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SubjectRE: [PATCH][2.6][2/5]Support for HPET based timer
Date
From

Fixmap is for HPET memory map address access. As the timer
initialization happen
early in the boot sequence (before vm initialization), we need to have
fixmap()
and fix_to_virt() to access HPET memory map address.

Yes. Most of the code is generic, and can run on other platforms. The
only reason
I have that check is because, I haven't got chance to test this patch on
other
platforms.

Thanks,
-Venkatesh

> -----Original Message-----
> From: Vojtech Pavlik [mailto:vojtech@suse.cz]
> Sent: Tuesday, August 19, 2003 3:39 PM
> To: Pallipadi, Venkatesh
> Cc: linux-kernel@vger.kernel.org; torvalds@osdl.org;
> Nakajima, Jun; Mallick, Asit K
> Subject: Re: [PATCH][2.6][2/5]Support for HPET based timer
>
>
> On Tue, Aug 19, 2003 at 12:20:02PM -0700, Pallipadi, Venkatesh wrote:
>
> > 2/5 - hpet2.patch - All the changes required to use HPET in place
> > of PIT as the kernel base-timer at IRQ 0.
>
> What are you using the fixmap() for? i386 doesn't have vsyscalls ...
>
> Why are you limiting the HPET vendor ID to Intel? This code will
> happily run on other vendor hardware as well ...
>
>
> > diff -purN linux-2.6.0-test1/arch/i386/kernel/apic.c
> linux-2.6.0-test1-hpet/arch/i386/kernel/apic.c
> > --- linux-2.6.0-test1/arch/i386/kernel/apic.c
> 2003-07-13 20:39:27.000000000 -0700
> > +++ linux-2.6.0-test1-hpet/arch/i386/kernel/apic.c
> 2003-08-13 11:36:24.000000000 -0700
> > @@ -34,6 +34,7 @@
> > #include <asm/pgalloc.h>
> > #include <asm/desc.h>
> > #include <asm/arch_hooks.h>
> > +#include <asm/hpet.h>
> >
> > #include <mach_apic.h>
> >
> > @@ -749,7 +750,8 @@ static unsigned int __init get_8254_time
> > return count;
> > }
> >
> > -void __init wait_8254_wraparound(void)
> > +/* next tick in 8254 can be caught by catching timer wraparound */
> > +static void __init wait_8254_wraparound(void)
> > {
> > unsigned int curr_count, prev_count=~0;
> > int delta;
> > @@ -771,6 +773,12 @@ void __init wait_8254_wraparound(void)
> > }
> >
> > /*
> > + * Default initialization for 8254 timers. If we use other
> timers like HPET,
> > + * we override this later
> > + */
> > +void (*wait_timer_tick)(void) = wait_8254_wraparound;
> > +
> > +/*
> > * This function sets up the local APIC timer, with a timeout of
> > * 'clocks' APIC bus clock. During calibration we actually call
> > * this function twice on the boot CPU, once with a bogus timeout
> > @@ -811,7 +819,7 @@ static void setup_APIC_timer(unsigned in
> > /*
> > * Wait for IRQ0's slice:
> > */
> > - wait_8254_wraparound();
> > + wait_timer_tick();
> >
> > __setup_APIC_LVTT(clocks);
> >
> > @@ -854,7 +862,7 @@ int __init calibrate_APIC_clock(void)
> > * (the current tick might have been already half done)
> > */
> >
> > - wait_8254_wraparound();
> > + wait_timer_tick();
> >
> > /*
> > * We wrapped around just now. Let's start:
> > @@ -867,7 +875,7 @@ int __init calibrate_APIC_clock(void)
> > * Let's wait LOOPS wraprounds:
> > */
> > for (i = 0; i < LOOPS; i++)
> > - wait_8254_wraparound();
> > + wait_timer_tick();
> >
> > tt2 = apic_read(APIC_TMCCT);
> > if (cpu_has_tsc)
> > diff -purN linux-2.6.0-test1/arch/i386/kernel/time.c
