ARM: plat-versatile: move FPGA irq driver to drivers/irqchip

This moves the Versatile FPGA interrupt controller driver, used in
the Integrator/AP, Integrator/CP and some Versatile boards, out
of arch/arm/plat-versatile and down to drivers/irqchip where we
have consensus that such drivers belong. The header file is
consequently moved to <linux/platform_data/irq-versatile-fpga.h>.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

3 files changed, 213 insertions, 1 deletions

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 1bb8bf6d7fd4..62ca575701d3 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -1 +1,8 @@
-# empty
+config VERSATILE_FPGA_IRQ
+	bool
+	select IRQ_DOMAIN
+
+config VERSATILE_FPGA_IRQ_NR
+       int
+       default 4
+       depends on VERSATILE_FPGA_IRQ
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 054321db4350..e2e6eb5d32f4 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -1 +1,2 @@
 obj-$(CONFIG_ARCH_BCM2835) += irq-bcm2835.o
+obj-$(CONFIG_VERSATILE_FPGA_IRQ) += irq-versatile-fpga.o
diff --git a/drivers/irqchip/irq-versatile-fpga.c b/drivers/irqchip/irq-versatile-fpga.c
new file mode 100644
index 000000000000..789b3e526930
--- /dev/null
+++ b/drivers/irqchip/irq-versatile-fpga.c
@@ -0,0 +1,204 @@
+/*
+ *  Support for Versatile FPGA-based IRQ controllers
+ */
+#include <linux/bitops.h>
+#include <linux/irq.h>
+#include <linux/io.h>
+#include <linux/irqchip/versatile-fpga.h>
+#include <linux/irqdomain.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+
+#include <asm/exception.h>
+#include <asm/mach/irq.h>
+
+#define IRQ_STATUS		0x00
+#define IRQ_RAW_STATUS		0x04
+#define IRQ_ENABLE_SET		0x08
+#define IRQ_ENABLE_CLEAR	0x0c
+#define INT_SOFT_SET		0x10
+#define INT_SOFT_CLEAR		0x14
+#define FIQ_STATUS		0x20
+#define FIQ_RAW_STATUS		0x24
+#define FIQ_ENABLE		0x28
+#define FIQ_ENABLE_SET		0x28
+#define FIQ_ENABLE_CLEAR	0x2C
+
+/**
+ * struct fpga_irq_data - irq data container for the FPGA IRQ controller
+ * @base: memory offset in virtual memory
+ * @chip: chip container for this instance
+ * @domain: IRQ domain for this instance
+ * @valid: mask for valid IRQs on this controller
+ * @used_irqs: number of active IRQs on this controller
+ */
+struct fpga_irq_data {
+	void __iomem *base;
+	struct irq_chip chip;
+	u32 valid;
+	struct irq_domain *domain;
+	u8 used_irqs;
+};
+
+/* we cannot allocate memory when the controllers are initially registered */
+static struct fpga_irq_data fpga_irq_devices[CONFIG_VERSATILE_FPGA_IRQ_NR];
+static int fpga_irq_id;
+
+static void fpga_irq_mask(struct irq_data *d)
+{
+	struct fpga_irq_data *f = irq_data_get_irq_chip_data(d);
+	u32 mask = 1 << d->hwirq;
+
+	writel(mask, f->base + IRQ_ENABLE_CLEAR);
+}
+
+static void fpga_irq_unmask(struct irq_data *d)
+{
+	struct fpga_irq_data *f = irq_data_get_irq_chip_data(d);
+	u32 mask = 1 << d->hwirq;
+
+	writel(mask, f->base + IRQ_ENABLE_SET);
+}
+
+static void fpga_irq_handle(unsigned int irq, struct irq_desc *desc)
+{
+	struct fpga_irq_data *f = irq_desc_get_handler_data(desc);
+	u32 status = readl(f->base + IRQ_STATUS);
+
+	if (status == 0) {
+		do_bad_IRQ(irq, desc);
+		return;
+	}
+
+	do {
+		irq = ffs(status) - 1;
+		status &= ~(1 << irq);
+		generic_handle_irq(irq_find_mapping(f->domain, irq));
+	} while (status);
+}
+
+/*
