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linux/drivers/isdn/pcbit/layer2.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

733 lines
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/*
* PCBIT-D low-layer interface
*
* Copyright (C) 1996 Universidade de Lisboa
*
* Written by Pedro Roque Marques (roque@di.fc.ul.pt)
*
* This software may be used and distributed according to the terms of
* the GNU General Public License, incorporated herein by reference.
*/
/*
* 19991203 - Fernando Carvalho - takion@superbofh.org
* Hacked to compile with egcs and run with current version of isdn modules
*/
/*
* Based on documentation provided by Inesc:
* - "Interface com bus do PC para o PCBIT e PCBIT-D", Inesc, Jan 93
*/
/*
* TODO: better handling of errors
* re-write/remove debug printks
*/
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/workqueue.h>
#include <linux/mm.h>
#include <linux/skbuff.h>
#include <linux/isdnif.h>
#include <asm/system.h>
#include <asm/io.h>
#include "pcbit.h"
#include "layer2.h"
#include "edss1.h"
#undef DEBUG_FRAG
/*
* task queue struct
*/
/*
* Layer 3 packet demultiplexer
* drv.c
*/
extern void pcbit_l3_receive(struct pcbit_dev *dev, ulong msg,
struct sk_buff *skb,
ushort hdr_len, ushort refnum);
/*
* Prototypes
*/
void pcbit_deliver(void *data);
static void pcbit_transmit(struct pcbit_dev *dev);
static void pcbit_recv_ack(struct pcbit_dev *dev, unsigned char ack);
static void pcbit_l2_error(struct pcbit_dev *dev);
static void pcbit_l2_active_conf(struct pcbit_dev *dev, u_char info);
static void pcbit_l2_err_recover(unsigned long data);
static void pcbit_firmware_bug(struct pcbit_dev *dev);
static __inline__ void
pcbit_sched_delivery(struct pcbit_dev *dev)
{
schedule_work(&dev->qdelivery);
}
/*
* Called from layer3
*/
int
pcbit_l2_write(struct pcbit_dev *dev, ulong msg, ushort refnum,
struct sk_buff *skb, unsigned short hdr_len)
{
struct frame_buf *frame,
*ptr;
unsigned long flags;
if (dev->l2_state != L2_RUNNING && dev->l2_state != L2_LOADING) {
dev_kfree_skb(skb);
return -1;
}
if ((frame = (struct frame_buf *) kmalloc(sizeof(struct frame_buf),
GFP_ATOMIC)) == NULL) {
printk(KERN_WARNING "pcbit_2_write: kmalloc failed\n");
dev_kfree_skb(skb);
return -1;
}
frame->msg = msg;
frame->refnum = refnum;
frame->copied = 0;
frame->hdr_len = hdr_len;
if (skb)
frame->dt_len = skb->len - hdr_len;
else
frame->dt_len = 0;
frame->skb = skb;
frame->next = NULL;
spin_lock_irqsave(&dev->lock, flags);
if (dev->write_queue == NULL) {
dev->write_queue = frame;
spin_unlock_irqrestore(&dev->lock, flags);
pcbit_transmit(dev);
} else {
for (ptr = dev->write_queue; ptr->next; ptr = ptr->next);
ptr->next = frame;
spin_unlock_irqrestore(&dev->lock, flags);
}
return 0;
}
static __inline__ void
pcbit_tx_update(struct pcbit_dev *dev, ushort len)
{
u_char info;
dev->send_seq = (dev->send_seq + 1) % 8;
dev->fsize[dev->send_seq] = len;
info = 0;
info |= dev->rcv_seq << 3;
info |= dev->send_seq;
writeb(info, dev->sh_mem + BANK4);
}
/*
* called by interrupt service routine or by write_2
*/
static void
pcbit_transmit(struct pcbit_dev *dev)
{
struct frame_buf *frame = NULL;
unsigned char unacked;
int flen; /* fragment frame length including all headers */
int free;
int count,
cp_len;
unsigned long flags;
unsigned short tt;
if (dev->l2_state != L2_RUNNING && dev->l2_state != L2_LOADING)
return;
unacked = (dev->send_seq + (8 - dev->unack_seq)) & 0x07;
spin_lock_irqsave(&dev->lock, flags);
if (dev->free > 16 && dev->write_queue && unacked < 7) {
if (!dev->w_busy)
dev->w_busy = 1;
else {
spin_unlock_irqrestore(&dev->lock, flags);
return;
}
frame = dev->write_queue;
free = dev->free;
spin_unlock_irqrestore(&dev->lock, flags);
