[PATCH v4 4/4] irqchip: Add bcm2836 interrupt controller for Raspberry Pi 2.

[Eric Anholt]

This interrupt controller is the new root interrupt controller with
the timer, PMU events, and IPIs, and the bcm2835's interrupt
controller is chained off of it to handle the peripherals.

I wrote the interrupt chip support, while Andrea Merello wrote the IPI
code.

Signed-off-by: Eric Anholt <eric@xxxxxxxxxx>
Signed-off-by: Andrea Merello <andrea.merello@xxxxxxxxx>
Acked-by: Stephen Warren <swarren@xxxxxxxxxxxxx>
---

v2: Rename functions/globals to bcm2836_arm_local.  Treat per-cpu
    interrupts as per-cpu in mask/unmask.  Add comments about how
    registers work.
v3: Drop debug printfs from PMU interrupt masking.
v4: Use cpu notifiers to unmask IPIs only when Linux wants the CPU up.

 drivers/irqchip/Makefile      |   1 +
 drivers/irqchip/irq-bcm2836.c | 275 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 276 insertions(+)
 create mode 100644 drivers/irqchip/irq-bcm2836.c

diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index b8d4e96..9727681 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -1,6 +1,7 @@
 obj-$(CONFIG_IRQCHIP)			+= irqchip.o
 
