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>

3 files changed, 193 insertions, 0 deletions

diff --git a/arch/arm/plat-spear/Makefile b/arch/arm/plat-spear/Makefile
index 6f4ad5e9462e..eb89540aeda9 100644
--- a/arch/arm/plat-spear/Makefile
+++ b/arch/arm/plat-spear/Makefile
@@ -4,3 +4,5 @@
 
 # Common support
 obj-y	:= clock.o padmux.o time.o
+
+obj-$(CONFIG_ARCH_SPEAR3XX)	+= shirq.o
diff --git a/arch/arm/plat-spear/include/plat/shirq.h b/arch/arm/plat-spear/include/plat/shirq.h
new file mode 100644
index 000000000000..03ed8b585dcf
--- /dev/null
+++ b/arch/arm/plat-spear/include/plat/shirq.h
@@ -0,0 +1,73 @@
+/*
+ * arch/arm/plat-spear/include/plat/shirq.h
+ *
+ * SPEAr platform shared irq layer header 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.
+ */
+
+#ifndef __PLAT_SHIRQ_H
+#define __PLAT_SHIRQ_H
+
+#include <linux/irq.h>
+#include <linux/types.h>
+
+/*
+ * struct shirq_dev_config: shared irq device configuration
+ *
+ * virq: virtual irq number of device
+ * enb_mask: enable mask of device
+ * status_mask: status mask of device
+ * clear_mask: clear mask of device
+ */
+struct shirq_dev_config {
+	u32 virq;
+	u32 enb_mask;
+	u32 status_mask;
+	u32 clear_mask;
+};
+
+/*
+ * struct shirq_regs: shared irq register configuration
+ *
+ * base: base address of shared irq register
+ * enb_reg: enable register offset
+ * reset_to_enb: val 1 indicates, we need to clear bit for enabling interrupt
+ * status_reg: status register offset
+ * status_reg_mask: status register valid mask
+ * clear_reg: clear register offset
+ * reset_to_clear: val 1 indicates, we need to clear bit for clearing interrupt
+ */
+struct shirq_regs {
+	void __iomem *base;
+	u32 enb_reg;
+	u32 reset_to_enb;
+	u32 status_reg;
+	u32 status_reg_mask;
+	u32 clear_reg;
+	u32 reset_to_clear;
+};
+
+/*
+ * struct spear_shirq: shared irq structure
+ *
+ * irq: hardware irq number
+ * dev_config: array of device config structures which are using "irq" line
+ * dev_count: size of dev_config array
+ * regs: register configuration for shared irq block
+ */
+struct spear_shirq {
+	u32 irq;
+	struct shirq_dev_config *dev_config;
+	u32 dev_count;
+	struct shirq_regs regs;
+};
+
+int spear_shirq_register(struct spear_shirq *shirq);
+
+#endif /* __PLAT_SHIRQ_H */
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;
+}