irqchip: Add Aspeed SCU interrupt controller

The Aspeed SOCs provide some interrupts through the System Control
Unit registers. Add an interrupt controller that provides these
interrupts to the system.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Link: https://lore.kernel.org/r/1579123790-6894-3-git-send-email-eajames@linux.ibm.com

3 files changed, 241 insertions, 1 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index f9f6e4060a92..ac21e7b779c9 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2697,6 +2697,7 @@ M:	Eddie James <eajames@linux.ibm.com>
 L:	linux-aspeed@lists.ozlabs.org (moderated for non-subscribers)
 S:	Maintained
 F:	Documentation/devicetree/bindings/interrupt-controller/aspeed,ast2xxx-scu-ic.txt
+F:	drivers/irqchip/irq-aspeed-scu-ic.c
 F:	include/dt-bindings/interrupt-controller/aspeed-scu-ic.h
 
 ASPEED VIDEO ENGINE DRIVER
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index e806dda690ea..6c9262c673bf 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -87,7 +87,7 @@ obj-$(CONFIG_MVEBU_SEI)			+= irq-mvebu-sei.o
 obj-$(CONFIG_LS_EXTIRQ)			+= irq-ls-extirq.o
 obj-$(CONFIG_LS_SCFG_MSI)		+= irq-ls-scfg-msi.o
 obj-$(CONFIG_EZNPS_GIC)			+= irq-eznps.o
-obj-$(CONFIG_ARCH_ASPEED)		+= irq-aspeed-vic.o irq-aspeed-i2c-ic.o
+obj-$(CONFIG_ARCH_ASPEED)		+= irq-aspeed-vic.o irq-aspeed-i2c-ic.o irq-aspeed-scu-ic.o
 obj-$(CONFIG_STM32_EXTI) 		+= irq-stm32-exti.o
 obj-$(CONFIG_QCOM_IRQ_COMBINER)		+= qcom-irq-combiner.o
 obj-$(CONFIG_IRQ_UNIPHIER_AIDET)	+= irq-uniphier-aidet.o
diff --git a/drivers/irqchip/irq-aspeed-scu-ic.c b/drivers/irqchip/irq-aspeed-scu-ic.c
new file mode 100644
index 000000000000..c90a3346b985
--- /dev/null
+++ b/drivers/irqchip/irq-aspeed-scu-ic.c
@@ -0,0 +1,239 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Aspeed AST24XX, AST25XX, and AST26XX SCU Interrupt Controller
+ * Copyright 2019 IBM Corporation
+ *
+ * Eddie James <eajames@linux.ibm.com>
+ */
+
+#include <linux/bitops.h>
+#include <linux/irq.h>
+#include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/irqdomain.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of_irq.h>
+#include <linux/regmap.h>
+
+#define ASPEED_SCU_IC_REG		0x018
+#define ASPEED_SCU_IC_SHIFT		0
+#define ASPEED_SCU_IC_ENABLE		GENMASK(6, ASPEED_SCU_IC_SHIFT)
+#define ASPEED_SCU_IC_NUM_IRQS		7
+#define ASPEED_SCU_IC_STATUS_SHIFT	16
+
+#define ASPEED_AST2600_SCU_IC0_REG	0x560
+#define ASPEED_AST2600_SCU_IC0_SHIFT	0
+#define ASPEED_AST2600_SCU_IC0_ENABLE	\
+	GENMASK(5, ASPEED_AST2600_SCU_IC0_SHIFT)
+#define ASPEED_AST2600_SCU_IC0_NUM_IRQS	6
+
+#define ASPEED_AST2600_SCU_IC1_REG	0x570
+#define ASPEED_AST2600_SCU_IC1_SHIFT	4
+#define ASPEED_AST2600_SCU_IC1_ENABLE	\
+	GENMASK(5, ASPEED_AST2600_SCU_IC1_SHIFT)
+#define ASPEED_AST2600_SCU_IC1_NUM_IRQS	2
+
+struct aspeed_scu_ic {
+	unsigned long irq_enable;
+	unsigned long irq_shift;
+	unsigned int num_irqs;
+	unsigned int reg;
+	struct regmap *scu;
+	struct irq_domain *irq_domain;
+};
+
+static void aspeed_scu_ic_irq_handler(struct irq_desc *desc)
+{
+	unsigned int irq;
+	unsigned int sts;
+	unsigned long bit;
+	unsigned long enabled;
+	unsigned long max;
+	unsigned long status;
+	struct aspeed_scu_ic *scu_ic = irq_desc_get_handler_data(desc);
+	struct irq_chip *chip = irq_desc_get_chip(desc);
+	unsigned int mask = scu_ic->irq_enable << ASPEED_SCU_IC_STATUS_SHIFT;
+
+	chained_irq_enter(chip, desc);
+
+	/*
+	 * The SCU IC has just one register to control its operation and read
+	 * status. The interrupt enable bits occupy the lower 16 bits of the
+	 * register, while the interrupt status bits occupy the upper 16 bits.