 obj-$(CONFIG_ARCH_BCM2835)		+= irq-bcm2835.o
+obj-$(CONFIG_ARCH_BCM2835)		+= irq-bcm2836.o
 obj-$(CONFIG_ARCH_EXYNOS)		+= exynos-combiner.o
 obj-$(CONFIG_ARCH_HIP04)		+= irq-hip04.o
 obj-$(CONFIG_ARCH_MMP)			+= irq-mmp.o
diff --git a/drivers/irqchip/irq-bcm2836.c b/drivers/irqchip/irq-bcm2836.c
new file mode 100644
index 0000000..052bd83
--- /dev/null
+++ b/drivers/irqchip/irq-bcm2836.c
@@ -0,0 +1,275 @@
+/*
+ * Root interrupt controller for the BCM2836 (Raspberry Pi 2).
+ *
+ * Copyright 2015 Broadcom
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/cpu.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/irqchip.h>
+#include <linux/irqdomain.h>
+#include <asm/exception.h>
+
+/*
+ * The low 2 bits identify the CPU that the GPU IRQ goes to, and the
+ * next 2 bits identify the CPU that the GPU FIQ goes to.
+ */
+#define LOCAL_GPU_ROUTING		0x00c
+/* When setting bits 0-3, enables PMU interrupts on that CPU. */
+#define LOCAL_PM_ROUTING_SET		0x010
+/* When setting bits 0-3, disables PMU interrupts on that CPU. */
+#define LOCAL_PM_ROUTING_CLR		0x014
+/*
+ * The low 4 bits of this are the CPU's timer IRQ enables, and the
+ * next 4 bits are the CPU's timer FIQ enables (which override the IRQ
+ * bits).
+ */
+#define LOCAL_TIMER_INT_CONTROL0	0x040
+/*
+ * The low 4 bits of this are the CPU's per-mailbox IRQ enables, and
+ * the next 4 bits are the CPU's per-mailbox FIQ enables (which
+ * override the IRQ bits).
+ */
+#define LOCAL_MAILBOX_INT_CONTROL0	0x050
+/*
+ * The CPU's interrupt status register.  Bits are defined by the the
+ * LOCAL_IRQ_* bits below.
+ */
+#define LOCAL_IRQ_PENDING0		0x060
+/* Same status bits as above, but for FIQ. */
+#define LOCAL_FIQ_PENDING0		0x070
+/*
+ * Mailbox0 write-to-set bits.  There are 16 mailboxes, 4 per CPU, and
+ * these bits are organized by mailbox number and then CPU number.  We
+ * use mailbox 0 for IPIs.  The mailbox's interrupt is raised while
+ * any bit is set.
+ */
+#define LOCAL_MAILBOX0_SET0		0x080
+/* Mailbox0 write-to-clear bits. */
+#define LOCAL_MAILBOX0_CLR0		0x0c0
+
+#define LOCAL_IRQ_CNTPSIRQ	0
+#define LOCAL_IRQ_CNTPNSIRQ	1
+#define LOCAL_IRQ_CNTHPIRQ	2
+#define LOCAL_IRQ_CNTVIRQ	3
+#define LOCAL_IRQ_MAILBOX0	4
+#define LOCAL_IRQ_MAILBOX1	5
+#define LOCAL_IRQ_MAILBOX2	6
+#define LOCAL_IRQ_MAILBOX3	7
+#define LOCAL_IRQ_GPU_FAST	8
+#define LOCAL_IRQ_PMU_FAST	9
+#define LAST_IRQ		LOCAL_IRQ_PMU_FAST
+
+struct bcm2836_arm_irqchip_intc {
+	struct irq_domain *domain;
+	void __iomem *base;
+};
+
+static struct bcm2836_arm_irqchip_intc intc  __read_mostly;
+
+static void bcm2836_arm_irqchip_mask_per_cpu_irq(unsigned int reg_offset,
+						 unsigned int bit,
+						 int cpu)
+{
+	void __iomem *reg = intc.base + reg_offset + 4 * cpu;
+
+	writel(readl(reg) & ~BIT(bit), reg);
+}
+
+static void bcm2836_arm_irqchip_unmask_per_cpu_irq(unsigned int reg_offset,
+						   unsigned int bit,
+						 int cpu)
+{
+	void __iomem *reg = intc.base + reg_offset + 4 * cpu;
+
+	writel(readl(reg) | BIT(bit), reg);
+}
+
+static void bcm2836_arm_irqchip_mask_timer_irq(struct irq_data *d)
+{
+	bcm2836_arm_irqchip_mask_per_cpu_irq(LOCAL_TIMER_INT_CONTROL0,
+					     d->hwirq - LOCAL_IRQ_CNTPSIRQ,
+					     smp_processor_id());
+}
+
+static void bcm2836_arm_irqchip_unmask_timer_irq(struct irq_data *d)
+{
+	bcm2836_arm_irqchip_unmask_per_cpu_irq(LOCAL_TIMER_INT_CONTROL0,
+					       d->hwirq - LOCAL_IRQ_CNTPSIRQ,
+					       smp_processor_id());
+}
+
+static struct irq_chip bcm2836_arm_irqchip_timer = {
+	.name = "bcm2836-timer",
+	.irq_mask = bcm2836_arm_irqchip_mask_timer_irq,
+	.irq_unmask = bcm2836_arm_irqchip_unmask_timer_irq
+};
+
+static void bcm2836_arm_irqchip_mask_pmu_irq(struct irq_data *d)
+{
+	writel(1 << smp_processor_id(), intc.base + LOCAL_PM_ROUTING_CLR);
+}
+
+static void bcm2836_arm_irqchip_unmask_pmu_irq(struct irq_data *d)
+{
+	writel(1 << smp_processor_id(), intc.base + LOCAL_PM_ROUTING_SET);
+}
+
+static struct irq_chip bcm2836_arm_irqchip_pmu = {
+	.name = "bcm2836-pmu",
+	.irq_mask = bcm2836_arm_irqchip_mask_pmu_irq,
+	.irq_unmask = bcm2836_arm_irqchip_unmask_pmu_irq
