omap2 clock: return -EINVAL if no clock enable code; fix dpll_ck enable

If the clock framework can't figure out how to enable a clock, return
-EINVAL to indicate that the clock cannot be enabled.  Previously the
code returned 0, which indicated success.

Also fix the "clock.c: Enable for dpll_ck without enable code" boot
warning by marking dpll_ck as ALWAYS_ENABLED.  This is not technically
true, since the DPLL can be bypassed; but since we currently have no
software infrastructure to control it directly, ALWAYS_ENABLED is a
sufficient fiction for dpll_ck.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap2/clock.c

@@ -218,7 +218,7 @@ static int _omap2_clk_enable(struct clk * clk)
 	if (unlikely(clk->enable_reg == 0)) {
 		printk(KERN_ERR "clock.c: Enable for %s without enable code\n",
 		       clk->name);
-		return 0;
+		return -EINVAL;
 	}
 
 	if (clk->enable_reg == OMAP_CM_REGADDR(PLL_MOD, CM_CLKEN)) {
@@ -259,8 +259,15 @@ static void _omap2_clk_disable(struct clk *clk)
 		return;
 	}
 
-	if (clk->enable_reg == 0)
+	if (clk->enable_reg == 0) {
+		/*
+		 * 'Independent' here refers to a clock which is not
+		 * controlled by its parent.
+		 */
+		printk(KERN_ERR "clock: clk_disable called on independent "
+		       "clock %s which has no enable_reg\n", clk->name);
 		return;
+	}
 
 	if (clk->enable_reg == OMAP_CM_REGADDR(PLL_MOD, CM_CLKEN)) {
 		omap2_clk_fixed_disable(clk);

arch/arm/mach-omap2/clock.h

@@ -630,7 +630,8 @@ static struct clk dpll_ck = {
 	.name		= "dpll_ck",
 	.parent		= &sys_ck,		/* Can be func_32k also */
 	.flags		= CLOCK_IN_OMAP242X | CLOCK_IN_OMAP243X |
-				RATE_PROPAGATES | RATE_CKCTL | CM_PLL_SEL1,
+				RATE_PROPAGATES | RATE_CKCTL | CM_PLL_SEL1 |
+				ALWAYS_ENABLED,
 	.recalc		= &omap2_clksel_recalc,
 };