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authorAtsushi Nemoto <anemo@mba.ocn.ne.jp>2006-10-23 15:21:27 (GMT)
committerRalf Baechle <ralf@linux-mips.org>2006-10-31 20:13:23 (GMT)
commit16b7b2ac0148e839da86af8747b6fa4aad43a9b7 (patch)
tree93912ae2e9c64f71a8cca028677fd918b9edf0fa /Documentation/mips
parent70e46f48cb5933119712ee27945309a4bfc98282 (diff)
[MIPS] Fixup migration to GENERIC_TIME
Since we already moved to GENERIC_TIME, we should implement alternatives of old do_gettimeoffset routines to get sub-jiffies resolution from gettimeofday(). This patch includes: * MIPS clocksource support (based on works by Manish Lachwani). * remove unused gettimeoffset routines and related codes. * remove unised 64bit do_div64_32(). * simplify mips_hpt_init. (no argument needed, __init tag) * simplify c0_hpt_timer_init. (no need to write to c0_count) * remove some hpt_init routines. * mips_hpt_mask variable to specify bitmask of hpt value. * convert jmr3927_do_gettimeoffset to jmr3927_hpt_read. * convert ip27_do_gettimeoffset to ip27_hpt_read. * convert bcm1480_do_gettimeoffset to bcm1480_hpt_read. * simplify sb1250 hpt functions. (no need to subtract and shift) Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'Documentation/mips')
-rw-r--r--Documentation/mips/time.README39
1 files changed, 8 insertions, 31 deletions
diff --git a/Documentation/mips/time.README b/Documentation/mips/time.README
index e1304b6..a4ce603 100644
--- a/Documentation/mips/time.README
+++ b/Documentation/mips/time.README
@@ -38,19 +38,14 @@ The new time code provide the following services:
a) Implements functions required by Linux common code:
time_init
- do_gettimeofday
- do_settimeofday
b) provides an abstraction of RTC and null RTC implementation as default.
extern unsigned long (*rtc_get_time)(void);
extern int (*rtc_set_time)(unsigned long);
- c) a set of gettimeoffset functions for different CPUs and different
- needs.
-
- d) high-level and low-level timer interrupt routines where the timer
- interrupt source may or may not be the CPU timer. The high-level
- routine is dispatched through do_IRQ() while the low-level is
+ c) high-level and low-level timer interrupt routines where the timer
+ interrupt source may or may not be the CPU timer. The high-level
+ routine is dispatched through do_IRQ() while the low-level is
dispatched in assemably code (usually int-handler.S)
@@ -73,8 +68,7 @@ the following functions or values:
c) (optional) board-specific RTC routines.
d) (optional) mips_hpt_frequency - It must be definied if the board
- is using CPU counter for timer interrupt or it is using fixed rate
- gettimeoffset().
+ is using CPU counter for timer interrupt.
PORTING GUIDE
@@ -89,16 +83,6 @@ Step 1: decide how you like to implement the time services.
If the answer is no, you need a timer to provide the timer interrupt
at 100 HZ speed.
- You cannot use the fast gettimeoffset functions, i.e.,
-
- unsigned long fixed_rate_gettimeoffset(void);
- unsigned long calibrate_div32_gettimeoffset(void);
- unsigned long calibrate_div64_gettimeoffset(void);
-
- You can use null_gettimeoffset() will gives the same time resolution as
- jiffy. Or you can implement your own gettimeoffset (probably based on
- some ad hoc hardware on your machine.)
-
c) The following sub steps assume your CPU has counter register.
Do you plan to use the CPU counter register as the timer interrupt
or use an exnternal timer?
@@ -123,8 +107,8 @@ Step 3: implement rtc routines, board_time_init() and plat_timer_setup()
board_time_init() -
a) (optional) set up RTC routines,
b) (optional) calibrate and set the mips_hpt_frequency
- (only needed if you intended to use fixed_rate_gettimeoffset
- or use cpu counter as timer interrupt source)
+ (only needed if you intended to use cpu counter as timer interrupt
+ source)
plat_timer_setup() -
a) (optional) over-write any choices made above by time_init().
@@ -154,8 +138,8 @@ for some of the functions in time.c.
For example, you may define your own timer interrupt routine, which does
some of its own processing and then calls timer_interrupt().
-You can also over-ride any of the built-in functions (gettimeoffset,
-RTC routines and/or timer interrupt routine).
+You can also over-ride any of the built-in functions (RTC routines
+and/or timer interrupt routine).
PORTING NOTES FOR SMP
@@ -187,10 +171,3 @@ You need to decide on your timer interrupt sources.
You can also do the low-level version of those interrupt routines,
following similar dispatching routes described above.
-
-Note about do_gettimeoffset():
-
- It is very likely the CPU counter registers are not sync'ed up in a SMP box.
- Therefore you cannot really use the many of the existing routines that
- are based on CPU counter. You should wirte your own gettimeoffset rouinte
- if you want intra-jiffy resolution.

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