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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)
481 lines
10 KiB
C
481 lines
10 KiB
C
/*
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* sound/oss/uart401.c
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*
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* MPU-401 UART driver (formerly uart401_midi.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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*
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* Changes:
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* Alan Cox Reformatted, removed sound_mem usage, use normal Linux
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* interrupt allocation. Protect against bogus unload
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* Fixed to allow IRQ > 15
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* Christoph Hellwig Adapted to module_init/module_exit
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* Arnaldo C. de Melo got rid of check_region
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*
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* Status:
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* Untested
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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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#include "sound_config.h"
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#include "mpu401.h"
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typedef struct uart401_devc
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{
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int base;
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int irq;
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int *osp;
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void (*midi_input_intr) (int dev, unsigned char data);
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int opened, disabled;
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volatile unsigned char input_byte;
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int my_dev;
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int share_irq;
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spinlock_t lock;
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}
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uart401_devc;
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#define DATAPORT (devc->base)
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#define COMDPORT (devc->base+1)
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#define STATPORT (devc->base+1)
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static int uart401_status(uart401_devc * devc)
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{
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return inb(STATPORT);
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}
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#define input_avail(devc) (!(uart401_status(devc)&INPUT_AVAIL))
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#define output_ready(devc) (!(uart401_status(devc)&OUTPUT_READY))
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static void uart401_cmd(uart401_devc * devc, unsigned char cmd)
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{
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outb((cmd), COMDPORT);
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}
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static int uart401_read(uart401_devc * devc)
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{
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return inb(DATAPORT);
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}
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static void uart401_write(uart401_devc * devc, 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 0x40
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#define INPUT_AVAIL 0x80
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#define MPU_ACK 0xFE
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#define MPU_RESET 0xFF
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#define UART_MODE_ON 0x3F
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static int reset_uart401(uart401_devc * devc);
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static void enter_uart_mode(uart401_devc * devc);
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static void uart401_input_loop(uart401_devc * devc)
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{
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int work_limit=30000;
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while (input_avail(devc) && --work_limit)
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{
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unsigned char c = uart401_read(devc);
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if (c == MPU_ACK)
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devc->input_byte = c;
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else if (devc->opened & OPEN_READ && devc->midi_input_intr)
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devc->midi_input_intr(devc->my_dev, c);
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}
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if(work_limit==0)
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printk(KERN_WARNING "Too much work in interrupt on uart401 (0x%X). UART jabbering ??\n", devc->base);
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}
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irqreturn_t uart401intr(int irq, void *dev_id)
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{
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uart401_devc *devc = dev_id;
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if (devc == NULL)
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{
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printk(KERN_ERR "uart401: bad devc\n");
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return IRQ_NONE;
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}
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if (input_avail(devc))
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uart401_input_loop(devc);
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return IRQ_HANDLED;
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}
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static int
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uart401_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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uart401_devc *devc = (uart401_devc *) midi_devs[dev]->devc;
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if (devc->opened)
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return -EBUSY;
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/* Flush the UART */
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while (input_avail(devc))
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uart401_read(devc);
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devc->midi_input_intr = input;
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devc->opened = mode;
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enter_uart_mode(devc);
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devc->disabled = 0;
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return 0;
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}
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static void uart401_close(int dev)
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{
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uart401_devc *devc = (uart401_devc *) midi_devs[dev]->devc;
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reset_uart401(devc);
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devc->opened = 0;
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}
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static int uart401_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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uart401_devc *devc = (uart401_devc *) midi_devs[dev]->devc;
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if (devc->disabled)
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return 1;
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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(&devc->lock,flags);
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if (input_avail(devc))
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uart401_input_loop(devc);
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spin_unlock_irqrestore(&devc->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(devc); timeout--);
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if (!output_ready(devc))
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{
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printk(KERN_WARNING "uart401: Timeout - Device not responding\n");
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devc->disabled = 1;
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reset_uart401(devc);
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enter_uart_mode(devc);
