lib: utils/irqchip/imsic: track IRQ enable state and restore EIE on warm init

Add an irq_state field to struct sbi_irqchip_hwirq_data with a single
IRQ_ENABLED flag (bit 0) to track whether a hardware interrupt has been
enabled via the irqchip framework. Set IRQ_ENABLED in
sbi_irqchip_unmask_hwirq() when the unmask callback is invoked.

Add sbi_irqchip_get_irq_state() as a private inline accessor and expose
sbi_irqchip_is_irq_enabled() as a public API for drivers to query the
enabled state of a hardware interrupt by chip pointer and hwirq number.

Refactor imsic_local_eix_update() to operate on a single interrupt ID
instead of a base+count range, simplifying the CSR bit manipulation to
a direct BIT(id) write without the inner loop. Update all call sites
accordingly.

Use sbi_irqchip_is_irq_enabled() in imsic_warm_irqchip_init() to
restore per-EIID EIE CSR state on warm boot and HSM resume based on
the saved irq_state, replacing the previous blanket disable of all
interrupts. This ensures that EIIDs enabled during hotplug/warminit
cycle are correctly re-enabled on the resuming hart without requiring
software to re-register or re-unmask each interrupt.

Signed-off-by: Oza Pawandeep <[email protected]>
Reviewed-by: Anup Patel <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Anup Patel <[email protected]>

3 files changed, 65 insertions, 28 deletions

diff --git a/include/sbi/sbi_irqchip.h b/include/sbi/sbi_irqchip.h
index ea012635..f5dbf1c7 100644
--- a/include/sbi/sbi_irqchip.h
+++ b/include/sbi/sbi_irqchip.h
@@ -168,4 +168,8 @@ int sbi_irqchip_init(struct sbi_scratch *scratch, bool cold_boot);
 /** Exit interrupt controllers */
 void sbi_irqchip_exit(struct sbi_scratch *scratch);
 
+/** Check if the interrupt is enabled */
+bool sbi_irqchip_is_hwirq_enabled(struct sbi_irqchip_device *chip,
+				   u32 hwirq);
+
 #endif
diff --git a/lib/sbi/sbi_irqchip.c b/lib/sbi/sbi_irqchip.c
index 0973f064..d6771fa8 100644
--- a/lib/sbi/sbi_irqchip.c
+++ b/lib/sbi/sbi_irqchip.c
@@ -20,6 +20,11 @@ struct sbi_irqchip_hwirq_data {
 	/** raw hardware interrupt handler */
 	int (*raw_handler)(struct sbi_irqchip_device *chip, u32 hwirq);
 
+#define IRQ_ENABLED	BIT(0)
+	/** interrupt state
+	 * bit 0 - 1: enabled, 0: disabled */
+	u32 irq_state;
+
 	/** target hart index */
 	u32 hart_index;
 
@@ -80,23 +85,54 @@ int sbi_irqchip_process_hwirq(struct sbi_irqchip_device *chip, u32 hwirq)
 	return data->raw_handler(chip, hwirq);
 }
 
+static inline u32 sbi_irqchip_get_irq_state(struct sbi_irqchip_device *chip,
+					     u32 hwirq)
+{
+	if (!chip || !chip->hwirqs || hwirq >= chip->num_hwirq)
+		return 0;
+
+	return chip->hwirqs[hwirq].irq_state;
+}
+
+bool sbi_irqchip_is_hwirq_enabled(struct sbi_irqchip_device *chip,
+				   u32 hwirq)
+{
+	return !!(sbi_irqchip_get_irq_state(chip, hwirq) & IRQ_ENABLED);
+}
+
 int sbi_irqchip_unmask_hwirq(struct sbi_irqchip_device *chip, u32 hwirq)
 {
+	struct sbi_irqchip_hwirq_data *data;
+
 	if (!chip || chip->num_hwirq <= hwirq)
 		return SBI_EINVAL;
 
+	data = &chip->hwirqs[hwirq];
+	if (sbi_irqchip_is_hwirq_enabled(chip, hwirq))
+		return SBI_EALREADY;
+
 	if (chip->hwirq_unmask)
 		chip->hwirq_unmask(chip, hwirq);
+
+	data->irq_state |= IRQ_ENABLED;
 	return 0;
 }
 
 int sbi_irqchip_mask_hwirq(struct sbi_irqchip_device *chip, u32 hwirq)
 {
+	struct sbi_irqchip_hwirq_data *data;
+
 	if (!chip || chip->num_hwirq <= hwirq)
 		return SBI_EINVAL;
 
