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aha/drivers/scsi/a3000.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

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#include <linux/types.h>
#include <linux/mm.h>
#include <linux/blkdev.h>
#include <linux/sched.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <asm/setup.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/amigaints.h>
#include <asm/amigahw.h>
#include <asm/irq.h>
#include "scsi.h"
#include <scsi/scsi_host.h>
#include "wd33c93.h"
#include "a3000.h"
#include<linux/stat.h>
#define DMA(ptr) ((a3000_scsiregs *)((ptr)->base))
#define HDATA(ptr) ((struct WD33C93_hostdata *)((ptr)->hostdata))
static struct Scsi_Host *a3000_host = NULL;
static irqreturn_t a3000_intr (int irq, void *dummy)
{
unsigned long flags;
unsigned int status = DMA(a3000_host)->ISTR;
if (!(status & ISTR_INT_P))
return IRQ_NONE;
if (status & ISTR_INTS)
{
spin_lock_irqsave(a3000_host->host_lock, flags);
wd33c93_intr (a3000_host);
spin_unlock_irqrestore(a3000_host->host_lock, flags);
return IRQ_HANDLED;
}
printk("Non-serviced A3000 SCSI-interrupt? ISTR = %02x\n", status);
return IRQ_NONE;
}
static int dma_setup(struct scsi_cmnd *cmd, int dir_in)
{
unsigned short cntr = CNTR_PDMD | CNTR_INTEN;
unsigned long addr = virt_to_bus(cmd->SCp.ptr);
/*
* if the physical address has the wrong alignment, or if
* physical address is bad, or if it is a write and at the
* end of a physical memory chunk, then allocate a bounce
* buffer
*/
if (addr & A3000_XFER_MASK ||
(!dir_in && mm_end_of_chunk (addr, cmd->SCp.this_residual)))
{
HDATA(a3000_host)->dma_bounce_len = (cmd->SCp.this_residual + 511)
& ~0x1ff;
HDATA(a3000_host)->dma_bounce_buffer =
kmalloc (HDATA(a3000_host)->dma_bounce_len, GFP_KERNEL);
/* can't allocate memory; use PIO */
if (!HDATA(a3000_host)->dma_bounce_buffer) {
HDATA(a3000_host)->dma_bounce_len = 0;
return 1;
}
if (!dir_in) {
/* copy to bounce buffer for a write */
if (cmd->use_sg) {
memcpy (HDATA(a3000_host)->dma_bounce_buffer,
cmd->SCp.ptr, cmd->SCp.this_residual);
} else
memcpy (HDATA(a3000_host)->dma_bounce_buffer,
cmd->request_buffer, cmd->request_bufflen);
}
addr = virt_to_bus(HDATA(a3000_host)->dma_bounce_buffer);
}
/* setup dma direction */
if (!dir_in)
cntr |= CNTR_DDIR;
/* remember direction */
HDATA(a3000_host)->dma_dir = dir_in;
DMA(a3000_host)->CNTR = cntr;
/* setup DMA *physical* address */
DMA(a3000_host)->ACR = addr;
if (dir_in)
/* invalidate any cache */
cache_clear (addr, cmd->SCp.this_residual);
else
/* push any dirty cache */
cache_push (addr, cmd->SCp.this_residual);
/* start DMA */
mb(); /* make sure setup is completed */
DMA(a3000_host)->ST_DMA = 1;
mb(); /* make sure DMA has started before next IO */
/* return success */
return 0;
}
static void dma_stop(struct Scsi_Host *instance, struct scsi_cmnd *SCpnt,
int status)
{
/* disable SCSI interrupts */
unsigned short cntr = CNTR_PDMD;
if (!HDATA(instance)->dma_dir)
cntr |= CNTR_DDIR;
DMA(instance)->CNTR = cntr;
mb(); /* make sure CNTR is updated before next IO */
/* flush if we were reading */
if (HDATA(instance)->dma_dir) {
DMA(instance)->FLUSH = 1;
mb(); /* don't allow prefetch */