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return 1;
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}
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uart401_write(devc, midi_byte);
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return 1;
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}
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static inline int uart401_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 uart401_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 uart401_kick(int dev)
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{
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}
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static inline int uart401_buffer_status(int dev)
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{
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return 0;
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}
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#define MIDI_SYNTH_NAME "MPU-401 UART"
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#define MIDI_SYNTH_CAPS SYNTH_CAP_INPUT
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#include "midi_synth.h"
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static const struct midi_operations uart401_operations =
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{
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.owner = THIS_MODULE,
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.info = {"MPU-401 (UART) MIDI", 0, 0, SNDCARD_MPU401},
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.converter = &std_midi_synth,
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.in_info = {0},
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.open = uart401_open,
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.close = uart401_close,
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.outputc = uart401_out,
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.start_read = uart401_start_read,
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.end_read = uart401_end_read,
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.kick = uart401_kick,
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.buffer_status = uart401_buffer_status,
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};
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static void enter_uart_mode(uart401_devc * devc)
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{
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int ok, timeout;
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unsigned long flags;
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spin_lock_irqsave(&devc->lock,flags);
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for (timeout = 30000; timeout > 0 && !output_ready(devc); timeout--);
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devc->input_byte = 0;
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uart401_cmd(devc, UART_MODE_ON);
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ok = 0;
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for (timeout = 50000; timeout > 0 && !ok; timeout--)
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if (devc->input_byte == MPU_ACK)
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ok = 1;
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else if (input_avail(devc))
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if (uart401_read(devc) == MPU_ACK)
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ok = 1;
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spin_unlock_irqrestore(&devc->lock,flags);
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}
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static int reset_uart401(uart401_devc * devc)
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{
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int ok, timeout, n;
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/*
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* Send the RESET command. Try again if no success at the first time.
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*/
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ok = 0;
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for (n = 0; n < 2 && !ok; n++)
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{
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for (timeout = 30000; timeout > 0 && !output_ready(devc); timeout--);
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devc->input_byte = 0;
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uart401_cmd(devc, MPU_RESET);
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/*
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* Wait at least 25 msec. This method is not accurate so let's make the
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* loop bit longer. Cannot sleep since this is called during boot.
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*/
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for (timeout = 50000; timeout > 0 && !ok; timeout--)
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{
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if (devc->input_byte == MPU_ACK) /* Interrupt */
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ok = 1;
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else if (input_avail(devc))
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{
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if (uart401_read(devc) == MPU_ACK)
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ok = 1;
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}
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}
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}
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if (ok)
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{
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DEB(printk("Reset UART401 OK\n"));
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}
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else
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DDB(printk("Reset UART401 failed - No hardware detected.\n"));
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if (ok)
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uart401_input_loop(devc); /*
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* Flush input before enabling interrupts
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*/
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return ok;
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}
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int probe_uart401(struct address_info *hw_config, struct module *owner)
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{
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uart401_devc *devc;
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char *name = "MPU-401 (UART) MIDI";
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int ok = 0;
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unsigned long flags;
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DDB(printk("Entered probe_uart401()\n"));
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/* Default to "not found" */
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hw_config->slots[4] = -1;
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if (!request_region(hw_config->io_base, 4, "MPU-401 UART")) {
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printk(KERN_INFO "uart401: could not request_region(%d, 4)\n", hw_config->io_base);
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return 0;
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}
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devc = kmalloc(sizeof(uart401_devc), GFP_KERNEL);
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if (!devc) {
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printk(KERN_WARNING "uart401: Can't allocate memory\n");
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goto cleanup_region;
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}
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devc->base = hw_config->io_base;
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devc->irq = hw_config->irq;
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devc->osp = hw_config->osp;
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devc->midi_input_intr = NULL;
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devc->opened = 0;
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devc->input_byte = 0;
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devc->my_dev = 0;
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devc->share_irq = 0;
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spin_lock_init(&devc->lock);
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spin_lock_irqsave(&devc->lock,flags);
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ok = reset_uart401(devc);
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spin_unlock_irqrestore(&devc->lock,flags);
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if (!ok)
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goto cleanup_devc;
