devflash.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#include	"u.h"
#include	"../port/lib.h"
#include	"mem.h"
#include	"dat.h"
#include	"fns.h"
#include	"../port/error.h"

enum {
	Nflash = 2,
	Maxwchunk=	1024,	/* maximum chunk written by one call to falg->write */
};


/*
 *  Flashes are either 8 or 16 bits wide.  On some installations (e.g., the
 *  bitsy, they are interleaved: address 0 is in the first chip, address 2
 *  on the second, address 4 on the first, etc.
 *  We define Funit as the unit that matches the width of a single flash chip,
 *  so Funit is either `uchar' or `ushort' (I haven't seen 32-bit wide flashes),
 *  and we define Fword as the unit that matches a set of interleaved Funits.
 *  We access interleaved flashes simultaneously, by doing single reads and
 *  writes to both.  The macro `mirror' takes a command and replicates it for
 *  this purpose.
 *  The Blast board has a non-interleaved 16-bit wide flash.  When doing
 *  writes to it, we must swap bytes.
 */

typedef struct FlashAlg FlashAlg;
typedef struct Flash Flash;
typedef struct FlashRegion FlashRegion;

#ifdef WIDTH8
	typedef		uchar		Funit;		/* Width of the flash (uchar or ushort) */
#	define		toendian(x)	(x)			/* Little or big endianness */
#	define		fromendian(x)	(x)
#	define		reg(x)		((x)<<1)
#	ifdef INTERLEAVED
#		define	mirror(x)		((x)<<8|(x))	/* Double query for interleaved flashes */
		typedef	ushort		Fword;		/* Width after interleaving */
#		define	Wshift		1
#	else
#		define 	mirror(x)		(x)
		typedef	uchar		Fword;
#		define	Wshift		0
#	endif
#else
	typedef		ushort		Funit;
#	define		toendian(x)	((x)<<8)
#	define		fromendian(x)	((x)>>8)
#	define		reg(x)		(x)
#	ifdef INTERLEAVED
#		define	mirror(x)		(toendian(x)<<16|toendian(x))
		typedef	ulong		Fword;
#		define	Wshift		2
#	else
#		define mirror(x)		toendian(x)
		typedef	ushort		Fword;
#		define	Wshift		1
#	endif
#endif

/* this defines a contiguous set of erase blocks of one size */
struct FlashRegion
{
	ulong	addr;	/* start of region */
	ulong	end;		/* end of region + 1 */
	ulong	n;		/* number of blocks */
	ulong	size;		/* size of each block */
};

struct Flash
{
	ISAConf;					/* contains size */
	RWlock;
	Fword		*p;
	ushort		algid;		/* access algorithm */
	FlashAlg		*alg;
	ushort		manid;		/* manufacturer id */
	ushort		devid;		/* device id */
	int			wbsize;		/* size of write buffer */ 
	ulong		nr;			/* number of regions */
	uchar		bootprotect;
	ulong		offset;		/* beginning offset of this flash */
	FlashRegion	r[32];
};

/* this defines a particular access algorithm */
struct FlashAlg
{
	int	id;
	char	*name;
	void	(*identify)(Flash*);	/* identify device */
	void	(*erase)(Flash*, ulong);	/* erase a region */
	void	(*write)(Flash*, void*, long, ulong);	/* write a region */
};

static void	ise_id(Flash*);
static void	ise_erase(Flash*, ulong);
static void	ise_write(Flash*, void*, long, ulong);

static void	afs_id(Flash*);
static void	afs_erase(Flash*, ulong);
static void	afs_write(Flash*, void*, long, ulong);

static ulong	blockstart(Flash*, ulong);
static ulong	blockend(Flash*, ulong);

FlashAlg falg[] =
{
	{ 1,	"Intel/Sharp Extended",	ise_id, ise_erase, ise_write	},
	{ 2,	"AMD/Fujitsu Standard",	afs_id, afs_erase, afs_write	},
};

Flash flashes[Nflash];

