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Date: Mon, 9 Sep 2013 21:26:14 +0200 From: Geert Uytterhoeven <geert@...ux-m68k.org> To: linux-m68k@...ts.linux-m68k.org Cc: Thorsten Glaser <tg@...bsd.de>, Theodore Ts'o <tytso@....edu>, linux-kernel@...r.kernel.org, Geert Uytterhoeven <geert@...ux-m68k.org> Subject: [PATCH/RFC 2/2] m68k/amiga: Provide mach_get_cycles() Use the 24-bit Time-Of-Day clock in CIA B, which is clocked by HSYNC. Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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