linux-kernel - [PATCH v3 2/2] irqchip/riscv-aplic: add support for hart indexes

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Message-ID: <20250107075835.1421602-3-vladimir.kondratiev@mobileye.com>
Date: Tue,  7 Jan 2025 09:58:35 +0200
From: Vladimir Kondratiev <vladimir.kondratiev@...ileye.com>
To: anup@...infault.org
Cc: aou@...s.berkeley.edu,
	conor+dt@...nel.org,
	krzk+dt@...nel.org,
	linux-kernel@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	palmer@...belt.com,
	paul.walmsley@...ive.com,
	robh@...nel.org,
	tglx@...utronix.de,
	vladimir.kondratiev@...ileye.com
Subject: [PATCH v3 2/2] irqchip/riscv-aplic: add support for hart indexes

Risc-V APLIC specification defines "hart index" in [1]:

Within a given interrupt domain, each of the domain’s harts has a
unique index number in the range 0 to 2^14 − 1 (= 16,383). The index
number a domain associates with a hart may or may not have any
relationship to the unique hart identifier (“hart ID”) that the
RISC-V Privileged Architecture assigns to the hart. Two different
interrupt domains may employ entirely different index numbers for
the same set of harts.

Further, this document says in "4.5 Memory-mapped control
region for an interrupt domain":

The array of IDC structures may include some for potential hart index
numbers that are not actual hart index numbers in the domain. For
example, the first IDC structure is always for hart index 0, but 0 is
not necessarily a valid index number for any hart in the domain.

Support arbitrary hart indexes specified in optional APLIC property
"riscv,hart-indexes" that should be array of u32 elements, one per
interrupt target. If this property not specified, fallback is to use
logical hart indexes within the domain.

[1]: https://github.com/riscv/riscv-aia

Signed-off-by: Vladimir Kondratiev <vladimir.kondratiev@...ileye.com>
---
 drivers/irqchip/irq-riscv-aplic-direct.c | 25 +++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/irqchip/irq-riscv-aplic-direct.c b/drivers/irqchip/irq-riscv-aplic-direct.c
index 7cd6b646774b..ea61329decb2 100644
--- a/drivers/irqchip/irq-riscv-aplic-direct.c
+++ b/drivers/irqchip/irq-riscv-aplic-direct.c
@@ -31,7 +31,7 @@ struct aplic_direct {
 };

 struct aplic_idc {
-	unsigned int		hart_index;
+	u32			hart_index;
 	void __iomem		*regs;
 	struct aplic_direct	*direct;
 };
@@ -219,6 +219,21 @@ static int aplic_direct_parse_parent_hwirq(struct device *dev, u32 index,
 	return 0;
 }

+static int aplic_direct_get_hart_index(struct device *dev, u32 logical_index,
+				       u32 *hart_index)
+{
+	static const char *prop_hart_index = "riscv,hart-indexes";
+	struct device_node *np = to_of_node(dev->fwnode);
+
+	if (!np || !of_property_present(np, prop_hart_index)) {
+		*hart_index = logical_index;
+		return 0;
+	}
+
+	return of_property_read_u32_index(np, prop_hart_index,
+					  logical_index, hart_index);
+}
+
 int aplic_direct_setup(struct device *dev, void __iomem *regs)
 {
 	int i, j, rc, cpu, current_cpu, setup_count = 0;
@@ -265,8 +280,12 @@ int aplic_direct_setup(struct device *dev, void __iomem *regs)
 		cpumask_set_cpu(cpu, &direct->lmask);

 		idc = per_cpu_ptr(&aplic_idcs, cpu);
-		idc->hart_index = i;
-		idc->regs = priv->regs + APLIC_IDC_BASE + i * APLIC_IDC_SIZE;
+		rc = aplic_direct_get_hart_index(dev, i, &idc->hart_index);
+		if (rc) {
+			dev_warn(dev, "hart index not found for IDC%d\n", i);
+			continue;
+		}
+		idc->regs = priv->regs + APLIC_IDC_BASE + idc->hart_index * APLIC_IDC_SIZE;
 		idc->direct = direct;

 		aplic_idc_set_delivery(idc, true);
-- 
2.43.0