On Tue, 2002-07-09 at 04:03, Mikael Pettersson wrote:
> On 08 Jul 2002 19:36:23 -0700, john stultz wrote:
> >Mainly I'm concerned about my usage of bt_ioremap. Early in the boot
> >processes, I need to map in a couple of chipset registers and poke
> >values into them.
>
> How early? If this is just to get gettimeofday() working, can't it
> wait until the regular initcalls are done?
I guess I might be able to pull it out and do the initialization
somewhere else, but really time_init() seems like the best spot.
> > However one of the registers needs to be kept mapped
> >for the life of the system (look for "cyclone_timer" below). I couldn't
> >find any documentation on whether memory mapped with bt_ioremap can be
> >held across mem_init(). It seems to "just work" but I wanted to find out
> >if I really should be re-mapping the register w/ ioremap once it becomes
> >available.
>
> If you look in include/asm-i386/fixmap.h you'll see that the BT ioremap
> pages are temporary, and they do disappear once mem_init() [or whatever]
> is done [pgtable.h sets VMALLOC_END to just below FIXADDR_START, which
> protects the permanent fixmaps but intensionally not the temporary ones].
> If it seemed to work for you then that's just luck, or perhaps it does
> work in highmem kernels?
>
> For things that must be mapped very early and continue to be mapped as
> long as the kernel is up, you need a permanent fixmap. fixmap.h has a
> number of permanent fixmaps defined #ifdef CONFIG_* and you can easily
> add your own there, under #ifdef CONFIG_X86_IBMEXA.
Thank you for the pointer. I gave it a whirl (see attached) and it seems
to work fine! If anyone notices that I'm still just horribly lucky and
I've done everything wrong, please let me know. :)
Thanks again for the feedback and suggestions!
-john
ps: Again, if anyone feels so inclined to try this patch, do note that
it depends on my tsc-disable patch to apply cleanly. Send me a note and
I'll fwd you my latest version.
--=-frIRiYKM2DZIIFH7DMEx
Content-Disposition: attachment; filename=linux-2.4.19-rc1_cyclone-timer_A2.patch
Content-Transfer-Encoding: quoted-printable
Content-Type: text/x-patch; name=linux-2.4.19-rc1_cyclone-timer_A2.patch;
charset=ISO-8859-1
diff -Nru a/Documentation/Configure.help b/Documentation/Configure.help
--- a/Documentation/Configure.help Tue Jul 9 18:49:52 2002
+++ b/Documentation/Configure.help Tue Jul 9 18:49:52 2002
@@ -257,6 +257,11 @@
You will need a new lynxer.elf file to flash your firmware with - send
email to Martin.Bligh@us.ibm.com
=20
+IBM Enterprise X-Architecture support
+CONFIG_X86_IBMEXA
+ This option makes use of a performance counter on the Cyclone chipset=20
+ for calculating do_gettimeofday, greatly improving its performance.=20
+
IO-APIC support on uniprocessors
CONFIG_X86_UP_IOAPIC
An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
diff -Nru a/arch/i386/config.in b/arch/i386/config.in
--- a/arch/i386/config.in Tue Jul 9 18:49:52 2002
+++ b/arch/i386/config.in Tue Jul 9 18:49:52 2002
@@ -201,6 +201,7 @@
bool 'Multi-node NUMA system support' CONFIG_X86_NUMA
if [ "$CONFIG_X86_NUMA" =3D "y" ]; then
bool 'Multiquad (IBM/Sequent) NUMAQ support' CONFIG_MULTIQUAD
+ bool 'IBM Enterprise X-Architecture support' CONFIG_X86_IBMEXA
fi
fi
=20
diff -Nru a/arch/i386/kernel/time.c b/arch/i386/kernel/time.c
--- a/arch/i386/kernel/time.c Tue Jul 9 18:49:52 2002
+++ b/arch/i386/kernel/time.c Tue Jul 9 18:49:52 2002
@@ -253,6 +253,92 @@
=20
static unsigned long (*do_gettimeoffset)(void) =3D do_slow_gettimeoffset;
=20
+
+
+#ifdef CONFIG_X86_IBMEXA
+#define CYCLONE_CBAR_ADDR 0xFEB00CD0
