Hi David,
> This driver allows to write I/O drivers in user-space and feed the input
> into the HID subsystem. It operates on the same level as USB-HID and
> Bluetooth-HID (HIDP). It does not provide support to write special HID
> device drivers but rather provides support for user-space I/O devices to
> feed their data into the kernel HID subsystem. The HID subsystem then
> loads the HID device drivers for the device and provides input-devices
> based on the user-space HID I/O device.
<snip>
> +#define UHID_NAME "uhid"
> +#define UHID_BUFSIZE 32
> +
> +struct uhid_device {
> + struct mutex devlock;
> + bool running;
> + struct device *parent;
> +
> + __u8 *rd_data;
> + uint rd_size;
> +
> + struct hid_device *hid;
> + struct uhid_event input_buf;
> +
> + wait_queue_head_t waitq;
> + spinlock_t qlock;
> + struct uhid_event assemble;
> + __u8 head;
> + __u8 tail;
> + struct uhid_event outq[UHID_BUFSIZE];
> +};
The kernel has a ringbuffer structure. Would it make sense to use that
one?
Or would using just a SKB queue be better?
> +static void uhid_queue(struct uhid_device *uhid, const struct uhid_event *ev)
> +{
> + __u8 newhead;
> +
> + newhead = (uhid->head + 1) % UHID_BUFSIZE;
> +
> + if (newhead != uhid->tail) {
> + memcpy(&uhid->outq[uhid->head], ev, sizeof(struct uhid_event));
> + uhid->head = newhead;
> + wake_up_interruptible(&uhid->waitq);
> + } else {
> + pr_warn("Output queue is full\n");
> + }
> +}
> +
> +static int uhid_hid_start(struct hid_device *hid)
> +{
> + struct uhid_device *uhid = hid->driver_data;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&uhid->qlock, flags);
> + memset(&uhid->assemble, 0, sizeof(uhid->assemble));
> + uhid->assemble.type = UHID_START;
> + uhid_queue(uhid, &uhid->assemble);
> + spin_unlock_irqrestore(&uhid->qlock, flags);
> +
> + return 0;
> +}
> +
> +static void uhid_hid_stop(struct hid_device *hid)
> +{
> + struct uhid_device *uhid = hid->driver_data;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&uhid->qlock, flags);
> + memset(&uhid->assemble, 0, sizeof(uhid->assemble));
> + uhid->assemble.type = UHID_STOP;
> + uhid_queue(uhid, &uhid->assemble);
> + spin_unlock_irqrestore(&uhid->qlock, flags);
> +
> + hid->claimed = 0;
> +}
> +
> +static int uhid_hid_open(struct hid_device *hid)
> +{
> + struct uhid_device *uhid = hid->driver_data;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&uhid->qlock, flags);
> + memset(&uhid->assemble, 0, sizeof(uhid->assemble));
> + uhid->assemble.type = UHID_OPEN;
> + uhid_queue(uhid, &uhid->assemble);
> + spin_unlock_irqrestore(&uhid->qlock, flags);
> +
> + return 0;
> +}
> +
> +static void uhid_hid_close(struct hid_device *hid)
> +{
> + struct uhid_device *uhid = hid->driver_data;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&uhid->qlock, flags);
> + memset(&uhid->assemble, 0, sizeof(uhid->assemble));
> + uhid->assemble.type = UHID_CLOSE;
> + uhid_queue(uhid, &uhid->assemble);
> + spin_unlock_irqrestore(&uhid->qlock, flags);
> +}
> +
> +static int uhid_hid_power(struct hid_device *hid, int level)
> +{
> + /* TODO: Handle PM-hints. This isn't mandatory so we simply return 0
> + * here.
> + */
> +
> + return 0;
> +}
> +
> +static int uhid_hid_input(struct input_dev *input, unsigned int type,
> + unsigned int code, int value)
> +{
> + struct hid_device *hid = input_get_drvdata(input);
> + struct uhid_device *uhid = hid->driver_data;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&uhid->qlock, flags);
> + memset(&uhid->assemble, 0, sizeof(uhid->assemble));
> +
> + uhid->assemble.type = UHID_OUTPUT_EV;
> + uhid->assemble.u.output_ev.type = type;
> + uhid->assemble.u.output_ev.code = code;
> + uhid->assemble.u.output_ev.value = value;
> +
> + uhid_queue(uhid, &uhid->assemble);
> + spin_unlock_irqrestore(&uhid->qlock, flags);
> +
> + return 0;
> +}
> +
> +static int uhid_hid_parse(struct hid_device *hid)
> +{
> + struct uhid_device *uhid = hid->driver_data;
> +
> + return hid_parse_report(hid, uhid->rd_data, uhid->rd_size);
> +}
> +
> +static int uhid_hid_get_raw(struct hid_device *hid, unsigned char rnum,
> + __u8 *buf, size_t count, unsigned char rtype)
> +{
> + /* TODO: we currently do not support this request. If we want this we
> + * would need some kind of stream-locking but it isn't needed by the
> + * main drivers, anyway.