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if (hw_config->name)
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name = hw_config->name;
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if (devc->irq < 0) {
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devc->share_irq = 1;
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devc->irq *= -1;
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} else
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devc->share_irq = 0;
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if (!devc->share_irq)
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if (request_irq(devc->irq, uart401intr, 0, "MPU-401 UART", devc) < 0) {
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printk(KERN_WARNING "uart401: Failed to allocate IRQ%d\n", devc->irq);
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devc->share_irq = 1;
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}
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devc->my_dev = sound_alloc_mididev();
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enter_uart_mode(devc);
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if (devc->my_dev == -1) {
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printk(KERN_INFO "uart401: Too many midi devices detected\n");
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goto cleanup_irq;
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}
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conf_printf(name, hw_config);
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midi_devs[devc->my_dev] = kmalloc(sizeof(struct midi_operations), GFP_KERNEL);
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if (!midi_devs[devc->my_dev]) {
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printk(KERN_ERR "uart401: Failed to allocate memory\n");
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goto cleanup_unload_mididev;
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}
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memcpy(midi_devs[devc->my_dev], &uart401_operations, sizeof(struct midi_operations));
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if (owner)
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midi_devs[devc->my_dev]->owner = owner;
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midi_devs[devc->my_dev]->devc = devc;
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midi_devs[devc->my_dev]->converter = kmalloc(sizeof(struct synth_operations), GFP_KERNEL);
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if (!midi_devs[devc->my_dev]->converter) {
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printk(KERN_WARNING "uart401: Failed to allocate memory\n");
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goto cleanup_midi_devs;
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}
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memcpy(midi_devs[devc->my_dev]->converter, &std_midi_synth, sizeof(struct synth_operations));
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strcpy(midi_devs[devc->my_dev]->info.name, name);
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midi_devs[devc->my_dev]->converter->id = "UART401";
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midi_devs[devc->my_dev]->converter->midi_dev = devc->my_dev;
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if (owner)
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midi_devs[devc->my_dev]->converter->owner = owner;
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hw_config->slots[4] = devc->my_dev;
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sequencer_init();
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devc->opened = 0;
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return 1;
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cleanup_midi_devs:
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kfree(midi_devs[devc->my_dev]);
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cleanup_unload_mididev:
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sound_unload_mididev(devc->my_dev);
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cleanup_irq:
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if (!devc->share_irq)
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free_irq(devc->irq, devc);
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cleanup_devc:
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kfree(devc);
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cleanup_region:
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release_region(hw_config->io_base, 4);
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return 0;
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}
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void unload_uart401(struct address_info *hw_config)
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{
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uart401_devc *devc;
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int n=hw_config->slots[4];
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/* Not set up */
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if(n==-1 || midi_devs[n]==NULL)
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return;
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/* Not allocated (erm ??) */
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devc = midi_devs[hw_config->slots[4]]->devc;
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if (devc == NULL)
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return;
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reset_uart401(devc);
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release_region(hw_config->io_base, 4);
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if (!devc->share_irq)
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free_irq(devc->irq, devc);
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if (devc)
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{
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kfree(midi_devs[devc->my_dev]->converter);
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kfree(midi_devs[devc->my_dev]);
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kfree(devc);
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devc = NULL;
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}
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/* This kills midi_devs[x] */
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sound_unload_mididev(hw_config->slots[4]);
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}
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EXPORT_SYMBOL(probe_uart401);
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EXPORT_SYMBOL(unload_uart401);
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EXPORT_SYMBOL(uart401intr);
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static struct address_info cfg_mpu;
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static int io = -1;
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static int irq = -1;
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module_param(io, int, 0444);
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module_param(irq, int, 0444);
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static int __init init_uart401(void)
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{
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cfg_mpu.irq = irq;
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cfg_mpu.io_base = io;
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/* Can be loaded either for module use or to provide functions
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to others */
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if (cfg_mpu.io_base != -1 && cfg_mpu.irq != -1) {
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printk(KERN_INFO "MPU-401 UART driver Copyright (C) Hannu Savolainen 1993-1997");
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if (!probe_uart401(&cfg_mpu, THIS_MODULE))
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return -ENODEV;
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}
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return 0;
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}
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static void __exit cleanup_uart401(void)
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{
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if (cfg_mpu.io_base != -1 && cfg_mpu.irq != -1)
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unload_uart401(&cfg_mpu);
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}
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module_init(init_uart401);
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module_exit(cleanup_uart401);
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#ifndef MODULE
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static int __init setup_uart401(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("uart401=", setup_uart401);
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#endif
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MODULE_LICENSE("GPL");
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