+#define CYCLONE_PMCC_OFFSET 0x51A0
+#define CYCLONE_MPMC_OFFSET 0x51D0
+#define CYCLONE_MPCS_OFFSET 0x51A8
+#define CYCLONE_TIMER_FREQ 100000000
+static u32* cyclone_timer; /*Cyclone MPMC0 register*/
+static void init_cyclone_clock(void)
+{
+ u32* reg;=09
+ u32 base; /*saved cyclone base address*/
+ u32 pageaddr; /*page that contains cyclone_timer register*/
+ u32 offset; /*offset from pageaddr to cyclone_timer register*/
+
+ /*find base address*/
+ reg =3D bt_ioremap(CYCLONE_CBAR_ADDR, 4);
+ if(!reg) return;
+ base =3D *reg;=09
+ bt_iounmap(reg, 4);
+
+ /*setup PMCC*/
+ reg =3D bt_ioremap(base + CYCLONE_PMCC_OFFSET, 8);
+ if(!reg) return;
+ reg[0] =3D 0x00000001;
+ bt_iounmap(reg, 8);
+
+ /*setup MPCS*/
+ reg =3D bt_ioremap(base + CYCLONE_MPCS_OFFSET, 8);
+ if(!reg) return;
+ reg[0] =3D 0x00000001;
+ bt_iounmap(reg, 8);
+
+ /*map in cyclone_timer w/ set_fixmap*/
+ pageaddr =3D (base + CYCLONE_MPMC_OFFSET)&PAGE_MASK;
+ offset =3D (base + CYCLONE_MPMC_OFFSET)&(~PAGE_MASK);
+
+ set_fixmap(FIX_CYCLONE_TIMER, pageaddr);
+=09
+ cyclone_timer =3D fix_to_virt(FIX_CYCLONE_TIMER) + offset;
+}
+
+static u32 last_cyclone_timer;
+
+static inline void mark_timeoffset_cyclone(void)
+{
+ int count;
+=09
+ /*quickly read the cyclone timer*/
+ if(cyclone_timer)
+ last_cyclone_timer =3D cyclone_timer[0];
+=09
+ /*calculate delay_at_last_interrupt*/
+ spin_lock(&i8253_lock);
+ outb_p(0x00, 0x43); /* latch the count ASAP */
+
+ count =3D inb_p(0x40); /* read the latched count */
+ count |=3D inb(0x40) << 8;
+ spin_unlock(&i8253_lock);
+
+ count =3D ((LATCH-1) - count) * TICK_SIZE;
+ delay_at_last_interrupt =3D (count + LATCH/2) / LATCH;
+}
+
+static unsigned long do_gettimeoffset_cyclone(void)
+{
+ u32 offset;
+
+ if(!cyclone_timer)
+ return delay_at_last_interrupt;
+
+ /* Read the cyclone timer */
+ offset =3D cyclone_timer[0];
+ =09
+ /* .. relative to previous jiffy*/
+ offset =3D offset - last_cyclone_timer;
+
+ /*convert cyclone ticks to microseconds*/=09
+ offset =3D offset*(1000000/CYCLONE_TIMER_FREQ);=20
+
+ /* our adjusted time offset in microseconds */
+ return delay_at_last_interrupt + offset;
+}
+#endif /*CONFIG_X86_IBMEXA*/
+
#else
=20
#define do_gettimeoffset() do_fast_gettimeoffset()
@@ -459,6 +545,7 @@
}
=20
static int use_tsc;
+static int use_cyclone =3D1; /*XXX should be autodetected*/
=20
/*
* This is the same as the above, except we _also_ save the current
@@ -506,6 +593,10 @@
count =3D ((LATCH-1) - count) * TICK_SIZE;
delay_at_last_interrupt =3D (count + LATCH/2) / LATCH;
}
+#ifdef CONFIG_X86_IBMEXA
+ if(use_cyclone)
+ mark_timeoffset_cyclone();
+#endif /*CONFIG_X86_IBMEXA*/
=20
do_timer_interrupt(irq, NULL, regs);
=20
@@ -695,6 +786,14 @@
}
}
}
+
+#ifdef CONFIG_X86_IBMEXA
+ if((!use_tsc) && use_cyclone){
+ printk("IBM EXA: Starting Cyclone Clock.\n");
+ do_gettimeoffset =3D do_gettimeoffset_cyclone;
+ init_cyclone_clock();
+ }
+#endif /*CONFIG_X86_IBMEXA*/
=20
#ifdef CONFIG_VISWS
printk("Starting Cobalt Timer system clock\n");
diff -Nru a/include/asm-i386/fixmap.h b/include/asm-i386/fixmap.h
--- a/include/asm-i386/fixmap.h Tue Jul 9 18:49:52 2002
+++ b/include/asm-i386/fixmap.h Tue Jul 9 18:49:52 2002
@@ -61,6 +61,9 @@
FIX_LI_PCIA, /* Lithium PCI Bridge A */
FIX_LI_PCIB, /* Lithium PCI Bridge B */
#endif
+#ifdef CONFIG_X86_IBMEXA
+ FIX_CYCLONE_TIMER, /*cyclone timer register*/
+#endif=20
#ifdef CONFIG_HIGHMEM
FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
FIX_KMAP_END =3D FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
--=-frIRiYKM2DZIIFH7DMEx--
-
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