> + */
> +
> + return -EOPNOTSUPP;
> +}
> +
> +static int uhid_hid_output_raw(struct hid_device *hid, __u8 *buf, size_t count,
> + unsigned char report_type)
> +{
> + struct uhid_device *uhid = hid->driver_data;
> + __u8 rtype;
> + unsigned long flags;
> +
> + switch (report_type) {
> + case HID_FEATURE_REPORT:
> + rtype = UHID_FEATURE_REPORT;
> + break;
> + case HID_OUTPUT_REPORT:
> + rtype = UHID_OUTPUT_REPORT;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + if (count < 1 || count > UHID_DATA_MAX)
> + return -EINVAL;
> +
> + spin_lock_irqsave(&uhid->qlock, flags);
> + memset(&uhid->assemble, 0, sizeof(uhid->assemble));
> +
> + uhid->assemble.type = UHID_OUTPUT;
> + uhid->assemble.u.output.size = count;
> + uhid->assemble.u.output.rtype = rtype;
> + memcpy(uhid->assemble.u.output.data, buf, count);
> +
> + uhid_queue(uhid, &uhid->assemble);
> + spin_unlock_irqrestore(&uhid->qlock, flags);
> +
> + return count;
> +}
> +
> +static struct hid_ll_driver uhid_hid_driver = {
> + .start = uhid_hid_start,
> + .stop = uhid_hid_stop,
> + .open = uhid_hid_open,
> + .close = uhid_hid_close,
> + .power = uhid_hid_power,
> + .hidinput_input_event = uhid_hid_input,
> + .parse = uhid_hid_parse,
> +};
> +
> +static int uhid_dev_create(struct uhid_device *uhid,
> + const struct uhid_event *ev)
> +{
> + struct hid_device *hid;
> + int ret;
> +
> + ret = mutex_lock_interruptible(&uhid->devlock);
> + if (ret)
> + return ret;
> +
> + if (uhid->running) {
> + ret = -EALREADY;
> + goto unlock;
> + }
> +
> + uhid->rd_size = ev->u.create.rd_size;
> + uhid->rd_data = kzalloc(uhid->rd_size, GFP_KERNEL);
> + if (!uhid->rd_data) {
> + ret = -ENOMEM;
> + goto unlock;
> + }
> +
> + if (copy_from_user(uhid->rd_data, ev->u.create.rd_data,
> + uhid->rd_size)) {
> + ret = -EFAULT;
> + goto err_free;
> + }
> +
> + hid = hid_allocate_device();
> + if (IS_ERR(hid)) {
> + ret = PTR_ERR(hid);
> + goto err_free;
> + }
> +
> + strncpy(hid->name, ev->u.create.name, 128);
> + hid->name[127] = 0;
> + hid->ll_driver = &uhid_hid_driver;
> + hid->hid_get_raw_report = uhid_hid_get_raw;
> + hid->hid_output_raw_report = uhid_hid_output_raw;
> + hid->bus = ev->u.create.bus;
> + hid->vendor = ev->u.create.vendor;
> + hid->product = ev->u.create.product;
> + hid->version = ev->u.create.version;
> + hid->country = ev->u.create.country;
> + hid->phys[0] = 0;
> + hid->uniq[0] = 0;
> + hid->driver_data = uhid;
> + hid->dev.parent = uhid->parent;
Here we have to make sure that we have all required information provided
by userspace. Anything else that HID might require to work better. Or
that BR/EDR or LE provides additionally over USB.