if (frame->copied == 0) {
/* Type 0 frame */
ulong msg;
if (frame->skb)
flen = FRAME_HDR_LEN + PREHDR_LEN + frame->skb->len;
else
flen = FRAME_HDR_LEN + PREHDR_LEN;
if (flen > free)
flen = free;
msg = frame->msg;
/*
* Board level 2 header
*/
pcbit_writew(dev, flen - FRAME_HDR_LEN);
pcbit_writeb(dev, GET_MSG_CPU(msg));
pcbit_writeb(dev, GET_MSG_PROC(msg));
/* TH */
pcbit_writew(dev, frame->hdr_len + PREHDR_LEN);
/* TD */
pcbit_writew(dev, frame->dt_len);
/*
* Board level 3 fixed-header
*/
/* LEN = TH */
pcbit_writew(dev, frame->hdr_len + PREHDR_LEN);
/* XX */
pcbit_writew(dev, 0);
/* C + S */
pcbit_writeb(dev, GET_MSG_CMD(msg));
pcbit_writeb(dev, GET_MSG_SCMD(msg));
/* NUM */
pcbit_writew(dev, frame->refnum);
count = FRAME_HDR_LEN + PREHDR_LEN;
} else {
/* Type 1 frame */
flen = 2 + (frame->skb->len - frame->copied);
if (flen > free)
flen = free;
/* TT */
tt = ((ushort) (flen - 2)) | 0x8000U; /* Type 1 */
pcbit_writew(dev, tt);
count = 2;
}
if (frame->skb) {
cp_len = frame->skb->len - frame->copied;
if (cp_len > flen - count)
cp_len = flen - count;
memcpy_topcbit(dev, frame->skb->data + frame->copied,
cp_len);
frame->copied += cp_len;
}
/* bookkeeping */
dev->free -= flen;
pcbit_tx_update(dev, flen);
spin_lock_irqsave(&dev->lock, flags);
if (frame->skb == NULL || frame->copied == frame->skb->len) {
dev->write_queue = frame->next;
if (frame->skb != NULL) {
/* free frame */
dev_kfree_skb(frame->skb);
}
kfree(frame);
}
dev->w_busy = 0;
spin_unlock_irqrestore(&dev->lock, flags);
} else {
spin_unlock_irqrestore(&dev->lock, flags);
#ifdef DEBUG
printk(KERN_DEBUG "unacked %d free %d write_queue %s\n",
unacked, dev->free, dev->write_queue ? "not empty" :
"empty");
#endif
}
}
/*
* deliver a queued frame to the upper layer
*/
void
pcbit_deliver(void *data)
{
struct frame_buf *frame;
unsigned long flags, msg;
struct pcbit_dev *dev = (struct pcbit_dev *) data;
spin_lock_irqsave(&dev->lock, flags);
while ((frame = dev->read_queue)) {
dev->read_queue = frame->next;
spin_unlock_irqrestore(&dev->lock, flags);
SET_MSG_CPU(msg, 0);
SET_MSG_PROC(msg, 0);
SET_MSG_CMD(msg, frame->skb->data[2]);
SET_MSG_SCMD(msg, frame->skb->data[3]);
frame->refnum = *((ushort *) frame->skb->data + 4);
frame->msg = *((ulong *) & msg);
skb_pull(frame->skb, 6);
pcbit_l3_receive(dev, frame->msg, frame->skb, frame->hdr_len,
frame->refnum);
kfree(frame);
spin_lock_irqsave(&dev->lock, flags);
}
spin_unlock_irqrestore(&dev->lock, flags);
}
/*
* Reads BANK 2 & Reassembles
*/
static void
pcbit_receive(struct pcbit_dev *dev)
{
unsigned short tt;
u_char cpu,
proc;
struct frame_buf *frame = NULL;
unsigned long flags;
u_char type1;
if (dev->l2_state != L2_RUNNING && dev->l2_state != L2_LOADING)
return;
tt = pcbit_readw(dev);
if ((tt & 0x7fffU) > 511) {
printk(KERN_INFO "pcbit: invalid frame length -> TT=%04x\n",
tt);
pcbit_l2_error(dev);
return;
}
if (!(tt & 0x8000U)) { /* Type 0 */
type1 = 0;
if (dev->read_frame) {
printk(KERN_DEBUG "pcbit_receive: Type 0 frame and read_frame != NULL\n");
/* discard previous queued frame */
if (dev->read_frame->skb)
kfree_skb(dev->read_frame->skb);
kfree(dev->read_frame);
dev->read_frame = NULL;
}
frame = kmalloc(sizeof(struct frame_buf), GFP_ATOMIC);
if (frame == NULL) {
printk(KERN_WARNING "kmalloc failed\n");
return;
}
memset(frame, 0, sizeof(struct frame_buf));
cpu = pcbit_readb(dev);
proc = pcbit_readb(dev);
if (cpu != 0x06 && cpu != 0x02) {
printk(KERN_DEBUG "pcbit: invalid cpu value\n");
kfree(frame);
pcbit_l2_error(dev);
return;
}
/*
* we discard cpu & proc on receiving
* but we read it to update the pointer
*/
frame->hdr_len = pcbit_readw(dev);
frame->dt_len = pcbit_readw(dev);
/*
* 0 sized packet
* I don't know if they are an error or not...
