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linux_dsm_epyc7002/arch/frv/kernel/dma.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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/* dma.c: DMA controller management on FR401 and the like
*
* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* 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.
*/
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <asm/dma.h>
#include <asm/gpio-regs.h>
#include <asm/irc-regs.h>
#include <asm/cpu-irqs.h>
struct frv_dma_channel {
uint8_t flags;
#define FRV_DMA_FLAGS_RESERVED 0x01
#define FRV_DMA_FLAGS_INUSE 0x02
#define FRV_DMA_FLAGS_PAUSED 0x04
uint8_t cap; /* capabilities available */
int irq; /* completion IRQ */
uint32_t dreqbit;
uint32_t dackbit;
uint32_t donebit;
const unsigned long ioaddr; /* DMA controller regs addr */
const char *devname;
dma_irq_handler_t handler;
void *data;
};
#define __get_DMAC(IO,X) ({ *(volatile unsigned long *)((IO) + DMAC_##X##x); })
#define __set_DMAC(IO,X,V) \
do { \
*(volatile unsigned long *)((IO) + DMAC_##X##x) = (V); \
mb(); \
} while(0)
#define ___set_DMAC(IO,X,V) \
do { \
*(volatile unsigned long *)((IO) + DMAC_##X##x) = (V); \
} while(0)
static struct frv_dma_channel frv_dma_channels[FRV_DMA_NCHANS] = {
[0] = {
.cap = FRV_DMA_CAP_DREQ | FRV_DMA_CAP_DACK | FRV_DMA_CAP_DONE,
.irq = IRQ_CPU_DMA0,
.dreqbit = SIR_DREQ0_INPUT,
.dackbit = SOR_DACK0_OUTPUT,
.donebit = SOR_DONE0_OUTPUT,
.ioaddr = 0xfe000900,
},
[1] = {
.cap = FRV_DMA_CAP_DREQ | FRV_DMA_CAP_DACK | FRV_DMA_CAP_DONE,
.irq = IRQ_CPU_DMA1,
.dreqbit = SIR_DREQ1_INPUT,
.dackbit = SOR_DACK1_OUTPUT,
.donebit = SOR_DONE1_OUTPUT,
.ioaddr = 0xfe000980,
},
[2] = {
.cap = FRV_DMA_CAP_DREQ | FRV_DMA_CAP_DACK,
.irq = IRQ_CPU_DMA2,
.dreqbit = SIR_DREQ2_INPUT,
.dackbit = SOR_DACK2_OUTPUT,
.ioaddr = 0xfe000a00,
},
[3] = {
.cap = FRV_DMA_CAP_DREQ | FRV_DMA_CAP_DACK,
.irq = IRQ_CPU_DMA3,
.dreqbit = SIR_DREQ3_INPUT,
.dackbit = SOR_DACK3_OUTPUT,
.ioaddr = 0xfe000a80,
},
[4] = {
.cap = FRV_DMA_CAP_DREQ,
.irq = IRQ_CPU_DMA4,
.dreqbit = SIR_DREQ4_INPUT,
.ioaddr = 0xfe001000,
},
[5] = {
.cap = FRV_DMA_CAP_DREQ,
.irq = IRQ_CPU_DMA5,
.dreqbit = SIR_DREQ5_INPUT,
.ioaddr = 0xfe001080,
},
[6] = {
.cap = FRV_DMA_CAP_DREQ,
.irq = IRQ_CPU_DMA6,
.dreqbit = SIR_DREQ6_INPUT,
.ioaddr = 0xfe001100,
},
[7] = {
.cap = FRV_DMA_CAP_DREQ,
.irq = IRQ_CPU_DMA7,
.dreqbit = SIR_DREQ7_INPUT,
.ioaddr = 0xfe001180,
},
};
static DEFINE_RWLOCK(frv_dma_channels_lock);
unsigned long frv_dma_inprogress;
#define frv_clear_dma_inprogress(channel) \
atomic_clear_mask(1 << (channel), &frv_dma_inprogress);
#define frv_set_dma_inprogress(channel) \
atomic_set_mask(1 << (channel), &frv_dma_inprogress);
/*****************************************************************************/
/*
* DMA irq handler - determine channel involved, grab status and call real handler
*/
static irqreturn_t dma_irq_handler(int irq, void *_channel)
{
struct frv_dma_channel *channel = _channel;
frv_clear_dma_inprogress(channel - frv_dma_channels);
return channel->handler(channel - frv_dma_channels,
__get_DMAC(channel->ioaddr, CSTR),
channel->data);
} /* end dma_irq_handler() */
/*****************************************************************************/
/*
* Determine which DMA controllers are present on this CPU
*/
void __init frv_dma_init(void)
{
unsigned long psr = __get_PSR();
int num_dma, i;
/* First, determine how many DMA channels are available */
switch (PSR_IMPLE(psr)) {
case PSR_IMPLE_FR405:
case PSR_IMPLE_FR451:
case PSR_IMPLE_FR501:
case PSR_IMPLE_FR551:
num_dma = FRV_DMA_8CHANS;
break;
case PSR_IMPLE_FR401:
default:
num_dma = FRV_DMA_4CHANS;
