[PATCH v3] clk: shmobile: div6: support selectable-input clocks

[Ulrich Hecht]

From: Ulrich Hecht <ulrich.hecht at gmail.com>

Adds support for DIV6 clocks with selectable parents as found in the r8a73a4,
r8a7740, sh73a0, and other SoCs.

Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas at gmail.com>
---

Changes since v2:
- add r8a73a4 to bindings
- use u32 where appropriate
- don't split error message

Changes since v1:
- make sure unrelated register bits are preserved
- use the plural for the clocks property in bindings

 .../bindings/clock/renesas,cpg-div6-clocks.txt     | 12 +++++++-
 drivers/clk/shmobile/clk-div6.c                    | 32 ++++++++++++++++++----
 2 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/Documentation/devicetree/bindings/clock/renesas,cpg-div6-clocks.txt b/Documentation/devicetree/bindings/clock/renesas,cpg-div6-clocks.txt
index 952e373..b002d2b 100644
--- a/Documentation/devicetree/bindings/clock/renesas,cpg-div6-clocks.txt
+++ b/Documentation/devicetree/bindings/clock/renesas,cpg-div6-clocks.txt
@@ -7,14 +7,24 @@ to 64.
 Required Properties:
 
   - compatible: Must be one of the following
+    - "renesas,r8a73a4-div6-clock" for R8A73A4 (R-Mobile APE6) DIV6 clocks
+    - "renesas,r8a7740-div6-clock" for R8A7740 (R-Mobile A1) DIV6 clocks
     - "renesas,r8a7790-div6-clock" for R8A7790 (R-Car H2) DIV6 clocks
     - "renesas,r8a7791-div6-clock" for R8A7791 (R-Car M2) DIV6 clocks
+    - "renesas,sh73a0-div6-clock" for SH73A0 (SH-MobileAG5) DIV6 clocks
     - "renesas,cpg-div6-clock" for generic DIV6 clocks
   - reg: Base address and length of the memory resource used by the DIV6 clock
-  - clocks: Reference to the parent clock
+  - clocks: Reference to the parent clock(s)
   - #clock-cells: Must be 0
   - clock-output-names: The name of the clock as a free-form string
 
+Optional Properties:
+
+  - renesas,src-shift: Bit position of the input clock selector (default:
+    fixed input clock)
+  - renesas,src-width: Bit width of the input clock selector (default: fixed
+    input clock)
+
 
 Example
 -------
diff --git a/drivers/clk/shmobile/clk-div6.c b/drivers/clk/shmobile/clk-div6.c
index f065f69..2282bec 100644
--- a/drivers/clk/shmobile/clk-div6.c
+++ b/drivers/clk/shmobile/clk-div6.c
@@ -38,9 +38,12 @@ struct div6_clock {
 
 static int cpg_div6_clock_enable(struct clk_hw *hw)
 {
+	u32 val;
 	struct div6_clock *clock = to_div6_clock(hw);
 
-	clk_writel(CPG_DIV6_DIV(clock->div - 1), clock->reg);
+	val = (clk_readl(clock->reg) & ~(CPG_DIV6_DIV_MASK | CPG_DIV6_CKSTP))
+		| CPG_DIV6_DIV(clock->div - 1);
+	clk_writel(val, clock->reg);
 
 	return 0;
 }
@@ -52,8 +55,8 @@ static void cpg_div6_clock_disable(struct clk_hw *hw)
 	/* DIV6 clocks require the divisor field to be non-zero when stopping
 	 * the clock.
 	 */
-	clk_writel(CPG_DIV6_CKSTP | CPG_DIV6_DIV(CPG_DIV6_DIV_MASK),
-		   clock->reg);
+	clk_writel(clk_readl(clock->reg) | CPG_DIV6_CKSTP | CPG_DIV6_DIV_MASK,
+		clock->reg);
 }
 
 static int cpg_div6_clock_is_enabled(struct clk_hw *hw)
@@ -94,12 +97,14 @@ static int cpg_div6_clock_set_rate(struct clk_hw *hw, unsigned long rate,
 {
 	struct div6_clock *clock = to_div6_clock(hw);
 	unsigned int div = cpg_div6_clock_calc_div(rate, parent_rate);
+	u32 val;
 
 	clock->div = div;
 
+	val = clk_readl(clock->reg) & ~CPG_DIV6_DIV_MASK;
 	/* Only program the new divisor if the clock isn't stopped. */
-	if (!(clk_readl(clock->reg) & CPG_DIV6_CKSTP))
-		clk_writel(CPG_DIV6_DIV(clock->div - 1), clock->reg);
+	if (!(val & CPG_DIV6_CKSTP))
+		clk_writel(val | CPG_DIV6_DIV(clock->div - 1), clock->reg);
 
 	return 0;
 }
@@ -121,6 +126,7 @@ static void __init cpg_div6_clock_init(struct device_node *np)
 	const char *name;
 	struct clk *clk;
 	int ret;
+	u32 src_shift, src_width;
 
 	clock = kzalloc(sizeof(*clock), GFP_KERNEL);
 	if (!clock) {
@@ -150,7 +156,21 @@ static void __init cpg_div6_clock_init(struct device_node *np)
 		goto error;
 	}
 
-	parent_name = of_clk_get_parent_name(np, 0);
+	if (!of_property_read_u32(np, "renesas,src-shift", &src_shift)) {
+		if (!of_property_read_u32(np, "renesas,src-width",
+					&src_width)) {
+			unsigned int parent_idx =
+				(clk_readl(clock->reg) >> src_shift) &
+				(BIT(src_width) - 1);
+			parent_name = of_clk_get_parent_name(np, parent_idx);
+		} else {
+			pr_err("%s: renesas,src-shift without renesas,src-width in %s\n",
+			       __func__, np->name);
+			goto error;
+		}
+	} else
+		parent_name = of_clk_get_parent_name(np, 0);
+
 	if (parent_name == NULL) {
 		pr_err("%s: failed to get %s DIV6 clock parent name\n",
 		       __func__, np->name);
-- 
1.8.4.5