* But they are very frequent
* Not documented
*/
if (frame->hdr_len == 0) {
kfree(frame);
#ifdef DEBUG
printk(KERN_DEBUG "0 sized frame\n");
#endif
pcbit_firmware_bug(dev);
return;
}
/* sanity check the length values */
if (frame->hdr_len > 1024 || frame->dt_len > 2048) {
#ifdef DEBUG
printk(KERN_DEBUG "length problem: ");
printk(KERN_DEBUG "TH=%04x TD=%04x\n",
frame->hdr_len,
frame->dt_len);
#endif
pcbit_l2_error(dev);
kfree(frame);
return;
}
/* minimum frame read */
frame->skb = dev_alloc_skb(frame->hdr_len + frame->dt_len +
((frame->hdr_len + 15) & ~15));
if (!frame->skb) {
printk(KERN_DEBUG "pcbit_receive: out of memory\n");
kfree(frame);
return;
}
/* 16 byte alignment for IP */
if (frame->dt_len)
skb_reserve(frame->skb, (frame->hdr_len + 15) & ~15);
} else {
/* Type 1 */
type1 = 1;
tt &= 0x7fffU;
if (!(frame = dev->read_frame)) {
printk("Type 1 frame and no frame queued\n");
/* usually after an error: toss frame */
dev->readptr += tt;
if (dev->readptr > dev->sh_mem + BANK2 + BANKLEN)
dev->readptr -= BANKLEN;
return;
}
}
memcpy_frompcbit(dev, skb_put(frame->skb, tt), tt);
frame->copied += tt;
spin_lock_irqsave(&dev->lock, flags);
if (frame->copied == frame->hdr_len + frame->dt_len) {
if (type1) {
dev->read_frame = NULL;
}
if (dev->read_queue) {
struct frame_buf *ptr;
for (ptr = dev->read_queue; ptr->next; ptr = ptr->next);
ptr->next = frame;
} else
dev->read_queue = frame;
} else {
dev->read_frame = frame;
}
spin_unlock_irqrestore(&dev->lock, flags);
}
/*
* The board sends 0 sized frames
* They are TDATA_CONFs that get messed up somehow
* gotta send a fake acknowledgment to the upper layer somehow
*/
static __inline__ void
pcbit_fake_conf(struct pcbit_dev *dev, struct pcbit_chan *chan)
{
isdn_ctrl ictl;
if (chan->queued) {
chan->queued--;
ictl.driver = dev->id;
ictl.command = ISDN_STAT_BSENT;
ictl.arg = chan->id;
dev->dev_if->statcallb(&ictl);
}
}
static void
pcbit_firmware_bug(struct pcbit_dev *dev)
{
struct pcbit_chan *chan;
chan = dev->b1;
if (chan->fsm_state == ST_ACTIVE) {
pcbit_fake_conf(dev, chan);
}
chan = dev->b2;
if (chan->fsm_state == ST_ACTIVE) {
pcbit_fake_conf(dev, chan);
}
}
irqreturn_t
pcbit_irq_handler(int interrupt, void *devptr)
{
struct pcbit_dev *dev;
u_char info,
ack_seq,
read_seq;
dev = (struct pcbit_dev *) devptr;
if (!dev) {
printk(KERN_WARNING "pcbit_irq_handler: wrong device\n");
return IRQ_NONE;
}
if (dev->interrupt) {
printk(KERN_DEBUG "pcbit: reentering interrupt hander\n");
return IRQ_HANDLED;
}
dev->interrupt = 1;
info = readb(dev->sh_mem + BANK3);
if (dev->l2_state == L2_STARTING || dev->l2_state == L2_ERROR) {
pcbit_l2_active_conf(dev, info);
dev->interrupt = 0;
return IRQ_HANDLED;
}
if (info & 0x40U) { /* E bit set */
#ifdef DEBUG
printk(KERN_DEBUG "pcbit_irq_handler: E bit on\n");
#endif
pcbit_l2_error(dev);
dev->interrupt = 0;
return IRQ_HANDLED;
}
if (dev->l2_state != L2_RUNNING && dev->l2_state != L2_LOADING) {
dev->interrupt = 0;
return IRQ_HANDLED;
}
ack_seq = (info >> 3) & 0x07U;
read_seq = (info & 0x07U);
dev->interrupt = 0;
if (read_seq != dev->rcv_seq) {
while (read_seq != dev->rcv_seq) {
pcbit_receive(dev);
dev->rcv_seq = (dev->rcv_seq + 1) % 8;
}
