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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)
283 lines
6.5 KiB
C
283 lines
6.5 KiB
C
/*
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* Architecture specific parts of the Floppy driver
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 1995
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*/
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#ifndef __ASM_X86_64_FLOPPY_H
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#define __ASM_X86_64_FLOPPY_H
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#include <linux/vmalloc.h>
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/*
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* The DMA channel used by the floppy controller cannot access data at
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* addresses >= 16MB
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*
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* Went back to the 1MB limit, as some people had problems with the floppy
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* driver otherwise. It doesn't matter much for performance anyway, as most
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* floppy accesses go through the track buffer.
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*/
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#define _CROSS_64KB(a,s,vdma) \
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(!(vdma) && ((unsigned long)(a)/K_64 != ((unsigned long)(a) + (s) - 1) / K_64))
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#define CROSS_64KB(a,s) _CROSS_64KB(a,s,use_virtual_dma & 1)
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#define SW fd_routine[use_virtual_dma&1]
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#define CSW fd_routine[can_use_virtual_dma & 1]
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#define fd_inb(port) inb_p(port)
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#define fd_outb(value,port) outb_p(value,port)
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#define fd_request_dma() CSW._request_dma(FLOPPY_DMA,"floppy")
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#define fd_free_dma() CSW._free_dma(FLOPPY_DMA)
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#define fd_enable_irq() enable_irq(FLOPPY_IRQ)
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#define fd_disable_irq() disable_irq(FLOPPY_IRQ)
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#define fd_free_irq() free_irq(FLOPPY_IRQ, NULL)
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#define fd_get_dma_residue() SW._get_dma_residue(FLOPPY_DMA)
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#define fd_dma_mem_alloc(size) SW._dma_mem_alloc(size)
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#define fd_dma_setup(addr, size, mode, io) SW._dma_setup(addr, size, mode, io)
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#define FLOPPY_CAN_FALLBACK_ON_NODMA
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static int virtual_dma_count;
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static int virtual_dma_residue;
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static char *virtual_dma_addr;
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static int virtual_dma_mode;
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static int doing_pdma;
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static irqreturn_t floppy_hardint(int irq, void *dev_id)
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{
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register unsigned char st;
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#undef TRACE_FLPY_INT
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#ifdef TRACE_FLPY_INT
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static int calls=0;
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static int bytes=0;
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static int dma_wait=0;
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#endif
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if (!doing_pdma)
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return floppy_interrupt(irq, dev_id);
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#ifdef TRACE_FLPY_INT
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if(!calls)
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bytes = virtual_dma_count;
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#endif
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{
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register int lcount;
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register char *lptr;
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st = 1;
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for(lcount=virtual_dma_count, lptr=virtual_dma_addr;
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lcount; lcount--, lptr++) {
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st=inb(virtual_dma_port+4) & 0xa0 ;
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if(st != 0xa0)
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break;
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if(virtual_dma_mode)
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outb_p(*lptr, virtual_dma_port+5);
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else
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*lptr = inb_p(virtual_dma_port+5);
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}
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virtual_dma_count = lcount;
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virtual_dma_addr = lptr;
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st = inb(virtual_dma_port+4);
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}
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#ifdef TRACE_FLPY_INT
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calls++;
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#endif
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if(st == 0x20)
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return IRQ_HANDLED;
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if(!(st & 0x20)) {
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virtual_dma_residue += virtual_dma_count;
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virtual_dma_count=0;
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#ifdef TRACE_FLPY_INT
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printk("count=%x, residue=%x calls=%d bytes=%d dma_wait=%d\n",
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virtual_dma_count, virtual_dma_residue, calls, bytes,
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dma_wait);
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calls = 0;
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dma_wait=0;
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#endif
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doing_pdma = 0;
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floppy_interrupt(irq, dev_id);
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return IRQ_HANDLED;
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}
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#ifdef TRACE_FLPY_INT
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if(!virtual_dma_count)
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dma_wait++;
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#endif
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return IRQ_HANDLED;
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}
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static void fd_disable_dma(void)
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{
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if(! (can_use_virtual_dma & 1))
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disable_dma(FLOPPY_DMA);
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doing_pdma = 0;
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virtual_dma_residue += virtual_dma_count;
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virtual_dma_count=0;
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}
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static int vdma_request_dma(unsigned int dmanr, const char * device_id)
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{
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return 0;
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}
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static void vdma_nop(unsigned int dummy)
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{
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}
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static int vdma_get_dma_residue(unsigned int dummy)
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{
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return virtual_dma_count + virtual_dma_residue;
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}
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static int fd_request_irq(void)
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{
