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Set clock prescale based on BIOS supplied value instead of trying to

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calculate an optimum value from (constant) parameters.
This should set the SCNTL3 register of the 53c860 and 53c875 to twice
the divider it used to be, since cards based on those chips seem to use
an 80MHz clock instead of the Clock Doubler feature and a 40MHz clock.
This commit is contained in:
Stefan Eßer 1996-08-26 22:38:07 +00:00
parent 8a15e7f475
commit 23da20014a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=17836
1 changed files with 16 additions and 7 deletions
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23
sys/pci/ncr.c
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@ -1,6 +1,6 @@
/**************************************************************************
**
** $Id: ncr.c,v 1.73 1996/06/12 05:10:44 gpalmer Exp $
** $Id: ncr.c,v 1.74 1996/08/05 19:39:51 se Exp $
**
** Device driver for the NCR 53C810 PCI-SCSI-Controller.
**
@ -1202,7 +1202,7 @@ static void ncr_complete (ncb_p np, ccb_p cp);
static int ncr_delta (struct timeval * from, struct timeval * to);
static void ncr_exception (ncb_p np);
static void ncr_free_ccb (ncb_p np, ccb_p cp, int flags);
static void ncr_getclock (ncb_p np);
static void ncr_getclock (ncb_p np, u_char scntl3);
static ccb_p ncr_get_ccb (ncb_p np, u_long flags, u_long t,u_long l);
static u_int32_t ncr_info (int unit);
static void ncr_init (ncb_p np, char * msg, u_long code);
@ -1254,7 +1254,7 @@ static void ncr_attach (pcici_t tag, int unit);
static char ident[] =
"\n$Id: ncr.c,v 1.73 1996/06/12 05:10:44 gpalmer Exp $\n";
"\n$Id: ncr.c,v 1.74 1996/08/05 19:39:51 se Exp $\n";
static const u_long ncr_version = NCR_VERSION * 11
+ (u_long) sizeof (struct ncb) * 7
@ -3354,7 +3354,7 @@ static void ncr_attach (pcici_t config_id, int unit)
** Find the right value for scntl3.
*/
ncr_getclock (np);
ncr_getclock (np, INB(nc_scntl3));
/*
** Reset chip.
@ -6767,16 +6767,16 @@ static u_long ncr_lookup(char * id)
#endif /* NCR_CLOCK */
static void ncr_getclock (ncb_p np)
static void ncr_getclock (ncb_p np, u_char scntl3)
{
u_char tbl[5] = {6,2,3,4,6};
u_char tbl[6] = {6,2,3,4,6,8};
u_char f;
u_char ns_clock = (1000/NCR_CLOCK);
/*
** Compute the best value for scntl3.
*/
/*
f = (2 * MIN_SYNC_PD - 1) / ns_clock;
if (!f ) f=1;
if (f>4) f=4;
@ -6791,6 +6791,15 @@ static void ncr_getclock (ncb_p np)
if (DEBUG_FLAGS & DEBUG_TIMING)
printf ("%s: sclk=%d async=%d sync=%d (ns) scntl3=0x%x\n",
ncr_name (np), ns_clock, np->ns_async, np->ns_sync, np->rv_scntl3);
*/
/*
* For now just preserve the BIOS setting ...
*/
np->rv_scntl3 = ((scntl3 & 0x7) << 4) -0x20 + (scntl3 & 0x7);
if (bootverbose) printf ("\tinitial value of SCNTL3 = %02x, final = %02x\n",
scntl3, np->rv_scntl3);
}
/*=========================================================================*/