[PATCH V5] gic: preserve gic V2 bypass bits in cpu ctrl register

[Feng Kan <fkan@apm.com>]

This change is made to preserve the GIC v2 bypass bits in the
GIC_CPU_CTRL register (also known as the GICC_CTLR register in spec).
This code will preserve all bits configured by the bootload regarding
v2 bypass group bits. In the X-Gene platform, the bypass functionality
is not used and bypass bits should not be changed by the kernel gic
code as it could lead to incorrect behavior.

Signed-off-by: Vinayak Kale <vkale@apm.com>
Acked-by: Anup Patel <apatel@apm.com>
Signed-off-by: Feng Kan <fkan@apm.com>
---
V5: Use macro to replace read modify write of cpu_ctrl register.
V4: Change to use bypass mask, change ot user more suitable variable name.
 drivers/irqchip/irq-gic.c |   16 +++++++++++++---
 1 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
index 4300b66..42e9bf4 100644
--- a/drivers/irqchip/irq-gic.c
+++ b/drivers/irqchip/irq-gic.c
@@ -97,6 +97,13 @@ struct irq_chip gic_arch_extn = {
 #define MAX_GIC_NR	1
 #endif
 
+#define set_cpuctrl(base, val)					\
+	do {							\
+		u32 bypass;					\
+		bypass = readl(base + GIC_CPU_CTRL) & 0x1e0;	\
+		writel_relaxed(bypass | val, base + GIC_CPU_CTRL);\
+	} while (0)
+
 static struct gic_chip_data gic_data[MAX_GIC_NR] __read_mostly;
 
 #ifdef CONFIG_GIC_NON_BANKED
@@ -449,13 +456,15 @@ static void gic_cpu_init(struct gic_chip_data *gic)
 		writel_relaxed(0xa0a0a0a0, dist_base + GIC_DIST_PRI + i * 4 / 4);
 
 	writel_relaxed(0xf0, base + GIC_CPU_PRIMASK);
-	writel_relaxed(1, base + GIC_CPU_CTRL);
+
+	set_cpuctrl(base, 1);
 }
 
 void gic_cpu_if_down(void)
 {
 	void __iomem *cpu_base = gic_data_cpu_base(&gic_data[0]);
-	writel_relaxed(0, cpu_base + GIC_CPU_CTRL);
+
+	set_cpuctrl(cpu_base, 0);
 }
 
 #ifdef CONFIG_CPU_PM
@@ -590,7 +599,8 @@ static void gic_cpu_restore(unsigned int gic_nr)
 		writel_relaxed(0xa0a0a0a0, dist_base + GIC_DIST_PRI + i * 4);
 
 	writel_relaxed(0xf0, cpu_base + GIC_CPU_PRIMASK);
-	writel_relaxed(1, cpu_base + GIC_CPU_CTRL);
+	
+	set_cpuctrl(cpu_base, 1);
 }
 
 static int gic_notifier(struct notifier_block *self, unsigned long cmd,	void *v)
-- 
1.7.6.1