> linux-2.6.0-test1-hpet/arch/i386/kernel/time.c
> > --- linux-2.6.0-test1/arch/i386/kernel/time.c
> 2003-07-13 20:34:29.000000000 -0700
> > +++ linux-2.6.0-test1-hpet/arch/i386/kernel/time.c
> 2003-08-18 12:36:25.000000000 -0700
> > @@ -60,6 +60,8 @@
> > #include <linux/timex.h>
> > #include <linux/config.h>
> >
> > +#include <asm/hpet.h>
> > +
> > #include <asm/arch_hooks.h>
> >
> > #include "io_ports.h"
> > @@ -298,6 +300,12 @@ void __init time_init(void)
> > xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
> > wall_to_monotonic.tv_nsec = -xtime.tv_nsec;
> >
> > +#ifdef CONFIG_HPET_TIMER
> > + if (hpet_enable() >= 0) {
> > + printk("Using HPET for base-timer\n");
> > + }
> > +#endif
> > +
> > cur_timer = select_timer();
> > time_init_hook();
> > }
> > diff -purN linux-2.6.0-test1/arch/i386/kernel/time_hpet.c
> linux-2.6.0-test1-hpet/arch/i386/kernel/time_hpet.c
> > --- linux-2.6.0-test1/arch/i386/kernel/time_hpet.c
> 1969-12-31 16:00:00.000000000 -0800
> > +++ linux-2.6.0-test1-hpet/arch/i386/kernel/time_hpet.c
> 2003-08-18 20:22:06.000000000 -0700
> > @@ -0,0 +1,153 @@
> > +/*
> > + * linux/arch/i386/kernel/time_hpet.c
> > + * This code largely copied from arch/x86_64/kernel/time.c
> > + * See that file for credits.
> > + *
> > + * 2003-06-30 Venkatesh Pallipadi - Additional changes
> for HPET support
> > + */
> > +
> > +#include <linux/errno.h>
> > +#include <linux/kernel.h>
> > +#include <linux/param.h>
> > +#include <linux/string.h>
> > +#include <linux/init.h>
> > +#include <linux/smp.h>
> > +
> > +#include <asm/timer.h>
> > +#include <asm/fixmap.h>
> > +#include <asm/apic.h>
> > +
> > +#include <linux/timex.h>
> > +#include <linux/config.h>
> > +
> > +#include <asm/hpet.h>
> > +
> > +unsigned long hpet_period; /* fsecs / HPET clock */
> > +unsigned long hpet_tick; /* hpet clks count per tick */
> > +unsigned long hpet_address; /* hpet memory map address */
> > +
> > +static int use_hpet; /* can be used for
> runtime check of hpet */
> > +static int boot_hpet_disable; /* boottime override
> for HPET timer */
> > +
> > +#define FSEC_TO_USEC (1000000000UL)
> > +
> > +#ifdef CONFIG_X86_LOCAL_APIC
> > +/*
> > + * HPET counters dont wrap around on every tick. They just
> change the
> > + * comparator value and continue. Next tick can be caught
> by checking
> > + * for a change in the comparator value. Used in apic.c.
> > + */
> > +void __init wait_hpet_tick(void)
> > +{
> > + unsigned int start_cmp_val, end_cmp_val;
> > +
> > + start_cmp_val = hpet_readl(HPET_T0_CMP);
> > + do {
> > + end_cmp_val = hpet_readl(HPET_T0_CMP);
> > + } while (start_cmp_val == end_cmp_val);
> > +}
> > +#endif
> > +
> > +/*
> > + * Check whether HPET was found by ACPI boot parse. If yes
> setup HPET
> > + * counter 0 for kernel base timer.
> > + */
> > +int __init hpet_enable(void)
> > +{
> > + unsigned int cfg, id;
> > + unsigned long tick_fsec_low, tick_fsec_high; /* tick in
> femto sec */
> > + unsigned long hpet_tick_rem;
> > +
> > + if (boot_hpet_disable)
> > + return -1;
> > +
> > + if (!hpet_address) {
> > + return -1;
> > + }
> > + set_fixmap_nocache(FIX_HPET_BASE, hpet_address);
> > + printk(KERN_INFO "HPET enabled at %#lx\n", hpet_address);
> > +
> > + /*
> > + * Read the period, compute tick and quotient.
