diff options
Diffstat (limited to 'packages/linux/nas100d-kernel/2.6.15/85-timer.patch')
| -rw-r--r-- | packages/linux/nas100d-kernel/2.6.15/85-timer.patch | 246 |
1 files changed, 0 insertions, 246 deletions
diff --git a/packages/linux/nas100d-kernel/2.6.15/85-timer.patch b/packages/linux/nas100d-kernel/2.6.15/85-timer.patch deleted file mode 100644 index e83120ca75..0000000000 --- a/packages/linux/nas100d-kernel/2.6.15/85-timer.patch +++ /dev/null @@ -1,246 +0,0 @@ ---- linux-2.6.15/arch/arm/mach-ixp4xx/common.c 1970-01-01 00:00:00.000000000 +0000 -+++ linux-2.6.15/arch/arm/mach-ixp4xx/common.c 1970-01-01 00:00:00.000000000 +0000 -@@ -239,36 +239,165 @@ void __init ixp4xx_init_irq(void) - * IXP4xx timer tick - * We use OS timer1 on the CPU for the timer tick and the timestamp - * counter as a source of real clock ticks to account for missed jiffies. -+ * -+ * 'CLOCK_TICK_RATE' is the nominal number of internal ticks per second, -+ * this is significantly greater than the actual number on any ixp4xx -+ * board. Neither this nor 'LATCH' are required by this code because -+ * the only requirement is to generate HZ timer_tick calls per second. - *************************************************************************/ -+#if TICK_NSEC * HZ != 1000000000 -+ /* This will cause the jiffies to drift unnecessarily. */ -+# error CLOCK_TICK_RATE should be a multiple of HZ for this code -+#endif -+ -+/* These are the control registers for the interrupt handler, they must -+ * only be read and written by the interrupt handler and by the init -+ * method (which sets them to 0). -+ */ -+static volatile u32 last_timer_time; -+static volatile int accumulated_error; -+ -+/* Most ixp4xx boards have 66.6666MHz crystals, so default to this, reset -+ * this from the board level code if required. The following variables -+ * must be *written* only by set_board_tick_rate -+ */ -+static u32 board_tick_rate; -+static u32 board_tick_per_1000; /* board_tick_rate/1000 */ -+static u32 timer_count; -+ -+/* The following symbol may be written to change the current tick rate, -+ * it is read by the interrupt handler and used to reload the timer. -+ * The 'real' value (the one in use) is 'board_tick_rate' above. -+ * NOTE: this can be tweaked to match the actual crystal on a particular -+ * machine. -+ */ -+volatile u32 ixp4xx_board_tick_rate = 66666600; -+EXPORT_SYMBOL(ixp4xx_board_tick_rate); -+ -+/* The set API may run asynchronously in the presence of interrupts, -+ * everything it does it is both atomic and complete (notice that it -+ * doesn't change any of the 'volatile' values). The mathematics in -+ * here require the following values. Changing the board tick rate -+ * implies an unknown error in the current timestamp tick count. -+ */ -+#if IXP4XX_OST_RELOAD_MASK != 3 || IXP4XX_OST_ENABLE != 1 -+# error unexpected value for timer reload mask -+#endif -+static void set_board_tick_rate(u32 rate) { -+ u32 reload; -+ -+ /* Store the two effectively informational rate values, the -+ * error calculation is (rate - count*HZ) (above), and rate -+ * is changed first, this can cause a temporary error which -+ * will be corrected on the next interrupt. -+ */ -+ board_tick_rate = rate; -+ board_tick_per_1000 = (rate+500)/1000; -+ -+ /* Calculate the correct value to load into the timer countdown -+ * register, the low two bits must be b01 (to enable the timer). -+ * Select the top bits to be as close to the desired value as -+ * possible. -+ * -+ * First find the best value, regardless of the low two bits - -+ * this is the value used in the interrupt calculation even though -+ * it cannot necessarily be set into the register. -+ */ -+ timer_count = (rate + (HZ/2))/HZ; -+ -+ /* Now the timer_ticks are being generated at this rate, calculate -+ * an appropriate value for the register. This stores a 30 bit -+ * value which gives a period of 4*x+1, we want: -+ * -+ * 4*x+1 = board_tick_rate/HZ -+ * -+ * This needs to be rounded to the closest 4*HZ value: -+ * -+ * x = ((board_tick_rate-HZ) + (4*HZ)/2) / 4*HZ -+ * x = (board_tick_rate+HZ) / (4*HZ); -+ */ -+ reload = (board_tick_rate + HZ) / HZ; -+ reload = (reload & ~IXP4XX_OST_RELOAD_MASK) | IXP4XX_OST_ENABLE; -+ *IXP4XX_OSRT1 = reload; - --static unsigned volatile last_jiffy_time; -+ /* If the clock is drifing, look in syslog: */ -+ printk(KERN_INFO "IXP4xx: FREQ=%d COUNT=%d\n", rate, reload); -+} - --#define CLOCK_TICKS_PER_USEC ((CLOCK_TICK_RATE + USEC_PER_SEC/2) / USEC_PER_SEC) -+/* This returns the time in timer ticks since the 'last_timer_time' -+ * recorded above. Use this to avoid arithmetic errors because of -+ * the overflow when the timer wraps. -+ */ -+static inline u32 