davinci clock setup: improve diagnostics

Minor tweak to the new DaVinci clock code:  look at the PSC module
to make sure the clock is enabled before reporting that it needs
disabling.  This improves the value of those diagnostics.

Docs report a variety of power-up states for peripherals.  DM355
seems to leave most things clocked (but in reset); else, most
clocks will still be off unless the bootloader enabled them.

Also includes a minor fix to the MDCTL write:  DM355 defines
that field as five bits; other cores define the extra bits as
must-be-zero.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

arch/arm/mach-davinci/clock.c

@@ -163,7 +163,11 @@ static int __init clk_disable_unused(void)
 		if (!(ck->flags & CLK_PSC))
 			continue;
 
-		printk(KERN_INFO "Clocks: disable unused %s\n", ck->name);
+		/* ignore if in Disabled or SwRstDisable states */
+		if (!davinci_psc_is_clk_active(ck->lpsc))
+			continue;
+
+		pr_info("Clocks: disable unused %s\n", ck->name);
 		davinci_psc_config(psc_domain(ck), ck->lpsc, 0);
 	}
 	spin_unlock_irq(&clockfw_lock);

arch/arm/mach-davinci/include/mach/psc.h

@@ -116,6 +116,7 @@
 #define DM646X_LPSC_TIMER1         35
 #define DM646X_LPSC_ARM_INTC       45
 
+extern int davinci_psc_is_clk_active(unsigned int id);
 extern void davinci_psc_config(unsigned int domain, unsigned int id,
 			       char enable);
 

arch/arm/mach-davinci/psc.c

@@ -39,6 +39,17 @@
 #define MDSTAT		0x800
 #define MDCTL		0xA00
 
+
+/* Return nonzero iff the domain's clock is active */
+int __init davinci_psc_is_clk_active(unsigned int id)
+{
+	void __iomem *psc_base = IO_ADDRESS(DAVINCI_PWR_SLEEP_CNTRL_BASE);
+	u32 mdstat = __raw_readl(psc_base + MDSTAT + 4 * id);
+
+	/* if clocked, state can be "Enable" or "SyncReset" */
+	return mdstat & BIT(12);
+}
+
 /* Enable or disable a PSC domain */
 void davinci_psc_config(unsigned int domain, unsigned int id, char enable)
 {
@@ -49,7 +60,7 @@ void davinci_psc_config(unsigned int domain, unsigned int id, char enable)
 	if (enable)
 		mdctl |= 0x00000003;	/* Enable Module */
 	else
-		mdctl &= 0xFFFFFFF2;	/* Disable Module */
+		mdctl &= 0xFFFFFFE2;	/* Disable Module */
 	__raw_writel(mdctl, psc_base + MDCTL + 4 * id);
 
 	pdstat = __raw_readl(psc_base + PDSTAT);