[PATCH 3/3] ARM: OMAP: hwmod: Look for hwmod/module level context lost count if supported

[Paul Walmsley]

Hi Rajendra,

I've combined your patches down to one patch and changed the logic a 
little bit.  It looks to me that the update and clear context registers 
can be done in one step, since an IP block shouldn't lose context when 
it's enabled.  But maybe I'm missing something?  

Anyway, I'd appreciate any comments you might have, and if you have an 
environment where you can test this patch, that would also be very 
welcome.


- Paul

From: Rajendra Nayak <rnayak at ti.com>
Date: Fri, 16 Dec 2011 04:12:48 -0700
Subject: [PATCH] ARM: OMAP: hwmod: Add support for per hwmod/module context
 lost count

OMAP4 has module specific context lost registers which makes it now
possible to have module level context loss count, instead of relying
on the powerdomain level context count.

Add 2 private hwmod api's to update/clear the hwmod/module specific
context lost counters/register.

Update the module specific context_lost_counter and clear the hardware
bits just after enabling the module.

omap_hwmod_get_context_loss_count() now returns the hwmod context loss
count them on platforms where they exist (OMAP4), else fall back on
the pwrdm level counters for older platforms.

Signed-off-by: Rajendra Nayak <rnayak at ti.com>
[paul at pwsan.com: added function kerneldoc, fixed structure kerneldoc,
 rearranged structure to avoid memory waste, marked fns as OMAP4-specific,
 prevent fn entry on non-OMAP4 chips, reduced indentation, merged update
 and clear, merged patches]
Signed-off-by: Paul Walmsley <paul at pwsan.com>
---
 arch/arm/mach-omap2/omap_hwmod.c             |   54 ++++++++++++++++++++++++--
 arch/arm/plat-omap/include/plat/omap_hwmod.h |    8 +++-
 2 files changed, 56 insertions(+), 6 deletions(-)

diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
index 0a89335..5702462 100644
--- a/arch/arm/mach-omap2/omap_hwmod.c
+++ b/arch/arm/mach-omap2/omap_hwmod.c
@@ -1435,6 +1435,42 @@ static int _reset(struct omap_hwmod *oh)
 }
 
 /**
+ * _omap4_update_context_lost - increment hwmod context loss counter if
+ * hwmod context was lost, and clear hardware context loss reg
+ * @oh: hwmod to check for context loss
+ *
+ * If the PRCM indicates that the hwmod @oh lost context, increment
+ * our in-memory context loss counter, and clear the RM_*_CONTEXT
+ * bits.  XXX Will not work correctly if the RM_*_CONTEXT register
+ * offset is 0 -- probably a flag should be used to avoid this
+ * situation, rather than testing @oh->prcm.omap4.context_offs.  No
+ * return value.
+ */
+static void _omap4_update_context_lost(struct omap_hwmod *oh)
+{
+	u32 r;
+
+	if (!cpu_is_omap44xx())
+		return;
+
+	if (!oh->prcm.omap4.context_offs)
+		return;
+
+	r = omap4_prminst_read_inst_reg(oh->clkdm->pwrdm.ptr->prcm_partition,
+					oh->clkdm->pwrdm.ptr->prcm_offs,
+					oh->prcm.omap4.context_offs);
+
+	if (!r)
+		return;
+
+	oh->prcm.omap4.context_lost_counter++;
+
+	omap4_prminst_write_inst_reg(r, oh->clkdm->pwrdm.ptr->prcm_partition,
+				     oh->clkdm->pwrdm.ptr->prcm_offs,
+				     oh->prcm.omap4.context_offs);
+}
+
+/**
  * _enable - enable an omap_hwmod
  * @oh: struct omap_hwmod *
  *
@@ -1512,6 +1548,8 @@ static int _enable(struct omap_hwmod *oh)
 	_enable_clocks(oh);
 	_enable_module(oh);
 
+	_omap4_update_context_lost(oh);
+
 	r = _wait_target_ready(oh);
 	if (!r) {
 		/*
@@ -2640,17 +2678,25 @@ ohsps_unlock:
  * omap_hwmod_get_context_loss_count - get lost context count
  * @oh: struct omap_hwmod *
  *
- * Query the powerdomain of of @oh to get the context loss
- * count for this device.
+ * Returns the context loss count of associated with @oh
+ * upon success, or zero if no context loss data is available.
  *
- * Returns the context loss count of the powerdomain assocated with @oh
- * upon success, or zero if no powerdomain exists for @oh.
+ * On OMAP4, this queries the per-hwmod context loss register,
+ * assuming one exists.  If not, or on OMAP2/3, this queries the
+ * enclosing powerdomain context loss count.
  */
 int omap_hwmod_get_context_loss_count(struct omap_hwmod *oh)
 {
 	struct powerdomain *pwrdm;
 	int ret = 0;
 
+	/*
+	 * XXX This should use a flag to determine whether to check
+	 * context_offs, as context_offs == 0 is potentially valid
+	 */
+	if (cpu_is_omap44xx() && oh->prcm.omap4.context_offs)
+		return oh->prcm.omap4.context_lost_counter;
+
 	pwrdm = omap_hwmod_get_pwrdm(oh);
 	if (pwrdm)
 		ret = pwrdm_get_context_loss_count(pwrdm);
diff --git a/arch/arm/plat-omap/include/plat/omap_hwmod.h b/arch/arm/plat-omap/include/plat/omap_hwmod.h
index 1a13c02..3aea95e 100644
--- a/arch/arm/plat-omap/include/plat/omap_hwmod.h
+++ b/arch/arm/plat-omap/include/plat/omap_hwmod.h
@@ -361,9 +361,12 @@ struct omap_hwmod_omap2_prcm {
 
 /**
  * struct omap_hwmod_omap4_prcm - OMAP4-specific PRCM data
- * @clkctrl_reg: PRCM address of the clock control register
- * @rstctrl_reg: address of the XXX_RSTCTRL register located in the PRM
+ * @clkctrl_offs: offset of the PRCM clock control register
+ * @rstctrl_offs: offset of the XXX_RSTCTRL register located in the PRM
+ * @context_offs: offset of the RM_*_CONTEXT register
  * @submodule_wkdep_bit: bit shift of the WKDEP range
+ * @modulemode: allowable modulemodes
+ * @context_lost_counter: Count of module level context lost
  */
 struct omap_hwmod_omap4_prcm {
 	u16		clkctrl_offs;
@@ -371,6 +374,7 @@ struct omap_hwmod_omap4_prcm {
 	u16		context_offs;
 	u8		submodule_wkdep_bit;
 	u8		modulemode;
+	unsigned	context_lost_counter;
 };
 
 
-- 
1.7.7.3