linux/drivers/usb/misc/usblcd.c
David Howells 7d12e780e0 IRQ: Maintain regs pointer globally rather than passing to IRQ handlers
Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
of passing regs around manually through all ~1800 interrupt handlers in the
Linux kernel.

The regs pointer is used in few places, but it potentially costs both stack
space and code to pass it around.  On the FRV arch, removing the regs parameter
from all the genirq function results in a 20% speed up of the IRQ exit path
(ie: from leaving timer_interrupt() to leaving do_IRQ()).

Where appropriate, an arch may override the generic storage facility and do
something different with the variable.  On FRV, for instance, the address is
maintained in GR28 at all times inside the kernel as part of general exception
handling.

Having looked over the code, it appears that the parameter may be handed down
through up to twenty or so layers of functions.  Consider a USB character
device attached to a USB hub, attached to a USB controller that posts its
interrupts through a cascaded auxiliary interrupt controller.  A character
device driver may want to pass regs to the sysrq handler through the input
layer which adds another few layers of parameter passing.

I've build this code with allyesconfig for x86_64 and i386.  I've runtested the
main part of the code on FRV and i386, though I can't test most of the drivers.
I've also done partial conversion for powerpc and MIPS - these at least compile
with minimal configurations.

This will affect all archs.  Mostly the changes should be relatively easy.
Take do_IRQ(), store the regs pointer at the beginning, saving the old one:

	struct pt_regs *old_regs = set_irq_regs(regs);

And put the old one back at the end:

	set_irq_regs(old_regs);

Don't pass regs through to generic_handle_irq() or __do_IRQ().

In timer_interrupt(), this sort of change will be necessary:

	-	update_process_times(user_mode(regs));
	-	profile_tick(CPU_PROFILING, regs);
	+	update_process_times(user_mode(get_irq_regs()));
	+	profile_tick(CPU_PROFILING);

I'd like to move update_process_times()'s use of get_irq_regs() into itself,
except that i386, alone of the archs, uses something other than user_mode().

Some notes on the interrupt handling in the drivers:

 (*) input_dev() is now gone entirely.  The regs pointer is no longer stored in
     the input_dev struct.

 (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking.  It does
     something different depending on whether it's been supplied with a regs
     pointer or not.

 (*) Various IRQ handler function pointers have been moved to type
     irq_handler_t.

Signed-Off-By: David Howells <dhowells@redhat.com>
(cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
2006-10-05 15:10:12 +01:00

