Message-Id: <20251202-preserve-aplic-imsic-v3-2-1844fbf1fe92@sifive.com>
Date: Tue, 02 Dec 2025 14:07:41 +0800
From: Nick Hu <nick.hu@...ive.com>
To: Anup Patel <anup@...infault.org>, Thomas Gleixner <tglx@...utronix.de>, 
 Paul Walmsley <pjw@...nel.org>, Palmer Dabbelt <palmer@...belt.com>, 
 Albert Ou <aou@...s.berkeley.edu>, Alexandre Ghiti <alex@...ti.fr>
Cc: linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 Yong-Xuan Wang <yongxuan.wang@...ive.com>, Cyan Yang <cyan.yang@...ive.com>, 
 Nutty Liu <liujingqi@...xincomputing.com>, Nick Hu <nick.hu@...ive.com>
Subject: [PATCH v3 2/2] irqchip/riscv-aplic: Preserve APLIC states across
 suspend/resume

The APLIC states might be reset when the platform enters a low power
state, but the register states are not being preserved and restored,
which prevents interrupt delivery after the platform resumes.
Solve this by adding a syscore ops and a power management notifier to
preserve and restore the APLIC states on suspend and resume.

Reviewed-by: Yong-Xuan Wang <yongxuan.wang@...ive.com>
Reviewed-by: Cyan Yang <cyan.yang@...ive.com>
Reviewed-by: Nutty Liu <liujingqi@...xincomputing.com>
Signed-off-by: Nick Hu <nick.hu@...ive.com>
---
 drivers/irqchip/irq-riscv-aplic-direct.c |  10 ++
 drivers/irqchip/irq-riscv-aplic-main.c   | 166 ++++++++++++++++++++++++++++++-
 drivers/irqchip/irq-riscv-aplic-main.h   |  19 ++++
 3 files changed, 194 insertions(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-riscv-aplic-direct.c b/drivers/irqchip/irq-riscv-aplic-direct.c
index c2a75bf3d20c64c1e1f0e863486633071ab115a7..5a9650225dd805539a2cdf7ca64c7addb4fea39d 100644
--- a/drivers/irqchip/irq-riscv-aplic-direct.c
+++ b/drivers/irqchip/irq-riscv-aplic-direct.c
@@ -8,6 +8,7 @@
 #include <linux/bitfield.h>
 #include <linux/bitops.h>
 #include <linux/cpu.h>
+#include <linux/cpumask.h>
 #include <linux/interrupt.h>
 #include <linux/irqchip.h>
 #include <linux/irqchip/chained_irq.h>
@@ -171,6 +172,15 @@ static void aplic_idc_set_delivery(struct aplic_idc *idc, bool en)
 	writel(de, idc->regs + APLIC_IDC_IDELIVERY);
 }
 
+void aplic_direct_restore_states(struct aplic_priv *priv)
+{
+	struct aplic_direct *direct = container_of(priv, struct aplic_direct, priv);
+	int cpu;
+
+	for_each_cpu(cpu, &direct->lmask)
+		aplic_idc_set_delivery(per_cpu_ptr(&aplic_idcs, cpu), true);
+}
+
 static int aplic_direct_dying_cpu(unsigned int cpu)
 {
 	if (aplic_direct_parent_irq)
diff --git a/drivers/irqchip/irq-riscv-aplic-main.c b/drivers/irqchip/irq-riscv-aplic-main.c
index 93e7c51f944abe4cb96fc7427c1f36ab7d2cbc4d..b760942e57f916d86b2d424dca8a3c6008f064e6 100644
--- a/drivers/irqchip/irq-riscv-aplic-main.c
+++ b/drivers/irqchip/irq-riscv-aplic-main.c
@@ -12,10 +12,165 @@
 #include <linux/of.h>
 #include <linux/of_irq.h>
 #include <linux/platform_device.h>
+#include <linux/pm_domain.h>
+#include <linux/pm_runtime.h>
 #include <linux/printk.h>
+#include <linux/syscore_ops.h>
 
 #include "irq-riscv-aplic-main.h"
 