+};
+
+static void bcm2836_arm_irqchip_mask_gpu_irq(struct irq_data *d)
+{
+}
+
+static void bcm2836_arm_irqchip_unmask_gpu_irq(struct irq_data *d)
+{
+}
+
+static struct irq_chip bcm2836_arm_irqchip_gpu = {
+	.name = "bcm2836-gpu",
+	.irq_mask = bcm2836_arm_irqchip_mask_gpu_irq,
+	.irq_unmask = bcm2836_arm_irqchip_unmask_gpu_irq
+};
+
+static void bcm2836_arm_irqchip_register_irq(int hwirq, struct irq_chip *chip)
+{
+	int irq = irq_create_mapping(intc.domain, hwirq);
+
+	irq_set_percpu_devid(irq);
+	irq_set_chip_and_handler(irq, chip, handle_percpu_devid_irq);
+	irq_set_status_flags(irq, IRQ_NOAUTOEN);
+}
+
+static void __exception_irq_entry bcm2836_arm_irqchip_handle_irq(
+	struct pt_regs *regs)
+{
+	int cpu = smp_processor_id();
+	u32 stat;
+
+	stat = readl_relaxed(intc.base + LOCAL_IRQ_PENDING0 + 4 * cpu);
+	if (stat & 0x10) {
+#ifdef CONFIG_SMP
+		void __iomem *mailbox0 = (intc.base +
+					  LOCAL_MAILBOX0_CLR0 + 16 * cpu);
+		u32 mbox_val = readl(mailbox0);
+		u32 ipi = ffs(mbox_val) - 1;
+
+		writel(1 << ipi, mailbox0);
+		handle_IPI(ipi, regs);
+#endif
+	} else {
+		u32 hwirq = ffs(stat) - 1;
+
+		handle_IRQ(irq_linear_revmap(intc.domain, hwirq), regs);
+	}
+}
+
+#ifdef CONFIG_SMP
+static void bcm2836_arm_irqchip_send_ipi(const struct cpumask *mask,
+					 unsigned int ipi)
+{
+	int cpu;
+	void __iomem *mailbox0_base = intc.base + LOCAL_MAILBOX0_SET0;
+
+	/*
+	 * Ensure that stores to normal memory are visible to the
+	 * other CPUs before issuing the IPI.
+	 */
+	dsb();
+
+	for_each_cpu(cpu, mask)	{
+		writel(1 << ipi, mailbox0_base + 16 * cpu);
+	}
+}
+
+/* Unmasks the IPI on the CPU when it's online. */
+static int bcm2836_arm_irqchip_cpu_notify(struct notifier_block *nfb,
+					  unsigned long action, void *hcpu)
+{
+	unsigned int cpu = (unsigned long)hcpu;
+	unsigned int int_reg = LOCAL_MAILBOX_INT_CONTROL0;
+	unsigned int mailbox = 0;
+
+	if (action == CPU_STARTING || action == CPU_STARTING_FROZEN)
+		bcm2836_arm_irqchip_unmask_per_cpu_irq(int_reg, mailbox, cpu);
+	else if (action == CPU_DYING)
+		bcm2836_arm_irqchip_mask_per_cpu_irq(int_reg, mailbox, cpu);
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block bcm2836_arm_irqchip_cpu_notifier = {
+	.notifier_call = bcm2836_arm_irqchip_cpu_notify,
+	.priority = 100,
+};
+#endif
+
+static const struct irq_domain_ops bcm2836_arm_irqchip_intc_ops = {
+	.xlate = irq_domain_xlate_onecell
+};
+
+static void
+bcm2836_arm_irqchip_smp_init(void)
+{
+#ifdef CONFIG_SMP
+	/* Unmask IPIs to the boot CPU. */
+	bcm2836_arm_irqchip_cpu_notify(&bcm2836_arm_irqchip_cpu_notifier,
+				       CPU_STARTING,
+				       (void *)smp_processor_id());
+	register_cpu_notifier(&bcm2836_arm_irqchip_cpu_notifier);
+
+	set_smp_cross_call(bcm2836_arm_irqchip_send_ipi);
+#endif
+}
+
+static int __init bcm2836_arm_irqchip_l1_intc_of_init(struct device_node *node,
+						      struct device_node *parent)
+{
+	intc.base = of_iomap(node, 0);
+	if (!intc.base) {
+		panic("%s: unable to map local interrupt registers\n",
+			node->full_name);
+	}
+
+	intc.domain = irq_domain_add_linear(node, LAST_IRQ + 1,
+					    &bcm2836_arm_irqchip_intc_ops,
+					    NULL);
+	if (!intc.domain)
+		panic("%s: unable to create IRQ domain\n", node->full_name);
+
+	bcm2836_arm_irqchip_register_irq(LOCAL_IRQ_CNTPSIRQ,
+					 &bcm2836_arm_irqchip_timer);
+	bcm2836_arm_irqchip_register_irq(LOCAL_IRQ_CNTPNSIRQ,
+					 &bcm2836_arm_irqchip_timer);
+	bcm2836_arm_irqchip_register_irq(LOCAL_IRQ_CNTHPIRQ,
+					 &bcm2836_arm_irqchip_timer);
+	bcm2836_arm_irqchip_register_irq(LOCAL_IRQ_CNTVIRQ,
+					 &bcm2836_arm_irqchip_timer);
+	bcm2836_arm_irqchip_register_irq(LOCAL_IRQ_GPU_FAST,
+					 &bcm2836_arm_irqchip_gpu);
+	bcm2836_arm_irqchip_register_irq(LOCAL_IRQ_PMU_FAST,
+					 &bcm2836_arm_irqchip_pmu);
+
+	bcm2836_arm_irqchip_smp_init();
+
+	set_handle_irq(bcm2836_arm_irqchip_handle_irq);
+	return 0;
+}
+
+IRQCHIP_DECLARE(bcm2836_arm_irqchip_l1_intc, "brcm,bcm2836-l1-intc",
+		bcm2836_arm_irqchip_l1_intc_of_init);
-- 
2.1.4

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