396 lines
10 KiB
C

/*****************************************************************************
* USBLCD Kernel Driver *
* Version 1.05 *
* (C) 2005 Georges Toth <g.toth@e-biz.lu> *
* *
* This file is licensed under the GPL. See COPYING in the package. *
* Based on usb-skeleton.c 2.0 by Greg Kroah-Hartman (greg@kroah.com) *
* *
* *
* 28.02.05 Complete rewrite of the original usblcd.c driver, *
* based on usb_skeleton.c. *
* This new driver allows more than one USB-LCD to be connected *
* and controlled, at once *
*****************************************************************************/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <asm/uaccess.h>
#include <linux/usb.h>
#define DRIVER_VERSION "USBLCD Driver Version 1.05"
#define USBLCD_MINOR 144
#define IOCTL_GET_HARD_VERSION 1
#define IOCTL_GET_DRV_VERSION 2
static struct usb_device_id id_table [] = {
{ .idVendor = 0x10D2, .match_flags = USB_DEVICE_ID_MATCH_VENDOR, },
{ },
};
MODULE_DEVICE_TABLE (usb, id_table);
struct usb_lcd {
struct usb_device * udev; /* init: probe_lcd */
struct usb_interface * interface; /* the interface for this device */
unsigned char * bulk_in_buffer; /* the buffer to receive data */
size_t bulk_in_size; /* the size of the receive buffer */
__u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */
__u8 bulk_out_endpointAddr; /* the address of the bulk out endpoint */
struct kref kref;
};
#define to_lcd_dev(d) container_of(d, struct usb_lcd, kref)
static struct usb_driver lcd_driver;
static void lcd_delete(struct kref *kref)
{
struct usb_lcd *dev = to_lcd_dev(kref);
usb_put_dev(dev->udev);
kfree (dev->bulk_in_buffer);
kfree (dev);
}
static int lcd_open(struct inode *inode, struct file *file)
{
struct usb_lcd *dev;
struct usb_interface *interface;
int subminor;
int retval = 0;
subminor = iminor(inode);
interface = usb_find_interface(&lcd_driver, subminor);
if (!interface) {
err ("USBLCD: %s - error, can't find device for minor %d",
__FUNCTION__, subminor);
retval = -ENODEV;
goto exit;
}
dev = usb_get_intfdata(interface);
if (!dev) {
retval = -ENODEV;
goto exit;
}
/* increment our usage count for the device */
kref_get(&dev->kref);
/* save our object in the file's private structure */
file->private_data = dev;
exit:
return retval;
}
static int lcd_release(struct inode *inode, struct file *file)
{
struct usb_lcd *dev;
dev = (struct usb_lcd *)file->private_data;
if (dev == NULL)
return -ENODEV;
/* decrement the count on our device */
kref_put(&dev->kref, lcd_delete);
return 0;
}
static ssize_t lcd_read(struct file *file, char __user * buffer, size_t count, loff_t *ppos)
{
struct usb_lcd *dev;
int retval = 0;
int bytes_read;
dev = (struct usb_lcd *)file->private_data;
/* do a blocking bulk read to get data from the device */
retval = usb_bulk_msg(dev->udev,
usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
dev->bulk_in_buffer,
min(dev->bulk_in_size, count),
&bytes_read, 10000);
/* if the read was successful, copy the data to userspace */
if (!retval) {
if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))
retval = -EFAULT;
else
retval = bytes_read;
}
return retval;
}
static int lcd_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
struct usb_lcd *dev;
u16 bcdDevice;
char buf[30];
dev = (struct usb_lcd *)file->private_data;
if (dev == NULL)
return -ENODEV;
switch (cmd) {
case IOCTL_GET_HARD_VERSION:
bcdDevice = le16_to_cpu((dev->udev)->descriptor.bcdDevice);
sprintf(buf,"%1d%1d.%1d%1d",
(bcdDevice & 0xF000)>>12,
(bcdDevice & 0xF00)>>8,
(bcdDevice & 0xF0)>>4,
(bcdDevice & 0xF));
if (copy_to_user((void __user *)arg,buf,strlen(buf))!=0)
return -EFAULT;
break;
case IOCTL_GET_DRV_VERSION:
sprintf(buf,DRIVER_VERSION);
if (copy_to_user((void __user *)arg,buf,strlen(buf))!=0)
return -EFAULT;
break;
default:
return -ENOTTY;
break;
}
return 0;
}
static void lcd_write_bulk_callback(struct urb *urb)
{
struct usb_lcd *dev;
dev = (struct usb_lcd *)urb->context;
/* sync/async unlink faults aren't errors */
if (urb->status &&
!(urb->status == -ENOENT ||
urb->status == -ECONNRESET ||
urb->status == -ESHUTDOWN)) {
dbg("USBLCD: %s - nonzero write bulk status received: %d",
__FUNCTION__, urb->status);
}
/* free up our allocated buffer */
usb_buffer_free(urb->dev, urb->transfer_buffer_length,
urb->transfer_buffer, urb->transfer_dma);
}
static ssize_t lcd_write(struct file *file, const char __user * user_buffer, size_t count, loff_t *ppos)
{
struct usb_lcd *dev;
int retval = 0;
struct urb *urb = NULL;
char *buf = NULL;
dev = (struct usb_lcd *)file->private_data;
/* verify that we actually have some data to write */
if (count == 0)
goto exit;