> + uhid->hid = hid;
> + uhid->running = true;
> +
> + ret = hid_add_device(hid);
> + if (ret) {
> + pr_err("Cannot register HID device\n");
> + goto err_hid;
> + }
> +
> + mutex_unlock(&uhid->devlock);
> +
> + return 0;
> +
> +err_hid:
> + hid_destroy_device(hid);
> + uhid->hid = NULL;
> + uhid->running = false;
> +err_free:
> + kfree(uhid->rd_data);
> +unlock:
> + mutex_unlock(&uhid->devlock);
> + return ret;
> +}
> +
> +static int uhid_dev_destroy(struct uhid_device *uhid)
> +{
> + int ret;
> +
> + ret = mutex_lock_interruptible(&uhid->devlock);
> + if (ret)
> + return ret;
> +
> + if (!uhid->running) {
> + ret = -EINVAL;
> + goto unlock;
> + }
> +
> + hid_destroy_device(uhid->hid);
> + kfree(uhid->rd_data);
> + uhid->running = false;
> +
> +unlock:
> + mutex_unlock(&uhid->devlock);
> + return ret;
> +}
> +
> +static int uhid_dev_input(struct uhid_device *uhid, struct uhid_event *ev)
> +{
> + int ret;
> +
> + ret = mutex_lock_interruptible(&uhid->devlock);
> + if (ret)
> + return ret;
> +
> + if (!uhid->running) {
> + ret = -EINVAL;
> + goto unlock;
> + }
> +
> + hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input.data,
> + ev->u.input.size, 0);
> +
> +unlock:
> + mutex_unlock(&uhid->devlock);
> + return ret;
> +}
> +
> +static int uhid_char_open(struct inode *inode, struct file *file)
> +{
> + struct uhid_device *uhid;
> +
> + uhid = kzalloc(sizeof(*uhid), GFP_KERNEL);
> + if (!uhid)
> + return -ENOMEM;
> +
> + mutex_init(&uhid->devlock);
> + spin_lock_init(&uhid->qlock);
> + init_waitqueue_head(&uhid->waitq);
> + uhid->running = false;
> + uhid->parent = NULL;
> +
> + file->private_data = uhid;
> + nonseekable_open(inode, file);
> +
> + return 0;
return nonseekable_open().
> +}
> +
> +static int uhid_char_release(struct inode *inode, struct file *file)
> +{
> + struct uhid_device *uhid = file->private_data;
> +
> + uhid_dev_destroy(uhid);
> + kfree(uhid);
> +
> + return 0;
> +}
> +
> +static ssize_t uhid_char_read(struct file *file, char __user *buffer,
> + size_t count, loff_t *ppos)
> +{
> + struct uhid_device *uhid = file->private_data;
> + int ret;
> + unsigned long flags;
> + size_t len;
> +
> + /* they need at least the "type" member of uhid_event */
> + if (count < sizeof(__u32))
> + return -EINVAL;
> +
> +try_again:
> + if (file->f_flags & O_NONBLOCK) {
> + if (uhid->head == uhid->tail)
> + return -EAGAIN;
> + } else {
> + ret = wait_event_interruptible(uhid->waitq,
> + uhid->head != uhid->tail);
> + if (ret)
> + return ret;
> + }
> +
> + ret = mutex_lock_interruptible(&uhid->devlock);
> + if (ret)
> + return ret;
> +
> + if (uhid->head == uhid->tail) {
> + mutex_unlock(&uhid->devlock);
> + goto try_again;
> + } else {
> + len = min(count, sizeof(*uhid->outq));
> + if (copy_to_user(buffer, &uhid->outq[uhid->tail], len)) {
> + ret = -EFAULT;
> + } else {
> + spin_lock_irqsave(&uhid->qlock, flags);
> + uhid->tail = (uhid->tail + 1) % UHID_BUFSIZE;
> + spin_unlock_irqrestore(&uhid->qlock, flags);
> + }
> + }
> +
> + mutex_unlock(&uhid->devlock);
> + return ret ? ret : len;
> +}
> +
> +static ssize_t uhid_char_write(struct file *file, const char __user *buffer,
> + size_t count, loff_t *ppos)
> +{
> + struct uhid_device *uhid = file->private_data;
> + int ret;
> + size_t len;
> +
> + /* we need at least the "type" member of uhid_event */
> + if (count < sizeof(__u32))
> + return -EINVAL;
> +
> + memset(&uhid->input_buf, 0, sizeof(uhid->input_buf));
> + len = min(count, sizeof(uhid->input_buf));
> + if (copy_from_user(&uhid->input_buf, buffer, len))
> + return -EFAULT;
> +
> + switch (uhid->input_buf.type) {
> + case UHID_CREATE:
> + ret = uhid_dev_create(uhid, &uhid->input_buf);
> + break;
> + case UHID_DESTROY:
> + ret = uhid_dev_destroy(uhid);
> + break;
> + case UHID_INPUT:
> + ret = uhid_dev_input(uhid, &uhid->input_buf);
> + break;
> + default:
> + ret = -EOPNOTSUPP;
switch and case should be on the same indentation.
