clk: renesas: rcar-gen3: Add spinlock

Protect the CPG register read-modify-write sequence with a spinlock.
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

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

@@ -30,14 +30,19 @@
 
 #define CPG_RCKCR_CKSEL	BIT(15)	/* RCLK Clock Source Select */
 
+static spinlock_t cpg_lock;
+
 static void cpg_reg_modify(void __iomem *reg, u32 clear, u32 set)
 {
+	unsigned long flags;
 	u32 val;
 
+	spin_lock_irqsave(&cpg_lock, flags);
 	val = readl(reg);
 	val &= ~clear;
 	val |= set;
 	writel(val, reg);
+	spin_unlock_irqrestore(&cpg_lock, flags);
 };
 
 struct cpg_simple_notifier {
@@ -615,5 +620,8 @@ int __init rcar_gen3_cpg_init(const struct rcar_gen3_cpg_pll_config *config,
 	if (attr)
 		cpg_quirks = (uintptr_t)attr->data;
 	pr_debug("%s: mode = 0x%x quirks = 0x%x\n", __func__, mode, cpg_quirks);
+
+	spin_lock_init(&cpg_lock);
+
 	return 0;
 }