+	 * The status bit for a given interrupt is always 16 bits shifted from
+	 * the enable bit for the same interrupt.
+	 * Therefore, perform the IRQ operations in the enable bit space by
+	 * shifting the status down to get the mapping and then back up to
+	 * clear the bit.
+	 */
+	regmap_read(scu_ic->scu, scu_ic->reg, &sts);
+	enabled = sts & scu_ic->irq_enable;
+	status = (sts >> ASPEED_SCU_IC_STATUS_SHIFT) & enabled;
+
+	bit = scu_ic->irq_shift;
+	max = scu_ic->num_irqs + bit;
+
+	for_each_set_bit_from(bit, &status, max) {
+		irq = irq_find_mapping(scu_ic->irq_domain,
+				       bit - scu_ic->irq_shift);
+		generic_handle_irq(irq);
+
+		regmap_update_bits(scu_ic->scu, scu_ic->reg, mask,
+				   BIT(bit + ASPEED_SCU_IC_STATUS_SHIFT));
+	}
+
+	chained_irq_exit(chip, desc);
+}
+
+static void aspeed_scu_ic_irq_mask(struct irq_data *data)
+{
+	struct aspeed_scu_ic *scu_ic = irq_data_get_irq_chip_data(data);
+	unsigned int mask = BIT(data->hwirq + scu_ic->irq_shift) |
+		(scu_ic->irq_enable << ASPEED_SCU_IC_STATUS_SHIFT);
+
+	/*
+	 * Status bits are cleared by writing 1. In order to prevent the mask
+	 * operation from clearing the status bits, they should be under the
+	 * mask and written with 0.
+	 */
+	regmap_update_bits(scu_ic->scu, scu_ic->reg, mask, 0);
+}
+
+static void aspeed_scu_ic_irq_unmask(struct irq_data *data)
+{
+	struct aspeed_scu_ic *scu_ic = irq_data_get_irq_chip_data(data);
+	unsigned int bit = BIT(data->hwirq + scu_ic->irq_shift);
+	unsigned int mask = bit |
+		(scu_ic->irq_enable << ASPEED_SCU_IC_STATUS_SHIFT);
+
+	/*
+	 * Status bits are cleared by writing 1. In order to prevent the unmask
+	 * operation from clearing the status bits, they should be under the
+	 * mask and written with 0.
