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linux-next/drivers/scsi/a2091.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/init.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 <linux/zorro.h>
#include <asm/irq.h>
#include <linux/spinlock.h>
#include "scsi.h"
#include <scsi/scsi_host.h>
#include "wd33c93.h"
#include "a2091.h"
#include<linux/stat.h>
#define DMA(ptr) ((a2091_scsiregs *)((ptr)->base))
#define HDATA(ptr) ((struct WD33C93_hostdata *)((ptr)->hostdata))
static irqreturn_t a2091_intr (int irq, void *_instance)
{
unsigned long flags;
unsigned int status;
struct Scsi_Host *instance = (struct Scsi_Host *)_instance;
status = DMA(instance)->ISTR;
if (!(status & (ISTR_INT_F|ISTR_INT_P)) || !(status & ISTR_INTS))
return IRQ_NONE;
spin_lock_irqsave(instance->host_lock, flags);
wd33c93_intr(instance);
spin_unlock_irqrestore(instance->host_lock, flags);
return IRQ_HANDLED;
}
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);
struct Scsi_Host *instance = cmd->device->host;
/* don't allow DMA if the physical address is bad */
if (addr & A2091_XFER_MASK ||
(!dir_in && mm_end_of_chunk (addr, cmd->SCp.this_residual)))
{
HDATA(instance)->dma_bounce_len = (cmd->SCp.this_residual + 511)
& ~0x1ff;
HDATA(instance)->dma_bounce_buffer =
kmalloc (HDATA(instance)->dma_bounce_len, GFP_KERNEL);
/* can't allocate memory; use PIO */
if (!HDATA(instance)->dma_bounce_buffer) {
HDATA(instance)->dma_bounce_len = 0;
return 1;
}
/* get the physical address of the bounce buffer */
addr = virt_to_bus(HDATA(instance)->dma_bounce_buffer);
/* the bounce buffer may not be in the first 16M of physmem */
if (addr & A2091_XFER_MASK) {
/* we could use chipmem... maybe later */
kfree (HDATA(instance)->dma_bounce_buffer);
HDATA(instance)->dma_bounce_buffer = NULL;
HDATA(instance)->dma_bounce_len = 0;
return 1;
}
if (!dir_in) {
/* copy to bounce buffer for a write */
if (cmd->use_sg)
#if 0
panic ("scsi%ddma: incomplete s/g support",
instance->host_no);
#else
memcpy (HDATA(instance)->dma_bounce_buffer,
cmd->SCp.ptr, cmd->SCp.this_residual);
#endif
else
memcpy (HDATA(instance)->dma_bounce_buffer,
cmd->request_buffer, cmd->request_bufflen);
}
}
/* setup dma direction */
if (!dir_in)
cntr |= CNTR_DDIR;
/* remember direction */
HDATA(cmd->device->host)->dma_dir = dir_in;
DMA(cmd->device->host)->CNTR = cntr;
/* setup DMA *physical* address */
DMA(cmd->device->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 */
DMA(cmd->device->host)->ST_DMA = 1;
/* 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;
/* disable SCSI interrupts */
DMA(instance)->CNTR = cntr;
/* flush if we were reading */
if (HDATA(instance)->dma_dir) {
DMA(instance)->FLUSH = 1;
while (!(DMA(instance)->ISTR & ISTR_FE_FLG))
;
}
/* clear a possible interrupt */
DMA(instance)->CINT = 1;
/* stop DMA */
DMA(instance)->SP_DMA = 1;
/* restore the CONTROL bits (minus the direction flag) */
DMA(instance)->CNTR = CNTR_PDMD | CNTR_INTEN;
/* copy from a bounce buffer, if necessary */
if (status && HDATA(instance)->dma_bounce_buffer) {
if (SCpnt && SCpnt->use_sg) {
#if 0
panic ("scsi%d: incomplete s/g support",
instance->host_no);
#else
if( HDATA(instance)->dma_dir )
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;
#endif
} 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 a2091_detect(struct scsi_host_template *tpnt)
{
static unsigned char called = 0;
struct Scsi_Host *instance;
unsigned long address;
struct zorro_dev *z = NULL;
wd33c93_regs regs;
int num_a2091 = 0;
if (!MACH_IS_AMIGA || called)
return 0;
called = 1;
tpnt->proc_name = "A2091";
tpnt->proc_info = &wd33c93_proc_info;
while ((z = zorro_find_device(ZORRO_WILDCARD, z))) {
if (z->id != ZORRO_PROD_CBM_A590_A2091_1 &&
z->id != ZORRO_PROD_CBM_A590_A2091_2)
continue;
address = z->resource.start;
if (!request_mem_region(address, 256, "wd33c93"))
continue;
instance = scsi_register (tpnt, sizeof (struct WD33C93_hostdata));
if (instance == NULL) {
release_mem_region(address, 256);
continue;
}
instance->base = ZTWO_VADDR(address);
instance->irq = IRQ_AMIGA_PORTS;
instance->unique_id = z->slotaddr;
DMA(instance)->DAWR = DAWR_A2091;
regs.SASR = &(DMA(instance)->SASR);
regs.SCMD = &(DMA(instance)->SCMD);
wd33c93_init(instance, regs, dma_setup, dma_stop, WD33C93_FS_8_10);
request_irq(IRQ_AMIGA_PORTS, a2091_intr, IRQF_SHARED, "A2091 SCSI",
instance);
DMA(instance)->CNTR = CNTR_PDMD | CNTR_INTEN;
num_a2091++;
}
return num_a2091;
}
static int a2091_bus_reset(struct scsi_cmnd *cmd)
{
/* FIXME perform bus-specific reset */
/* FIXME 2: kill this function, and let midlayer fall back
to the same action, calling wd33c93_host_reset() */
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 = "A2901",
.name = "Commodore A2091/A590 SCSI",
.detect = a2091_detect,
.release = a2091_release,
.queuecommand = wd33c93_queuecommand,
.eh_abort_handler = wd33c93_abort,
.eh_bus_reset_handler = a2091_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 = DISABLE_CLUSTERING
};
#include "scsi_module.c"
int a2091_release(struct Scsi_Host *instance)
{
#ifdef MODULE
DMA(instance)->CNTR = 0;
release_mem_region(ZTWO_PADDR(instance->base), 256);
free_irq(IRQ_AMIGA_PORTS, instance);
wd33c93_release();
#endif
return 1;
}
MODULE_LICENSE("GPL");
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