7d12e780e0
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)
121 lines
3.0 KiB
C
121 lines
3.0 KiB
C
/*
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* i2sbus driver -- private definitions
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*
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* Copyright 2006 Johannes Berg <johannes@sipsolutions.net>
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*
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* GPL v2, can be found in COPYING.
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*/
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#ifndef __I2SBUS_H
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#define __I2SBUS_H
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#include <linux/interrupt.h>
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#include <linux/spinlock.h>
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#include <linux/mutex.h>
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#include <sound/pcm.h>
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#include <asm/prom.h>
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#include <asm/pmac_feature.h>
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#include <asm/dbdma.h>
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#include "i2sbus-interface.h"
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#include "../soundbus.h"
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struct i2sbus_control {
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struct list_head list;
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struct macio_chip *macio;
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};
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#define MAX_DBDMA_COMMANDS 32
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struct dbdma_command_mem {
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dma_addr_t bus_addr;
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dma_addr_t bus_cmd_start;
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struct dbdma_cmd *cmds;
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void *space;
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int size;
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u32 running:1;
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};
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struct pcm_info {
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u32 created:1, /* has this direction been created with alsa? */
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active:1; /* is this stream active? */
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/* runtime information */
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struct snd_pcm_substream *substream;
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int current_period;
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u32 frame_count;
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struct dbdma_command_mem dbdma_ring;
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volatile struct dbdma_regs __iomem *dbdma;
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};
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enum {
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aoa_resource_i2smmio = 0,
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aoa_resource_txdbdma,
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aoa_resource_rxdbdma,
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};
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struct i2sbus_dev {
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struct soundbus_dev sound;
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struct macio_dev *macio;
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struct i2sbus_control *control;
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volatile struct i2s_interface_regs __iomem *intfregs;
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struct resource resources[3];
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struct resource *allocated_resource[3];
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int interrupts[3];
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char rnames[3][32];
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/* info about currently active substreams */
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struct pcm_info out, in;
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snd_pcm_format_t format;
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unsigned int rate;
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/* list for a single controller */
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struct list_head item;
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/* number of bus on controller */
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int bus_number;
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/* for use by control layer */
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struct pmf_function *enable,
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*cell_enable,
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*cell_disable,
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*clock_enable,
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*clock_disable;
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/* locks */
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/* spinlock for low-level interrupt locking */
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spinlock_t low_lock;
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/* mutex for high-level consistency */
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struct mutex lock;
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};
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#define soundbus_dev_to_i2sbus_dev(sdev) \
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container_of(sdev, struct i2sbus_dev, sound)
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/* pcm specific functions */
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extern int
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i2sbus_attach_codec(struct soundbus_dev *dev, struct snd_card *card,
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struct codec_info *ci, void *data);
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extern void
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i2sbus_detach_codec(struct soundbus_dev *dev, void *data);
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extern irqreturn_t
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i2sbus_tx_intr(int irq, void *devid);
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extern irqreturn_t
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i2sbus_rx_intr(int irq, void *devid);
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/* control specific functions */
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extern int i2sbus_control_init(struct macio_dev* dev,
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struct i2sbus_control **c);
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extern void i2sbus_control_destroy(struct i2sbus_control *c);
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extern int i2sbus_control_add_dev(struct i2sbus_control *c,
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struct i2sbus_dev *i2sdev);
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extern void i2sbus_control_remove_dev(struct i2sbus_control *c,
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struct i2sbus_dev *i2sdev);
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extern int i2sbus_control_enable(struct i2sbus_control *c,
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struct i2sbus_dev *i2sdev);
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extern int i2sbus_control_cell(struct i2sbus_control *c,
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struct i2sbus_dev *i2sdev,
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int enable);
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extern int i2sbus_control_clock(struct i2sbus_control *c,
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struct i2sbus_dev *i2sdev,
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int enable);
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#endif /* __I2SBUS_H */
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