[2/5] omap: Implement common omap_has_feature

Commit Message

Tony Lindgren July 8, 2010, 9:37 a.m. UTC

None

Comments

Tony Lindgren July 9, 2010, 7:08 a.m. UTC | #1

* Nishanth Menon <[e-mail]> [100708 17:46]:
> Tony Lindgren had written, on 07/08/2010 04:37 AM, the following:
> >
> >@@ -112,6 +114,12 @@ void omap_get_die_id(struct omap_die_id *odi)
> > 	odi->id_3 = read_tap_reg(OMAP_TAP_DIE_ID_3);
> > }
> >+u32 omap2_has_feature(u32 feat_mask)
> >+{
> >+	/* REVISIT: Add necessary omap2 feature tests here */
> >+	return ((feat_mask & omap_features) == feat_mask);
> >+}
> >+
>
> I did consider this path initially,
> a) Additional functional call overhead here. some of the calls to
> has_feature() will get called through pretty active paths, we would
> like it to be minimized to compile time optimized inline function as
> much as possible.(no reason why this cant me a inline macro in
> cpu.h?) -

Well it should not matter how slow this code is, it should only be
used to initialize things during __init.

Any code doing detection after initialization is wrong.

Regards,

Tony
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Nishanth Menon July 9, 2010, 4:53 p.m. UTC | #2

Tony Lindgren had written, on 07/09/2010 02:08 AM, the following:
> * Nishanth Menon <[e-mail]> [100708 17:46]:
>> Tony Lindgren had written, on 07/08/2010 04:37 AM, the following:
>>> @@ -112,6 +114,12 @@ void omap_get_die_id(struct omap_die_id *odi)
>>> 	odi->id_3 = read_tap_reg(OMAP_TAP_DIE_ID_3);
>>> }
>>> +u32 omap2_has_feature(u32 feat_mask)
>>> +{
>>> +	/* REVISIT: Add necessary omap2 feature tests here */
>>> +	return ((feat_mask & omap_features) == feat_mask);
>>> +}
>>> +
>> I did consider this path initially,
>> a) Additional functional call overhead here. some of the calls to
>> has_feature() will get called through pretty active paths, we would
>> like it to be minimized to compile time optimized inline function as
>> much as possible.(no reason why this cant me a inline macro in
>> cpu.h?) -
> 
> Well it should not matter how slow this code is, it should only be
> used to initialize things during __init.
> 
> Any code doing detection after initialization is wrong.
couple of reasons why this may not make sense:
a) drivers can be modules -e.g. lets say dss driver would like to know 
if vrfb OR tiler is used -> __init wont make sense
b) has_feature could be used as part of data flow to make decision what 
is to be done.

e.g.

lets say dma chaining as a feature OR dma list as a feature, we should 
allow for usage such as the following:
int chain_dma(...)
{
	if (!omap_has_feature(OMAP_HAS_DMA_CHAINING)) {
		return -EINVAL;
	}
}

this means that we would prefer these kind of path to be high 
performance paths (data paths) - aka inline functions make more sense 
than incurring a function call overhead.

Patch

diff --git a/arch/arm/mach-omap2/id.c b/arch/arm/mach-omap2/id.c
index fd1904b..a2e5965 100644
--- a/arch/arm/mach-omap2/id.c
+++ b/arch/arm/mach-omap2/id.c
@@ -29,7 +29,9 @@ 
 
 static struct omap_chip_id omap_chip;
 static unsigned int omap_revision;
+static u32 omap_features;
 
+/* REVISIT: Get rid of omap3_features */
 u32 omap3_features;
 
 unsigned int omap_rev(void)
@@ -112,6 +114,12 @@  void omap_get_die_id(struct omap_die_id *odi)
 	odi->id_3 = read_tap_reg(OMAP_TAP_DIE_ID_3);
 }
 
+u32 omap2_has_feature(u32 feat_mask)
+{
+	/* REVISIT: Add necessary omap2 feature tests here */
+	return ((feat_mask & omap_features) == feat_mask);
+}
+
 static void __init omap24xx_check_revision(void)
 {
 	int i, j;
@@ -164,6 +172,15 @@  static void __init omap24xx_check_revision(void)
 	if ((omap_rev() >> 8) & 0x0f)
 		pr_info("ES%x", (omap_rev() >> 12) & 0xf);
 	pr_info("\n");
+
+	omap_features = 0;
+	omap_init_features(omap2_has_feature);
+}
+
+u32 omap3_has_feature(u32 feat_mask)
+{
+	/* REVISIT: Add necessary omap3 feature tests here */
+	return ((feat_mask & omap_features) == feat_mask);
 }
 
 #define OMAP3_CHECK_FEATURE(status,feat)				\
@@ -194,6 +211,11 @@  static void __init omap3_check_features(void)
 	 * TODO: Get additional info (where applicable)
 	 *       e.g. Size of L2 cache.
 	 */
+
+	/* REVISIT: Get rid of omap3_features */
+	omap_features = omap3_features;
+
+	omap_init_features(omap3_has_feature);
 }
 
 static void __init omap3_check_revision(void)
@@ -277,6 +299,12 @@  static void __init omap3_check_revision(void)
 	}
 }
 
+u32 omap4_has_feature(u32 feat_mask)
+{
+	/* REVISIT: Add necessary omap4 feature tests here */
+	return ((feat_mask & omap_features) == feat_mask);
+}
+
 static void __init omap4_check_revision(void)
 {
 	u32 idcode;
@@ -297,6 +325,10 @@  static void __init omap4_check_revision(void)
 		omap_revision = OMAP4430_REV_ES1_0;
 		omap_chip.oc |= CHIP_IS_OMAP4430ES1;
 		pr_info("OMAP%04x %s\n", omap_rev() >> 16, rev_name);
+
+		omap_features = 0;
+		omap_init_features(omap4_has_feature);
+
 		return;
 	}
 
diff --git a/arch/arm/plat-omap/common.c b/arch/arm/plat-omap/common.c
index 893a53a..d00b242 100644
--- a/arch/arm/plat-omap/common.c
+++ b/arch/arm/plat-omap/common.c
@@ -89,6 +89,21 @@  void __init omap_reserve(void)
 	omap_vram_reserve_sdram_lmb();
 }
 
+static int (*_omap_check_feature)(u32 feat_mask);
+
+u32 omap_has_feature(u32 feat_mask)
+{
+	if (!_omap_check_feature)
+		return 0;
+
+	return _omap_check_feature(feat_mask);
+}
+
+void __init omap_init_features(u32 (*check_feature)(u32 feat))
+{
+	_omap_check_feature = check_feature;
+}
+
 /*
  * 32KHz clocksource ... always available, on pretty most chips except
  * OMAP 730 and 1510.  Other timers could be used as clocksources, with
diff --git a/arch/arm/plat-omap/include/plat/cpu.h b/arch/arm/plat-omap/include/plat/cpu.h
index aa2f4f0..127df06 100644
--- a/arch/arm/plat-omap/include/plat/cpu.h
+++ b/arch/arm/plat-omap/include/plat/cpu.h
@@ -49,6 +49,9 @@  struct omap_chip_id {
 	u8 type;
 };
 
+u32 omap_has_feature(u32 feat_mask);
+void omap_init_features(u32 (*check_feature)(u32 feat));
+
 #define OMAP_CHIP_INIT(x)	{ .oc = x }
 
 /*