irqchip: Add support for TI-NSPIRE irqchip

This patch adds support for the interrupt controllers found in some
TI-Nspire models.

FIQ support was taken out to simplify the driver code and may be added
in later. Since Linux on this platform doesn't really use FIQs, this
wasn't really that important in the first place.

[ tglx: Made zevio_handle_irq static and reordered __init functions ]

Signed-off-by: Daniel Tang <dt.tangr@gmail.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Link: http://lkml.kernel.org/r/1386223937-12189-1-git-send-email-dt.tangr@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

3 files changed, 146 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/interrupt-controller/lsi,zevio-intc.txt b/Documentation/devicetree/bindings/interrupt-controller/lsi,zevio-intc.txt
new file mode 100644
index 000000000000..aee38e7c13e7
--- /dev/null
+++ b/Documentation/devicetree/bindings/interrupt-controller/lsi,zevio-intc.txt
@@ -0,0 +1,18 @@
+TI-NSPIRE interrupt controller
+
+Required properties:
+- compatible: Compatible property value should be "lsi,zevio-intc".
+
+- reg: Physical base address of the controller and length of memory mapped
+        region.
+
+- interrupt-controller : Identifies the node as an interrupt controller
+
+Example:
+
+interrupt-controller {
+        compatible = "lsi,zevio-intc";
+        interrupt-controller;
+        reg = <0xDC000000 0x1000>;
+        #interrupt-cells = <1>;
+};
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index c60b9010b152..292b10645fd8 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -20,5 +20,6 @@ obj-$(CONFIG_SIRF_IRQ)			+= irq-sirfsoc.o
 obj-$(CONFIG_RENESAS_INTC_IRQPIN)       += irq-renesas-intc-irqpin.o
 obj-$(CONFIG_RENESAS_IRQC)              += irq-renesas-irqc.o
 obj-$(CONFIG_VERSATILE_FPGA_IRQ)        += irq-versatile-fpga.o
+obj-$(CONFIG_ARCH_NSPIRE)               += irq-zevio.o
 obj-$(CONFIG_ARCH_VT8500)               += irq-vt8500.o
 obj-$(CONFIG_TB10X_IRQC)                += irq-tb10x.o
diff --git a/drivers/irqchip/irq-zevio.c b/drivers/irqchip/irq-zevio.c
new file mode 100644
index 000000000000..8ed04c4a43ee
--- /dev/null
+++ b/drivers/irqchip/irq-zevio.c
@@ -0,0 +1,127 @@
+/*
+ *  linux/drivers/irqchip/irq-zevio.c
+ *
+ *  Copyright (C) 2013 Daniel Tang <tangrs@tangrs.id.au>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+
+#include <asm/mach/irq.h>
+#include <asm/exception.h>
+
+#include "irqchip.h"
+
+#define IO_STATUS       0x000
+#define IO_RAW_STATUS   0x004
+#define IO_ENABLE       0x008
+#define IO_DISABLE      0x00C
+#define IO_CURRENT      0x020
+#define IO_RESET        0x028
+#define IO_MAX_PRIOTY   0x02C
+
+#define IO_IRQ_BASE     0x000
+#define IO_FIQ_BASE     0x100
+
+#define IO_INVERT_SEL   0x200
+#define IO_STICKY_SEL   0x204
+#define IO_PRIORITY_SEL 0x300
+
+#define MAX_INTRS       32
+#define FIQ_START       MAX_INTRS
+
+static struct irq_domain *zevio_irq_domain;
+static void __iomem *zevio_irq_io;
+
+static void zevio_irq_ack(struct irq_data *irqd)
+{
+        struct irq_chip_generic *gc = irq_data_get_irq_chip_data(irqd);
+        struct irq_chip_regs *regs =
+                &container_of(irqd->chip, struct irq_chip_type, chip)->regs;
+
+        readl(gc->reg_base + regs->ack);
+}
+
+static asmlinkage void __exception_irq_entry zevio_handle_irq(struct pt_regs *regs)
+{
+        int irqnr;
+
+        while (readl(zevio_irq_io + IO_STATUS)) {
+                irqnr = readl(zevio_irq_io + IO_CURRENT);
+                irqnr = irq_find_mapping(zevio_irq_domain, irqnr);
+                handle_IRQ(irqnr, regs);
+        };
+}
+
+static void __init zevio_init_irq_base(void __iomem *base)
+{
+        /* Disable all interrupts */
+        writel(~0, base + IO_DISABLE);
+
+        /* Accept interrupts of all priorities */
+        writel(0xF, base + IO_MAX_PRIOTY);
+
+        /* Reset existing interrupts */
+        readl(base + IO_RESET);
+}
+
+static int __init zevio_of_init(struct device_node *node,
+                                struct device_node *parent)
+{
+        unsigned int clr = IRQ_NOREQUEST | IRQ_NOPROBE | IRQ_NOAUTOEN;
+        struct irq_chip_generic *gc;
+        int ret;
+
+        if (WARN_ON(zevio_irq_io || zevio_irq_domain))
+                return -EBUSY;
+
+        zevio_irq_io = of_iomap(node, 0);
+        BUG_ON(!zevio_irq_io);
+
+        /* Do not invert interrupt status bits */
+        writel(~0, zevio_irq_io + IO_INVERT_SEL);
+
+        /* Disable sticky interrupts */
+        writel(0, zevio_irq_io + IO_STICKY_SEL);
+
+        /* We don't use IRQ priorities. Set each IRQ to highest priority. */
+        memset_io(zevio_irq_io + IO_PRIORITY_SEL, 0, MAX_INTRS * sizeof(u32));
+
+        /* Init IRQ and FIQ */
+        zevio_init_irq_base(zevio_irq_io + IO_IRQ_BASE);
+        zevio_init_irq_base(zevio_irq_io + IO_FIQ_BASE);
+
+        zevio_irq_domain = irq_domain_add_linear(node, MAX_INTRS,
+                                                 &irq_generic_chip_ops, NULL);
+        BUG_ON(!zevio_irq_domain);
+
+        ret = irq_alloc_domain_generic_chips(zevio_irq_domain, MAX_INTRS, 1,
+                                             "zevio_intc", handle_level_irq,
+                                             clr, 0, IRQ_GC_INIT_MASK_CACHE);
+        BUG_ON(ret);
+
+        gc = irq_get_domain_generic_chip(zevio_irq_domain, 0);
+        gc->reg_base                            = zevio_irq_io;
+        gc->chip_types[0].chip.irq_ack          = zevio_irq_ack;
+        gc->chip_types[0].chip.irq_mask         = irq_gc_mask_disable_reg;
+        gc->chip_types[0].chip.irq_unmask       = irq_gc_unmask_enable_reg;
+        gc->chip_types[0].regs.mask             = IO_IRQ_BASE + IO_ENABLE;
+        gc->chip_types[0].regs.enable           = IO_IRQ_BASE + IO_ENABLE;
+        gc->chip_types[0].regs.disable          = IO_IRQ_BASE + IO_DISABLE;
+        gc->chip_types[0].regs.ack              = IO_IRQ_BASE + IO_RESET;
+
+        set_handle_irq(zevio_handle_irq);
+
+        pr_info("TI-NSPIRE classic IRQ controller\n");
+        return 0;
+}
+
+IRQCHIP_DECLARE(zevio_irq, "lsi,zevio-intc", zevio_of_init);