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

[Vladimir Kondratiev]

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 214 − 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.

Support arbitrary hart indexes specified in optional APLIC property
"riscv,hart-index" that should be array of u32 elements, one per
interrupt target. If this property not specified, fallback is to use
hart ids, with hart index for each APLIC to be (hartid - hartid0)
where hartid0 is hart id for the 1-st target.

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

Signed-off-by: Vladimir Kondratiev <vladimir.kondratiev at mobileye.com>
---
 drivers/irqchip/irq-riscv-aplic-direct.c | 25 ++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-riscv-aplic-direct.c b/drivers/irqchip/irq-riscv-aplic-direct.c
index 7cd6b646774b..80c82e34e894 100644
--- a/drivers/irqchip/irq-riscv-aplic-direct.c
+++ b/drivers/irqchip/irq-riscv-aplic-direct.c
@@ -221,12 +221,15 @@ static int aplic_direct_parse_parent_hwirq(struct device *dev, u32 index,
 
 int aplic_direct_setup(struct device *dev, void __iomem *regs)
 {
+	static const char *prop_hart_index = "riscv,hart-index";
 	int i, j, rc, cpu, current_cpu, setup_count = 0;
 	struct aplic_direct *direct;
 	struct irq_domain *domain;
 	struct aplic_priv *priv;
 	struct aplic_idc *idc;
 	unsigned long hartid;
+	unsigned long hartid0;
+	u32 *hart_index = NULL;
 	u32 v, hwirq;
 
 	direct = devm_kzalloc(dev, sizeof(*direct), GFP_KERNEL);
@@ -240,6 +243,22 @@ int aplic_direct_setup(struct device *dev, void __iomem *regs)
 		return rc;
 	}
 
+	rc = device_property_count_u32(dev, prop_hart_index);
+	if (rc == -ENODATA)
+		rc = 0;
+	if (rc > 0 && rc != priv->nr_idcs)
+		rc = -EOVERFLOW;
+	if (rc > 0) {
+		hart_index = devm_kcalloc(dev, priv->nr_idcs, sizeof(*hart_index), GFP_KERNEL);
+		if (!hart_index)
+			return -ENOMEM;
+		rc = device_property_read_u32_array(dev, prop_hart_index,
+						    hart_index, priv->nr_idcs);
+	}
+	if (rc < 0) {
+		dev_err(dev, "APLIC property \"%s\" error %pe\n", prop_hart_index, ERR_PTR(rc));
+		return rc;
+	}
 	/* Setup per-CPU IDC and target CPU mask */
 	current_cpu = get_cpu();
 	for (i = 0; i < priv->nr_idcs; i++) {
@@ -249,6 +268,8 @@ int aplic_direct_setup(struct device *dev, void __iomem *regs)
 			continue;
 		}
 
+		if (i == 0)
+			hartid0 = hartid;
 		/*
 		 * Skip interrupts other than external interrupts for
 		 * current privilege level.
@@ -265,8 +286,8 @@ 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;
+		idc->hart_index = hart_index ? hart_index[i] : hartid - hartid0;
+		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