ARM: 6091/1: ST SPEAr: Adding support for shared irq layer

Multiple peripherals in SPEAr share common hardware interrupt lines.
This patch adds support for a shared irq layer, which registers hardware
irqs by itself and exposes virtual irq numbers to peripherals.

Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 118 insertions, 0 deletions

diff --git a/arch/arm/plat-spear/shirq.c b/arch/arm/plat-spear/shirq.c
new file mode 100644
index 000000000000..2172d6946aea
--- /dev/null
+++ b/arch/arm/plat-spear/shirq.c
@@ -0,0 +1,118 @@
+/*
+ * arch/arm/plat-spear/shirq.c
+ *
+ * SPEAr platform shared irq layer source file
+ *
+ * Copyright (C) 2009 ST Microelectronics
+ * Viresh Kumar<viresh.kumar@st.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/spinlock.h>
+#include <plat/shirq.h>
+
+struct spear_shirq *shirq;
+static DEFINE_SPINLOCK(lock);
+
+static void shirq_irq_mask(unsigned irq)
+{
+	struct spear_shirq *shirq = get_irq_chip_data(irq);
+	u32 val, id = irq - shirq->dev_config[0].virq;
+	unsigned long flags;
+
+	if ((shirq->regs.enb_reg == -1) || shirq->dev_config[id].enb_mask == -1)
+		return;
+
+	spin_lock_irqsave(&lock, flags);
+	val = readl(shirq->regs.base + shirq->regs.enb_reg);
+	if (shirq->regs.reset_to_enb)
+		val |= shirq->dev_config[id].enb_mask;
+	else
+		val &= ~(shirq->dev_config[id].enb_mask);
+	writel(val, shirq->regs.base + shirq->regs.enb_reg);
+	spin_unlock_irqrestore(&lock, flags);
+}
+
+static void shirq_irq_unmask(unsigned irq)
+{
+	struct spear_shirq *shirq = get_irq_chip_data(irq);
+	u32 val, id = irq - shirq->dev_config[0].virq;
+	unsigned long flags;
+
+	if ((shirq->regs.enb_reg == -1) || shirq->dev_config[id].enb_mask == -1)
+		return;
+
+	spin_lock_irqsave(&lock, flags);
+	val = readl(shirq->regs.base + shirq->regs.enb_reg);
+	if (shirq->regs.reset_to_enb)
+		val &= ~(shirq->dev_config[id].enb_mask);
+	else
+		val |= shirq->dev_config[id].enb_mask;
+	writel(val, shirq->regs.base + shirq->regs.enb_reg);
+	spin_unlock_irqrestore(&lock, flags);
+}
+
+static struct irq_chip shirq_chip = {
+	.name		= "spear_shirq",
+	.ack		= shirq_irq_mask,
+	.mask		= shirq_irq_mask,
+	.unmask		= shirq_irq_unmask,
+};
+
+static void shirq_handler(unsigned irq, struct irq_desc *desc)
+{
+	u32 i, val, mask;
+	struct spear_shirq *shirq = get_irq_data(irq);
+
+	desc->chip->ack(irq);
+	while ((val = readl(shirq->regs.base + shirq->regs.status_reg) &
+				shirq->regs.status_reg_mask)) {
+		for (i = 0; (i < shirq->dev_count) && val; i++) {
+			if (!(shirq->dev_config[i].status_mask & val))
+				continue;
+
+			generic_handle_irq(shirq->dev_config[i].virq);
+
+			/* clear interrupt */
+			val &= ~shirq->dev_config[i].status_mask;
+			if ((shirq->regs.clear_reg == -1) ||
+					shirq->dev_config[i].clear_mask == -1)
+				continue;
+			mask = readl(shirq->regs.base + shirq->regs.clear_reg);
+			if (shirq->regs.reset_to_clear)
+				mask &= ~shirq->dev_config[i].clear_mask;
+			else
+				mask |= shirq->dev_config[i].clear_mask;
+			writel(mask, shirq->regs.base + shirq->regs.clear_reg);
+		}
+	}
+	desc->chip->unmask(irq);
+}
+
+int spear_shirq_register(struct spear_shirq *shirq)
+{
+	int i;
+
+	if (!shirq || !shirq->dev_config || !shirq->regs.base)
+		return -EFAULT;
+
+	if (!shirq->dev_count)
+		return -EINVAL;
+
+	set_irq_chained_handler(shirq->irq, shirq_handler);
+	for (i = 0; i < shirq->dev_count; i++) {
+		set_irq_chip(shirq->dev_config[i].virq, &shirq_chip);
+		set_irq_handler(shirq->dev_config[i].virq, handle_simple_irq);
+		set_irq_flags(shirq->dev_config[i].virq, IRQF_VALID);
+		set_irq_chip_data(shirq->dev_config[i].virq, shirq);
+	}
+
+	set_irq_data(shirq->irq, shirq);
+	return 0;
+}