irqchip/renesas-rzv2h: Add suspend/resume support

On RZ/G3E using PSCI, s2ram powers down the SoC. Add suspend/resume
callbacks to restore IRQ type for NMI, TINT and external IRQ interrupts.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260113125315.359967-3-biju.das.jz@bp.renesas.com

Author: bijudas

drivers/irqchip/irq-renesas-rzv2h.c

@@ -20,6 +20,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/reset.h>
 #include <linux/spinlock.h>
+#include <linux/syscore_ops.h>
 
 /* DT "interrupts" indexes */
 #define ICU_IRQ_START				1
@@ -89,6 +90,18 @@
 #define ICU_RZG3E_TSSEL_MAX_VAL			0x8c
 #define ICU_RZV2H_TSSEL_MAX_VAL			0x55
 
+/**
+ * struct rzv2h_irqc_reg_cache - registers cache (necessary for suspend/resume)
+ * @nitsr: ICU_NITSR register
+ * @iitsr: ICU_IITSR register
+ * @titsr: ICU_TITSR registers
+ */
+struct rzv2h_irqc_reg_cache {
+	u32	nitsr;
+	u32	iitsr;
+	u32	titsr[2];
+};
+
 /**
  * struct rzv2h_hw_info - Interrupt Control Unit controller hardware info structure.
  * @tssel_lut:		TINT lookup table
@@ -118,13 +131,15 @@ struct rzv2h_hw_info {
  * @fwspec:	IRQ firmware specific data
  * @lock:	Lock to serialize access to hardware registers
  * @info:	Pointer to struct rzv2h_hw_info
+ * @cache:	Registers cache for suspend/resume
  */
-struct rzv2h_icu_priv {
+static struct rzv2h_icu_priv {
 	void __iomem			*base;
 	struct irq_fwspec		fwspec[ICU_NUM_IRQ];
 	raw_spinlock_t			lock;
 	const struct rzv2h_hw_info	*info;
-};
+	struct rzv2h_irqc_reg_cache	cache;
+} *rzv2h_icu_data;
 
 void rzv2h_icu_register_dma_req(struct platform_device *icu_dev, u8 dmac_index, u8 dmac_channel,
 				u16 req_no)
@@ -412,6 +427,44 @@ static int rzv2h_icu_set_type(struct irq_data *d, unsigned int type)
 	return irq_chip_set_type_parent(d, IRQ_TYPE_LEVEL_HIGH);
 }
 
+static int rzv2h_irqc_irq_suspend(void *data)
+{
+	struct rzv2h_irqc_reg_cache *cache = &rzv2h_icu_data->cache;
+	void __iomem *base = rzv2h_icu_data->base;
+
+	cache->nitsr = readl_relaxed(base + ICU_NITSR);
+	cache->iitsr = readl_relaxed(base + ICU_IITSR);
+	for (unsigned int i = 0; i < 2; i++)
+		cache->titsr[i] = readl_relaxed(base + rzv2h_icu_data->info->t_offs + ICU_TITSR(i));
+
+	return 0;
+}
+
+static void rzv2h_irqc_irq_resume(void *data)
+{
+	struct rzv2h_irqc_reg_cache *cache = &rzv2h_icu_data->cache;
+	void __iomem *base = rzv2h_icu_data->base;
+
+	/*
+	 * Restore only interrupt type. TSSRx will be restored at the
+	 * request of pin controller to avoid spurious interrupts due
+	 * to invalid PIN states.
+	 */
+	for (unsigned int i = 0; i < 2; i++)
+		writel_relaxed(cache->titsr[i], base + rzv2h_icu_data->info->t_offs + ICU_TITSR(i));
+	writel_relaxed(cache->iitsr, base + ICU_IITSR);
+	writel_relaxed(cache->nitsr, base + ICU_NITSR);
+}
+
+static const struct syscore_ops rzv2h_irqc_syscore_ops = {
+	.suspend	= rzv2h_irqc_irq_suspend,
+	.resume		= rzv2h_irqc_irq_resume,
+};
+
+static struct syscore rzv2h_irqc_syscore = {
+	.ops = &rzv2h_irqc_syscore_ops,
+};
+
 static const struct irq_chip rzv2h_icu_chip = {
 	.name			= "rzv2h-icu",
 	.irq_eoi		= rzv2h_icu_eoi,
@@ -495,7 +548,6 @@ static int rzv2h_icu_probe_common(struct platform_device *pdev, struct device_no
 {
 	struct irq_domain *irq_domain, *parent_domain;
 	struct device_node *node = pdev->dev.of_node;
-	struct rzv2h_icu_priv *rzv2h_icu_data;
 	struct reset_control *resetn;
 	int ret;
 
@@ -553,6 +605,8 @@ static int rzv2h_icu_probe_common(struct platform_device *pdev, struct device_no
 
 	rzv2h_icu_data->info = hw_info;
 
+	register_syscore(&rzv2h_irqc_syscore);
+
 	/*
 	 * coccicheck complains about a missing put_device call before returning, but it's a false
 	 * positive. We still need &pdev->dev after successfully returning from this function.