[PATCH 10/13] clk: renesas: Handle E3/D3 RPCSRC clock

[Marek Vasut]

From: Hai Pham <hai.pham.ud at renesas.com>

The RPCSRC clock divider on R-Car D3 is very similar to the one on R-Car
E3, but uses a different pre-divider for the PLL0 parent.  Add a new
macro to describe it, reusing the existing clock type for R-Car E3.

As both E3/D3 RPCSRC clock divider are different from the rest of R-Car
Gen3, keep the original implementation from Linux.

Based on Linux commit 40745482eec8 ("clk: renesas: r8a774c0: Add RPC
clocks") by Lad Prabhakar and 9d18f81b3535 ("clk: renesas: r8a77995: Add
RPC clocks") by Geert Uytterhoeven.

Signed-off-by: Hai Pham <hai.pham.ud at renesas.com>
Signed-off-by: Marek Vasut <marek.vasut+renesas at mailbox.org> # Add D3 tweaks
---
 drivers/clk/renesas/clk-rcar-gen3.c | 31 +++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/clk/renesas/clk-rcar-gen3.c b/drivers/clk/renesas/clk-rcar-gen3.c
index 84bd7fe8b00..aea8b1e8390 100644
--- a/drivers/clk/renesas/clk-rcar-gen3.c
+++ b/drivers/clk/renesas/clk-rcar-gen3.c
@@ -358,6 +358,37 @@ static u64 gen3_clk_get_rate64(struct clk *clk)
 						     CPG_RPCCKCR_DIV_POST_MASK,
 						     cpg_rpcsrc_div_table, "RPCSRC");
 
+	case CLK_TYPE_GEN3_D3_RPCSRC:
+	case CLK_TYPE_GEN3_E3_RPCSRC:
+		/*
+		 * Register RPCSRC as fixed factor clock based on the
+		 * MD[4:1] pins and CPG_RPCCKCR[4:3] register value for
+		 * which has been set prior to booting the kernel.
+		 */
+		value = (readl(priv->base + CPG_RPCCKCR) & GENMASK(4, 3)) >> 3;
+
+		switch (value) {
+		case 0:
+			div = 5;
+			break;
+		case 1:
+			div = 3;
+			break;
+		case 2:
+			div = core->div;
+			break;
+		case 3:
+		default:
+			div = 2;
+			break;
+		}
+
+		rate = gen3_clk_get_rate64(&parent) / div;
+		debug("%s[%i] E3/D3 RPCSRC clk: parent=%i div=%u => rate=%llu\n",
+		      __func__, __LINE__, (core->parent >> 16) & 0xffff, div, rate);
+
+		return rate;
+
 	case CLK_TYPE_GEN3_RPC:
 	case CLK_TYPE_GEN4_RPC:
 		return rcar_clk_get_rate64_div_table(core->parent,
-- 
2.39.0