clk: renesas: mstp: Support 8-bit registers for r7s72100

The RZ/A1 is different than the other Renesas SOCs because the MSTP
registers are 8-bit instead of 32-bit and if you try writing values as
32-bit nothing happens...meaning this driver never worked for r7s72100.

Fixes: b6face404f38 ("ARM: shmobile: r7s72100: add essential clock nodes to dtsi")
Signed-off-by: Chris Brandt <chris.brandt@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

drivers/clk/renesas/clk-mstp.c

@@ -37,12 +37,14 @@
  * @smstpcr: module stop control register
  * @mstpsr: module stop status register (optional)
  * @lock: protects writes to SMSTPCR
+ * @width_8bit: registers are 8-bit, not 32-bit
  */
 struct mstp_clock_group {
 	struct clk_onecell_data data;
 	void __iomem *smstpcr;
 	void __iomem *mstpsr;
 	spinlock_t lock;
+	bool width_8bit;
 };
 
 /**
@@ -59,6 +61,18 @@ struct mstp_clock {
 
 #define to_mstp_clock(_hw) container_of(_hw, struct mstp_clock, hw)
 
+static inline u32 cpg_mstp_read(struct mstp_clock_group *group,
+				u32 __iomem *reg)
+{
+	return group->width_8bit ? readb(reg) : clk_readl(reg);
+}
+
+static inline void cpg_mstp_write(struct mstp_clock_group *group, u32 val,
+				  u32 __iomem *reg)
+{
+	group->width_8bit ? writeb(val, reg) : clk_writel(val, reg);
+}
+
 static int cpg_mstp_clock_endisable(struct clk_hw *hw, bool enable)
 {
 	struct mstp_clock *clock = to_mstp_clock(hw);
@@ -70,12 +84,12 @@ static int cpg_mstp_clock_endisable(struct clk_hw *hw, bool enable)
 
 	spin_lock_irqsave(&group->lock, flags);
 
-	value = clk_readl(group->smstpcr);
+	value = cpg_mstp_read(group, group->smstpcr);
 	if (enable)
 		value &= ~bitmask;
 	else
 		value |= bitmask;
-	clk_writel(value, group->smstpcr);
+	cpg_mstp_write(group, value, group->smstpcr);
 
 	spin_unlock_irqrestore(&group->lock, flags);
 
@@ -83,7 +97,7 @@ static int cpg_mstp_clock_endisable(struct clk_hw *hw, bool enable)
 		return 0;
 
 	for (i = 1000; i > 0; --i) {
-		if (!(clk_readl(group->mstpsr) & bitmask))
+		if (!(cpg_mstp_read(group, group->mstpsr) & bitmask))
 			break;
 		cpu_relax();
 	}
@@ -114,9 +128,9 @@ static int cpg_mstp_clock_is_enabled(struct clk_hw *hw)
 	u32 value;
 
 	if (group->mstpsr)
-		value = clk_readl(group->mstpsr);
+		value = cpg_mstp_read(group, group->mstpsr);
 	else
-		value = clk_readl(group->smstpcr);
+		value = cpg_mstp_read(group, group->smstpcr);
 
 	return !(value & BIT(clock->bit_index));
 }
@@ -188,6 +202,9 @@ static void __init cpg_mstp_clocks_init(struct device_node *np)
 		return;
 	}
 
+	if (of_device_is_compatible(np, "renesas,r7s72100-mstp-clocks"))
+		group->width_8bit = true;
+
 	for (i = 0; i < MSTP_MAX_CLOCKS; ++i)
 		clks[i] = ERR_PTR(-ENOENT);