Hi Vaibhav,

On 3/30/2012 8:54, Vaibhav Hiremath wrote:

Current OMAP code supports couple of clocksource options based
on compilation flag (CONFIG_OMAP_32K_TIMER). The 32KHz sync-timer
and a gptimer which can run on 32KHz or system clock (e.g 38.4 MHz).
So there can be 3 options -

1. 32KHz sync-timer
2. Sys_clock based (e.g 13/19.2/26/38.4 MHz) gptimer
3. 32KHz based gptimer.

The optional gptimer based clocksource was added so that it can
give the high precision than sync-timer, so expected usage was 2
and not 3.
Unfortunately option 2, clocksource doesn't meet the requirement of
free-running clock as per clocksource need. It stops in low power states
when sys_clock is cut. That makes gptimer based clocksource option
useless for OMAP2/3/4 devices with sys_clock as a clock input.
Option 3 will still work but it is no better than 32K sync-timer
based clocksource.

So ideally we can kill the gptimer based clocksource option but there
are some OMAP based derivative SoCs like AM33XX which doesn't have
32K sync-timer hardware IP and need to fallback on 32KHz based gptimer
clocksource.
Considering above, make sync-timer and gptimer clocksource runtime
selectable so that both OMAP and AMXXXX continue to use the same code.

Use hwmod database lookup mechanism, through which at run-time
we can identify availability of 32k-sync timer on the device,
else fall back to gptimer.

Signed-off-by: Vaibhav Hiremath <redacted>
Signed-off-by: Felipe Balbi <redacted>
CC: Santosh Shilimkar <redacted>
Cc: Benoit Cousson <redacted>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tarun Kanti DebBarma <redacted>
Cc: Ming Lei <tom.leiming@gmail.com>
---
 arch/arm/mach-omap1/timer32k.c           |    6 ++-
 arch/arm/mach-omap2/timer.c              |   45 +++++++++-------
 arch/arm/plat-omap/counter_32k.c         |   86 ++++++++++++-----------------
 arch/arm/plat-omap/include/plat/common.h |    2 +-
 4 files changed, 68 insertions(+), 71 deletions(-)

[...]

If omap_init_clocksource_32k() fails should we also call BUG_ON here?

-

-		timer_32k_base = base;
-
-		/*
-		 * 120000 rough estimate from the calculations in
-		 * __clocksource_updatefreq_scale.
-		 */
-		clocks_calc_mult_shift(&persistent_mult, &persistent_shift,
-				32768, NSEC_PER_SEC, 120000);
-
-		if (clocksource_mmio_init(base, "32k_counter", 32768, 250, 32,
-					  clocksource_mmio_readl_up))
-			printk(err, "32k_counter");
-
-		setup_sched_clock(omap_32k_read_sched_clock, 32, 32768);
-	}
+	void __iomem *base;
+	struct clk *sync_32k_ick;
+
+	if (!pbase || !size)
+		return -ENODEV;
+	/*
+	 * For this to work we must have a static mapping in io.c
+	 * for this area
+	 */
+	base = ioremap(pbase, size);
+	if (!base)
+		return -ENODEV;
+
+	sync_32k_ick = clk_get(NULL, "omap_32ksync_ick");
+	if (!IS_ERR(sync_32k_ick))
+		clk_enable(sync_32k_ick);

I know that this is carry over from the original code, but seems that if
clk_get fails we should return an error. So maybe ...


	sync_32k_ick = clk_get(NULL, "omap_32ksync_ick");
	if (IS_ERR(sync_32k_ick))
		return -ENODEV;

	clk_enable(sync_32k_ick);

+
+	timer_32k_base = base;
+
+	/*
+	 * 120000 rough estimate from the calculations in
+	 * __clocksource_updatefreq_scale.
+	 */
+	clocks_calc_mult_shift(&persistent_mult, &persistent_shift,
+			32768, NSEC_PER_SEC, 120000);
+
+	if (clocksource_mmio_init(base, "32k_counter", 32768, 250, 32,
+				clocksource_mmio_readl_up))
+		pr_err("32k_counter: can't register clocksource!\n");
+

Extra line added here that should be removed.

Cheers
Jon