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![David Howells](/assets/img/avatar_default.png)
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)
361 lines
7.1 KiB
C
361 lines
7.1 KiB
C
/*
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* sound/oss/uart6850.c
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*
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*
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* Copyright (C) by Hannu Savolainen 1993-1997
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*
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* OSS/Free for Linux is distributed under the GNU GENERAL PUBLIC LICENSE (GPL)
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* Version 2 (June 1991). See the "COPYING" file distributed with this software
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* for more info.
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* Extended by Alan Cox for Red Hat Software. Now a loadable MIDI driver.
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* 28/4/97 - (C) Copyright Alan Cox. Released under the GPL version 2.
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*
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* Alan Cox: Updated for new modular code. Removed snd_* irq handling. Now
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* uses native linux resources
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* Christoph Hellwig: Adapted to module_init/module_exit
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* Jeff Garzik: Made it work again, in theory
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* FIXME: If the request_irq() succeeds, the probe succeeds. Ug.
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*
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* Status: Testing required (no shit -jgarzik)
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*
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*
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*/
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/module.h>
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#include <linux/spinlock.h>
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/* Mon Nov 22 22:38:35 MET 1993 marco@driq.home.usn.nl:
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* added 6850 support, used with COVOX SoundMaster II and custom cards.
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*/
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#include "sound_config.h"
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static int uart6850_base = 0x330;
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static int *uart6850_osp;
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#define DATAPORT (uart6850_base)
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#define COMDPORT (uart6850_base+1)
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#define STATPORT (uart6850_base+1)
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static int uart6850_status(void)
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{
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return inb(STATPORT);
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}
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#define input_avail() (uart6850_status()&INPUT_AVAIL)
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#define output_ready() (uart6850_status()&OUTPUT_READY)
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static void uart6850_cmd(unsigned char cmd)
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{
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outb(cmd, COMDPORT);
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}
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static int uart6850_read(void)
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{
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return inb(DATAPORT);
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}
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static void uart6850_write(unsigned char byte)
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{
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outb(byte, DATAPORT);
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}
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#define OUTPUT_READY 0x02 /* Mask for data ready Bit */
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#define INPUT_AVAIL 0x01 /* Mask for Data Send Ready Bit */
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#define UART_RESET 0x95
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#define UART_MODE_ON 0x03
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static int uart6850_opened;
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static int uart6850_irq;
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static int uart6850_detected;
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static int my_dev;
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static DEFINE_SPINLOCK(lock);
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static void (*midi_input_intr) (int dev, unsigned char data);
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static void poll_uart6850(unsigned long dummy);
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static DEFINE_TIMER(uart6850_timer, poll_uart6850, 0, 0);
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static void uart6850_input_loop(void)
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{
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int count = 10;
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while (count)
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{
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/*
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* Not timed out
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*/
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if (input_avail())
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{
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unsigned char c = uart6850_read();
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count = 100;
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if (uart6850_opened & OPEN_READ)
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midi_input_intr(my_dev, c);
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}
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else
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{
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while (!input_avail() && count)
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count--;
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}
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}
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}
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static irqreturn_t m6850intr(int irq, void *dev_id)
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{
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if (input_avail())
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uart6850_input_loop();
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return IRQ_HANDLED;
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}
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/*
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* It looks like there is no input interrupts in the UART mode. Let's try
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* polling.
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*/
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static void poll_uart6850(unsigned long dummy)
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{
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unsigned long flags;
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if (!(uart6850_opened & OPEN_READ))
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return; /* Device has been closed */
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spin_lock_irqsave(&lock,flags);
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if (input_avail())
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uart6850_input_loop();
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uart6850_timer.expires = 1 + jiffies;
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add_timer(&uart6850_timer);
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/*
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* Come back later
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*/
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spin_unlock_irqrestore(&lock,flags);
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}
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static int uart6850_open(int dev, int mode,
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void (*input) (int dev, unsigned char data),
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void (*output) (int dev)
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)
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{
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if (uart6850_opened)
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{
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/* printk("Midi6850: Midi busy\n");*/
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return -EBUSY;
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};
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uart6850_cmd(UART_RESET);
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uart6850_input_loop();
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midi_input_intr = input;
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uart6850_opened = mode;
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poll_uart6850(0); /*
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* Enable input polling
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*/
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return 0;
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}
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static void uart6850_close(int dev)
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{
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uart6850_cmd(UART_MODE_ON);
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del_timer(&uart6850_timer);
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uart6850_opened = 0;
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}
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static int uart6850_out(int dev, unsigned char midi_byte)
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{
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int timeout;
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unsigned long flags;
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/*
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* Test for input since pending input seems to block the output.