> + }
> +
> + /* return "count" not "len" to not confuse the caller */
> + return ret ? ret : count;
> +}
> +
> +static unsigned int uhid_char_poll(struct file *file, poll_table *wait)
> +{
> + struct uhid_device *uhid = file->private_data;
> +
> + poll_wait(file, &uhid->waitq, wait);
> +
> + if (uhid->head != uhid->tail)
> + return POLLIN | POLLRDNORM;
> +
> + return 0;
> +}
> +
> +static const struct file_operations uhid_fops = {
> + .owner = THIS_MODULE,
> + .open = uhid_char_open,
> + .release = uhid_char_release,
> + .read = uhid_char_read,
> + .write = uhid_char_write,
> + .poll = uhid_char_poll,
> + .llseek = no_llseek,
> +};
> +
> +static struct miscdevice uhid_misc = {
> + .fops = &uhid_fops,
> + .minor = MISC_DYNAMIC_MINOR,
> + .name = UHID_NAME,
> +};
> +
> +static int __init uhid_init(void)
> +{
> + return misc_register(&uhid_misc);
> +}
> +
> +static void __exit uhid_exit(void)
> +{
> + misc_deregister(&uhid_misc);
> +}
> +
> +module_init(uhid_init);
> +module_exit(uhid_exit);
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("David Herrmann <dh.herrmann@xxxxxxxxx>");
> +MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem");
> diff --git a/include/linux/Kbuild b/include/linux/Kbuild
> index c94e717..b8d5ed0 100644
> --- a/include/linux/Kbuild
> +++ b/include/linux/Kbuild
> @@ -370,6 +370,7 @@ header-y += tty.h
> header-y += types.h
> header-y += udf_fs_i.h
> header-y += udp.h
> +header-y += uhid.h
> header-y += uinput.h
> header-y += uio.h
> header-y += ultrasound.h
> diff --git a/include/linux/uhid.h b/include/linux/uhid.h
> new file mode 100644
> index 0000000..67d9c8d
> --- /dev/null
> +++ b/include/linux/uhid.h
> @@ -0,0 +1,84 @@
> +#ifndef __UHID_H_
> +#define __UHID_H_
> +
> +/*
> + * User-space I/O driver support for HID subsystem
> + * Copyright (c) 2012 David Herrmann
> + */
> +
> +/*
> + * 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.
> + */
> +
> +/*
> + * Public header for user-space communication. We try to keep every structure
> + * aligned but to be safe we also use __attribute__((packed)). Therefore, the
> + * communication should be ABI compatible even between architectures.
> + */
> +
> +#include <linux/input.h>
> +#include <linux/types.h>
> +
> +enum uhid_event_type {
Can we add an UHID_UNSPEC or UHID_INVALID here for the 0 value.
> + UHID_CREATE,
> + UHID_DESTROY,
> + UHID_START,
> + UHID_STOP,
> + UHID_OPEN,
> + UHID_CLOSE,
> + UHID_OUTPUT,
> + UHID_OUTPUT_EV,
> + UHID_INPUT,
> +};
> +
> +struct uhid_create_req {
> + __u8 name[128];
> + __u8 __user *rd_data;
> + __u16 rd_size;
> +
> + __u16 bus;
> + __u32 vendor;
> + __u32 product;
> + __u32 version;
> + __u32 country;
> +} __attribute__((packed));
__packed please and all others.
> +
> +#define UHID_DATA_MAX 4096
> +
> +enum uhid_report_type {
> + UHID_FEATURE_REPORT,
> + UHID_OUTPUT_REPORT,
> +};
> +
> +struct uhid_input_req {
> + __u8 data[UHID_DATA_MAX];
> + __u16 size;
> +} __attribute__((packed));
> +
> +struct uhid_output_req {
> + __u8 data[UHID_DATA_MAX];
> + __u16 size;
> + __u8 rtype;
> +} __attribute__((packed));
> +
> +struct uhid_output_ev_req {
> + __u16 type;
> + __u16 code;
> + __s32 value;
> +} __attribute__((packed));
> +
> +struct uhid_event {
> + __u32 type;
> +
> + union {
> + struct uhid_create_req create;
> + struct uhid_input_req input;
> + struct uhid_output_req output;
> + struct uhid_output_ev_req output_ev;
> + } u;
> +} __attribute__((packed));
What about adding another __u32 len here? Just so we can do some extra
length checks if needed.
Regards
Marcel
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