--- /dev/null
+// 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);
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