+ * Handle each interrupt in a single FPGA IRQ controller.  Returns non-zero
+ * if we've handled at least one interrupt.  This does a single read of the
+ * status register and handles all interrupts in order from LSB first.
+ */
+static int handle_one_fpga(struct fpga_irq_data *f, struct pt_regs *regs)
+{
+	int handled = 0;
+	int irq;
+	u32 status;
+
+	while ((status  = readl(f->base + IRQ_STATUS))) {
+		irq = ffs(status) - 1;
+		handle_IRQ(irq_find_mapping(f->domain, irq), regs);
+		handled = 1;
+	}
+
+	return handled;
+}
+
+/*
+ * Keep iterating over all registered FPGA IRQ controllers until there are
+ * no pending interrupts.
+ */
+asmlinkage void __exception_irq_entry fpga_handle_irq(struct pt_regs *regs)
+{
+	int i, handled;
+
+	do {
+		for (i = 0, handled = 0; i < fpga_irq_id; ++i)
+			handled |= handle_one_fpga(&fpga_irq_devices[i], regs);
+	} while (handled);
+}
+
+static int fpga_irqdomain_map(struct irq_domain *d, unsigned int irq,
+		irq_hw_number_t hwirq)
+{
+	struct fpga_irq_data *f = d->host_data;
+
+	/* Skip invalid IRQs, only register handlers for the real ones */
+	if (!(f->valid & BIT(hwirq)))
+		return -ENOTSUPP;
+	irq_set_chip_data(irq, f);
+	irq_set_chip_and_handler(irq, &f->chip,
+				handle_level_irq);
+	set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);
+	return 0;
+}
+
+static struct irq_domain_ops fpga_irqdomain_ops = {
+	.map = fpga_irqdomain_map,
+	.xlate = irq_domain_xlate_onetwocell,
+};
+
+void __init fpga_irq_init(void __iomem *base, const char *name, int irq_start,
+			  int parent_irq, u32 valid, struct device_node *node)
+{
+	struct fpga_irq_data *f;
+	int i;
+
+	if (fpga_irq_id >= ARRAY_SIZE(fpga_irq_devices)) {
+		pr_err("%s: too few FPGA IRQ controllers, increase CONFIG_PLAT_VERSATILE_FPGA_IRQ_NR\n", __func__);
+		return;
+	}
+	f = &fpga_irq_devices[fpga_irq_id];
+	f->base = base;
+	f->chip.name = name;
+	f->chip.irq_ack = fpga_irq_mask;
+	f->chip.irq_mask = fpga_irq_mask;
+	f->chip.irq_unmask = fpga_irq_unmask;
+	f->valid = valid;
+
+	if (parent_irq != -1) {
+		irq_set_handler_data(parent_irq, f);
+		irq_set_chained_handler(parent_irq, fpga_irq_handle);
+	}
+
+	/* This will also allocate irq descriptors */
+	f->domain = irq_domain_add_simple(node, fls(valid), irq_start,
+					  &fpga_irqdomain_ops, f);
+
+	/* This will allocate all valid descriptors in the linear case */
+	for (i = 0; i < fls(valid); i++)
+		if (valid & BIT(i)) {
+			if (!irq_start)
+				irq_create_mapping(f->domain, i);
+			f->used_irqs++;
+		}
+
+	pr_info("FPGA IRQ chip %d \"%s\" @ %p, %u irqs\n",
+		fpga_irq_id, name, base, f->used_irqs);
+
+	fpga_irq_id++;
+}
+
+#ifdef CONFIG_OF
+int __init fpga_irq_of_init(struct device_node *node,
+			    struct device_node *parent)
+{
+	struct fpga_irq_data *f;
+	void __iomem *base;
+	u32 clear_mask;
+	u32 valid_mask;
+
+	if (WARN_ON(!node))
+		return -ENODEV;
+
+	base = of_iomap(node, 0);
+	WARN(!base, "unable to map fpga irq registers\n");
+
+	if (of_property_read_u32(node, "clear-mask", &clear_mask))
+		clear_mask = 0;
+
+	if (of_property_read_u32(node, "valid-mask", &valid_mask))
+		valid_mask = 0;
+
+	fpga_irq_init(base, node->name, 0, -1, valid_mask, node);
+
+	writel(clear_mask, base + IRQ_ENABLE_CLEAR);
+	writel(clear_mask, base + FIQ_ENABLE_CLEAR);
+
+	return 0;
+}
+#endif