+static LIST_HEAD(aplics);
+
+static void aplic_restore_states(struct aplic_priv *priv)
+{
+	struct aplic_saved_regs *saved_regs = &priv->saved_hw_regs;
+	struct aplic_src_ctrl *srcs;
+	void __iomem *regs;
+	u32 nr_irqs, i;
+
+	regs = priv->regs;
+	writel(saved_regs->domaincfg, regs + APLIC_DOMAINCFG);
+#ifdef CONFIG_RISCV_M_MODE
+	writel(saved_regs->msiaddr, regs + APLIC_xMSICFGADDR);
+	writel(saved_regs->msiaddrh, regs + APLIC_xMSICFGADDRH);
+#endif
+	/*
+	 * The sourcecfg[i] has to be restored prior to the target[i], interrupt-pending and
+	 * interrupt-enable bits. The AIA specification states that "Whenever interrupt source i is
+	 * inactive in an interrupt domain, the corresponding interrupt-pending and interrupt-enable
+	 * bits within the domain are read-only zeros, and register target[i] is also read-only
+	 * zero."
+	 */
+	nr_irqs = priv->nr_irqs;
+	for (i = 0; i < nr_irqs; i++) {
+		srcs = &priv->saved_hw_regs.srcs[i];
+		writel(srcs->sourcecfg, regs + APLIC_SOURCECFG_BASE + i * sizeof(u32));
+		writel(srcs->target, regs + APLIC_TARGET_BASE + i * sizeof(u32));
+	}
+
+	for (i = 0; i <= nr_irqs; i += 32) {
+		srcs = &priv->saved_hw_regs.srcs[i];
+		writel(-1U, regs + APLIC_CLRIE_BASE + (i / 32) * sizeof(u32));
+		writel(srcs->ie, regs + APLIC_SETIE_BASE + (i / 32) * sizeof(u32));
+
+		/* Re-trigger the interrupts if it forwards interrupts to target harts by MSIs */
+		if (!priv->nr_idcs)
+			writel(readl(regs + APLIC_CLRIP_BASE + (i / 32) * sizeof(u32)),
+			       regs + APLIC_SETIP_BASE + (i / 32) * sizeof(u32));
+	}
+
+	if (priv->nr_idcs)
+		aplic_direct_restore_states(priv);
+}
+
+static void aplic_save_states(struct aplic_priv *priv)
+{
+	struct aplic_src_ctrl *srcs;
+	void __iomem *regs;
+	u32 i, nr_irqs;
+
+	regs = priv->regs;
+	nr_irqs = priv->nr_irqs;
+	/* The valid interrupt source IDs range from 1 to N, where N is priv->nr_irqs */
+	for (i = 0; i < nr_irqs; i++) {
+		srcs = &priv->saved_hw_regs.srcs[i];
+		srcs->target = readl(regs + APLIC_TARGET_BASE + i * sizeof(u32));
+
+		if (i % 32)
+			continue;
+
+		srcs->ie = readl(regs + APLIC_SETIE_BASE + (i / 32) * sizeof(u32));
+	}
+
+	/* Save the nr_irqs bit if needed */
+	if (!(nr_irqs % 32)) {
+		srcs = &priv->saved_hw_regs.srcs[nr_irqs];
+		srcs->ie = readl(regs + APLIC_SETIE_BASE + (nr_irqs / 32) * sizeof(u32));
+	}
+}
+
+static int aplic_syscore_suspend(void)
+{
+	struct aplic_priv *priv;
+
+	list_for_each_entry(priv, &aplics, head)
+		aplic_save_states(priv);
+
+	return 0;
+}
+
+static void aplic_syscore_resume(void)
+{
+	struct aplic_priv *priv;
+
+	list_for_each_entry(priv, &aplics, head)
+		aplic_restore_states(priv);
+}
+
+static struct syscore_ops aplic_syscore_ops = {
+	.suspend = aplic_syscore_suspend,
+	.resume = aplic_syscore_resume,
+};
+
+static int aplic_pm_notifier(struct notifier_block *nb, unsigned long action, void *data)
+{
+	struct aplic_priv *priv = container_of(nb, struct aplic_priv, genpd_nb);
+
+	switch (action) {
+	case GENPD_NOTIFY_PRE_OFF:
+		aplic_save_states(priv);
+		break;
+	case GENPD_NOTIFY_ON:
+		aplic_restore_states(priv);
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static void aplic_pm_remove(void *data)
+{
+	struct aplic_priv *priv = data;
+	struct device *dev = priv->dev;
+
+	list_del(&priv->head);
+	if (dev->pm_domain)
+		dev_pm_genpd_remove_notifier(dev);
+}
+
+static int aplic_pm_add(struct device *dev, struct aplic_priv *priv)
+{
+	struct aplic_src_ctrl *srcs;
+	int ret;
+
+	srcs = devm_kzalloc(dev, (priv->nr_irqs + 1) * sizeof(*srcs), GFP_KERNEL);
+	if (!srcs)
+		return -ENOMEM;
+
+	priv->saved_hw_regs.srcs = srcs;
+	list_add(&priv->head, &aplics);
+	if (dev->pm_domain) {
+		priv->genpd_nb.notifier_call = aplic_pm_notifier;
+		ret = dev_pm_genpd_add_notifier(dev, &priv->genpd_nb);
+		if (ret)
+			goto remove_head;
+
+		ret = devm_pm_runtime_enable(dev);
+		if (ret)
+			goto remove_notifier;
+	}
+
+	return devm_add_action_or_reset(dev, aplic_pm_remove, priv);
+
+remove_notifier:
+	dev_pm_genpd_remove_notifier(dev);
+remove_head:
+	list_del(&priv->head);
+	return ret;
+}
+
 void aplic_irq_unmask(struct irq_data *d)
 {
 	struct aplic_priv *priv = irq_data_get_irq_chip_data(d);
@@ -60,6 +215,8 @@ int aplic_irq_set_type(struct irq_data *d, unsigned int type)
 	sourcecfg += (d->hwirq - 1) * sizeof(u32);
 	writel(val, sourcecfg);
 
