Messages in this thread Patch in this message | | | Subject | Re: [RFC] bt_ioremap question / cyclone-timer_A1 patch | From | john stultz <> | Date | 09 Jul 2002 19:18:59 -0700 |
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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. 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 +IBM Enterprise X-Architecture support +CONFIG_X86_IBMEXA + This option makes use of a performance counter on the Cyclone chipset + for calculating do_gettimeofday, greatly improving its performance. + 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" = "y" ]; then bool 'Multiquad (IBM/Sequent) NUMAQ support' CONFIG_MULTIQUAD + bool 'IBM Enterprise X-Architecture support' CONFIG_X86_IBMEXA fi fi 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 @@ static unsigned long (*do_gettimeoffset)(void) = do_slow_gettimeoffset; + + +#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; + 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 = bt_ioremap(CYCLONE_CBAR_ADDR, 4); + if(!reg) return; + base = *reg; + bt_iounmap(reg, 4); + + /*setup PMCC*/ + reg = bt_ioremap(base + CYCLONE_PMCC_OFFSET, 8); + if(!reg) return; + reg[0] = 0x00000001; + bt_iounmap(reg, 8); + + /*setup MPCS*/ + reg = bt_ioremap(base + CYCLONE_MPCS_OFFSET, 8); + if(!reg) return; + reg[0] = 0x00000001; + bt_iounmap(reg, 8); + + /*map in cyclone_timer w/ set_fixmap*/ + pageaddr = (base + CYCLONE_MPMC_OFFSET)&PAGE_MASK; + offset = (base + CYCLONE_MPMC_OFFSET)&(~PAGE_MASK); + + set_fixmap(FIX_CYCLONE_TIMER, pageaddr); + + cyclone_timer = fix_to_virt(FIX_CYCLONE_TIMER) + offset; +} + +static u32 last_cyclone_timer; + +static inline void mark_timeoffset_cyclone(void) +{ + int count; + + /*quickly read the cyclone timer*/ + if(cyclone_timer) + last_cyclone_timer = cyclone_timer[0]; + + /*calculate delay_at_last_interrupt*/ + spin_lock(&i8253_lock); + outb_p(0x00, 0x43); /* latch the count ASAP */ + + count = inb_p(0x40); /* read the latched count */ + count |= inb(0x40) << 8; + spin_unlock(&i8253_lock); + + count = ((LATCH-1) - count) * TICK_SIZE; + delay_at_last_interrupt = (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 = cyclone_timer[0]; + + /* .. relative to previous jiffy*/ + offset = offset - last_cyclone_timer; + + /*convert cyclone ticks to microseconds*/ + offset = offset*(1000000/CYCLONE_TIMER_FREQ); + + /* our adjusted time offset in microseconds */ + return delay_at_last_interrupt + offset; +} +#endif /*CONFIG_X86_IBMEXA*/ + #else #define do_gettimeoffset() do_fast_gettimeoffset() @@ -459,6 +545,7 @@ } static int use_tsc; +static int use_cyclone =1; /*XXX should be autodetected*/ /* * This is the same as the above, except we _also_ save the current @@ -506,6 +593,10 @@ count = ((LATCH-1) - count) * TICK_SIZE; delay_at_last_interrupt = (count + LATCH/2) / LATCH; } +#ifdef CONFIG_X86_IBMEXA + if(use_cyclone) + mark_timeoffset_cyclone(); +#endif /*CONFIG_X86_IBMEXA*/ do_timer_interrupt(irq, NULL, regs); @@ -695,6 +786,14 @@ } } } + +#ifdef CONFIG_X86_IBMEXA + if((!use_tsc) && use_cyclone){ + printk("IBM EXA: Starting Cyclone Clock.\n"); + do_gettimeoffset = do_gettimeoffset_cyclone; + init_cyclone_clock(); + } +#endif /*CONFIG_X86_IBMEXA*/ #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 #ifdef CONFIG_HIGHMEM FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */ FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1, | |