[PATCH v9 03/10] irqchip/riscv-intc: Introduce Andes hart-level interrupt controller

[Yu Chien Peter Lin <peterlin@andestech.com>]

Add support for the Andes hart-level interrupt controller. This
controller provides interrupt mask/unmask functions to access the
custom register (SLIE) where the non-standard S-mode local interrupt
enable bits are located. The base of custom interrupt number is set
to 256.

To share the riscv_intc_domain_map() with the generic RISC-V INTC and
ACPI, add a chip parameter to riscv_intc_init_common(), so it can be
passed to the irq_domain_set_info() as a private data.

Andes hart-level interrupt controller requires the "andestech,cpu-intc"
compatible string to be present in interrupt-controller of cpu node to
enable the use of custom local interrupt source.
e.g.,

  cpu0: cpu@0 {
      compatible = "andestech,ax45mp", "riscv";
      ...
      cpu0-intc: interrupt-controller {
          #interrupt-cells = <0x01>;
          compatible = "andestech,cpu-intc", "riscv,cpu-intc";
          interrupt-controller;
      };
  };

Signed-off-by: Yu Chien Peter Lin <peterlin@andestech.com>
Reviewed-by: Randolph <randolph@andestech.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
---
Changes v1 -> v2:
  - New patch
Changes v2 -> v3:
  - Return -ENXIO if no valid compatible INTC found
  - Allow falling back to generic RISC-V INTC
Changes v3 -> v4: (Suggested by Thomas [1])
  - Add comment to andes irq chip function
  - Refine code flow to share with generic RISC-V INTC and ACPI
  - Move Andes specific definitions to include/linux/soc/andes/irq.h
Changes v4 -> v5: (Suggested by Thomas)
  - Fix commit message
  - Subtract ANDES_SLI_CAUSE_BASE from d->hwirq to calculate the value of mask
  - Do not set chip_data to the chip itself with irq_domain_set_info()
  - Follow reverse fir tree order variable declarations
Changes v5 -> v6:
  - To follow the naming on datasheet, rename ANDES_RV_IRQ_PMU to ANDES_RV_IRQ_PMOVI
  - Initialize the riscv_intc_* global variables for Andes INTC (Suggested by Anup)
  - Use BITS_PER_LONG to compute the bit mask of SIE/SLIE as they are 64-bit registers (32-bit for RV32)
Changes v6 -> v7:
  - No change
Changes v7 -> v8:
  - Include Reviewed-by tags from Anup
Changes v8 -> v9:
  - No functional change

[1] https://patchwork.kernel.org/project/linux-riscv/patch/20231019135723.3657156-1-peterlin@andestech.com/
---
 drivers/irqchip/irq-riscv-intc.c | 58 ++++++++++++++++++++++++++++----
 include/linux/soc/andes/irq.h    | 18 ++++++++++
 2 files changed, 69 insertions(+), 7 deletions(-)
 create mode 100644 include/linux/soc/andes/irq.h

diff --git a/drivers/irqchip/irq-riscv-intc.c b/drivers/irqchip/irq-riscv-intc.c
index 684875c39728..0cd6b48a5dbf 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 <linux/soc/andes/irq.h>
 
 static struct irq_domain *intc_domain;
 static unsigned int riscv_intc_nr_irqs __ro_after_init = BITS_PER_LONG;
@@ -48,6 +49,31 @@ static void riscv_intc_irq_unmask(struct irq_data *d)
 	csr_set(CSR_IE, BIT(d->hwirq));
 }
 
+static void andes_intc_irq_mask(struct irq_data *d)
+{
+	/*
+	 * Andes specific S-mode local interrupt causes (hwirq)
+	 * are defined as (256 + n) and controlled by n-th bit
+	 * of SLIE.
+	 */
+	unsigned int mask = BIT(d->hwirq % BITS_PER_LONG);
+
+	if (d->hwirq < ANDES_SLI_CAUSE_BASE)
+		csr_clear(CSR_IE, mask);
+	else
+		csr_clear(ANDES_CSR_SLIE, mask);
+}
+
+static void andes_intc_irq_unmask(struct irq_data *d)
+{
+	unsigned int mask = BIT(d->hwirq % BITS_PER_LONG);
+
+	if (d->hwirq < ANDES_SLI_CAUSE_BASE)
+		csr_set(CSR_IE, mask);
+	else
+		csr_set(ANDES_CSR_SLIE, mask);
+}
+
 static void riscv_intc_irq_eoi(struct irq_data *d)
 {
 	/*
@@ -71,12 +97,21 @@ static struct irq_chip riscv_intc_chip = {
 	.irq_eoi = riscv_intc_irq_eoi,
 };
 
