[RFC 3/3] irqchip: Add Realtek RTD1295 mux driver

["Andreas Färber" <afaerber@suse.de>]

This irq mux driver is derived from the RTD1295 vendor DT and assumes a linear
mapping between intr_en and intr_status registers. Code for RTD119x indicates
this may not always be the case (i2c_3).

The register initialization was copied from QNAP's mach-rtk119x/rtk_irq_mux.c
as a boot fix, without full insights into what exactly this is changing (TODO).

Signed-off-by: Andreas Färber <afaerber@suse.de>
---
 drivers/irqchip/Makefile          |   1 +
 drivers/irqchip/irq-rtd119x-mux.c | 201 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 202 insertions(+)
 create mode 100644 drivers/irqchip/irq-rtd119x-mux.c

diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index e88d856cc09c..46202a0b7d96 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -78,3 +78,4 @@ obj-$(CONFIG_EZNPS_GIC)			+= irq-eznps.o
 obj-$(CONFIG_ARCH_ASPEED)		+= irq-aspeed-vic.o irq-aspeed-i2c-ic.o
 obj-$(CONFIG_STM32_EXTI) 		+= irq-stm32-exti.o
 obj-$(CONFIG_QCOM_IRQ_COMBINER)		+= qcom-irq-combiner.o
+obj-$(CONFIG_ARCH_REALTEK)		+= irq-rtd119x-mux.o
diff --git a/drivers/irqchip/irq-rtd119x-mux.c b/drivers/irqchip/irq-rtd119x-mux.c
new file mode 100644
index 000000000000..c6c1ba126bf3
--- /dev/null
+++ b/drivers/irqchip/irq-rtd119x-mux.c
@@ -0,0 +1,201 @@
+/*
+ * Realtek RTD129x IRQ mux
+ *
+ * Copyright (c) 2017 Andreas Färber
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <linux/io.h>
+#include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/irqdomain.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/slab.h>
+
+struct rtd119x_irq_mux_info {
+	unsigned intr_status;
+	unsigned intr_en;
+};
+
+struct rtd119x_irq_mux_data {
+	void __iomem *intr_status;
+	void __iomem *intr_en;
+	int irq;
+	struct irq_domain *domain;
+	spinlock_t lock;
+};
+
+static void rtd119x_mux_irq_handle(struct irq_desc *desc)
+{
+	struct rtd119x_irq_mux_data *data = irq_desc_get_handler_data(desc);
+	struct irq_chip *chip = irq_desc_get_chip(desc);
+	u32 intr_en, intr_status, status;
+	int ret;
+
+	chained_irq_enter(chip, desc);
+
+	spin_lock(&data->lock);
+	intr_en     = readl(data->intr_en);
+	intr_status = readl(data->intr_status);
+	spin_unlock(&data->lock);
+
+	status = intr_status & intr_en;
+	if (status != 0) {
+		unsigned irq = __ffs(status);
+		ret = generic_handle_irq(irq_find_mapping(data->domain, irq));
+		if (ret == 0) {
+			spin_lock(&data->lock);
+			intr_status = readl(data->intr_status);
+			intr_status |= BIT(irq - 1);
+			writel(intr_status, data->intr_status);
+			spin_unlock(&data->lock);
+		}
+	}
+
+	chained_irq_exit(chip, desc);
+}
+
+static void rtd119x_mux_mask_irq(struct irq_data *data)
+{
+	struct rtd119x_irq_mux_data *mux_data = irq_data_get_irq_chip_data(data);
+	u32 intr_status;
+
+	intr_status = readl(mux_data->intr_status);
+	intr_status |= BIT(data->hwirq);
+	writel(intr_status, mux_data->intr_status);
+}
+
+static void rtd119x_mux_unmask_irq(struct irq_data *data)
+{
+	struct rtd119x_irq_mux_data *mux_data = irq_data_get_irq_chip_data(data);
+	u32 intr_en;
+
+	intr_en = readl(mux_data->intr_en);
+	intr_en |= BIT(data->hwirq);
+	writel(intr_en, mux_data->intr_en);