break;
}
/* Now mark all of the non-existent channels as reserved */
for(i = num_dma; i < FRV_DMA_NCHANS; i++)
frv_dma_channels[i].flags = FRV_DMA_FLAGS_RESERVED;
} /* end frv_dma_init() */
/*****************************************************************************/
/*
* allocate a DMA controller channel and the IRQ associated with it
*/
int frv_dma_open(const char *devname,
unsigned long dmamask,
int dmacap,
dma_irq_handler_t handler,
unsigned long irq_flags,
void *data)
{
struct frv_dma_channel *channel;
int dma, ret;
uint32_t val;
write_lock(&frv_dma_channels_lock);
ret = -ENOSPC;
for (dma = FRV_DMA_NCHANS - 1; dma >= 0; dma--) {
channel = &frv_dma_channels[dma];
if (!test_bit(dma, &dmamask))
continue;
if ((channel->cap & dmacap) != dmacap)
continue;
if (!frv_dma_channels[dma].flags)
goto found;
}
goto out;
found:
ret = request_irq(channel->irq, dma_irq_handler, irq_flags, devname, channel);
if (ret < 0)
goto out;
/* okay, we've allocated all the resources */
channel = &frv_dma_channels[dma];
channel->flags |= FRV_DMA_FLAGS_INUSE;
channel->devname = devname;
channel->handler = handler;
channel->data = data;
/* Now make sure we are set up for DMA and not GPIO */
/* SIR bit must be set for DMA to work */
__set_SIR(channel->dreqbit | __get_SIR());
/* SOR bits depend on what the caller requests */
val = __get_SOR();
if(dmacap & FRV_DMA_CAP_DACK)
val |= channel->dackbit;
else
val &= ~channel->dackbit;
if(dmacap & FRV_DMA_CAP_DONE)
val |= channel->donebit;
else
val &= ~channel->donebit;
__set_SOR(val);
ret = dma;
out:
write_unlock(&frv_dma_channels_lock);
return ret;
} /* end frv_dma_open() */
EXPORT_SYMBOL(frv_dma_open);
/*****************************************************************************/
/*
* close a DMA channel and its associated interrupt
*/
void frv_dma_close(int dma)
{
struct frv_dma_channel *channel = &frv_dma_channels[dma];
unsigned long flags;
write_lock_irqsave(&frv_dma_channels_lock, flags);
free_irq(channel->irq, channel);
frv_dma_stop(dma);
channel->flags &= ~FRV_DMA_FLAGS_INUSE;
write_unlock_irqrestore(&frv_dma_channels_lock, flags);
} /* end frv_dma_close() */
EXPORT_SYMBOL(frv_dma_close);
/*****************************************************************************/
/*
* set static configuration on a DMA channel
*/
void frv_dma_config(int dma, unsigned long ccfr, unsigned long cctr, unsigned long apr)
{
unsigned long ioaddr = frv_dma_channels[dma].ioaddr;
___set_DMAC(ioaddr, CCFR, ccfr);
___set_DMAC(ioaddr, CCTR, cctr);
___set_DMAC(ioaddr, APR, apr);
mb();
} /* end frv_dma_config() */
EXPORT_SYMBOL(frv_dma_config);
/*****************************************************************************/
/*
* start a DMA channel
*/
void frv_dma_start(int dma,
unsigned long sba, unsigned long dba,
unsigned long pix, unsigned long six, unsigned long bcl)
{
unsigned long ioaddr = frv_dma_channels[dma].ioaddr;
___set_DMAC(ioaddr, SBA, sba);
___set_DMAC(ioaddr, DBA, dba);
___set_DMAC(ioaddr, PIX, pix);
___set_DMAC(ioaddr, SIX, six);
___set_DMAC(ioaddr, BCL, bcl);
___set_DMAC(ioaddr, CSTR, 0);
mb();
__set_DMAC(ioaddr, CCTR, __get_DMAC(ioaddr, CCTR) | DMAC_CCTRx_ACT);
frv_set_dma_inprogress(dma);
} /* end frv_dma_start() */
EXPORT_SYMBOL(frv_dma_start);
/*****************************************************************************/
/*
* restart a DMA channel that's been stopped in circular addressing mode by comparison-end
*/
void frv_dma_restart_circular(int dma, unsigned long six)
{
unsigned long ioaddr = frv_dma_channels[dma].ioaddr;
___set_DMAC(ioaddr, SIX, six);
___set_DMAC(ioaddr, CSTR, __get_DMAC(ioaddr, CSTR) & ~DMAC_CSTRx_CE);
mb();
