2");