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*/
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spin_lock_irqsave(&lock,flags);
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if (input_avail())
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uart6850_input_loop();
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spin_unlock_irqrestore(&lock,flags);
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/*
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* Sometimes it takes about 13000 loops before the output becomes ready
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* (After reset). Normally it takes just about 10 loops.
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*/
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for (timeout = 30000; timeout > 0 && !output_ready(); timeout--); /*
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* Wait
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*/
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if (!output_ready())
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{
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printk(KERN_WARNING "Midi6850: Timeout\n");
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return 0;
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}
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uart6850_write(midi_byte);
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return 1;
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}
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static inline int uart6850_command(int dev, unsigned char *midi_byte)
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{
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return 1;
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}
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static inline int uart6850_start_read(int dev)
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{
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return 0;
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}
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static inline int uart6850_end_read(int dev)
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{
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return 0;
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}
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static inline void uart6850_kick(int dev)
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{
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}
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static inline int uart6850_buffer_status(int dev)
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{
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return 0; /*
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* No data in buffers
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*/
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}
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#define MIDI_SYNTH_NAME "6850 UART Midi"
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#define MIDI_SYNTH_CAPS SYNTH_CAP_INPUT
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#include "midi_synth.h"
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static struct midi_operations uart6850_operations =
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{
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.owner = THIS_MODULE,
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.info = {"6850 UART", 0, 0, SNDCARD_UART6850},
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.converter = &std_midi_synth,
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.in_info = {0},
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.open = uart6850_open,
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.close = uart6850_close,
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.outputc = uart6850_out,
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.start_read = uart6850_start_read,
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.end_read = uart6850_end_read,
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.kick = uart6850_kick,
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.command = uart6850_command,
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.buffer_status = uart6850_buffer_status
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};
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static void __init attach_uart6850(struct address_info *hw_config)
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{
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int ok, timeout;
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unsigned long flags;
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if (!uart6850_detected)
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return;
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if ((my_dev = sound_alloc_mididev()) == -1)
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{
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printk(KERN_INFO "uart6850: Too many midi devices detected\n");
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return;
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}
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uart6850_base = hw_config->io_base;
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uart6850_osp = hw_config->osp;
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uart6850_irq = hw_config->irq;
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spin_lock_irqsave(&lock,flags);
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for (timeout = 30000; timeout > 0 && !output_ready(); timeout--); /*
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* Wait
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*/
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uart6850_cmd(UART_MODE_ON);
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ok = 1;
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spin_unlock_irqrestore(&lock,flags);
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conf_printf("6850 Midi Interface", hw_config);
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std_midi_synth.midi_dev = my_dev;
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hw_config->slots[4] = my_dev;
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midi_devs[my_dev] = &uart6850_operations;
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sequencer_init();
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}
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static inline int reset_uart6850(void)
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{
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uart6850_read();
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return 1; /*
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* OK
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*/
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}
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static int __init probe_uart6850(struct address_info *hw_config)
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{
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int ok;
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uart6850_osp = hw_config->osp;
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uart6850_base = hw_config->io_base;
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uart6850_irq = hw_config->irq;
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if (request_irq(uart6850_irq, m6850intr, 0, "MIDI6850", NULL) < 0)
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return 0;
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ok = reset_uart6850();
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uart6850_detected = ok;
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return ok;
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}
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static void __exit unload_uart6850(struct address_info *hw_config)
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{
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free_irq(hw_config->irq, NULL);
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sound_unload_mididev(hw_config->slots[4]);
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}
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static struct address_info cfg_mpu;
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static int __initdata io = -1;
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static int __initdata irq = -1;
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module_param(io, int, 0);
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module_param(irq, int, 0);
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static int __init init_uart6850(void)
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{
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cfg_mpu.io_base = io;
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cfg_mpu.irq = irq;
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if (cfg_mpu.io_base == -1 || cfg_mpu.irq == -1) {
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printk(KERN_INFO "uart6850: irq and io must be set.\n");
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return -EINVAL;
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}
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if (probe_uart6850(&cfg_mpu))
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return -ENODEV;
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attach_uart6850(&cfg_mpu);
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return 0;
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}
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static void __exit cleanup_uart6850(void)
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{
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unload_uart6850(&cfg_mpu);
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}
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module_init(init_uart6850);
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module_exit(cleanup_uart6850);
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#ifndef MODULE
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static int __init setup_uart6850(char *str)
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{
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/* io, irq */
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int ints[3];
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str = get_options(str, ARRAY_SIZE(ints), ints);
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io = ints[1];
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irq = ints[2];
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return 1;
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}
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__setup("uart6850=", setup_uart6850);
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#endif
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MODULE_LICENSE("GPL");
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