+	if (!sbi_irqchip_is_hwirq_enabled(chip, hwirq))
+		return SBI_EALREADY;
+
 	if (chip->hwirq_mask)
 		chip->hwirq_mask(chip, hwirq);
+
+	data = &chip->hwirqs[hwirq];
+	data->irq_state &= ~IRQ_ENABLED;
 	return 0;
 }
 
diff --git a/lib/utils/irqchip/imsic.c b/lib/utils/irqchip/imsic.c
index fef77203..f6da9f7e 100644
--- a/lib/utils/irqchip/imsic.c
+++ b/lib/utils/irqchip/imsic.c
@@ -225,29 +225,20 @@ static struct sbi_ipi_device imsic_ipi_device = {
 	.ipi_send	= imsic_ipi_send
 };
 
-static void imsic_local_eix_update(unsigned long base_id,
-				   unsigned long num_id, bool pend, bool val)
+static void imsic_local_eix_update(unsigned long id,
+				   bool pend, bool val)
 {
-	unsigned long i, isel, ireg;
-	unsigned long id = base_id, last_id = base_id + num_id;
+	unsigned long isel, ireg = 0;
 
-	while (id < last_id) {
-		isel = id / __riscv_xlen;
-		isel *= __riscv_xlen / IMSIC_EIPx_BITS;
-		isel += (pend) ? IMSIC_EIP0 : IMSIC_EIE0;
+	isel = id / __riscv_xlen;
+	isel *= __riscv_xlen / IMSIC_EIPx_BITS;
+	isel += (pend) ? IMSIC_EIP0 : IMSIC_EIE0;
+	ireg |= BIT(id);
 
-		ireg = 0;
-		for (i = id & (__riscv_xlen - 1);
-		     (id < last_id) && (i < __riscv_xlen); i++) {
-			ireg |= BIT(i);
-			id++;
-		}
-
-		if (val)
-			imsic_csr_set(isel, ireg);
-		else
-			imsic_csr_clear(isel, ireg);
-	}
+	if (val)
+		imsic_csr_set(isel, ireg);
+	else
+		imsic_csr_clear(isel, ireg);
 }
 
 void imsic_local_irqchip_init(void)
@@ -275,13 +266,14 @@ void imsic_local_irqchip_init(void)
 	imsic_csr_write(IMSIC_EIDELIVERY, IMSIC_ENABLE_EIDELIVERY);
 
 	/* Enable IPI */
-	imsic_local_eix_update(IMSIC_IPI_ID, 1, false, true);
+	imsic_local_eix_update(IMSIC_IPI_ID, false, true);
 }
 
 static int imsic_warm_irqchip_init(struct sbi_irqchip_device *dev)
 {
 	struct imsic_data *imsic;
 	struct imsic_data *hart_imsic;
+	int i;
 
 	imsic = container_of(dev, struct imsic_data, irqchip);
 	hart_imsic = imsic_get_data(current_hartindex());
@@ -291,11 +283,16 @@ static int imsic_warm_irqchip_init(struct sbi_irqchip_device *dev)
 		!hart_imsic->targets_mmode)
 		return SBI_EINVAL;
 
-	/* Disable all interrupts */
-	imsic_local_eix_update(1, imsic->num_ids, false, false);
+	/* enable interrutps based on the irq state */
+	for (i = 1; i < imsic->num_ids; i++) {
+		if (sbi_irqchip_is_hwirq_enabled(&imsic->irqchip, i) == true)
+			imsic_local_eix_update(i, true, true);
+		else
+			imsic_local_eix_update(i, false, false);
+	}
 
 	/* Clear IPI pending */
-	imsic_local_eix_update(IMSIC_IPI_ID, 1, true, false);
+	imsic_local_eix_update(IMSIC_IPI_ID, true, false);
 
 	/* Local IMSIC initialization */
 	imsic_local_irqchip_init();
@@ -395,8 +392,8 @@ static void imsic_hwirq_cleanup(struct sbi_irqchip_device *chip, u32 hwirq)
 	if (!imsic || !imsic->targets_mmode)
 		return;
 
-	imsic_local_eix_update(hwirq, 1, false, false);
-	imsic_local_eix_update(hwirq, 1, true, false);
+	imsic_local_eix_update(hwirq, false, false);
+	imsic_local_eix_update(hwirq, true, false);
 }
 
 static void imsic_hwirq_eoi(struct sbi_irqchip_device *chip, u32 hwirq)
@@ -529,7 +526,7 @@ static void imsic_hwirq_mask(struct sbi_irqchip_device *chip, u32 hwirq)
 	if (!imsic || !imsic->targets_mmode)
 		return;
 
-	imsic_local_eix_update(hwirq, 1, false, false);
+	imsic_local_eix_update(hwirq, false, false);
 }
 
 static void imsic_hwirq_unmask(struct sbi_irqchip_device *chip, u32 hwirq)
@@ -546,7 +543,7 @@ static void imsic_hwirq_unmask(struct sbi_irqchip_device *chip, u32 hwirq)
 	if (!hwirq || hwirq == IMSIC_IPI_ID)
 		return;
 
-	imsic_local_eix_update(hwirq, 1, false, true);
+	imsic_local_eix_update(hwirq, false, true);
 }
 
 static struct sbi_irqchip_device imsic_device = {