irqchip: vf610-mscm-ir: Add support for Vybrid MSCM interrupt router

This adds support for Vybrid's interrupt router. On VF6xx models,
almost all peripherals can be used by either of the two CPU's,
the Cortex-A5 or the Cortex-M4. The interrupt router routes the
peripheral interrupts to the configured CPU.

This IRQ chip driver configures the interrupt router to route
the requested interrupt to the CPU the kernel is running on.
The driver makes use of the irqdomain hierarchy support. The
parent is given by the device tree. This should be one of the
two possible parents either ARM GIC or the ARM NVIC interrupt
controller. The latter is currently not yet supported.

Note that there is no resource control mechnism implemented to
avoid concurrent access of the same peripheral. The user needs
to make sure to use device trees which assign the peripherals
orthogonally. However, this driver warns the user in case the
interrupt is already configured for the other CPU. This provides
a poor man's resource controller.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Stefan Agner <stefan@agner.ch>
Link: https://lkml.kernel.org/r/1425249689-32354-2-git-send-email-stefan@agner.ch
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

2 files changed, 213 insertions, 0 deletions

diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 42965d2476bb..9176c76eb164 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -37,6 +37,7 @@ obj-$(CONFIG_TB10X_IRQC)		+= irq-tb10x.o
 obj-$(CONFIG_XTENSA)			+= irq-xtensa-pic.o
 obj-$(CONFIG_XTENSA_MX)			+= irq-xtensa-mx.o
 obj-$(CONFIG_IRQ_CROSSBAR)		+= irq-crossbar.o
+obj-$(CONFIG_SOC_VF610)			+= irq-vf610-mscm-ir.o
 obj-$(CONFIG_BCM7120_L2_IRQ)		+= irq-bcm7120-l2.o
 obj-$(CONFIG_BRCMSTB_L2_IRQ)		+= irq-brcmstb-l2.o
 obj-$(CONFIG_KEYSTONE_IRQ)		+= irq-keystone.o
diff --git a/drivers/irqchip/irq-vf610-mscm-ir.c b/drivers/irqchip/irq-vf610-mscm-ir.c
new file mode 100644
index 000000000000..9521057d4744
--- /dev/null
+++ b/drivers/irqchip/irq-vf610-mscm-ir.c
@@ -0,0 +1,212 @@
+/*
+ * Copyright (C) 2014-2015 Toradex AG
+ * Author: Stefan Agner <stefan@agner.ch>
+ *
+ * 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.
+ *
+ *
+ * IRQ chip driver for MSCM interrupt router available on Vybrid SoC's.
+ * The interrupt router is between the CPU's interrupt controller and the
+ * peripheral. The router allows to route the peripheral interrupts to
+ * one of the two available CPU's on Vybrid VF6xx SoC's (Cortex-A5 or
+ * Cortex-M4). The router will be configured transparently on a IRQ
+ * request.
+ *
+ * o All peripheral interrupts of the Vybrid SoC can be routed to
+ *   CPU 0, CPU 1 or both. The routing is useful for dual-core
+ *   variants of Vybrid SoC such as VF6xx. This driver routes the
+ *   requested interrupt to the CPU currently running on.
+ *
+ * o It is required to setup the interrupt router even on single-core
+ *   variants of Vybrid.
+ */
+
+#include <linux/cpu_pm.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
+#include <linux/mfd/syscon.h>
+#include <dt-bindings/interrupt-controller/arm-gic.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+#include <linux/regmap.h>
+
+#include "irqchip.h"
+
+#define MSCM_CPxNUM		0x4
+
+#define MSCM_IRSPRC(n)		(0x80 + 2 * (n))
+#define MSCM_IRSPRC_CPEN_MASK	0x3
+
+#define MSCM_IRSPRC_NUM		112
+
+struct vf610_mscm_ir_chip_data {
+	void __iomem *mscm_ir_base;
+	u16 cpu_mask;
+	u16 saved_irsprc[MSCM_IRSPRC_NUM];
+};
+
+static struct vf610_mscm_ir_chip_data *mscm_ir_data;
+
+static inline void vf610_mscm_ir_save(struct vf610_mscm_ir_chip_data *data)
+{
+	int i;
+
+	for (i = 0; i < MSCM_IRSPRC_NUM; i++)
+		data->saved_irsprc[i] = readw_relaxed(data->mscm_ir_base + MSCM_IRSPRC(i));
+}
+
+static inline void vf610_mscm_ir_restore(struct vf610_mscm_ir_chip_data *data)
+{
+	int i;
+
+	for (i = 0; i < MSCM_IRSPRC_NUM; i++)
+		writew_relaxed(data->saved_irsprc[i], data->mscm_ir_base + MSCM_IRSPRC(i));
