[PATCH 04/13] irqchip/gic: support RealView variant setup

[Linus Walleij]

The ARM RealView PB11MPCore reference design has some special
bits in a system controller register to set up the GIC in one
of three modes: legacy, new with DCC, new without DCC. The
register is also used to enable FIQ.

Since the platform will not boot unless this register is set
up to "new with DCC" mode, we need a special quirk to be
compiled-in for the RealView platforms.

If we find the right compatible string on the GIC TestChip,
we enable this quirk by looking up the system controller and
enabling the special bits.

We depend on the CONFIG_REALVIEW_DT Kconfig symbol as the old
boardfile code has the same fix hardcoded, and this is only
needed for the attempts to modernize the RealView code using
device tree.

After fixing this, the PB11MPCore boots with device tree
only.

Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: Jason Cooper <jason at lakedaemon.net>
Cc: Marc Zyngier <marc.zyngier at arm.com>
Signed-off-by: Linus Walleij <linus.walleij at linaro.org>
---
Looking for an ACK for this (unless the irqchip maintainers
barf at it) so I can take it through the ARM SoC tree.
---
 drivers/irqchip/Makefile           |  1 +
 drivers/irqchip/irq-gic-realview.c | 39 ++++++++++++++++++++++++++++++++++++++
 drivers/irqchip/irq-gic-realview.h |  5 +++++
 drivers/irqchip/irq-gic.c          |  4 ++++
 4 files changed, 49 insertions(+)
 create mode 100644 drivers/irqchip/irq-gic-realview.c
 create mode 100644 drivers/irqchip/irq-gic-realview.h

diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index bb3048f00e64..7a7d4182777d 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_ARCH_SUNXI)		+= irq-sun4i.o
 obj-$(CONFIG_ARCH_SUNXI)		+= irq-sunxi-nmi.o
 obj-$(CONFIG_ARCH_SPEAR3XX)		+= spear-shirq.o
 obj-$(CONFIG_ARM_GIC)			+= irq-gic.o irq-gic-common.o
+obj-$(CONFIG_REALVIEW_DT)		+= irq-gic-realview.o
 obj-$(CONFIG_ARM_GIC_V2M)		+= irq-gic-v2m.o
 obj-$(CONFIG_ARM_GIC_V3)		+= irq-gic-v3.o irq-gic-common.o
 obj-$(CONFIG_ARM_GIC_V3_ITS)		+= irq-gic-v3-its.o irq-gic-v3-its-pci-msi.o irq-gic-v3-its-platform-msi.o
diff --git a/drivers/irqchip/irq-gic-realview.c b/drivers/irqchip/irq-gic-realview.c
new file mode 100644
index 000000000000..2e8a4b129f5f
--- /dev/null
+++ b/drivers/irqchip/irq-gic-realview.c
@@ -0,0 +1,39 @@
+/*
+ * Special GIC quirks for the ARM RealView
+ * Copyright (C) 2015 Linus Walleij
+ */
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/mfd/syscon.h>
+#include <linux/bitops.h>
+
+#define REALVIEW_SYS_LOCK_OFFSET	0x20
+#define REALVIEW_PB11MP_SYS_PLD_CTRL1	0x74
+#define VERSATILE_LOCK_VAL		0xA05F
+#define PLD_INTMODE_MASK		BIT(22)|BIT(23)|BIT(24)
+#define PLD_INTMODE_LEGACY		0x0
+#define PLD_INTMODE_NEW_DCC		BIT(22)
+#define PLD_INTMODE_NEW_NO_DCC		BIT(23)
+#define PLD_INTMODE_FIQ_ENABLE		BIT(24)
+
+void __init realview_gic_init(struct device_node *np)
+{
+	static struct regmap *map;
+
+	/* The PB11MPCore GIC needs to be configured in the syscon */
+	if (of_device_is_compatible(np, "arm,tc11mp-gic")) {
+		map = syscon_regmap_lookup_by_compatible("arm,realview-pb11mp-syscon");
+		if (!IS_ERR(map)) {
+			/* new irq mode with no DCC */
+			regmap_write(map, REALVIEW_SYS_LOCK_OFFSET,
+				     VERSATILE_LOCK_VAL);
+			regmap_update_bits(map, REALVIEW_PB11MP_SYS_PLD_CTRL1,
+					   PLD_INTMODE_NEW_NO_DCC,
+					   PLD_INTMODE_MASK);
+			regmap_write(map, REALVIEW_SYS_LOCK_OFFSET, 0x0000);
+			pr_info("TC11MP GIC: set up interrupt controller to NEW mode, no DCC\n");
+		} else {
+			pr_err("TC11MP GIC setup: could not find syscon\n");
+		}
+	}
+}
diff --git a/drivers/irqchip/irq-gic-realview.h b/drivers/irqchip/irq-gic-realview.h
new file mode 100644
index 000000000000..06ebdfc523a8
--- /dev/null
+++ b/drivers/irqchip/irq-gic-realview.h
@@ -0,0 +1,5 @@
+#ifdef CONFIG_REALVIEW_DT
+void realview_gic_init(struct device_node *np);
+#else
+static void realview_gic_init(struct device_node *np) {}
+#endif
diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
index 5376d1cb0a4f..bd021e1e4847 100644
--- a/drivers/irqchip/irq-gic.c
+++ b/drivers/irqchip/irq-gic.c
@@ -50,6 +50,7 @@
 #include <asm/virt.h>
 
 #include "irq-gic-common.h"
+#include "irq-gic-realview.h"
 
 union gic_base {
 	void __iomem *common_base;
@@ -1158,6 +1159,9 @@ gic_of_init(struct device_node *node, struct device_node *parent)
 	cpu_base = of_iomap(node, 1);
 	WARN(!cpu_base, "unable to map gic cpu registers\n");
 
+	/* Special quirk for ARM RealView */
+	realview_gic_init(node);
+
 	/*
 	 * Disable split EOI/Deactivate if either HYP is not available
 	 * or the CPU interface is too small.
-- 
2.4.3