pcbit_sched_delivery(dev);
}
if (ack_seq != dev->unack_seq) {
pcbit_recv_ack(dev, ack_seq);
}
info = dev->rcv_seq << 3;
info |= dev->send_seq;
writeb(info, dev->sh_mem + BANK4);
return IRQ_HANDLED;
}
static void
pcbit_l2_active_conf(struct pcbit_dev *dev, u_char info)
{
u_char state;
state = dev->l2_state;
#ifdef DEBUG
printk(KERN_DEBUG "layer2_active_confirm\n");
#endif
if (info & 0x80U) {
dev->rcv_seq = info & 0x07U;
dev->l2_state = L2_RUNNING;
} else
dev->l2_state = L2_DOWN;
if (state == L2_STARTING)
wake_up_interruptible(&dev->set_running_wq);
if (state == L2_ERROR && dev->l2_state == L2_RUNNING) {
pcbit_transmit(dev);
}
}
static void
pcbit_l2_err_recover(unsigned long data)
{
struct pcbit_dev *dev;
struct frame_buf *frame;
dev = (struct pcbit_dev *) data;
del_timer(&dev->error_recover_timer);
if (dev->w_busy || dev->r_busy) {
init_timer(&dev->error_recover_timer);
dev->error_recover_timer.expires = jiffies + ERRTIME;
add_timer(&dev->error_recover_timer);
return;
}
dev->w_busy = dev->r_busy = 1;
if (dev->read_frame) {
if (dev->read_frame->skb)
kfree_skb(dev->read_frame->skb);
kfree(dev->read_frame);
dev->read_frame = NULL;
}
if (dev->write_queue) {
frame = dev->write_queue;
#ifdef FREE_ON_ERROR
dev->write_queue = dev->write_queue->next;
if (frame->skb) {
dev_kfree_skb(frame->skb);
}
kfree(frame);
#else
frame->copied = 0;
#endif
}
dev->rcv_seq = dev->send_seq = dev->unack_seq = 0;
dev->free = 511;
dev->l2_state = L2_ERROR;
/* this is an hack... */
pcbit_firmware_bug(dev);
dev->writeptr = dev->sh_mem;
dev->readptr = dev->sh_mem + BANK2;
writeb((0x80U | ((dev->rcv_seq & 0x07) << 3) | (dev->send_seq & 0x07)),
dev->sh_mem + BANK4);
dev->w_busy = dev->r_busy = 0;
}
static void
pcbit_l2_error(struct pcbit_dev *dev)
{
if (dev->l2_state == L2_RUNNING) {
printk(KERN_INFO "pcbit: layer 2 error\n");
#ifdef DEBUG
log_state(dev);
#endif
dev->l2_state = L2_DOWN;
init_timer(&dev->error_recover_timer);
dev->error_recover_timer.function = &pcbit_l2_err_recover;
dev->error_recover_timer.data = (ulong) dev;
dev->error_recover_timer.expires = jiffies + ERRTIME;
add_timer(&dev->error_recover_timer);
}
}
/*
* Description:
* if board acks frames
* update dev->free
* call pcbit_transmit to write possible queued frames
*/
static void
pcbit_recv_ack(struct pcbit_dev *dev, unsigned char ack)
{
int i,
count;
int unacked;
unacked = (dev->send_seq + (8 - dev->unack_seq)) & 0x07;
/* dev->unack_seq < ack <= dev->send_seq; */
if (unacked) {
if (dev->send_seq > dev->unack_seq) {
if (ack <= dev->unack_seq || ack > dev->send_seq) {
printk(KERN_DEBUG
"layer 2 ack unacceptable - dev %d",
dev->id);
pcbit_l2_error(dev);
} else if (ack > dev->send_seq && ack <= dev->unack_seq) {
printk(KERN_DEBUG
"layer 2 ack unacceptable - dev %d",
dev->id);
pcbit_l2_error(dev);
}
}
/* ack is acceptable */
i = dev->unack_seq;
do {
dev->unack_seq = i = (i + 1) % 8;
dev->free += dev->fsize[i];
} while (i != ack);
count = 0;
while (count < 7 && dev->write_queue) {
u8 lsend_seq = dev->send_seq;
pcbit_transmit(dev);
if (dev->send_seq == lsend_seq)
break;
count++;
}
} else
printk(KERN_DEBUG "recv_ack: unacked = 0\n");
}
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