[PATCH v4 1/7] OMAP2+: clockdomain: Add an api to read idle mode

[Paul Walmsley]

Hi

On Fri, 1 Jul 2011, Benoit Cousson wrote:

> From: Rajendra Nayak <rnayak at ti.com>
> 
> Add a clockdomain api to check if hardware supervised
> idle transitions are enabled on a clockdomain.
> 
> Thanks to Todd Poynor <toddpoynor at google.com> for a
> better function name suggestion.
> 
> Signed-off-by: Rajendra Nayak <rnayak at ti.com>
> Cc: Paul Walmsley <paul at pwsan.com>
> Cc: Todd Poynor <toddpoynor at google.com>

I've been looking at this patch and the subsequent one.  Two thoughts 
occurred to me.

The first is that clkdm_allows_idle() shouldn't need to touch the CM 
hardware at all, since all clockdomain auto-idle mode changes should go 
through the clockdomain code.  So we can just keep an in-memory flag in 
the struct clockdomain and avoid the slow CM register access.

The second is that the name 'clkdm_allows_idle', while a better name 
than the original, still doesn't seem right.  Naïvely, I'd expect a 
function with that name to reveal whether the clockdomain supports 
auto-idle mode, not to test its current state.  So this function has been 
renamed to 'clkdm_in_hwsup'.  This name seems slightly uglier, but more 
accurate.

Updated patch below, queued for 3.1 at git://git.pwsan.com/linux-2.6 in 
the 'clockdomain_a_3.1' branch.


- Paul

From: Paul Walmsley <paul at pwsan.com>
Date: Thu, 7 Jul 2011 22:55:08 -0600
Subject: [PATCH] OMAP2+: clockdomain: add clkdm_in_hwsup()

Add a new function, clkdm_in_hwsup(), that returns true if a clockdomain
is configured for hardware-supervised idle.  It does not actually read the
hardware; rather, it checks an internal flag in the struct clockdomain, which
is changed when the clockdomain is switched in and out of hardware-supervised
idle.  This should be safe, since all changes to the idle mode should
pass through the clockdomain code.

Based on a set of patches by Rajendra Nayak <rnayak at ti.com> which do
the same thing by checking the hardware bits.  This approach should be
faster and more compact.

Signed-off-by: Paul Walmsley <paul at pwsan.com>
Cc: Rajendra Nayak <rnayak at ti.com>
Cc: Todd Poynor <toddpoynor at google.com>
Cc: Benoît Cousson <b-cousson at ti.com>
---
 arch/arm/mach-omap2/clockdomain.c |   30 ++++++++++++++++++++++++++++--
 arch/arm/mach-omap2/clockdomain.h |    6 ++++++
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mach-omap2/clockdomain.c b/arch/arm/mach-omap2/clockdomain.c
index 5a57de5..239b558 100644
--- a/arch/arm/mach-omap2/clockdomain.c
+++ b/arch/arm/mach-omap2/clockdomain.c
@@ -1,8 +1,8 @@
 /*
  * OMAP2/3/4 clockdomain framework functions
  *
- * Copyright (C) 2008-2010 Texas Instruments, Inc.
- * Copyright (C) 2008-2010 Nokia Corporation
+ * Copyright (C) 2008-2011 Texas Instruments, Inc.
+ * Copyright (C) 2008-2011 Nokia Corporation
  *
  * Written by Paul Walmsley and Jouni Högander
  * Added OMAP4 specific support by Abhijit Pagare <abhijitpagare at ti.com>
@@ -704,6 +704,8 @@ int clkdm_sleep(struct clockdomain *clkdm)
 
 	pr_debug("clockdomain: forcing sleep on %s\n", clkdm->name);
 
+	clkdm->_flags &= ~_CLKDM_FLAG_HWSUP_ENABLED;
+
 	return arch_clkdm->clkdm_sleep(clkdm);
 }
 
@@ -732,6 +734,8 @@ int clkdm_wakeup(struct clockdomain *clkdm)
 
 	pr_debug("clockdomain: forcing wakeup on %s\n", clkdm->name);
 