__set_DMAC(ioaddr, CCTR, __get_DMAC(ioaddr, CCTR) | DMAC_CCTRx_ACT);
frv_set_dma_inprogress(dma);
} /* end frv_dma_restart_circular() */
EXPORT_SYMBOL(frv_dma_restart_circular);
/*****************************************************************************/
/*
* stop a DMA channel
*/
void frv_dma_stop(int dma)
{
unsigned long ioaddr = frv_dma_channels[dma].ioaddr;
uint32_t cctr;
___set_DMAC(ioaddr, CSTR, 0);
cctr = __get_DMAC(ioaddr, CCTR);
cctr &= ~(DMAC_CCTRx_IE | DMAC_CCTRx_ACT);
cctr |= DMAC_CCTRx_FC; /* fifo clear */
__set_DMAC(ioaddr, CCTR, cctr);
__set_DMAC(ioaddr, BCL, 0);
frv_clear_dma_inprogress(dma);
} /* end frv_dma_stop() */
EXPORT_SYMBOL(frv_dma_stop);
/*****************************************************************************/
/*
* test interrupt status of DMA channel
*/
int is_frv_dma_interrupting(int dma)
{
unsigned long ioaddr = frv_dma_channels[dma].ioaddr;
return __get_DMAC(ioaddr, CSTR) & (1 << 23);
} /* end is_frv_dma_interrupting() */
EXPORT_SYMBOL(is_frv_dma_interrupting);
/*****************************************************************************/
/*
* dump data about a DMA channel
*/
void frv_dma_dump(int dma)
{
unsigned long ioaddr = frv_dma_channels[dma].ioaddr;
unsigned long cstr, pix, six, bcl;
cstr = __get_DMAC(ioaddr, CSTR);
pix = __get_DMAC(ioaddr, PIX);
six = __get_DMAC(ioaddr, SIX);
bcl = __get_DMAC(ioaddr, BCL);
printk("DMA[%d] cstr=%lx pix=%lx six=%lx bcl=%lx\n", dma, cstr, pix, six, bcl);
} /* end frv_dma_dump() */
EXPORT_SYMBOL(frv_dma_dump);
/*****************************************************************************/
/*
* pause all DMA controllers
* - called by clock mangling routines
* - caller must be holding interrupts disabled
*/
void frv_dma_pause_all(void)
{
struct frv_dma_channel *channel;
unsigned long ioaddr;
unsigned long cstr, cctr;
int dma;
write_lock(&frv_dma_channels_lock);
for (dma = FRV_DMA_NCHANS - 1; dma >= 0; dma--) {
channel = &frv_dma_channels[dma];
if (!(channel->flags & FRV_DMA_FLAGS_INUSE))
continue;
ioaddr = channel->ioaddr;
cctr = __get_DMAC(ioaddr, CCTR);
if (cctr & DMAC_CCTRx_ACT) {
cctr &= ~DMAC_CCTRx_ACT;
__set_DMAC(ioaddr, CCTR, cctr);
do {
cstr = __get_DMAC(ioaddr, CSTR);
} while (cstr & DMAC_CSTRx_BUSY);
if (cstr & DMAC_CSTRx_FED)
channel->flags |= FRV_DMA_FLAGS_PAUSED;
frv_clear_dma_inprogress(dma);
}
}
} /* end frv_dma_pause_all() */
EXPORT_SYMBOL(frv_dma_pause_all);
/*****************************************************************************/
/*
* resume paused DMA controllers
* - called by clock mangling routines
* - caller must be holding interrupts disabled
*/
void frv_dma_resume_all(void)
{
struct frv_dma_channel *channel;
unsigned long ioaddr;
unsigned long cstr, cctr;
int dma;
for (dma = FRV_DMA_NCHANS - 1; dma >= 0; dma--) {
channel = &frv_dma_channels[dma];
if (!(channel->flags & FRV_DMA_FLAGS_PAUSED))
continue;
ioaddr = channel->ioaddr;
cstr = __get_DMAC(ioaddr, CSTR);
cstr &= ~(DMAC_CSTRx_FED | DMAC_CSTRx_INT);
__set_DMAC(ioaddr, CSTR, cstr);
cctr = __get_DMAC(ioaddr, CCTR);
cctr |= DMAC_CCTRx_ACT;
__set_DMAC(ioaddr, CCTR, cctr);
channel->flags &= ~FRV_DMA_FLAGS_PAUSED;
frv_set_dma_inprogress(dma);
}
write_unlock(&frv_dma_channels_lock);
} /* end frv_dma_resume_all() */
EXPORT_SYMBOL(frv_dma_resume_all);
/*****************************************************************************/
/*
* dma status clear
*/
void frv_dma_status_clear(int dma)
{
unsigned long ioaddr = frv_dma_channels[dma].ioaddr;
uint32_t cctr;
___set_DMAC(ioaddr, CSTR, 0);
cctr = __get_DMAC(ioaddr, CCTR);
} /* end frv_dma_status_clear() */
EXPORT_SYMBOL(frv_dma_status_clear);
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