/*
 *  common flash interface
 */
static uchar
cfigetc(Flash *flash, int off)
{
	uchar rv;

	flash->p[reg(0x55)] = mirror(0x98);
	rv = fromendian(flash->p[reg(off)]);
	flash->p[reg(0x55)] = mirror(0xFF);
	return rv;
}

static ushort
cfigets(Flash *flash, int off)
{
	return (cfigetc(flash, off+1)<<8)|cfigetc(flash, off);
}

static ulong
cfigetl(Flash *flash, int off)
{
	return (cfigetc(flash, off+3)<<24)|(cfigetc(flash, off+2)<<16)|
		(cfigetc(flash, off+1)<<8)|cfigetc(flash, off);
}

static void
cfiquery(Flash *flash)
{
	uchar q, r, y;
	ulong x, addr;

	q = cfigetc(flash, 0x10);
	r = cfigetc(flash, 0x11);
	y = cfigetc(flash, 0x12);
	if(q != 'Q' || r != 'R' || y != 'Y'){
		print("cfi query failed: %ux %ux %ux\n", q, r, y);
		return;
	}
	flash->algid = cfigetc(flash, 0x13);
	flash->size = (sizeof(Fword)/sizeof(Funit)) * (1<<(cfigetc(flash, 0x27)));
	flash->wbsize = (sizeof(Fword)/sizeof(Funit)) * (1<<(cfigetc(flash, 0x2a)));
	flash->nr = cfigetc(flash, 0x2c);
	if(flash->nr > nelem(flash->r)){
		print("cfi reports > %d regions\n", nelem(flash->r));
		flash->nr = nelem(flash->r);
	}
	addr = 0;
	for(q = 0; q < flash->nr; q++){
		x = cfigetl(flash, q+0x2d);
		flash->r[q].size = (sizeof(Fword)/sizeof(Funit)) * 256 * (x>>16);
		flash->r[q].n = (x&0xffff)+1;
		flash->r[q].addr = addr;
		addr += flash->r[q].size*flash->r[q].n;
		flash->r[q].end = addr;
	}
}

/*
 *  flash device interface
 */

enum
{
	Qtopdir,
	Q2nddir,
	Qfctl,
	Qfdata,

	Maxpart= 8,
};


typedef struct FPart FPart;
struct FPart
{
	Flash	*flash;
	char		*name;
	char		*ctlname;
	ulong	start;
	ulong	end;
};
static FPart	part[Maxpart];

#define FQID(p,q)	((p)<<8|(q))
#define FTYPE(q)	((q) & 0xff)
#define FPART(q)	(&part[(q) >>8])

static int
gen(Chan *c, char*, Dirtab*, int, int i, Dir *dp)
{
	Qid q;
	FPart *fp;

	q.vers = 0;

	/* top level directory contains the name of the network */
	if(c->qid.path == Qtopdir){
		switch(i){
		case DEVDOTDOT:
			q.path = Qtopdir;
			q.type = QTDIR;
			devdir(c, q, "#F", 0, eve, DMDIR|0555, dp);
			break;
		case 0:
			q.path = Q2nddir;
			q.type = QTDIR;
			devdir(c, q, "flash", 0, eve, DMDIR|0555, dp);
			break;
		default:
			return -1;
		}
		return 1;
	}

	/* second level contains all partitions and their control files */
	switch(i) {
	case DEVDOTDOT:
		q.path = Qtopdir;
		q.type = QTDIR;
		devdir(c, q, "#F", 0, eve, DMDIR|0555, dp);
		break;
	default:
		if(i >= 2*Maxpart)
			return -1;
		fp = &part[i>>1];
		if(fp->name == nil)
			return 0;
		if(i & 1){
			q.path = FQID(i>>1, Qfdata);
			q.type = QTFILE;
			devdir(c, q, fp->name, fp->end-fp->start, eve, 0660, dp);
		} else {
			q.path = FQID(i>>1, Qfctl);
			q.type = QTFILE;
			devdir(c, q, fp->ctlname, 0, eve, 0660, dp);
		}
		break;
	}
	return 1;
}

static Flash *
findflash(ulong addr)
{
	Flash *flash;

	for (flash = flashes; flash < flashes + Nflash; flash++)
		if(addr >= flash->offset && addr < flash->offset + flash->size)
			return flash;
	return nil;
}

static FPart*
findpart(char *name)
{
	int i;

	for(i = 0; i < Maxpart; i++)
		if(part[i].name != nil && strcmp(name, part[i].name) == 0)
			break;
	if(i >= Maxpart)
		return nil;
	return &part[i];
}

static void
addpart(FPart *fp, char *name, ulong start, ulong end)
{
	int i;
	char ctlname[64];
	Flash *flash;
	if (start > end)
		error(Ebadarg);
	if(fp == nil){
		flash = findflash(start);
		if (flash == nil || end > flash->offset + flash->size)
			error(Ebadarg);
		start -= flash->offset;
		end -= flash->offset;
	} else {
		start += fp->start;
		end += fp->start;
		if(start >= fp->end || end > fp->end){
			error(Ebadarg);
		}
		flash = fp->flash;
	}
	if(blockstart(flash, start) != start)
		error("must start on erase boundary");
	if(blockstart(flash, end) != end && end != flash->size)
		error("must end on erase boundary");