+}
+
+static int vf610_mscm_ir_notifier(struct notifier_block *self,
+				  unsigned long cmd, void *v)
+{
+	switch (cmd) {
+	case CPU_CLUSTER_PM_ENTER:
+		vf610_mscm_ir_save(mscm_ir_data);
+		break;
+	case CPU_CLUSTER_PM_ENTER_FAILED:
+	case CPU_CLUSTER_PM_EXIT:
+		vf610_mscm_ir_restore(mscm_ir_data);
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block mscm_ir_notifier_block = {
+	.notifier_call = vf610_mscm_ir_notifier,
+};
+
+static void vf610_mscm_ir_enable(struct irq_data *data)
+{
+	irq_hw_number_t hwirq = data->hwirq;
+	struct vf610_mscm_ir_chip_data *chip_data = data->chip_data;
+	u16 irsprc;
+
+	irsprc = readw_relaxed(chip_data->mscm_ir_base + MSCM_IRSPRC(hwirq));
+	irsprc &= MSCM_IRSPRC_CPEN_MASK;
+
+	WARN_ON(irsprc & ~chip_data->cpu_mask);
+
+	writew_relaxed(chip_data->cpu_mask,
+		       chip_data->mscm_ir_base + MSCM_IRSPRC(hwirq));
+
+	irq_chip_unmask_parent(data);
+}
+
+static void vf610_mscm_ir_disable(struct irq_data *data)
+{
+	irq_hw_number_t hwirq = data->hwirq;
+	struct vf610_mscm_ir_chip_data *chip_data = data->chip_data;
+
+	writew_relaxed(0x0, chip_data->mscm_ir_base + MSCM_IRSPRC(hwirq));
+
+	irq_chip_mask_parent(data);
+}
+
+static struct irq_chip vf610_mscm_ir_irq_chip = {
+	.name			= "mscm-ir",
+	.irq_mask		= irq_chip_mask_parent,
+	.irq_unmask		= irq_chip_unmask_parent,
+	.irq_eoi		= irq_chip_eoi_parent,
+	.irq_enable		= vf610_mscm_ir_enable,
+	.irq_disable		= vf610_mscm_ir_disable,
+	.irq_retrigger		= irq_chip_retrigger_hierarchy,
+	.irq_set_affinity	= irq_chip_set_affinity_parent,
+};
+
+static int vf610_mscm_ir_domain_alloc(struct irq_domain *domain, unsigned int virq,
+				      unsigned int nr_irqs, void *arg)
+{
+	int i;
+	irq_hw_number_t hwirq;
+	struct of_phandle_args *irq_data = arg;
+	struct of_phandle_args gic_data;
+
+	if (irq_data->args_count != 2)
+		return -EINVAL;
+
+	hwirq = irq_data->args[0];
+	for (i = 0; i < nr_irqs; i++)
+		irq_domain_set_hwirq_and_chip(domain, virq + i, hwirq + i,
+					      &vf610_mscm_ir_irq_chip,
+					      domain->host_data);
+
+	gic_data.np = domain->parent->of_node;
+	gic_data.args_count = 3;
+	gic_data.args[0] = GIC_SPI;
+	gic_data.args[1] = irq_data->args[0];
+	gic_data.args[2] = irq_data->args[1];
+	return irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, &gic_data);
+}
+
+static const struct irq_domain_ops mscm_irq_domain_ops = {
+	.xlate = irq_domain_xlate_twocell,
+	.alloc = vf610_mscm_ir_domain_alloc,
+	.free = irq_domain_free_irqs_common,
+};
+
+static int __init vf610_mscm_ir_of_init(struct device_node *node,
+			       struct device_node *parent)
+{
+	struct irq_domain *domain, *domain_parent;
+	struct regmap *mscm_cp_regmap;
+	int ret, cpuid;
+
+	domain_parent = irq_find_host(parent);
+	if (!domain_parent) {
+		pr_err("vf610_mscm_ir: interrupt-parent not found\n");
+		return -EINVAL;
+	}
+
+	mscm_ir_data = kzalloc(sizeof(*mscm_ir_data), GFP_KERNEL);
+	if (!mscm_ir_data)
+		return -ENOMEM;
+
+	mscm_ir_data->mscm_ir_base = of_io_request_and_map(node, 0, "mscm-ir");
+
+	if (!mscm_ir_data->mscm_ir_base) {
+		pr_err("vf610_mscm_ir: unable to map mscm register\n");
+		ret = -ENOMEM;
+		goto out_free;
+	}
+
+	mscm_cp_regmap = syscon_regmap_lookup_by_phandle(node, "fsl,cpucfg");
+	if (IS_ERR(mscm_cp_regmap)) {
+		ret = PTR_ERR(mscm_cp_regmap);
+		pr_err("vf610_mscm_ir: regmap lookup for cpucfg failed\n");
+		goto out_unmap;
+	}
+
+	regmap_read(mscm_cp_regmap, MSCM_CPxNUM, &cpuid);
+	mscm_ir_data->cpu_mask = 0x1 << cpuid;
+
+	domain = irq_domain_add_hierarchy(domain_parent, 0,
+					  MSCM_IRSPRC_NUM, node,
+					  &mscm_irq_domain_ops, mscm_ir_data);
+	if (!domain) {
+		ret = -ENOMEM;
+		goto out_unmap;
+	}
+
+	cpu_pm_register_notifier(&mscm_ir_notifier_block);
+
+	return 0;
+
+out_unmap:
+	iounmap(mscm_ir_data->mscm_ir_base);
+out_free:
+	kfree(mscm_ir_data);
+	return ret;
+}
+IRQCHIP_DECLARE(vf610_mscm_ir, "fsl,vf610-mscm-ir", vf610_mscm_ir_of_init);