+	priv->saved_hw_regs.srcs[d->hwirq - 1].sourcecfg = val;
+
 	return 0;
 }
 
@@ -82,6 +239,7 @@ int aplic_irqdomain_translate(struct irq_fwspec *fwspec, u32 gsi_base,
 
 void aplic_init_hw_global(struct aplic_priv *priv, bool msi_mode)
 {
+	struct aplic_saved_regs *saved_regs = &priv->saved_hw_regs;
 	u32 val;
 #ifdef CONFIG_RISCV_M_MODE
 	u32 valh;
@@ -95,6 +253,8 @@ void aplic_init_hw_global(struct aplic_priv *priv, bool msi_mode)
 		valh |= FIELD_PREP(APLIC_xMSICFGADDRH_HHXS, priv->msicfg.hhxs);
 		writel(val, priv->regs + APLIC_xMSICFGADDR);
 		writel(valh, priv->regs + APLIC_xMSICFGADDRH);
+		saved_regs->msiaddr = val;
+		saved_regs->msiaddrh = valh;
 	}
 #endif
 
@@ -106,6 +266,8 @@ void aplic_init_hw_global(struct aplic_priv *priv, bool msi_mode)
 	writel(val, priv->regs + APLIC_DOMAINCFG);
 	if (readl(priv->regs + APLIC_DOMAINCFG) != val)
 		dev_warn(priv->dev, "unable to write 0x%x in domaincfg\n", val);
+
+	saved_regs->domaincfg = val;
 }
 
 static void aplic_init_hw_irqs(struct aplic_priv *priv)
@@ -176,7 +338,7 @@ int aplic_setup_priv(struct aplic_priv *priv, struct device *dev, void __iomem *
 	/* Setup initial state APLIC interrupts */
 	aplic_init_hw_irqs(priv);
 
-	return 0;
+	return aplic_pm_add(dev, priv);
 }
 
 static int aplic_probe(struct platform_device *pdev)
@@ -209,6 +371,8 @@ static int aplic_probe(struct platform_device *pdev)
 	if (rc)
 		dev_err_probe(dev, rc, "failed to setup APLIC in %s mode\n",
 			      msi_mode ? "MSI" : "direct");
+	else
+		register_syscore_ops(&aplic_syscore_ops);
 
 #ifdef CONFIG_ACPI
 	if (!acpi_disabled)
diff --git a/drivers/irqchip/irq-riscv-aplic-main.h b/drivers/irqchip/irq-riscv-aplic-main.h
index b0ad8cde69b1314c6db5ef3cc7070c843c381790..2d8ad7138541ad68a08349d9ed59a2554e520753 100644
--- a/drivers/irqchip/irq-riscv-aplic-main.h
+++ b/drivers/irqchip/irq-riscv-aplic-main.h
@@ -23,7 +23,25 @@ struct aplic_msicfg {
 	u32			lhxw;
 };
 
+struct aplic_src_ctrl {
+	u32			sourcecfg;
+	u32			target;
+	u32			ie;
+};
+
+struct aplic_saved_regs {
+	u32			domaincfg;
+#ifdef CONFIG_RISCV_M_MODE
+	u32			msiaddr;
+	u32			msiaddrh;
+#endif
+	struct aplic_src_ctrl	*srcs;
+};
+
 struct aplic_priv {
+	struct list_head	head;
+	struct notifier_block	genpd_nb;
+	struct aplic_saved_regs	saved_hw_regs;
 	struct device		*dev;
 	u32			gsi_base;
 	u32			nr_irqs;
@@ -40,6 +58,7 @@ int aplic_irqdomain_translate(struct irq_fwspec *fwspec, u32 gsi_base,
 			      unsigned long *hwirq, unsigned int *type);
 void aplic_init_hw_global(struct aplic_priv *priv, bool msi_mode);
 int aplic_setup_priv(struct aplic_priv *priv, struct device *dev, void __iomem *regs);
+void aplic_direct_restore_states(struct aplic_priv *priv);
 int aplic_direct_setup(struct device *dev, void __iomem *regs);
 #ifdef CONFIG_RISCV_APLIC_MSI
 int aplic_msi_setup(struct device *dev, void __iomem *regs);

-- 
2.34.1

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