while (!(DMA(instance)->ISTR & ISTR_FE_FLG))
barrier();
mb(); /* no IO until FLUSH is done */
}
/* clear a possible interrupt */
/* I think that this CINT is only necessary if you are
* using the terminal count features. HM 7 Mar 1994
*/
DMA(instance)->CINT = 1;
/* stop DMA */
DMA(instance)->SP_DMA = 1;
mb(); /* make sure DMA is stopped before next IO */
/* restore the CONTROL bits (minus the direction flag) */
DMA(instance)->CNTR = CNTR_PDMD | CNTR_INTEN;
mb(); /* make sure CNTR is updated before next IO */
/* copy from a bounce buffer, if necessary */
if (status && HDATA(instance)->dma_bounce_buffer) {
if (SCpnt && SCpnt->use_sg) {
if (HDATA(instance)->dma_dir && SCpnt)
memcpy (SCpnt->SCp.ptr,
HDATA(instance)->dma_bounce_buffer,
SCpnt->SCp.this_residual);
kfree (HDATA(instance)->dma_bounce_buffer);
HDATA(instance)->dma_bounce_buffer = NULL;
HDATA(instance)->dma_bounce_len = 0;
} else {
if (HDATA(instance)->dma_dir && SCpnt)
memcpy (SCpnt->request_buffer,
HDATA(instance)->dma_bounce_buffer,
SCpnt->request_bufflen);
kfree (HDATA(instance)->dma_bounce_buffer);
HDATA(instance)->dma_bounce_buffer = NULL;
HDATA(instance)->dma_bounce_len = 0;
}
}
}
int __init a3000_detect(struct scsi_host_template *tpnt)
{
wd33c93_regs regs;
if (!MACH_IS_AMIGA || !AMIGAHW_PRESENT(A3000_SCSI))
return 0;
if (!request_mem_region(0xDD0000, 256, "wd33c93"))
return 0;
tpnt->proc_name = "A3000";
tpnt->proc_info = &wd33c93_proc_info;
a3000_host = scsi_register (tpnt, sizeof(struct WD33C93_hostdata));
if (a3000_host == NULL)
goto fail_register;
a3000_host->base = ZTWO_VADDR(0xDD0000);
a3000_host->irq = IRQ_AMIGA_PORTS;
DMA(a3000_host)->DAWR = DAWR_A3000;
regs.SASR = &(DMA(a3000_host)->SASR);
regs.SCMD = &(DMA(a3000_host)->SCMD);
wd33c93_init(a3000_host, regs, dma_setup, dma_stop, WD33C93_FS_12_15);
if (request_irq(IRQ_AMIGA_PORTS, a3000_intr, IRQF_SHARED, "A3000 SCSI",
a3000_intr))
goto fail_irq;
DMA(a3000_host)->CNTR = CNTR_PDMD | CNTR_INTEN;
return 1;
fail_irq:
wd33c93_release();
scsi_unregister(a3000_host);
fail_register:
release_mem_region(0xDD0000, 256);
return 0;
}
static int a3000_bus_reset(struct scsi_cmnd *cmd)
{
/* FIXME perform bus-specific reset */
/* FIXME 2: kill this entire function, which should
cause mid-layer to call wd33c93_host_reset anyway? */
spin_lock_irq(cmd->device->host->host_lock);
wd33c93_host_reset(cmd);
spin_unlock_irq(cmd->device->host->host_lock);
return SUCCESS;
}
#define HOSTS_C
static struct scsi_host_template driver_template = {
.proc_name = "A3000",
.name = "Amiga 3000 built-in SCSI",
.detect = a3000_detect,
.release = a3000_release,
.queuecommand = wd33c93_queuecommand,
.eh_abort_handler = wd33c93_abort,
.eh_bus_reset_handler = a3000_bus_reset,
.eh_host_reset_handler = wd33c93_host_reset,
.can_queue = CAN_QUEUE,
.this_id = 7,
.sg_tablesize = SG_ALL,
.cmd_per_lun = CMD_PER_LUN,
.use_clustering = ENABLE_CLUSTERING
};
#include "scsi_module.c"
int a3000_release(struct Scsi_Host *instance)
{
wd33c93_release();
DMA(instance)->CNTR = 0;
release_mem_region(0xDD0000, 256);
free_irq(IRQ_AMIGA_PORTS, a3000_intr);
return 1;
}
MODULE_LICENSE("GPL");
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