Initial commit: Schunix as it stands before the SchOS rename
An x86-64 operating system built from xv6, now largely rewritten: SMP, a copy-on-write root filesystem (SchFS), PCI/USB/virtio drivers, a TTF rasteriser, and a Linux-numbered syscall ABI. No history before this point -- the tree was never under version control. This commit exists so the rename that follows has something to undo to.
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Nexoniarz
commit
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275 changed files with 51417 additions and 0 deletions
208
kernel/dev/ide.c
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208
kernel/dev/ide.c
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// Simple PIO-based (non-DMA) IDE driver code.
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#include "types.h"
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#include "defs.h"
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#include "irq.h"
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#include "param.h"
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#include "memlayout.h"
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#include "mmu.h"
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#include "proc.h"
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#include "x86.h"
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#include "traps.h"
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#include "spinlock.h"
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#include "sleeplock.h"
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#include "fs.h"
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#include "buf.h"
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#define SECTOR_SIZE 512
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#define IDE_BSY 0x80
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#define IDE_DRDY 0x40
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#define IDE_DF 0x20
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#define IDE_ERR 0x01
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#define IDE_CMD_READ 0x20
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#define IDE_CMD_WRITE 0x30
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#define IDE_CMD_RDMUL 0xc4
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#define IDE_CMD_WRMUL 0xc5
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// idequeue points to the buf now being read/written to the disk.
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// idequeue->qnext points to the next buf to be processed.
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// You must hold idelock while manipulating queue.
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static struct spinlock idelock;
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static struct buf *idequeue;
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static int havedisk0;
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static int havedisk1;
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static void idestart(struct buf*);
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// Wait for the drive to become ready, or give up.
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//
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// This used to be an unbounded `while`. On a machine with nothing attached to
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// the primary channel the status register reads 0xFF forever, so the very
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// first call from ideinit() hung the kernel -- no panic, no message, just a
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// dead machine right after the VGA banner. That is not an exotic
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// configuration: it is every CD boot, and most hardware newer than IDE.
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//
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// The bound is deliberately enormous. A real drive answers in microseconds;
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// this only expires when there is nothing there at all.
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static int
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idewait(int checkerr)
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{
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int r = 0;
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for(int i = 0; i < 20000000; i++){
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r = inb(0x1f7);
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if((r & (IDE_BSY|IDE_DRDY)) == IDE_DRDY){
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if(checkerr && (r & (IDE_DF|IDE_ERR)) != 0)
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return -1;
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return 0;
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}
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}
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return -1;
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}
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static void
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ide_irq(void *arg)
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{
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(void)arg;
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ideintr();
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}
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void
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ideinit(void)
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{
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initlock(&idelock, "ide");
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// ISA signalling: edge-triggered, active high. Everything at a fixed
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// legacy port is wired this way; PCI devices are not.
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irq_register(IRQ_IDE, ide_irq, 0, "ide", 0);
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// A timeout here means there is no drive on this channel. Say so and leave
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// havedisk0/1 clear: with a ramdisk root there is nothing else the system
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// needs from IDE, and booting on is strictly better than stopping.
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if(idewait(0) < 0){
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cprintf("ide: no drive on the primary channel\n");
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return;
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}
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havedisk0 = 1;
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// Check if disk 1 is present
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outb(0x1f6, 0xe0 | (1<<4));
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for(int i=0; i<1000; i++){
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if(inb(0x1f7) != 0){
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havedisk1 = 1;
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break;
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}
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}
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// Switch back to disk 0.
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outb(0x1f6, 0xe0 | (0<<4));
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}
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// Is there actually a drive there? Callers that probe -- rather than callers
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// that know what they are looking for -- have to ask, because reading an
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// absent drive is a bug and iderw() treats it as one.
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int
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ide_disk_present(int dev)
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{
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return dev == 0 ? havedisk0 : havedisk1;
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}
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// Start the request for b. Caller must hold idelock.
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static void
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idestart(struct buf *b)
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{
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if(b == 0)
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panic("idestart");
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if(b->blockno >= FSSIZE)
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panic("incorrect blockno");
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int sector_per_block = BSIZE/SECTOR_SIZE;
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int sector = b->blockno * sector_per_block;
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int read_cmd = (sector_per_block == 1) ? IDE_CMD_READ : IDE_CMD_RDMUL;
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int write_cmd = (sector_per_block == 1) ? IDE_CMD_WRITE : IDE_CMD_WRMUL;
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if (sector_per_block > 7) panic("idestart");
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idewait(0);
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outb(0x3f6, 0); // generate interrupt
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outb(0x1f2, sector_per_block); // number of sectors
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outb(0x1f3, sector & 0xff);
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outb(0x1f4, (sector >> 8) & 0xff);
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outb(0x1f5, (sector >> 16) & 0xff);
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outb(0x1f6, 0xe0 | ((b->dev&1)<<4) | ((sector>>24)&0x0f));
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if(b->flags & B_DIRTY){
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outb(0x1f7, write_cmd);
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outsl(0x1f0, b->data, BSIZE/4);
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} else {
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outb(0x1f7, read_cmd);
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}
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}
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// Interrupt handler.
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void
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ideintr(void)
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{
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struct buf *b;
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// First queued buffer is the active request.
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acquire(&idelock);
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if((b = idequeue) == 0){
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release(&idelock);
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// cprintf("spurious IDE interrupt\n");
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return;
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}
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idequeue = b->qnext;
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// Read data if needed.
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if(!(b->flags & B_DIRTY) && idewait(1) >= 0)
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insl(0x1f0, b->data, BSIZE/4);
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// Wake process waiting for this buf.
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b->flags |= B_VALID;
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b->flags &= ~B_DIRTY;
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wakeup(b);
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// Start disk on next buf in queue.
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if(idequeue != 0)
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idestart(idequeue);
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release(&idelock);
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}
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//PAGEBREAK!
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// Sync buf with disk.
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// If B_DIRTY is set, write buf to disk, clear B_DIRTY, set B_VALID.
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// Else if B_VALID is not set, read buf from disk, set B_VALID.
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void
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iderw(struct buf *b)
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{
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struct buf **pp;
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if(!holdingsleep(&b->lock))
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panic("iderw: buf not locked");
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if((b->flags & (B_VALID|B_DIRTY)) == B_VALID)
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panic("iderw: nothing to do");
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if(b->dev != 0 && !havedisk1)
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panic("iderw: ide disk 1 not present");
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if(b->dev == 0 && !havedisk0)
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panic("iderw: ide disk 0 not present");
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acquire(&idelock); //DOC:acquire-lock
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// Append b to idequeue.
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b->qnext = 0;
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for(pp=&idequeue; *pp; pp=&(*pp)->qnext) //DOC:insert-queue
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;
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*pp = b;
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// Start disk if necessary.
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if(idequeue == b)
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idestart(b);
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// Wait for request to finish.
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while((b->flags & (B_VALID|B_DIRTY)) != B_VALID){
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sleep(b, &idelock);
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}
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release(&idelock);
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}
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