> > + */
> > + id = hpet_readl(HPET_ID);
> > +
> > + /*
> > + * We are checking for value '1' or more in number field.
> > + * So, we are OK with HPET_EMULATE_RTC part too, where we need
> > + * to have atleast 2 timers.
> > + */
> > + if (!(id & HPET_ID_NUMBER) ||
> > + !(id & HPET_ID_LEGSUP))
> > + return -1;
> > +
> > + if (((id & HPET_ID_VENDOR) >> HPET_ID_VENDOR_SHIFT) !=
> > + HPET_ID_VENDOR_8086)
> > + return -1;
> > +
> > + hpet_period = hpet_readl(HPET_PERIOD);
> > + if ((hpet_period < HPET_MIN_PERIOD) || (hpet_period >
> HPET_MAX_PERIOD))
> > + return -1;
> > +
> > + /*
> > + * 64 bit math
> > + * First changing tick into fsec
> > + * Then 64 bit div to find number of hpet clk per tick
> > + */
> > + ASM_MUL64_REG(tick_fsec_low, tick_fsec_high,
> > + KERNEL_TICK_USEC, FSEC_TO_USEC);
> > + ASM_DIV64_REG(hpet_tick, hpet_tick_rem,
> > + hpet_period, tick_fsec_low, tick_fsec_high);
> > +
> > + if (hpet_tick_rem > (hpet_period >> 1))
> > + hpet_tick++; /* rounding the result */
> > +
> > + /*
> > + * Stop the timers and reset the main counter.
> > + */
> > + cfg = hpet_readl(HPET_CFG);
> > + cfg &= ~HPET_CFG_ENABLE;
> > + hpet_writel(cfg, HPET_CFG);
> > + hpet_writel(0, HPET_COUNTER);
> > + hpet_writel(0, HPET_COUNTER + 4);
> > +
> > + /*
> > + * Set up timer 0, as periodic with first interrupt to
> happen at
> > + * hpet_tick, and period also hpet_tick.
> > + */
> > + cfg = hpet_readl(HPET_T0_CFG);
> > + cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC |
> > + HPET_TN_SETVAL | HPET_TN_32BIT;
> > + hpet_writel(cfg, HPET_T0_CFG);
> > + hpet_writel(hpet_tick, HPET_T0_CMP);
> > +
> > + /*
> > + * Go!
> > + */
> > + cfg = hpet_readl(HPET_CFG);
> > + cfg |= HPET_CFG_ENABLE | HPET_CFG_LEGACY;
> > + hpet_writel(cfg, HPET_CFG);
> > +
> > + use_hpet = 1;
> > +#ifdef CONFIG_X86_LOCAL_APIC
> > + wait_timer_tick = wait_hpet_tick;
> > +#endif
> > + return 0;
> > +}
> > +
> > +int is_hpet_enabled(void)
> > +{
> > + return use_hpet;
> > +}
> > +
> > +static int __init hpet_setup(char* str)
> > +{
> > + if (str) {
> > + if (!strncmp("disable", str, 7))
> > + boot_hpet_disable = 1;
> > + }
> > + return 1;
> > +}
> > +
> > +__setup("hpet=", hpet_setup);
> > +
> > diff -purN linux-2.6.0-test1/include/asm-i386/apic.h
> linux-2.6.0-test1-hpet/include/asm-i386/apic.h
> > --- linux-2.6.0-test1/include/asm-i386/apic.h
> 2003-07-13 20:38:53.000000000 -0700
> > +++ linux-2.6.0-test1-hpet/include/asm-i386/apic.h
> 2003-08-13 11:34:37.000000000 -0700
> > @@ -64,6 +64,8 @@ static inline void ack_APIC_irq(void)
> > apic_write_around(APIC_EOI, 0);
> > }
> >
> > +extern void (*wait_timer_tick)(void);
> > +
> > extern int get_maxlvt(void);
> > extern void clear_local_APIC(void);
> > extern void connect_bsp_APIC (void);