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if(can_use_virtual_dma)
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return request_irq(FLOPPY_IRQ, floppy_hardint,
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IRQF_DISABLED, "floppy", NULL);
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else
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return request_irq(FLOPPY_IRQ, floppy_interrupt,
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IRQF_DISABLED, "floppy", NULL);
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}
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static unsigned long dma_mem_alloc(unsigned long size)
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{
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return __get_dma_pages(GFP_KERNEL|__GFP_NORETRY,get_order(size));
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}
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static unsigned long vdma_mem_alloc(unsigned long size)
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{
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return (unsigned long) vmalloc(size);
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}
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#define nodma_mem_alloc(size) vdma_mem_alloc(size)
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static void _fd_dma_mem_free(unsigned long addr, unsigned long size)
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{
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if((unsigned long) addr >= (unsigned long) high_memory)
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vfree((void *)addr);
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else
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free_pages(addr, get_order(size));
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}
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#define fd_dma_mem_free(addr, size) _fd_dma_mem_free(addr, size)
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static void _fd_chose_dma_mode(char *addr, unsigned long size)
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{
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if(can_use_virtual_dma == 2) {
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if((unsigned long) addr >= (unsigned long) high_memory ||
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isa_virt_to_bus(addr) >= 0x1000000 ||
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_CROSS_64KB(addr, size, 0))
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use_virtual_dma = 1;
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else
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use_virtual_dma = 0;
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} else {
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use_virtual_dma = can_use_virtual_dma & 1;
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}
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}
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#define fd_chose_dma_mode(addr, size) _fd_chose_dma_mode(addr, size)
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static int vdma_dma_setup(char *addr, unsigned long size, int mode, int io)
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{
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doing_pdma = 1;
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virtual_dma_port = io;
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virtual_dma_mode = (mode == DMA_MODE_WRITE);
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virtual_dma_addr = addr;
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virtual_dma_count = size;
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virtual_dma_residue = 0;
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return 0;
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}
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static int hard_dma_setup(char *addr, unsigned long size, int mode, int io)
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{
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#ifdef FLOPPY_SANITY_CHECK
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if (CROSS_64KB(addr, size)) {
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printk("DMA crossing 64-K boundary %p-%p\n", addr, addr+size);
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return -1;
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}
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#endif
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/* actual, physical DMA */
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doing_pdma = 0;
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clear_dma_ff(FLOPPY_DMA);
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set_dma_mode(FLOPPY_DMA,mode);
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set_dma_addr(FLOPPY_DMA,isa_virt_to_bus(addr));
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set_dma_count(FLOPPY_DMA,size);
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enable_dma(FLOPPY_DMA);
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return 0;
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}
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static struct fd_routine_l {
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int (*_request_dma)(unsigned int dmanr, const char * device_id);
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void (*_free_dma)(unsigned int dmanr);
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int (*_get_dma_residue)(unsigned int dummy);
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unsigned long (*_dma_mem_alloc) (unsigned long size);
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int (*_dma_setup)(char *addr, unsigned long size, int mode, int io);
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} fd_routine[] = {
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{
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request_dma,
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free_dma,
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get_dma_residue,
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dma_mem_alloc,
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hard_dma_setup
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},
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{
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vdma_request_dma,
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vdma_nop,
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vdma_get_dma_residue,
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vdma_mem_alloc,
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vdma_dma_setup
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}
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};
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static int FDC1 = 0x3f0;
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static int FDC2 = -1;
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/*
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* Floppy types are stored in the rtc's CMOS RAM and so rtc_lock
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* is needed to prevent corrupted CMOS RAM in case "insmod floppy"
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* coincides with another rtc CMOS user. Paul G.
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*/
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#define FLOPPY0_TYPE ({ \
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unsigned long flags; \
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unsigned char val; \
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spin_lock_irqsave(&rtc_lock, flags); \
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val = (CMOS_READ(0x10) >> 4) & 15; \
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spin_unlock_irqrestore(&rtc_lock, flags); \
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val; \
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})
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#define FLOPPY1_TYPE ({ \
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unsigned long flags; \
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unsigned char val; \
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spin_lock_irqsave(&rtc_lock, flags); \
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val = CMOS_READ(0x10) & 15; \
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spin_unlock_irqrestore(&rtc_lock, flags); \
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val; \
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})
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#define N_FDC 2
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#define N_DRIVE 8
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#define FLOPPY_MOTOR_MASK 0xf0
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#define AUTO_DMA
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#define EXTRA_FLOPPY_PARAMS
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#endif /* __ASM_X86_64_FLOPPY_H */
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