ARM: gic: Use cpu pm notifiers to save gic state

When the cpu is powered down in a low power mode, the gic cpu
interface may be reset, and when the cpu cluster is powered
down, the gic distributor may also be reset.

This patch uses CPU_PM_ENTER and CPU_PM_EXIT notifiers to save
and restore the gic cpu interface registers, and the
CPU_CLUSTER_PM_ENTER and CPU_CLUSTER_PM_EXIT notifiers to save
and restore the gic distributor registers.

Original-author: Gary King <gking@nvidia.com>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-and-Acked-by: Shawn Guo <shawn.guo@linaro.org>
Tested-by: Vishwanath BS <vishwanath.bs@ti.com>

2 files changed, 195 insertions, 0 deletions

diff --git a/arch/arm/common/gic.c b/arch/arm/common/gic.c
index 3227ca952a12..66c7c4820108 100644
--- a/arch/arm/common/gic.c
+++ b/arch/arm/common/gic.c
@@ -26,6 +26,7 @@
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/smp.h>
+#include <linux/cpu_pm.h>
 #include <linux/cpumask.h>
 #include <linux/io.h>
 
@@ -276,6 +277,8 @@ static void __init gic_dist_init(struct gic_chip_data *gic,
         if (gic_irqs > 1020)
                 gic_irqs = 1020;
 
+        gic->gic_irqs = gic_irqs;
+
         /*
          * Set all global interrupts to be level triggered, active low.
          */
@@ -343,6 +346,189 @@ static void __cpuinit gic_cpu_init(struct gic_chip_data *gic)
         writel_relaxed(1, base + GIC_CPU_CTRL);
 }
 