+	clkdm->_flags &= ~_CLKDM_FLAG_HWSUP_ENABLED;
+
 	return arch_clkdm->clkdm_wakeup(clkdm);
 }
 
@@ -762,6 +766,8 @@ void clkdm_allow_idle(struct clockdomain *clkdm)
 	pr_debug("clockdomain: enabling automatic idle transitions for %s\n",
 		 clkdm->name);
 
+	clkdm->_flags |= _CLKDM_FLAG_HWSUP_ENABLED;
+
 	arch_clkdm->clkdm_allow_idle(clkdm);
 	pwrdm_clkdm_state_switch(clkdm);
 }
@@ -792,9 +798,29 @@ void clkdm_deny_idle(struct clockdomain *clkdm)
 	pr_debug("clockdomain: disabling automatic idle transitions for %s\n",
 		 clkdm->name);
 
+	clkdm->_flags &= ~_CLKDM_FLAG_HWSUP_ENABLED;
+
 	arch_clkdm->clkdm_deny_idle(clkdm);
 }
 
+/**
+ * clkdm_in_hwsup - is clockdomain @clkdm have hardware-supervised idle enabled?
+ * @clkdm: struct clockdomain *
+ *
+ * Returns true if clockdomain @clkdm currently has
+ * hardware-supervised idle enabled, or false if it does not or if
+ * @clkdm is NULL.  It is only valid to call this function after
+ * clkdm_init() has been called.  This function does not actually read
+ * bits from the hardware; it instead tests an in-memory flag that is
+ * changed whenever the clockdomain code changes the auto-idle mode.
+ */
+bool clkdm_in_hwsup(struct clockdomain *clkdm)
+{
+	if (!clkdm)
+		return false;
+
+	return (clkdm->_flags & _CLKDM_FLAG_HWSUP_ENABLED) ? true : false;
+}
 
 /* Clockdomain-to-clock/hwmod framework interface code */
 
diff --git a/arch/arm/mach-omap2/clockdomain.h b/arch/arm/mach-omap2/clockdomain.h
index 8e0da64..8782a5c 100644
--- a/arch/arm/mach-omap2/clockdomain.h
+++ b/arch/arm/mach-omap2/clockdomain.h
@@ -83,6 +83,9 @@ struct clkdm_dep {
 	const struct omap_chip_id omap_chip;
 };
 
+/* Possible flags for struct clockdomain._flags */
+#define _CLKDM_FLAG_HWSUP_ENABLED		BIT(0)
+
 /**
  * struct clockdomain - OMAP clockdomain
  * @name: clockdomain name
@@ -90,6 +93,7 @@ struct clkdm_dep {
  * @clktrctrl_reg: CLKSTCTRL reg for the given clock domain
  * @clktrctrl_mask: CLKTRCTRL/AUTOSTATE field mask in CM_CLKSTCTRL reg
  * @flags: Clockdomain capability flags
+ * @_flags: Flags for use only by internal clockdomain code
  * @dep_bit: Bit shift of this clockdomain's PM_WKDEP/CM_SLEEPDEP bit
  * @prcm_partition: (OMAP4 only) PRCM partition ID for this clkdm's registers
  * @cm_inst: (OMAP4 only) CM instance register offset
@@ -114,6 +118,7 @@ struct clockdomain {
 	} pwrdm;
 	const u16 clktrctrl_mask;
 	const u8 flags;
+	u8 _flags;
 	const u8 dep_bit;
 	const u8 prcm_partition;
 	const s16 cm_inst;
@@ -178,6 +183,7 @@ int clkdm_clear_all_sleepdeps(struct clockdomain *clkdm);
 
 void clkdm_allow_idle(struct clockdomain *clkdm);
 void clkdm_deny_idle(struct clockdomain *clkdm);
+bool clkdm_in_hwsup(struct clockdomain *clkdm);
 
 int clkdm_wakeup(struct clockdomain *clkdm);
 int clkdm_sleep(struct clockdomain *clkdm);
-- 
1.7.5.4