[PATCH] irqchip: bcm2835: Add FIQ support

[Noralf Trønnes]

Add a duplicate irq range with an offset on the hwirq's so the
driver can detect that enable_fiq() is used.
Tested with downstream dwc_otg USB controller driver.

Signed-off-by: Noralf Trønnes <noralf at tronnes.org>
---
 arch/arm/mach-bcm/Kconfig     |  1 +
 drivers/irqchip/irq-bcm2835.c | 53 ++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 48 insertions(+), 6 deletions(-)

diff --git a/arch/arm/mach-bcm/Kconfig b/arch/arm/mach-bcm/Kconfig
index 8b11f44..7cfef7b 100644
--- a/arch/arm/mach-bcm/Kconfig
+++ b/arch/arm/mach-bcm/Kconfig
@@ -114,6 +114,7 @@ config ARCH_BCM2835
 	select ARM_ERRATA_411920
 	select ARM_TIMER_SP804
 	select CLKSRC_OF
+	select FIQ
 	select PINCTRL
 	select PINCTRL_BCM2835
 	help
diff --git a/drivers/irqchip/irq-bcm2835.c b/drivers/irqchip/irq-bcm2835.c
index 5916d6c..db66246 100644
--- a/drivers/irqchip/irq-bcm2835.c
+++ b/drivers/irqchip/irq-bcm2835.c
@@ -56,7 +56,7 @@
 #include "irqchip.h"
 
 /* Put the bank and irq (32 bits) into the hwirq */
-#define MAKE_HWIRQ(b, n)	((b << 5) | (n))
+#define MAKE_HWIRQ(b, n)	(((b) << 5) | (n))
 #define HWIRQ_BANK(i)		(i >> 5)
 #define HWIRQ_BIT(i)		BIT(i & 0x1f)
 
@@ -72,9 +72,13 @@
 					| SHORTCUT1_MASK | SHORTCUT2_MASK)
 
 #define REG_FIQ_CONTROL		0x0c
+#define REG_FIQ_ENABLE		0x80
+#define REG_FIQ_DISABLE		0
 
 #define NR_BANKS		3
 #define IRQS_PER_BANK		32
+#define NUMBER_IRQS		MAKE_HWIRQ(NR_BANKS, 0)
+#define FIQ_START		(NR_IRQS_BANK0 + MAKE_HWIRQ(NR_BANKS - 1, 0))
 
 static int reg_pending[] __initconst = { 0x00, 0x04, 0x08 };
 static int reg_enable[] __initconst = { 0x18, 0x10, 0x14 };
@@ -98,14 +102,38 @@ static struct armctrl_ic intc __read_mostly;
 static void __exception_irq_entry bcm2835_handle_irq(
 	struct pt_regs *regs);
 
+static inline unsigned int hwirq_to_fiq(unsigned long hwirq)
+{
+	hwirq -= NUMBER_IRQS;
+	/*
+	 * The hwirq numbering used in this driver is:
+	 *   BASE (0-7) GPU1 (32-63) GPU2 (64-95).
+	 * This differ from the one used in the FIQ register:
+	 *   GPU1 (0-31) GPU2 (32-63) BASE (64-71)
+	 */
+	if (hwirq >= 32)
+		return hwirq - 32;
+
+	return hwirq + 64;
+}
+
 static void armctrl_mask_irq(struct irq_data *d)
 {
-	writel_relaxed(HWIRQ_BIT(d->hwirq), intc.disable[HWIRQ_BANK(d->hwirq)]);
+	if (d->hwirq >= NUMBER_IRQS)
+		writel_relaxed(REG_FIQ_DISABLE, intc.base + REG_FIQ_CONTROL);
+	else
+		writel_relaxed(HWIRQ_BIT(d->hwirq),
+			       intc.disable[HWIRQ_BANK(d->hwirq)]);
 }
 
 static void armctrl_unmask_irq(struct irq_data *d)
 {
-	writel_relaxed(HWIRQ_BIT(d->hwirq), intc.enable[HWIRQ_BANK(d->hwirq)]);
+	if (d->hwirq >= NUMBER_IRQS)
+		writel_relaxed(REG_FIQ_ENABLE | hwirq_to_fiq(d->hwirq),
+			       intc.base + REG_FIQ_CONTROL);
+	else
+		writel_relaxed(HWIRQ_BIT(d->hwirq),
+			       intc.enable[HWIRQ_BANK(d->hwirq)]);
 }
 
 static struct irq_chip armctrl_chip = {
@@ -150,8 +178,9 @@ static int __init armctrl_of_init(struct device_node *node,
 		panic("%s: unable to map IC registers\n",
 			node->full_name);
 
-	intc.domain = irq_domain_add_linear(node, MAKE_HWIRQ(NR_BANKS, 0),
-			&armctrl_ops, NULL);
+	intc.base = base;
+	intc.domain = irq_domain_add_linear(node, NUMBER_IRQS * 2,
+					    &armctrl_ops, NULL);
 	if (!intc.domain)
 		panic("%s: unable to create IRQ domain\n", node->full_name);
 
@@ -168,8 +197,20 @@ static int __init armctrl_of_init(struct device_node *node,
 			set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);
 		}
 	}
-
 	set_handle_irq(bcm2835_handle_irq);
+
+	/* Make a duplicate irq range which is used to enable FIQ */
+	for (b = 0; b < NR_BANKS; b++) {
+		for (i = 0; i < bank_irqs[b]; i++) {
+			irq = irq_create_mapping(intc.domain,
+					MAKE_HWIRQ(b, i) + NUMBER_IRQS);
+			BUG_ON(irq <= 0);
+			irq_set_chip(irq, &armctrl_chip);
+			set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);
+		}
+	}
+	init_FIQ(FIQ_START);
+
 	return 0;
 }
 
-- 
2.2.2