ARM: OMAP4: clock: add support for determine_rate for omap4 regm4xen DPLL

Similarly to OMAP3 noncore DPLL, the implementation of this DPLL clock
type is wrong. This patch adds basic functionality for determine_rate
for this clock type which will be taken into use in the patches following
later.
Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>

arch/arm/mach-omap2/dpll44xx.c

@@ -207,3 +207,44 @@ long omap4_dpll_regm4xen_round_rate(struct clk_hw *hw,
 
 	return dd->last_rounded_rate;
 }
+
+/**
+ * omap4_dpll_regm4xen_determine_rate - determine rate for a DPLL
+ * @hw: pointer to the clock to determine rate for
+ * @rate: target rate for the DPLL
+ * @best_parent_rate: pointer for returning best parent rate
+ * @best_parent_clk: pointer for returning best parent clock
+ *
+ * Determines which DPLL mode to use for reaching a desired rate.
+ * Checks whether the DPLL shall be in bypass or locked mode, and if
+ * locked, calculates the M,N values for the DPLL via round-rate.
+ * Returns a positive clock rate with success, negative error value
+ * in failure.
+ */
+long omap4_dpll_regm4xen_determine_rate(struct clk_hw *hw, unsigned long rate,
+					unsigned long *best_parent_rate,
+					struct clk **best_parent_clk)
+{
+	struct clk_hw_omap *clk = to_clk_hw_omap(hw);
+	struct dpll_data *dd;
+
+	if (!hw || !rate)
+		return -EINVAL;
+
+	dd = clk->dpll_data;
+	if (!dd)
+		return -EINVAL;
+
+	if (__clk_get_rate(dd->clk_bypass) == rate &&
+	    (dd->modes & (1 << DPLL_LOW_POWER_BYPASS))) {
+		*best_parent_clk = dd->clk_bypass;
+	} else {
+		rate = omap4_dpll_regm4xen_round_rate(hw, rate,
+						      best_parent_rate);
+		*best_parent_clk = dd->clk_ref;
+	}
+
+	*best_parent_rate = rate;
+
+	return rate;
+}

include/linux/clk/ti.h

@@ -270,6 +270,10 @@ unsigned long omap4_dpll_regm4xen_recalc(struct clk_hw *hw,
 long omap4_dpll_regm4xen_round_rate(struct clk_hw *hw,
 				    unsigned long target_rate,
 				    unsigned long *parent_rate);
+long omap4_dpll_regm4xen_determine_rate(struct clk_hw *hw,
+					unsigned long rate,
+					unsigned long *best_parent_rate,
+					struct clk **best_parent_clk);
 u8 omap2_init_dpll_parent(struct clk_hw *hw);
 unsigned long omap3_dpll_recalc(struct clk_hw *hw, unsigned long parent_rate);
 long omap2_dpll_round_rate(struct clk_hw *hw, unsigned long target_rate,