[v4,02/13] irqchip/riscv-intc: Allow large non-standard interrupt number

Commit Message

Yu Chien Peter Lin Nov. 22, 2023, 12:12 p.m. UTC

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

This limitation prevents us from fully utilizing the available
local interrupt sources. Additionally, the hwirqs used on RISC-V
are sparse, with only interrupt numbers 1, 5 and 9 (plus Sscofpmf
or T-Head's PMU irq) 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 <[e-mail]>
Reviewed-by: Charles Ci-Jyun Wu <[e-mail]>
Reviewed-by: Leo Yu-Chi Liang <[e-mail]>
---
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

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

Comments

Thomas Gleixner Dec. 8, 2023, 3:54 p.m. UTC | #1

On Wed, Nov 22 2023 at 20:12, Yu Chien Peter Lin wrote:
> Currently, the implementation of the RISC-V INTC driver uses the
> interrupt cause as hwirq and has a limitation of supporting a

s/hwirq/hardware interrupt/

Please spell things out. We are not on Xitter here.

> maximum of 64 hwirqs. However, according to the privileged spec,
> interrupt causes >= 16 are defined for platform use.
>
> This limitation prevents us from fully utilizing the available

This limitation prevents to fully utilize the ... 

> local interrupt sources. Additionally, the hwirqs used on RISC-V
> are sparse, with only interrupt numbers 1, 5 and 9 (plus Sscofpmf
> or T-Head's PMU irq) 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.

Yu Chien Peter Lin Dec. 12, 2023, 10:17 a.m. UTC | #2

Hi Thomas,

On Fri, Dec 08, 2023 at 04:54:34PM +0100, Thomas Gleixner wrote:
> On Wed, Nov 22 2023 at 20:12, Yu Chien Peter Lin wrote:
> > Currently, the implementation of the RISC-V INTC driver uses the
> > interrupt cause as hwirq and has a limitation of supporting a
> 
> s/hwirq/hardware interrupt/
> 
> Please spell things out. We are not on Xitter here.
> 
> > maximum of 64 hwirqs. However, according to the privileged spec,
> > interrupt causes >= 16 are defined for platform use.
> >
> > This limitation prevents us from fully utilizing the available
> 
> This limitation prevents to fully utilize the ... 

Okay, will fix.

Thanks,
Peter Lin

Patch

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;
 }