[v9,02/10] irqchip/riscv-intc: Allow large non-standard interrupt number

Commit Message

Yu-Chien Peter Lin Feb. 22, 2024, 8:39 a.m. UTC

Currently, the implementation of the RISC-V INTC driver uses the
interrupt cause as the hardware interrupt number, with a maximum of
64 interrupts. However, the platform can expand the interrupt number
further for custom local interrupts.

To fully utilize the available local interrupt sources, switch
to using irq_domain_create_tree() that creates the radix tree
map, add global variables (riscv_intc_nr_irqs, riscv_intc_custom_base
and riscv_intc_custom_nr_irqs) to determine the valid range of local
interrupt number (hwirq).

Signed-off-by: Yu Chien Peter Lin <[e-mail]>
Reviewed-by: Randolph <[e-mail]>
Reviewed-by: Anup Patel <[e-mail]>
Reviewed-by: Atish Patra <[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
Changes v4 -> v5: (Suggested by Thomas)
  - Fix commit message
Changes v5 -> v6: (Suggested by Anup [2])
  - Add riscv_intc_* global variables for checking the range of valid
    interrupt number in riscv_intc_domain_alloc()
  - Advertise the number of interrupts allowed
Changes v6 -> v7:
  - No functional change
Changes v7 -> v8:
  - Include Reviewed-by tags from Anup and Atish
Changes v8 -> v9 (Suggested by Thomas [3]):
  - Fix coding style 
  - Update hwirq range checks
  - Update riscv_intc_* global variables initialization

[1] https://patchwork.kernel.org/project/linux-riscv/patch/[e-mail]/#25573085
[2] https://patchwork.kernel.org/project/linux-riscv/patch/[e-mail]/#25636589
[3] https://patchwork.kernel.org/project/linux-riscv/patch/[e-mail]/#25710584
---
 drivers/irqchip/irq-riscv-intc.c | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

Comments

Thomas Gleixner Feb. 22, 2024, 9:33 p.m. UTC | #1

On Thu, Feb 22 2024 at 16:39, Yu Chien Peter Lin wrote:
> Currently, the implementation of the RISC-V INTC driver uses the
> interrupt cause as the hardware interrupt number, with a maximum of
> 64 interrupts. However, the platform can expand the interrupt number
> further for custom local interrupts.
>
> To fully utilize the available local interrupt sources, switch
> to using irq_domain_create_tree() that creates the radix tree
> map, add global variables (riscv_intc_nr_irqs, riscv_intc_custom_base
> and riscv_intc_custom_nr_irqs) to determine the valid range of local
> interrupt number (hwirq).
>
> Signed-off-by: Yu Chien Peter Lin <[e-mail]>
> Reviewed-by: Randolph <[e-mail]>
> Reviewed-by: Anup Patel <[e-mail]>
> Reviewed-by: Atish Patra <[e-mail]>

Reviewed-by: Thomas Gleixner <[e-mail]>

Patch

diff --git a/drivers/irqchip/irq-riscv-intc.c b/drivers/irqchip/irq-riscv-intc.c
index e8d01b14ccdd..684875c39728 100644
--- a/drivers/irqchip/irq-riscv-intc.c
+++ b/drivers/irqchip/irq-riscv-intc.c
@@ -19,15 +19,16 @@ 
 #include <linux/smp.h>
 
 static struct irq_domain *intc_domain;
+static unsigned int riscv_intc_nr_irqs __ro_after_init = BITS_PER_LONG;
+static unsigned int riscv_intc_custom_base __ro_after_init = BITS_PER_LONG;
+static unsigned int riscv_intc_custom_nr_irqs __ro_after_init;
 
 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);
 }
 
 /*
@@ -93,6 +94,14 @@  static int riscv_intc_domain_alloc(struct irq_domain *domain,
 	if (ret)
 		return ret;
 
+	/*
+	 * Only allow hwirq for which we have corresponding standard or
+	 * custom interrupt enable register.
+	 */
+	if ((hwirq >= riscv_intc_nr_irqs && hwirq < riscv_intc_custom_base) ||
+	    (hwirq >= riscv_intc_custom_base + riscv_intc_custom_nr_irqs))
+		return -EINVAL;
+
 	for (i = 0; i < nr_irqs; i++) {
 		ret = riscv_intc_domain_map(domain, virq + i, hwirq + i);
 		if (ret)
@@ -117,8 +126,7 @@  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;
@@ -132,7 +140,11 @@  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);
+	pr_info("%d local interrupts mapped\n", riscv_intc_nr_irqs);
+	if (riscv_intc_custom_nr_irqs) {
+		pr_info("%d custom local interrupts mapped\n",
+			riscv_intc_custom_nr_irqs);
+	}
 
 	return 0;
 }