[PATCH v6 05/14] irqchip/riscv-intc: Add support for RISC-V AIA

[Anup Patel <apatel@xxxxxxxxxxxxxxxx>]

The RISC-V advanced interrupt architecture (AIA) extends the per-HART
local interrupts in following ways:
1. Minimum 64 local interrupts for both RV32 and RV64
2. Ability to process multiple pending local interrupts in same
   interrupt handler
3. Priority configuration for each local interrupts
4. Special CSRs to configure/access the per-HART MSI controller

We add support for #1 and #2 described above in the RISC-V intc driver.

Signed-off-by: Anup Patel <apatel@xxxxxxxxxxxxxxxx>
---
 drivers/irqchip/irq-riscv-intc.c | 34 ++++++++++++++++++++++++++------
 1 file changed, 28 insertions(+), 6 deletions(-)

diff --git a/drivers/irqchip/irq-riscv-intc.c b/drivers/irqchip/irq-riscv-intc.c
index 4e2704bc25fb..1a0fc87152c5 100644
--- a/drivers/irqchip/irq-riscv-intc.c
+++ b/drivers/irqchip/irq-riscv-intc.c
@@ -17,6 +17,7 @@
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/smp.h>
+#include <asm/hwcap.h>
 
 static struct irq_domain *intc_domain;
 
@@ -30,6 +31,15 @@ static asmlinkage void riscv_intc_irq(struct pt_regs *regs)
 	generic_handle_domain_irq(intc_domain, cause);
 }
 
+static asmlinkage void riscv_intc_aia_irq(struct pt_regs *regs)
+{
+	unsigned long topi;
+
+	while ((topi = csr_read(CSR_TOPI)))
+		generic_handle_domain_irq(intc_domain,
+					  topi >> TOPI_IID_SHIFT);
+}
+
 /*
  * On RISC-V systems local interrupts are masked or unmasked by writing
  * the SIE (Supervisor Interrupt Enable) CSR.  As CSRs can only be written
@@ -39,12 +49,18 @@ static asmlinkage void riscv_intc_irq(struct pt_regs *regs)
 
 static void riscv_intc_irq_mask(struct irq_data *d)
 {
-	csr_clear(CSR_IE, BIT(d->hwirq));
+	if (IS_ENABLED(CONFIG_32BIT) && d->hwirq >= BITS_PER_LONG)
+		csr_clear(CSR_IEH, BIT(d->hwirq - BITS_PER_LONG));
+	else
+		csr_clear(CSR_IE, BIT(d->hwirq));
 }
 
 static void riscv_intc_irq_unmask(struct irq_data *d)
 {
-	csr_set(CSR_IE, BIT(d->hwirq));
+	if (IS_ENABLED(CONFIG_32BIT) && d->hwirq >= BITS_PER_LONG)
+		csr_set(CSR_IEH, BIT(d->hwirq - BITS_PER_LONG));
+	else
+		csr_set(CSR_IE, BIT(d->hwirq));
 }
 
 static void riscv_intc_irq_eoi(struct irq_data *d)
@@ -115,16 +131,20 @@ static struct fwnode_handle *riscv_intc_hwnode(void)
 
 static int __init riscv_intc_init_common(struct fwnode_handle *fn)
 {
-	int rc;
+	int rc, nr_irqs = riscv_isa_extension_available(NULL, SxAIA) ?
+			  64 : BITS_PER_LONG;
 
-	intc_domain = irq_domain_create_linear(fn, BITS_PER_LONG,
+	intc_domain = irq_domain_create_linear(fn, nr_irqs,
 					       &riscv_intc_domain_ops, NULL);
 	if (!intc_domain) {
 		pr_err("unable to add IRQ domain\n");
 		return -ENXIO;
 	}
 
-	rc = set_handle_irq(&riscv_intc_irq);
+	if (riscv_isa_extension_available(NULL, SxAIA))
+		rc = set_handle_irq(&riscv_intc_aia_irq);
+	else
+		rc = set_handle_irq(&riscv_intc_irq);
 	if (rc) {
 		pr_err("failed to set irq handler\n");
 		return rc;
@@ -132,7 +152,9 @@ 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%s\n",
+		nr_irqs, riscv_isa_extension_available(NULL, SxAIA) ?
+			 " using AIA" : "");
 
 	return 0;
 }
-- 
2.34.1