clk: renesas: rcar-gen3: Add support for RCKSEL clock selection

Add a clock type and macro for defining clocks where the parent and
divider are selected based on the value of the RCKCR.CKSEL bit.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>

drivers/clk/renesas/rcar-gen3-cpg.c

 /*
  * R-Car Gen3 Clock Pulse Generator
  *
- * Copyright (C) 2015-2016 Glider bvba
+ * Copyright (C) 2015-2018 Glider bvba
  *
  * Based on clk-rcar-gen3.c
  *
@@ -31,6 +31,8 @@
 #define CPG_PLL2CR		0x002c
 #define CPG_PLL4CR		0x01f4
 
+#define CPG_RCKCR_CKSEL	BIT(15)	/* RCLK Clock Source Select */
+
 struct cpg_simple_notifier {
 	struct notifier_block nb;
 	void __iomem *reg;
@@ -444,7 +446,7 @@ struct clk * __init rcar_gen3_cpg_clk_register(struct device *dev,
 	unsigned int div = 1;
 	u32 value;
 
-	parent = clks[core->parent & 0xffff];	/* CLK_TYPE_PE uses high bits */
+	parent = clks[core->parent & 0xffff];	/* some types use high bits */
 	if (IS_ERR(parent))
 		return ERR_CAST(parent);
 
@@ -524,7 +526,7 @@ struct clk * __init rcar_gen3_cpg_clk_register(struct device *dev,
 
 			if (clk_get_rate(clks[cpg_clk_extalr])) {
 				parent = clks[cpg_clk_extalr];
-				value |= BIT(15);
+				value |= CPG_RCKCR_CKSEL;
 			}
 
 			writel(value, csn->reg);
@@ -570,6 +572,21 @@ struct clk * __init rcar_gen3_cpg_clk_register(struct device *dev,
 		div = cpg_pll_config->osc_prediv * core->div;
 		break;
 
+	case CLK_TYPE_GEN3_RCKSEL:
+		/*
+		 * Clock selectable between two parents and two fixed dividers
+		 * using RCKCR.CKSEL
+		 */
+		if (readl(base + CPG_RCKCR) & CPG_RCKCR_CKSEL) {
+			div = core->div & 0xffff;
+		} else {
+			parent = clks[core->parent >> 16];
+			if (IS_ERR(parent))
+				return ERR_CAST(parent);
+			div = core->div >> 16;
+		}
+		break;
+
 	default:
 		return ERR_PTR(-EINVAL);
 	}

drivers/clk/renesas/rcar-gen3-cpg.h

 /*
  * R-Car Gen3 Clock Pulse Generator
  *
- * Copyright (C) 2015-2016 Glider bvba
+ * Copyright (C) 2015-2018 Glider bvba
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -24,6 +24,7 @@ enum rcar_gen3_clk_types {
 	CLK_TYPE_GEN3_Z,
 	CLK_TYPE_GEN3_Z2,
 	CLK_TYPE_GEN3_OSC,	/* OSC EXTAL predivider and fixed divider */
+	CLK_TYPE_GEN3_RCKSEL,	/* Select parent/divider using RCKCR.CKSEL */
 };
 
 #define DEF_GEN3_SD(_name, _id, _parent, _offset)	\
@@ -37,6 +38,10 @@ enum rcar_gen3_clk_types {
 #define DEF_GEN3_OSC(_name, _id, _parent, _div)		\
 	DEF_BASE(_name, _id, CLK_TYPE_GEN3_OSC, _parent, .div = _div)
 
+#define DEF_GEN3_RCKSEL(_name, _id, _parent0, _div0, _parent1, _div1) \
+	DEF_BASE(_name, _id, CLK_TYPE_GEN3_RCKSEL,	\
+		 (_parent0) << 16 | (_parent1),	.div = (_div0) << 16 | (_div1))
+
 struct rcar_gen3_cpg_pll_config {
 	u8 extal_div;
 	u8 pll1_mult;