	fp = findpart(name);
	if(fp != nil)
		error(Eexist);
	for(i = 0; i < Maxpart; i++)
		if(part[i].name == nil)
			break;
	if(i == Maxpart)
		error("no more partitions");
	fp = &part[i];
	kstrdup(&fp->name, name);
	snprint(ctlname, sizeof ctlname, "%sctl", name);
	kstrdup(&fp->ctlname, ctlname);
	fp->flash = flash;
	fp->start = start;
	fp->end = end;
}

static void
rempart(FPart *fp)
{
	char *p, *cp;

	p = fp->name;
	fp->name = nil;
	cp = fp->ctlname;
	fp->ctlname = nil;
	free(p);
	free(cp);
}

void
flashinit(void)
{
	int i, ctlrno;
	char *fname;
	ulong offset;
	Flash *flash;

	offset = 0;
	for (ctlrno = 0; ctlrno < Nflash; ctlrno++){
		flash = flashes + ctlrno;
		if(isaconfig("flash", ctlrno, flash) == 0)
			continue;
		flash->p = (Fword*)flash->mem;
		cfiquery(flash);
		for(i = 0; i < nelem(falg); i++)
			if(flash->algid == falg[i].id){
				flash->alg = &falg[i];
				(*flash->alg->identify)(flash);
				break;
			}
		flash->bootprotect = 1;
		flash->offset = offset;
		fname = malloc(8);
		sprint(fname, "flash%d", ctlrno);
		addpart(nil, fname, offset, offset + flash->size);
		offset += flash->size;
	}
}

static Chan*
flashattach(char* spec)
{
	return devattach('F', spec);
}

static Walkqid*
flashwalk(Chan *c, Chan *nc, char **name, int nname)
{
	return devwalk(c, nc, name, nname, nil, 0, gen);
}

static int	 
flashstat(Chan *c, uchar *db, int n)
{
	return devstat(c, db, n, nil, 0, gen);
}

static Chan*
flashopen(Chan* c, int omode)
{
	omode = openmode(omode);
	if(strcmp(up->user, eve)!=0)
		error(Eperm);
	return devopen(c, omode, nil, 0, gen);
}

static void	 
flashclose(Chan*)
{
}

static long
flashctlread(FPart *fp, void* a, long n, vlong off)
{
	char *buf, *p, *e;
	int i;
	ulong addr, end;
	Flash *flash;

	flash = fp->flash;
	buf = smalloc(1024);
	e = buf + 1024;
	p = seprint(buf, e, "0x%-9lux 0x%-9lux 0x%-9lux 0x%-9x 0x%-9ux 0x%-9ux\n",
		flash->offset, fp->start, fp->end-fp->start, flash->wbsize, flash->manid, flash->devid);
	addr = fp->start;
	for(i = 0; i < flash->nr && addr < fp->end; i++)
		if(flash->r[i].addr <= addr && flash->r[i].end > addr){
			if(fp->end <= flash->r[i].end)
				end = fp->end;
			else
				end = flash->r[i].end;
			p = seprint(p, e, "0x%-9lux 0x%-9lux 0x%-9lux\n", addr,
				(end-addr)/flash->r[i].size, flash->r[i].size);
			addr = end;
		}
	n = readstr(off, a, n, buf);
	free(buf);
	return n;
}

static long
flashdataread(FPart *fp, void* a, long n, vlong off)
{
	Flash *flash;

	flash = fp->flash;
	rlock(flash);
	if(waserror()){
		runlock(flash);
		nexterror();
	}
	if(fp->name == nil)
		error("partition vanished");
	if(!iseve())
		error(Eperm);
	off += fp->start;
	if(off >= fp->end)
		n = 0;
	if(off+n >= fp->end)
		n = fp->end - off;
	if(n > 0)
		memmove(a, ((uchar*)flash->mem)+off, n);
	runlock(flash);
	poperror();

	return n;
}

static long	 
flashread(Chan* c, void* a, long n, vlong off)
{
	int t;

	if(c->qid.type == QTDIR)
		return devdirread(c, a, n, nil, 0, gen);
	t = FTYPE(c->qid.path);
	switch(t){
	default:
		error(Eperm);
	case Qfctl:
		n = flashctlread(FPART(c->qid.path), a, n, off);
		break;
	case Qfdata:
		n = flashdataread(FPART(c->qid.path), a, n, off);
		break;
	}
	return n;
}

static void
bootprotect(ulong addr)
{