+#ifdef CONFIG_CPU_PM
+/*
+ * Saves the GIC distributor registers during suspend or idle.  Must be called
+ * with interrupts disabled but before powering down the GIC.  After calling
+ * this function, no interrupts will be delivered by the GIC, and another
+ * platform-specific wakeup source must be enabled.
+ */
+static void gic_dist_save(unsigned int gic_nr)
+{
+        unsigned int gic_irqs;
+        void __iomem *dist_base;
+        int i;
+
+        if (gic_nr >= MAX_GIC_NR)
+                BUG();
+
+        gic_irqs = gic_data[gic_nr].gic_irqs;
+        dist_base = gic_data[gic_nr].dist_base;
+
+        if (!dist_base)
+                return;
+
+        for (i = 0; i < DIV_ROUND_UP(gic_irqs, 16); i++)
+                gic_data[gic_nr].saved_spi_conf[i] =
+                        readl_relaxed(dist_base + GIC_DIST_CONFIG + i * 4);
+
+        for (i = 0; i < DIV_ROUND_UP(gic_irqs, 4); i++)
+                gic_data[gic_nr].saved_spi_target[i] =
+                        readl_relaxed(dist_base + GIC_DIST_TARGET + i * 4);
+
+        for (i = 0; i < DIV_ROUND_UP(gic_irqs, 32); i++)
+                gic_data[gic_nr].saved_spi_enable[i] =
+                        readl_relaxed(dist_base + GIC_DIST_ENABLE_SET + i * 4);
+}
+
+/*
+ * Restores the GIC distributor registers during resume or when coming out of
+ * idle.  Must be called before enabling interrupts.  If a level interrupt
+ * that occured while the GIC was suspended is still present, it will be
+ * handled normally, but any edge interrupts that occured will not be seen by
+ * the GIC and need to be handled by the platform-specific wakeup source.
+ */
+static void gic_dist_restore(unsigned int gic_nr)
+{
+        unsigned int gic_irqs;
+        unsigned int i;
+        void __iomem *dist_base;
+
+        if (gic_nr >= MAX_GIC_NR)
+                BUG();
+
+        gic_irqs = gic_data[gic_nr].gic_irqs;
+        dist_base = gic_data[gic_nr].dist_base;
+
+        if (!dist_base)
+                return;
+
+        writel_relaxed(0, dist_base + GIC_DIST_CTRL);
+
+        for (i = 0; i < DIV_ROUND_UP(gic_irqs, 16); i++)
+                writel_relaxed(gic_data[gic_nr].saved_spi_conf[i],
+                        dist_base + GIC_DIST_CONFIG + i * 4);
+
+        for (i = 0; i < DIV_ROUND_UP(gic_irqs, 4); i++)
+                writel_relaxed(0xa0a0a0a0,
+                        dist_base + GIC_DIST_PRI + i * 4);
+
+        for (i = 0; i < DIV_ROUND_UP(gic_irqs, 4); i++)
+                writel_relaxed(gic_data[gic_nr].saved_spi_target[i],
+                        dist_base + GIC_DIST_TARGET + i * 4);
+
+        for (i = 0; i < DIV_ROUND_UP(gic_irqs, 32); i++)
+                writel_relaxed(gic_data[gic_nr].saved_spi_enable[i],
+                        dist_base + GIC_DIST_ENABLE_SET + i * 4);
+
+        writel_relaxed(1, dist_base + GIC_DIST_CTRL);
+}
+
+static void gic_cpu_save(unsigned int gic_nr)
+{
+        int i;
+        u32 *ptr;
+        void __iomem *dist_base;
+        void __iomem *cpu_base;
+
+        if (gic_nr >= MAX_GIC_NR)
+                BUG();
+
+        dist_base = gic_data[gic_nr].dist_base;
+        cpu_base = gic_data[gic_nr].cpu_base;
+
+        if (!dist_base || !cpu_base)
+                return;
+
+        ptr = __this_cpu_ptr(gic_data[gic_nr].saved_ppi_enable);
+        for (i = 0; i < DIV_ROUND_UP(32, 32); i++)
+                ptr[i] = readl_relaxed(dist_base + GIC_DIST_ENABLE_SET + i * 4);
+
+        ptr = __this_cpu_ptr(gic_data[gic_nr].saved_ppi_conf);
+        for (i = 0; i < DIV_ROUND_UP(32, 16); i++)
+                ptr[i] = readl_relaxed(dist_base + GIC_DIST_CONFIG + i * 4);
+
+}
+
+static void gic_cpu_restore(unsigned int gic_nr)
+{
+        int i;
+        u32 *ptr;
+        void __iomem *dist_base;
+        void __iomem *cpu_base;
+
+        if (gic_nr >= MAX_GIC_NR)
+                BUG();
+
+        dist_base = gic_data[gic_nr].dist_base;
+        cpu_base = gic_data[gic_nr].cpu_base;
+
+        if (!dist_base || !cpu_base)
+                return;
+
+        ptr = __this_cpu_ptr(gic_data[gic_nr].saved_ppi_enable);
+        for (i = 0; i < DIV_ROUND_UP(32, 32); i++)
+                writel_relaxed(ptr[i], dist_base + GIC_DIST_ENABLE_SET + i * 4);
+
+        ptr = __this_cpu_ptr(gic_data[gic_nr].saved_ppi_conf);
+        for (i = 0; i < DIV_ROUND_UP(32, 16); i++)
+                writel_relaxed(ptr[i], dist_base + GIC_DIST_CONFIG + i * 4);
+
+        for (i = 0; i < DIV_ROUND_UP(32, 4); i++)
+                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);
+}
+
+static int gic_notifier(struct notifier_block *self, unsigned long cmd, void *v)
+{
+        int i;
+
+        for (i = 0; i < MAX_GIC_NR; i++) {
+                switch (cmd) {
+                case CPU_PM_ENTER:
+                        gic_cpu_save(i);
+                        break;
+                case CPU_PM_ENTER_FAILED:
+                case CPU_PM_EXIT:
+                        gic_cpu_restore(i);
+                        break;
+                case CPU_CLUSTER_PM_ENTER:
+                        gic_dist_save(i);
+                        break;
+                case CPU_CLUSTER_PM_ENTER_FAILED:
+                case CPU_CLUSTER_PM_EXIT:
+                        gic_dist_restore(i);
+                        break;
+                }
+        }
+
+        return NOTIFY_OK;
+}
+
+static struct notifier_block gic_notifier_block = {
+        .notifier_call = gic_notifier,
+};
+
+static void __init gic_pm_init(struct gic_chip_data *gic)
+{
+        gic->saved_ppi_enable = __alloc_percpu(DIV_ROUND_UP(32, 32) * 4,
+                sizeof(u32));
+        BUG_ON(!gic->saved_ppi_enable);
+
+        gic->saved_ppi_conf = __alloc_percpu(DIV_ROUND_UP(32, 16) * 4,
+                sizeof(u32));
+        BUG_ON(!gic->saved_ppi_conf);
+
+        cpu_pm_register_notifier(&gic_notifier_block);
+}
+#else
+static void __init gic_pm_init(struct gic_chip_data *gic)
+{
+}
+#endif
+
 void __init gic_init(unsigned int gic_nr, unsigned int irq_start,
         void __iomem *dist_base, void __iomem *cpu_base)
 {
@@ -360,6 +546,7 @@ void __init gic_init(unsigned int gic_nr, unsigned int irq_start,
 
         gic_dist_init(gic, irq_start);
         gic_cpu_init(gic);
+        gic_pm_init(gic);
 }
 
 void __cpuinit gic_secondary_init(unsigned int gic_nr)
diff --git a/arch/arm/include/asm/hardware/gic.h b/arch/arm/include/asm/hardware/gic.h
index 435d3f86c708..c5627057b1c7 100644
--- a/arch/arm/include/asm/hardware/gic.h
+++ b/arch/arm/include/asm/hardware/gic.h
@@ -46,6 +46,14 @@ struct gic_chip_data {
         unsigned int irq_offset;
         void __iomem *dist_base;
         void __iomem *cpu_base;
+#ifdef CONFIG_CPU_PM
+        u32 saved_spi_enable[DIV_ROUND_UP(1020, 32)];
+        u32 saved_spi_conf[DIV_ROUND_UP(1020, 16)];
+        u32 saved_spi_target[DIV_ROUND_UP(1020, 4)];
+        u32 __percpu *saved_ppi_enable;
+        u32 __percpu *saved_ppi_conf;
+#endif
+        unsigned int gic_irqs;
 };
 #endif