/* create a urb, and a buffer for it, and copy the data to the urb */
urb = usb_alloc_urb(0, GFP_KERNEL);
if (!urb)
return -ENOMEM;
buf = usb_buffer_alloc(dev->udev, count, GFP_KERNEL, &urb->transfer_dma);
if (!buf) {
retval = -ENOMEM;
goto error;
}
if (copy_from_user(buf, user_buffer, count)) {
retval = -EFAULT;
goto error;
}
/* initialize the urb properly */
usb_fill_bulk_urb(urb, dev->udev,
usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
buf, count, lcd_write_bulk_callback, dev);
urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
/* send the data out the bulk port */
retval = usb_submit_urb(urb, GFP_KERNEL);
if (retval) {
err("USBLCD: %s - failed submitting write urb, error %d", __FUNCTION__, retval);
goto error;
}
/* release our reference to this urb, the USB core will eventually free it entirely */
usb_free_urb(urb);
exit:
return count;
error:
usb_buffer_free(dev->udev, count, buf, urb->transfer_dma);
usb_free_urb(urb);
return retval;
}
static const struct file_operations lcd_fops = {
.owner = THIS_MODULE,
.read = lcd_read,
.write = lcd_write,
.open = lcd_open,
.ioctl = lcd_ioctl,
.release = lcd_release,
};
/*
* usb class driver info in order to get a minor number from the usb core,
* and to have the device registered with the driver core
*/
static struct usb_class_driver lcd_class = {
.name = "lcd%d",
.fops = &lcd_fops,
.minor_base = USBLCD_MINOR,
};
static int lcd_probe(struct usb_interface *interface, const struct usb_device_id *id)
{
struct usb_lcd *dev = NULL;
struct usb_host_interface *iface_desc;
struct usb_endpoint_descriptor *endpoint;
size_t buffer_size;
int i;
int retval = -ENOMEM;
/* allocate memory for our device state and initialize it */
dev = kzalloc(sizeof(*dev), GFP_KERNEL);
if (dev == NULL) {
err("Out of memory");
goto error;
}
kref_init(&dev->kref);
dev->udev = usb_get_dev(interface_to_usbdev(interface));
dev->interface = interface;
if (le16_to_cpu(dev->udev->descriptor.idProduct) != 0x0001) {
warn(KERN_INFO "USBLCD model not supported.");
return -ENODEV;
}
/* set up the endpoint information */
/* use only the first bulk-in and bulk-out endpoints */
iface_desc = interface->cur_altsetting;
for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
endpoint = &iface_desc->endpoint[i].desc;
if (!dev->bulk_in_endpointAddr &&
usb_endpoint_is_bulk_in(endpoint)) {
/* we found a bulk in endpoint */
buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
dev->bulk_in_size = buffer_size;
dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
if (!dev->bulk_in_buffer) {
err("Could not allocate bulk_in_buffer");
goto error;
}
}
if (!dev->bulk_out_endpointAddr &&
usb_endpoint_is_bulk_out(endpoint)) {
/* we found a bulk out endpoint */
dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
}
}
if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
err("Could not find both bulk-in and bulk-out endpoints");
goto error;
}
/* save our data pointer in this interface device */
usb_set_intfdata(interface, dev);
/* we can register the device now, as it is ready */
retval = usb_register_dev(interface, &lcd_class);
if (retval) {
/* something prevented us from registering this driver */
err("Not able to get a minor for this device.");
usb_set_intfdata(interface, NULL);
goto error;
}
i = le16_to_cpu(dev->udev->descriptor.bcdDevice);
info("USBLCD Version %1d%1d.%1d%1d found at address %d",
(i & 0xF000)>>12,(i & 0xF00)>>8,(i & 0xF0)>>4,(i & 0xF),
dev->udev->devnum);
/* let the user know what node this device is now attached to */
info("USB LCD device now attached to USBLCD-%d", interface->minor);
return 0;
error:
if (dev)
kref_put(&dev->kref, lcd_delete);
return retval;
}
static void lcd_disconnect(struct usb_interface *interface)
{
struct usb_lcd *dev;
int minor = interface->minor;
/* prevent skel_open() from racing skel_disconnect() */
lock_kernel();
dev = usb_get_intfdata(interface);
usb_set_intfdata(interface, NULL);
/* give back our minor */
usb_deregister_dev(interface, &lcd_class);
unlock_kernel();
/* decrement our usage count */
kref_put(&dev->kref, lcd_delete);
info("USB LCD #%d now disconnected", minor);
}
static struct usb_driver lcd_driver = {
.name = "usblcd",
.probe = lcd_probe,
.disconnect = lcd_disconnect,
.id_table = id_table,
};
static int __init usb_lcd_init(void)
{
int result;
result = usb_register(&lcd_driver);
if (result)
err("usb_register failed. Error number %d", result);
return result;
}
static void __exit usb_lcd_exit(void)
{
usb_deregister(&lcd_driver);
}
module_init(usb_lcd_init);
module_exit(usb_lcd_exit);
MODULE_AUTHOR("Georges Toth <g.toth@e-biz.lu>");
MODULE_DESCRIPTION(DRIVER_VERSION);
MODULE_LICENSE("GPL");