[PATCH v2 2/2] irqchip: add TS-4800 interrupt controller

[Damien Riegel]

This commit adds support for the TS-4800 interrupt controller. This
controller is instantiated in a companion FPGA, and multiplex interrupts
for other FPGA IPs.

As this component is external to the SoC, the SoC might need to reserve
pins, so this controller is implemented as a platform driver and doesn't
use the IRQCHIP_DECLARE construct.

Signed-off-by: Damien Riegel <damien.riegel@xxxxxxxxxxxxxxxxxxxx>
---
Changes in v2:
 - Added chained_irq_{enter,exit} in interrupt handler.

 drivers/irqchip/Kconfig      |   6 ++
 drivers/irqchip/Makefile     |   1 +
 drivers/irqchip/irq-ts4800.c | 163 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 170 insertions(+)
 create mode 100644 drivers/irqchip/irq-ts4800.c

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 27b52c8..e734772 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -137,6 +137,12 @@ config TB10X_IRQC
 	select IRQ_DOMAIN
 	select GENERIC_IRQ_CHIP
 
+config TS4800_IRQ
+	tristate "TS-4800 IRQ controller"
+	select IRQ_DOMAIN
+	help
+	  Support for the TS-4800 FPGA IRQ controller
+
 config VERSATILE_FPGA_IRQ
 	bool
 	select IRQ_DOMAIN
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index bb3048f..ca9de01 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -39,6 +39,7 @@ obj-$(CONFIG_ARCH_NSPIRE)		+= irq-zevio.o
 obj-$(CONFIG_ARCH_VT8500)		+= irq-vt8500.o
 obj-$(CONFIG_ST_IRQCHIP)		+= irq-st.o
 obj-$(CONFIG_TB10X_IRQC)		+= irq-tb10x.o
+obj-$(CONFIG_TS4800_IRQ)		+= irq-ts4800.o
 obj-$(CONFIG_XTENSA)			+= irq-xtensa-pic.o
 obj-$(CONFIG_XTENSA_MX)			+= irq-xtensa-mx.o
 obj-$(CONFIG_IRQ_CROSSBAR)		+= irq-crossbar.o
diff --git a/drivers/irqchip/irq-ts4800.c b/drivers/irqchip/irq-ts4800.c
new file mode 100644
index 0000000..1dc5f3d
--- /dev/null
+++ b/drivers/irqchip/irq-ts4800.c
@@ -0,0 +1,163 @@
+/*
+ * Multiplexed-IRQs driver for TS-4800's FPGA
+ *
+ * Copyright (c) 2015 - Savoir-faire Linux
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/irqdomain.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+
+#define IRQ_MASK        0x4
+#define IRQ_STATUS      0x8
+
+struct ts4800_irq_data {
+	void __iomem            *base;
+	struct irq_domain       *domain;
+	struct irq_chip         irq_chip;
+};
+
+static void ts4800_irq_mask(struct irq_data *d)
+{
+	struct ts4800_irq_data *data = irq_data_get_irq_chip_data(d);
+	u16 mask = 1 << d->hwirq;
+	u16 reg = readw(data->base + IRQ_MASK);
+
+	writew(reg | mask, data->base + IRQ_MASK);
+}
+
+static void ts4800_irq_unmask(struct irq_data *d)
+{
+	struct ts4800_irq_data *data = irq_data_get_irq_chip_data(d);
+	u16 mask = 1 << d->hwirq;
+	u16 reg = readw(data->base + IRQ_MASK);
+
+	writew(reg & ~mask, data->base + IRQ_MASK);
+}
+
+static int ts4800_irqdomain_map(struct irq_domain *d, unsigned int irq,
+				irq_hw_number_t hwirq)
+{
+	struct ts4800_irq_data *data = d->host_data;
+
+	irq_set_chip_and_handler(irq, &data->irq_chip, handle_simple_irq);
+	irq_set_chip_data(irq, data);
+	irq_set_noprobe(irq);
+
+	return 0;
+}
+
+struct irq_domain_ops ts4800_ic_ops = {
+	.map = ts4800_irqdomain_map,
+	.xlate = irq_domain_xlate_onecell,
+};
+
+static void ts4800_ic_chained_handle_irq(struct irq_desc *desc)
+{
+	struct ts4800_irq_data *data = irq_desc_get_handler_data(desc);
+	struct irq_chip *chip = irq_desc_get_chip(desc);
+	u16 status = readw(data->base + IRQ_STATUS);
+
+	chained_irq_enter(chip, desc);
+
+	if (unlikely(status == 0)) {
+		handle_bad_irq(desc);
+		goto out;
+	}
+
+	do {
+		unsigned int bit = __ffs(status);
+		int irq = irq_find_mapping(data->domain, bit);
+
+		status &= ~(1 << bit);
+		generic_handle_irq(irq);
+	} while (status);
+
+out:
+	chained_irq_exit(chip, desc);
+}
+
+static int ts4800_ic_probe(struct platform_device *pdev)
+{
+	struct device_node *node = pdev->dev.of_node;
+	struct ts4800_irq_data *data;
+	struct irq_chip *irq_chip;
+	struct resource *res;
+	int parent_irq;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	data->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(data->base))
+		return PTR_ERR(data->base);
+
+	writew(0xFFFF, data->base + IRQ_MASK);
+
+	parent_irq = irq_of_parse_and_map(node, 0);
+	if (!parent_irq) {
+		dev_err(&pdev->dev, "failed to get parent IRQ\n");
+		return -EINVAL;
+	}
+
+	irq_chip = &data->irq_chip;
+	irq_chip->name = dev_name(&pdev->dev);
+	irq_chip->irq_mask = ts4800_irq_mask;
+	irq_chip->irq_unmask = ts4800_irq_unmask;
+
+	data->domain = irq_domain_add_linear(node, 8, &ts4800_ic_ops, data);
+	if (!data->domain) {
+		dev_err(&pdev->dev, "cannot add IRQ domain\n");
+		return -ENOMEM;
+	}
+
+	irq_set_chained_handler_and_data(parent_irq,
+					 ts4800_ic_chained_handle_irq, data);
+
+	platform_set_drvdata(pdev, data);
+
+	return 0;
+}
+
+static int ts4800_ic_remove(struct platform_device *pdev)
+{
+	struct ts4800_irq_data *data = platform_get_drvdata(pdev);
+
+	irq_domain_remove(data->domain);
+
+	return 0;
+}
+
+static const struct of_device_id ts4800_ic_of_match[] = {
+	{ .compatible = "technologic,ts4800-irqc", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, ts4800_ic_of_match);
+
+static struct platform_driver ts4800_ic_driver = {
+	.probe  = ts4800_ic_probe,
+	.remove = ts4800_ic_remove,
+	.driver = {
+		.name = "ts4800-irqc",
+		.of_match_table = ts4800_ic_of_match,
+	},
+};
+module_platform_driver(ts4800_ic_driver);
+
+MODULE_AUTHOR("Damien Riegel <damien.riegel@xxxxxxxxxxxxxxxxxxxx>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:ts4800_irqc");
-- 
2.5.0

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