Use the 24-bit Time-Of-Day clock in CIA B, which is clocked by HSYNC.
Signed-off-by: Geert Uytterhoeven <[email protected]>
---
1. Completely untested! It does compile ;-)
2. Is a 24-bit counter running at 15-31 kHz good enough?
Two cascaded 16-bit CIA timers running from the 700 kHz E-clock would
be better, but as jiffies use CIA B Timer A and the floppy driver uses
CIA A Timer B, we don't have two available timers in the same CIA
without some code shuffling.
3. What are the semantics of get_cycles()?
Does it have to be a "nice" counter, or can there be some
irregularities?
I.e. can I add one more line
x = (x << 8) | ciab.talo; // low byte of 700 kHz timer
to get 32 bits?
arch/m68k/amiga/config.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/arch/m68k/amiga/config.c b/arch/m68k/amiga/config.c
index acd9c16..914e056 100644
--- a/arch/m68k/amiga/config.c
+++ b/arch/m68k/amiga/config.c
@@ -358,6 +358,20 @@ static void __init amiga_identify(void)
#undef AMIGAHW_ANNOUNCE
}
+
+static cycles_t amiga_get_cycles(void)
+{
+ cycles_t x;
+
+ /* CIA B 24-bit TOD is clocked by HSYNC */
+ x = ciab.todhi;
+ x = (x << 8) | ciab.todmid;
+ x = (x << 8) | ciab.todlo;
+
+ return x;
+}
+
+
/*
* Setup the Amiga configuration info
*/
@@ -395,6 +409,8 @@ void __init config_amiga(void)
mach_heartbeat = amiga_heartbeat;
#endif
+ mach_get_cycles = amiga_get_cycles;
+
/* Fill in the clock value (based on the 700 kHz E-Clock) */
amiga_colorclock = 5*amiga_eclock; /* 3.5 MHz */
--
1.7.9.5
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