+	 */
+	regmap_update_bits(scu_ic->scu, scu_ic->reg, mask, bit);
+}
+
+static int aspeed_scu_ic_irq_set_affinity(struct irq_data *data,
+					  const struct cpumask *dest,
+					  bool force)
+{
+	return -EINVAL;
+}
+
+static struct irq_chip aspeed_scu_ic_chip = {
+	.name			= "aspeed-scu-ic",
+	.irq_mask		= aspeed_scu_ic_irq_mask,
+	.irq_unmask		= aspeed_scu_ic_irq_unmask,
+	.irq_set_affinity	= aspeed_scu_ic_irq_set_affinity,
+};
+
+static int aspeed_scu_ic_map(struct irq_domain *domain, unsigned int irq,
+			     irq_hw_number_t hwirq)
+{
+	irq_set_chip_and_handler(irq, &aspeed_scu_ic_chip, handle_level_irq);
+	irq_set_chip_data(irq, domain->host_data);
+
+	return 0;
+}
+
+static const struct irq_domain_ops aspeed_scu_ic_domain_ops = {
+	.map = aspeed_scu_ic_map,
+};
+
+static int aspeed_scu_ic_of_init_common(struct aspeed_scu_ic *scu_ic,
+					struct device_node *node)
+{
+	int irq;
+	int rc = 0;
+
+	if (!node->parent) {
+		rc = -ENODEV;
+		goto err;
+	}
+
+	scu_ic->scu = syscon_node_to_regmap(node->parent);
+	if (IS_ERR(scu_ic->scu)) {
+		rc = PTR_ERR(scu_ic->scu);
+		goto err;
+	}
+
+	irq = irq_of_parse_and_map(node, 0);
+	if (irq < 0) {
+		rc = irq;
+		goto err;
+	}
+
+	scu_ic->irq_domain = irq_domain_add_linear(node, scu_ic->num_irqs,
+						   &aspeed_scu_ic_domain_ops,
+						   scu_ic);
+	if (!scu_ic->irq_domain) {
+		rc = -ENOMEM;
+		goto err;
+	}
+
+	irq_set_chained_handler_and_data(irq, aspeed_scu_ic_irq_handler,
+					 scu_ic);
+
+	return 0;
+
+err:
+	kfree(scu_ic);
+
+	return rc;
+}
+
+static int __init aspeed_scu_ic_of_init(struct device_node *node,
+					struct device_node *parent)
+{
+	struct aspeed_scu_ic *scu_ic = kzalloc(sizeof(*scu_ic), GFP_KERNEL);
+
+	if (!scu_ic)
+		return -ENOMEM;
+
+	scu_ic->irq_enable = ASPEED_SCU_IC_ENABLE;
+	scu_ic->irq_shift = ASPEED_SCU_IC_SHIFT;
+	scu_ic->num_irqs = ASPEED_SCU_IC_NUM_IRQS;
+	scu_ic->reg = ASPEED_SCU_IC_REG;
+
+	return aspeed_scu_ic_of_init_common(scu_ic, node);
+}
+
+static int __init aspeed_ast2600_scu_ic0_of_init(struct device_node *node,
+						 struct device_node *parent)
+{
+	struct aspeed_scu_ic *scu_ic = kzalloc(sizeof(*scu_ic), GFP_KERNEL);
+
+	if (!scu_ic)
+		return -ENOMEM;
+
+	scu_ic->irq_enable = ASPEED_AST2600_SCU_IC0_ENABLE;
+	scu_ic->irq_shift = ASPEED_AST2600_SCU_IC0_SHIFT;
+	scu_ic->num_irqs = ASPEED_AST2600_SCU_IC0_NUM_IRQS;
+	scu_ic->reg = ASPEED_AST2600_SCU_IC0_REG;
+
+	return aspeed_scu_ic_of_init_common(scu_ic, node);
+}
+
+static int __init aspeed_ast2600_scu_ic1_of_init(struct device_node *node,
+						 struct device_node *parent)
+{
+	struct aspeed_scu_ic *scu_ic = kzalloc(sizeof(*scu_ic), GFP_KERNEL);
+
+	if (!scu_ic)
+		return -ENOMEM;
+
+	scu_ic->irq_enable = ASPEED_AST2600_SCU_IC1_ENABLE;
+	scu_ic->irq_shift = ASPEED_AST2600_SCU_IC1_SHIFT;
+	scu_ic->num_irqs = ASPEED_AST2600_SCU_IC1_NUM_IRQS;
+	scu_ic->reg = ASPEED_AST2600_SCU_IC1_REG;
+
+	return aspeed_scu_ic_of_init_common(scu_ic, node);
+}
+
+IRQCHIP_DECLARE(ast2400_scu_ic, "aspeed,ast2400-scu-ic", aspeed_scu_ic_of_init);
+IRQCHIP_DECLARE(ast2500_scu_ic, "aspeed,ast2500-scu-ic", aspeed_scu_ic_of_init);
+IRQCHIP_DECLARE(ast2600_scu_ic0, "aspeed,ast2600-scu-ic0",
+		aspeed_ast2600_scu_ic0_of_init);
+IRQCHIP_DECLARE(ast2600_scu_ic1, "aspeed,ast2600-scu-ic1",
+		aspeed_ast2600_scu_ic1_of_init);