irqchip/renesas-rzv2h: Prevent TINT spurious interrupt during resume

A glitch in the edge detection circuit can cause a spurious interrupt. The
hardware manual recommends clearing the status flag after setting the
ICU_TSSRk register as a countermeasure.

Currently, a spurious interrupt is generated on the resume path of s2idle
for the PMIC RTC TINT interrupt due to a glitch related to unnecessary
enabling/disabling of the TINT enable bit.

Fix this issue by not setting TSSR(TINT Source) and TITSR(TINT Detection
Method Selection) registers if the values are the same as those set
in these registers.

Fixes: 0d7605e75ac2 ("irqchip: Add RZ/V2H(P) Interrupt Control Unit (ICU) driver")
Signed-off-by: Biju Das <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Cc: [e-mail]
Link: https://patch.msgid.link/[e-mail]

drivers/irqchip/irq-renesas-rzv2h.c

···
 	u32 titsr, titsr_k, titsel_n, tien;
 	struct rzv2h_icu_priv *priv;
 	u32 tssr, tssr_k, tssel_n;
+	u32 titsr_cur, tssr_cur;
 	unsigned int hwirq;
 	u32 tint, sense;
 	int tint_nr;
···
 	guard(raw_spinlock)(&priv->lock);
 
 	tssr = readl_relaxed(priv->base + priv->info->t_offs + ICU_TSSR(tssr_k));
+	titsr = readl_relaxed(priv->base + priv->info->t_offs + ICU_TITSR(titsr_k));
+
+	tssr_cur = field_get(ICU_TSSR_TSSEL_MASK(tssel_n, priv->info->field_width), tssr);
+	titsr_cur = field_get(ICU_TITSR_TITSEL_MASK(titsel_n), titsr);
+	if (tssr_cur == tint && titsr_cur == sense)
+		return 0;
+
 	tssr &= ~(ICU_TSSR_TSSEL_MASK(tssel_n, priv->info->field_width) | tien);
 	tssr |= ICU_TSSR_TSSEL_PREP(tint, tssel_n, priv->info->field_width);
 
 	writel_relaxed(tssr, priv->base + priv->info->t_offs + ICU_TSSR(tssr_k));
 
-	titsr = readl_relaxed(priv->base + priv->info->t_offs + ICU_TITSR(titsr_k));
 	titsr &= ~ICU_TITSR_TITSEL_MASK(titsel_n);
 	titsr |= ICU_TITSR_TITSEL_PREP(sense, titsel_n);