+static struct irq_chip andes_intc_chip = {
+	.name		= "RISC-V INTC",
+	.irq_mask	= andes_intc_irq_mask,
+	.irq_unmask	= andes_intc_irq_unmask,
+	.irq_eoi	= riscv_intc_irq_eoi,
+};
+
 static int riscv_intc_domain_map(struct irq_domain *d, unsigned int irq,
 				 irq_hw_number_t hwirq)
 {
+	struct irq_chip *chip = d->host_data;
+
 	irq_set_percpu_devid(irq);
-	irq_domain_set_info(d, irq, hwirq, &riscv_intc_chip, d->host_data,
-			    handle_percpu_devid_irq, NULL, NULL);
+	irq_domain_set_info(d, irq, hwirq, chip, NULL, handle_percpu_devid_irq,
+			    NULL, NULL);
 
 	return 0;
 }
@@ -122,11 +157,12 @@ static struct fwnode_handle *riscv_intc_hwnode(void)
 	return intc_domain->fwnode;
 }
 
-static int __init riscv_intc_init_common(struct fwnode_handle *fn)
+static int __init riscv_intc_init_common(struct fwnode_handle *fn,
+					 struct irq_chip *chip)
 {
 	int rc;
 
-	intc_domain = irq_domain_create_tree(fn, &riscv_intc_domain_ops, NULL);
+	intc_domain = irq_domain_create_tree(fn, &riscv_intc_domain_ops, chip);
 	if (!intc_domain) {
 		pr_err("unable to add IRQ domain\n");
 		return -ENXIO;
@@ -152,8 +188,9 @@ static int __init riscv_intc_init_common(struct fwnode_handle *fn)
 static int __init riscv_intc_init(struct device_node *node,
 				  struct device_node *parent)
 {
-	int rc;
+	struct irq_chip *chip = &riscv_intc_chip;
 	unsigned long hartid;
+	int rc;
 
 	rc = riscv_of_parent_hartid(node, &hartid);
 	if (rc < 0) {
@@ -178,10 +215,17 @@ static int __init riscv_intc_init(struct device_node *node,
 		return 0;
 	}
 
-	return riscv_intc_init_common(of_node_to_fwnode(node));
+	if (of_device_is_compatible(node, "andestech,cpu-intc")) {
+		riscv_intc_custom_base = ANDES_SLI_CAUSE_BASE;
+		riscv_intc_custom_nr_irqs = ANDES_RV_IRQ_LAST;
+		chip = &andes_intc_chip;
+	}
+
+	return riscv_intc_init_common(of_node_to_fwnode(node), chip);
 }
 
 IRQCHIP_DECLARE(riscv, "riscv,cpu-intc", riscv_intc_init);
+IRQCHIP_DECLARE(andes, "andestech,cpu-intc", riscv_intc_init);
 
 #ifdef CONFIG_ACPI
 
@@ -208,7 +252,7 @@ static int __init riscv_intc_acpi_init(union acpi_subtable_headers *header,
 		return -ENOMEM;
 	}
 
-	return riscv_intc_init_common(fn);
+	return riscv_intc_init_common(fn, &riscv_intc_chip);
 }
 
 IRQCHIP_ACPI_DECLARE(riscv_intc, ACPI_MADT_TYPE_RINTC, NULL,
diff --git a/include/linux/soc/andes/irq.h b/include/linux/soc/andes/irq.h
new file mode 100644
index 000000000000..edc3182d6e66
--- /dev/null
+++ b/include/linux/soc/andes/irq.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2023 Andes Technology Corporation
+ */
+#ifndef __ANDES_IRQ_H
+#define __ANDES_IRQ_H
+
+/* Andes PMU irq number */
+#define ANDES_RV_IRQ_PMOVI		18
+#define ANDES_RV_IRQ_LAST		ANDES_RV_IRQ_PMOVI
+#define ANDES_SLI_CAUSE_BASE		256
+
+/* Andes PMU related registers */
+#define ANDES_CSR_SLIE			0x9c4
+#define ANDES_CSR_SLIP			0x9c5
+#define ANDES_CSR_SCOUNTEROF		0x9d4
+
+#endif /* __ANDES_IRQ_H */
-- 
2.34.1