+}
+
+static int rtd119x_mux_set_affinity(struct irq_data *d,
+			const struct cpumask *mask_val, bool force)
+{
+	struct rtd119x_irq_mux_data *mux_data = irq_data_get_irq_chip_data(d);
+	struct irq_chip *chip = irq_get_chip(mux_data->irq);
+	struct irq_data *data = irq_get_irq_data(mux_data->irq);
+
+	if (chip && chip->irq_set_affinity)
+		return chip->irq_set_affinity(data, mask_val, force);
+
+	return -EINVAL;
+}
+
+static struct irq_chip rtd119x_mux_irq_chip = {
+	.name			= "rtd119x-mux",
+	.irq_mask		= rtd119x_mux_mask_irq,
+	.irq_unmask		= rtd119x_mux_unmask_irq,
+	.irq_set_affinity	= rtd119x_mux_set_affinity,
+};
+
+static int rtd119x_mux_irq_domain_xlate(struct irq_domain *d,
+		struct device_node *controller,
+		const u32 *intspec, unsigned int intsize,
+		unsigned long *out_hwirq,
+		unsigned int *out_type)
+{
+	if (irq_domain_get_of_node(d) != controller)
+		return -EINVAL;
+
+	if (intsize < 1)
+		return -EINVAL;
+
+	*out_hwirq = intspec[0];
+	*out_type = 0;
+
+	return 0;
+}
+
+static int rtd119x_mux_irq_domain_map(struct irq_domain *d,
+		unsigned int irq, irq_hw_number_t hw)
+{
+	struct rtd119x_irq_mux_data *data = d->host_data;
+
+	irq_set_chip_and_handler(irq, &rtd119x_mux_irq_chip, handle_level_irq);
+	irq_set_chip_data(irq, data);
+	irq_set_probe(irq);
+
+	return 0;
+}
+
+static struct irq_domain_ops rtd119x_mux_irq_domain_ops = {
+	.xlate	= rtd119x_mux_irq_domain_xlate,
+	.map	= rtd119x_mux_irq_domain_map,
+};
+
+static int __init rtd119x_irq_mux_init(struct device_node *node,
+				       struct device_node *parent,
+				       const struct rtd119x_irq_mux_info *info)
+{
+	struct rtd119x_irq_mux_data *data;
+	void __iomem *base;
+	u32 val;
+
+	base = of_iomap(node, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->intr_status = base + info->intr_status;
+	data->intr_en     = base + info->intr_en;
+
+	data->irq = irq_of_parse_and_map(node, 0);
+	if (data->irq <= 0) {
+		kfree(data);
+		return -EINVAL;
+	}
+
+	data->domain = irq_domain_add_linear(node, 32,
+				&rtd119x_mux_irq_domain_ops, data);
+	if (!data->domain) {
+		kfree(data);
+		return -ENOMEM;
+	}
+
+	/* TODO Investigate why these are necessary (from downstream rtk119x rtk_irq_mux.c) */
+	val = readl(data->intr_en);
+	val &= ~BIT(2);
+	writel(val, data->intr_en);
+
+	writel(BIT(2), data->intr_status);
+
+	irq_set_chained_handler_and_data(data->irq, rtd119x_mux_irq_handle, data);
+
+	return 0;
+}
+
+static const struct rtd119x_irq_mux_info rtd1295_iso_irq_mux_info = {
+	.intr_status	= 0x0,
+	.intr_en	= 0x40,
+};
+
+static int __init rtd1295_iso_irq_mux_init(struct device_node *node,
+					   struct device_node *parent)
+{
+	return rtd119x_irq_mux_init(node, parent, &rtd1295_iso_irq_mux_info);
+}
+IRQCHIP_DECLARE(rtd1295_iso_mux, "realtek,rtd1295-iso-irq-mux", rtd1295_iso_irq_mux_init);
+
+static const struct rtd119x_irq_mux_info rtd1295_irq_mux_info = {
+	.intr_status	= 0xc,
+	.intr_en	= 0x80,
+};
+
+static int __init rtd1295_irq_mux_init(struct device_node *node,
+				       struct device_node *parent)
+{
+	return rtd119x_irq_mux_init(node, parent, &rtd1295_irq_mux_info);
+}
+IRQCHIP_DECLARE(rtd1295_mux, "realtek,rtd1295-irq-mux", rtd1295_irq_mux_init);
-- 
2.12.3