> > diff -purN linux-2.6.0-test1/include/asm-i386/fixmap.h
> linux-2.6.0-test1-hpet/include/asm-i386/fixmap.h
> > --- linux-2.6.0-test1/include/asm-i386/fixmap.h
> 2003-07-13 20:29:30.000000000 -0700
> > +++ linux-2.6.0-test1-hpet/include/asm-i386/fixmap.h
> 2003-08-14 13:10:31.000000000 -0700
> > @@ -44,6 +44,9 @@
> > enum fixed_addresses {
> > FIX_HOLE,
> > FIX_VSYSCALL,
> > +#ifdef CONFIG_HPET_TIMER
> > + FIX_HPET_BASE,
> > +#endif
> > #ifdef CONFIG_X86_LOCAL_APIC
> > FIX_APIC_BASE, /* local (CPU) APIC) -- required for
> SMP or not */
> > #endif
> > diff -purN linux-2.6.0-test1/include/asm-i386/hpet.h
> linux-2.6.0-test1-hpet/include/asm-i386/hpet.h
> > --- linux-2.6.0-test1/include/asm-i386/hpet.h
> 1969-12-31 16:00:00.000000000 -0800
> > +++ linux-2.6.0-test1-hpet/include/asm-i386/hpet.h
> 2003-08-18 20:22:40.000000000 -0700
> > @@ -0,0 +1,104 @@
> > +
> > +#ifndef _I386_HPET_H
> > +#define _I386_HPET_H
> > +
> > +#ifdef CONFIG_HPET_TIMER
> > +
> > +#include <linux/errno.h>
> > +#include <linux/module.h>
> > +#include <linux/sched.h>
> > +#include <linux/kernel.h>
> > +#include <linux/param.h>
> > +#include <linux/string.h>
> > +#include <linux/mm.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/time.h>
> > +#include <linux/delay.h>
> > +#include <linux/init.h>
> > +#include <linux/smp.h>
> > +
> > +#include <asm/io.h>
> > +#include <asm/smp.h>
> > +#include <asm/irq.h>
> > +#include <asm/msr.h>
> > +#include <asm/delay.h>
> > +#include <asm/mpspec.h>
> > +#include <asm/uaccess.h>
> > +#include <asm/processor.h>
> > +
> > +#include <linux/timex.h>
> > +#include <linux/config.h>
> > +
> > +#include <asm/fixmap.h>
> > +
> > +/*
> > + * Documentation on HPET can be found at:
> > + * http://www.intel.com/ial/home/sp/pcmmspec.htm
> > + * ftp://download.intel.com/ial/home/sp/mmts098.pdf
> > + */
> > +
> > +#define HPET_ID 0x000
> > +#define HPET_PERIOD 0x004
> > +#define HPET_CFG 0x010
> > +#define HPET_STATUS 0x020
> > +#define HPET_COUNTER 0x0f0
> > +#define HPET_T0_CFG 0x100
> > +#define HPET_T0_CMP 0x108
> > +#define HPET_T0_ROUTE 0x110
> > +#define HPET_T1_CFG 0x120
> > +#define HPET_T1_CMP 0x128
> > +#define HPET_T1_ROUTE 0x130
> > +#define HPET_T2_CFG 0x140
> > +#define HPET_T2_CMP 0x148
> > +#define HPET_T2_ROUTE 0x150
> > +
> > +#define HPET_ID_VENDOR 0xffff0000
> > +#define HPET_ID_LEGSUP 0x00008000
> > +#define HPET_ID_NUMBER 0x00001f00
> > +#define HPET_ID_REV 0x000000ff
> > +
> > +#define HPET_ID_VENDOR_SHIFT 16
> > +#define HPET_ID_VENDOR_8086 0x8086
> > +
> > +#define HPET_CFG_ENABLE 0x001
> > +#define HPET_CFG_LEGACY 0x002
> > +
> > +#define HPET_TN_ENABLE 0x004
> > +#define HPET_TN_PERIODIC 0x008
> > +#define HPET_TN_PERIODIC_CAP 0x010
> > +#define HPET_TN_SETVAL 0x040
> > +#define HPET_TN_32BIT 0x100
> > +