ixp4xx_timer_delta(void) -+{ -+ return *IXP4XX_OSTS - last_timer_time; -+} - - /* IRQs are disabled before entering here from do_gettimeofday() */ - static unsigned long ixp4xx_gettimeoffset(void) - { -- u32 elapsed; -- -- elapsed = *IXP4XX_OSTS - last_jiffy_time; -+ /* Return the offset of the current time from the last time -+ * timer tick in microseconds. This is only used for the -+ * gettimeofday call. -+ * -+ * The result of this API is at most about 20000 (for a 50Hz -+ * HZ - 20000 uS/tick), the input delta is at most about -+ * 1.3M - 21 bits. -+ */ -+ u32 delta = ixp4xx_timer_delta(); /* About 21 bits max */ -+ /* return delta * 1000000 / board_tick_rate; */ -+ return (delta * 1000 + board_tick_per_1000/2) / board_tick_per_1000; -+} - -- return elapsed / CLOCK_TICKS_PER_USEC; -+/* This is the correct adjustment to the counter to compensate for an -+ * error iff timer_count-1 <= exact_count <= timer_count+1 -+ */ -+static inline int adjustment(int error) { -+ if (error >= HZ) -+ return 1; -+ else if (error <= -HZ) -+ return -1; -+ return 0; - } - - static irqreturn_t ixp4xx_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) - { -+ u32 rate; -+ u32 count; -+ int error; -+ - write_seqlock(&xtime_lock); - - /* Clear Pending Interrupt by writing '1' to it */ - *IXP4XX_OSST = IXP4XX_OSST_TIMER_1_PEND; - -+ /* If the board tick rate has been changed update the cached -+ * value. -+ */ -+ if (ixp4xx_board_tick_rate != board_tick_rate) { -+ set_board_tick_rate(ixp4xx_board_tick_rate); -+ accumulated_error = 0; -+ } -+ - /* - * Catch up with the real idea of time -+ * -+ * board_tick_rate: actual ixp4xx ticks/second, read-only -+ * accumulated_error: aggregate error/tick * HZ, read/write -+ * timer_count: best ixp4xx ticks per timer_tick, read-only - */ -- while ((*IXP4XX_OSTS - last_jiffy_time) > LATCH) { -+ rate = board_tick_rate; -+ error = accumulated_error; -+ count = timer_count; -+ do { -+ u32 adjusted_count = count + adjustment(error); -+ if (ixp4xx_timer_delta() < adjusted_count) -+ break; - timer_tick(regs); -- last_jiffy_time += LATCH; -- } -+ last_timer_time += adjusted_count; -+ error += rate - adjusted_count*HZ; -+ } while (1); -+ accumulated_error = error; - - write_sequnlock(&xtime_lock); - -@@ -281,17 +410,30 @@ static struct irqaction ixp4xx_timer_irq - .handler = ixp4xx_timer_interrupt, - }; - -+u32 ixp4xx_get_board_tick_rate(void) { -+ return board_tick_rate; -+} -+ -+EXPORT_SYMBOL(ixp4xx_get_board_tick_rate); -+ -+void ixp4xx_set_board_tick_rate(u32 rate) { -+ ixp4xx_board_tick_rate = rate; -+} -+ -+EXPORT_SYMBOL(ixp4xx_set_board_tick_rate); -+ - static void __init ixp4xx_timer_init(void) - { - /* Clear Pending Interrupt by writing '1' to it */ - *IXP4XX_OSST = IXP4XX_OSST_TIMER_1_PEND; - - /* Setup the Timer counter value */ -- *IXP4XX_OSRT1 = (LATCH & ~IXP4XX_OST_RELOAD_MASK) | IXP4XX_OST_ENABLE; -+ set_board_tick_rate(ixp4xx_board_tick_rate); - - /* Reset time-stamp counter */ - *IXP4XX_OSTS = 0; -- last_jiffy_time = 0; -+ last_timer_time = 0; -+ accumulated_error = 0; - - /* Connect the interrupt handler and enable the interrupt */ - setup_irq(IRQ_IXP4XX_TIMER1, &ixp4xx_timer_irq); -@@ -337,4 +479,3 @@ void __init ixp4xx_sys_init(void) - ARRAY_SIZE(ixp46x_devices)); - } - } -- ---- linux-2.6.15/include/asm-arm/arch-ixp4xx/timex.h 1970-01-01 00:00:00.000000000 +0000 -+++ linux-2.6.15/include/asm-arm/arch-ixp4xx/timex.h 1970-01-01 00:00:00.000000000 +0000 -@@ -6,10 +6,23 @@ - #include <asm/hardware.h> - - /* -- * We use IXP425 General purpose timer for our timer needs, it runs at -- * 66.66... MHz. We do a convulted calculation of CLOCK_TICK_RATE b/c the -- * timer register ignores the bottom 2 bits of the LATCH value. -+ * In linux/timex.h 'LATCH' is defined as CLOCK_TICK_RATE/HZ and -+ * is the number of internal counts per timer interrupt. Thus -+ * CLOCK_TICK_RATE is LATCH*HZ. -+ * -+ * The actual values of these numbers do not matter, because they -+ * are only used to calculate ACTHZ (rate/latch as a 24.8 fixed -+ * point number), so the value here gives a LATCH of 1 and pretty -+ * much guarantees to flush out any off-by-one errors. -+ * -+ * ACTHZ is equal to HZ, because CLOCK_TICK_RATE is a multiple of -+ * HZ, this is checked in the ixp4xx/common.c code. - */ --#define FREQ 66666666 --#define CLOCK_TICK_RATE (((FREQ / HZ & ~IXP4XX_OST_RELOAD_MASK) + 1) * HZ) -+#define CLOCK_TICK_RATE HZ - -+/* The following allow the exact board tick rate to be set and -+ * discovered. The value should be exactly twice the frequency -+ * (in Hz) of the onboard crystal. -+ */ -+extern u32 ixp4xx_get_board_tick_rate(void); -+extern void ixp4xx_set_board_tick_rate(u32 new_rate); |