[PATCH v5 02/16] irqchip/riscv-intc: Allow large non-standard interrupt number

[Yu Chien Peter Lin]

Currently, the implementation of the RISC-V INTC driver uses the
interrupt cause as hardware interrupt number and has a limitation of
supporting a maximum of 64 interrupts. However, according to the
privileged spec, interrupt causes >= 16 are defined for platform use.

This limitation prevents to fully utilize the available local interrupt
sources. Additionally, the interrupt number used on RISC-V are sparse,
with only interrupt numbers 1, 5 and 9 (plus Sscofpmf or T-Head's PMU
interrupt) being currently used for supervisor mode.

Switch to using irq_domain_create_tree() to create the radix tree
map, so a larger number of hardware interrupts can be handled.

Signed-off-by: Yu Chien Peter Lin <peterlin at andestech.com>
Reviewed-by: Charles Ci-Jyun Wu <dminus at andestech.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang at andestech.com>
---
Changes v1 -> v2:
  - Fixed irq mapping failure checking (suggested by Clément and Anup)
Changes v2 -> v3:
  - No change
Changes v3 -> v4: (Suggested by Thomas [1])
  - Use pr_warn_ratelimited instead
  - Fix coding style and commit message
Changes v4 -> v5: (Suggested by Thomas)
  - Fix commit message

[1] https://patchwork.kernel.org/project/linux-riscv/patch/20231023004100.2663486-3-peterlin@andestech.com/#25573085
---
 drivers/irqchip/irq-riscv-intc.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/irqchip/irq-riscv-intc.c b/drivers/irqchip/irq-riscv-intc.c
index e8d01b14ccdd..2fdd40f2a791 100644
--- a/drivers/irqchip/irq-riscv-intc.c
+++ b/drivers/irqchip/irq-riscv-intc.c
@@ -24,10 +24,9 @@ static asmlinkage void riscv_intc_irq(struct pt_regs *regs)
 {
 	unsigned long cause = regs->cause & ~CAUSE_IRQ_FLAG;
 
-	if (unlikely(cause >= BITS_PER_LONG))
-		panic("unexpected interrupt cause");
-
-	generic_handle_domain_irq(intc_domain, cause);
+	if (generic_handle_domain_irq(intc_domain, cause))
+		pr_warn_ratelimited("Failed to handle interrupt (cause: %ld)\n",
+				    cause);
 }
 
 /*
@@ -117,8 +116,7 @@ static int __init riscv_intc_init_common(struct fwnode_handle *fn)
 {
 	int rc;
 
-	intc_domain = irq_domain_create_linear(fn, BITS_PER_LONG,
-					       &riscv_intc_domain_ops, NULL);
+	intc_domain = irq_domain_create_tree(fn, &riscv_intc_domain_ops, NULL);
 	if (!intc_domain) {
 		pr_err("unable to add IRQ domain\n");
 		return -ENXIO;
@@ -132,8 +130,6 @@ static int __init riscv_intc_init_common(struct fwnode_handle *fn)
 
 	riscv_set_intc_hwnode_fn(riscv_intc_hwnode);
 
-	pr_info("%d local interrupts mapped\n", BITS_PER_LONG);
-
 	return 0;
 }
 
-- 
2.34.1