> > +/* Use our own asm for 64 bit multiply/divide */
> > +#define ASM_MUL64_REG(eax_out,edx_out,reg_in,eax_in)
> \
> > + __asm__ __volatile__("mull %2"
> \
> > + :"=a" (eax_out), "=d" (edx_out)
> \
> > + :"r" (reg_in), "0" (eax_in))
> > +
> > +#define
> ASM_DIV64_REG(eax_out,edx_out,reg_in,eax_in,edx_in) \
> > + __asm__ __volatile__("divl %2"
> \
> > + :"=a" (eax_out), "=d" (edx_out)
> \
> > + :"r" (reg_in), "0" (eax_in),
> "1" (edx_in))
> > +
> > +#define hpet_readl(a)
> readl(fix_to_virt(FIX_HPET_BASE) + a)
> > +#define hpet_writel(d,a) writel(d,
> fix_to_virt(FIX_HPET_BASE) + a)
> > +
> > +#define KERNEL_TICK_USEC (1000000UL/HZ) /* tick value
> in microsec */
> > +/* Max HPET Period is 10^8 femto sec as in HPET spec */
> > +#define HPET_MAX_PERIOD (100000000UL)
> > +/*
> > + * Min HPET period is 10^5 femto sec just for safety. If
> it is less than this,
> > + * then 32 bit HPET counter wrapsaround in less than 0.5 sec.
> > + */
> > +#define HPET_MIN_PERIOD (100000UL)
> > +
> > +extern unsigned long hpet_period; /* fsecs / HPET clock */
> > +extern unsigned long hpet_tick; /* hpet clks count per tick */
> > +extern unsigned long hpet_address; /* hpet memory map address */
> > +extern unsigned long hpet_virt_address; /* hpet kernel
> virtual address */
> > +
> > +extern int hpet_enable(void);
> > +extern int is_hpet_enabled(void);
> > +
> > +#endif /* CONFIG_HPET_TIMER */
> > +#endif /* _I386_HPET_H */
> > diff -purN linux-2.6.0-test1/include/asm-i386/mc146818rtc.h
> linux-2.6.0-test1-hpet/include/asm-i386/mc146818rtc.h
> > --- linux-2.6.0-test1/include/asm-i386/mc146818rtc.h
> 2003-07-13 20:36:37.000000000 -0700
> > +++ linux-2.6.0-test1-hpet/include/asm-i386/mc146818rtc.h
> 2003-08-18 20:23:43.000000000 -0700
> > @@ -24,6 +24,10 @@ outb_p((addr),RTC_PORT(0)); \
> > outb_p((val),RTC_PORT(1)); \
> > })
> >
> > +#ifdef CONFIG_HPET_TIMER
> > +#define RTC_IRQ 0
> > +#else
> > #define RTC_IRQ 8
> > +#endif
> >
> > #endif /* _ASM_MC146818RTC_H */
> > diff -purN
> linux-2.6.0-test1/Documentation/kernel-parameters.txt
> linux-2.6.0-test1-hpet/Documentation/kernel-parameters.txt
> > --- linux-2.6.0-test1/Documentation/kernel-parameters.txt
> 2003-07-13 20:39:36.000000000 -0700
> > +++
> linux-2.6.0-test1-hpet/Documentation/kernel-parameters.txt
> 2003-08-18 20:37:41.000000000 -0700
> > @@ -212,7 +212,10 @@ running once the system is up.
> > when calculating gettimeofday(). If
> specicified timesource
> > is not avalible, it defaults to PIT.
> > Format: { pit | tsc | cyclone | ... }
> > -
> > +
> > + hpet= [IA-32,HPET] option to disable HPET and use PIT.
> > + Format: disable
> > +
> > cm206= [HW,CD]
> > Format: { auto | [<io>,][<irq>] }
> >
> >
> >
>
>
>
> --
> Vojtech Pavlik
> SuSE Labs, SuSE CR
>
-
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