[PATCH 3/9] irqchip/riscv-intc: Add support for RISC-V AIA

[Anup Patel <apatel@ventanamicro.com>]

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

This patch adds support for RISC-V AIA in the RISC-V intc driver.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
 drivers/irqchip/irq-riscv-intc.c | 37 ++++++++++++++++++++++++++------
 1 file changed, 31 insertions(+), 6 deletions(-)

diff --git a/drivers/irqchip/irq-riscv-intc.c b/drivers/irqchip/irq-riscv-intc.c
index 784d25645704..e72969295241 100644
--- a/drivers/irqchip/irq-riscv-intc.c
+++ b/drivers/irqchip/irq-riscv-intc.c
@@ -16,6 +16,7 @@
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/smp.h>
+#include <asm/hwcap.h>
 
 static struct irq_domain *intc_domain;
 
@@ -29,6 +30,15 @@ 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
@@ -38,12 +48,18 @@ 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 (d->hwirq < BITS_PER_LONG)
+		csr_clear(CSR_IE, BIT(d->hwirq));
+	else
+		csr_clear(CSR_IEH, BIT(d->hwirq - BITS_PER_LONG));
 }
 
 static void riscv_intc_irq_unmask(struct irq_data *d)
 {
-	csr_set(CSR_IE, BIT(d->hwirq));
+	if (d->hwirq < BITS_PER_LONG)
+		csr_set(CSR_IE, BIT(d->hwirq));
+	else
+		csr_set(CSR_IEH, BIT(d->hwirq - BITS_PER_LONG));
 }
 
 static struct irq_chip riscv_intc_chip = {
@@ -98,7 +114,7 @@ static struct fwnode_handle *riscv_intc_hwnode(void)
 static int __init riscv_intc_init(struct device_node *node,
 				  struct device_node *parent)
 {
-	int rc;
+	int rc, nr_irqs;
 	unsigned long hartid;
 
 	rc = riscv_of_parent_hartid(node, &hartid);
@@ -116,14 +132,21 @@ static int __init riscv_intc_init(struct device_node *node,
 	if (riscv_hartid_to_cpuid(hartid) != smp_processor_id())
 		return 0;
 
-	intc_domain = irq_domain_add_linear(node, BITS_PER_LONG,
+	nr_irqs = BITS_PER_LONG;
+	if (riscv_isa_extension_available(NULL, SxAIA) && BITS_PER_LONG == 32)
+		nr_irqs = nr_irqs * 2;
+
+	intc_domain = irq_domain_add_linear(node, 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;
@@ -131,7 +154,9 @@ static int __init riscv_intc_init(struct device_node *node,
 
 	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