ARM: 8730/1: B15: Add suspend/resume hooks

The Broadcom Brahma-B15 CPU readahead cache registers will be restored
to their Power-on-Reset values after a S3 suspend/resume cycles, so we
want to restore what we had enabled before.

Another thing we want to take care of is disabling the read-ahead cache
prior to suspending to avoid any sort of side effect with the spinlock
we need to grab to serialize register accesses.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

diff --git a/arch/arm/mm/cache-b15-rac.c b/arch/arm/mm/cache-b15-rac.c
index d85b63211759011607506224bb8cec3d6c0244e6..9ee1d89cced0cf054032ec39231d0a225b07d149 100644 (file)
--- a/arch/arm/mm/cache-b15-rac.c
+++ b/arch/arm/mm/cache-b15-rac.c
@@ -15,6 +15,7 @@
 #include <linux/of_address.h>
 #include <linux/notifier.h>
 #include <linux/cpu.h>
+#include <linux/syscore_ops.h>
 
 #include <asm/cacheflush.h>
 #include <asm/hardware/cache-b15-rac.h>
@@ -41,6 +42,10 @@ extern void v7_flush_kern_cache_all(void);
                                         RACENPREF_MASK << RACENDATA_SHIFT)
 
 #define RAC_ENABLED                    0
+/* Special state where we want to bypass the spinlock and call directly
+ * into the v7 cache maintenance operations during suspend/resume
+ */
+#define RAC_SUSPENDED                  1
 
 static void __iomem *b15_rac_base;
 static DEFINE_SPINLOCK(rac_lock);
@@ -96,6 +101,12 @@ void b15_flush_##name(void)                                 \
        unsigned int do_flush;                                  \
        u32 val = 0;                                            \
                                                                \
+       if (test_bit(RAC_SUSPENDED, &b15_rac_flags)) {          \
+               v7_flush_##name();                              \
+               bar;                                            \
+               return;                                         \
+       }                                                       \
+                                                               \
        spin_lock(&rac_lock);                                   \
        do_flush = test_bit(RAC_ENABLED, &b15_rac_flags);       \
        if (do_flush)                                           \
@@ -208,6 +219,39 @@ static int b15_rac_dead_cpu(unsigned int cpu)
 }
 #endif /* CONFIG_HOTPLUG_CPU */
 
+#ifdef CONFIG_PM_SLEEP
+static int b15_rac_suspend(void)
+{
+       /* Suspend the read-ahead cache oeprations, forcing our cache
+        * implementation to fallback to the regular ARMv7 calls.
+        *
+        * We are guaranteed to be running on the boot CPU at this point and
+        * with every other CPU quiesced, so setting RAC_SUSPENDED is not racy
+        * here.
+        */
+       rac_config0_reg = b15_rac_disable_and_flush();
+       set_bit(RAC_SUSPENDED, &b15_rac_flags);
+
+       return 0;
+}
+
+static void b15_rac_resume(void)
+{
+       /* Coming out of a S3 suspend/resume cycle, the read-ahead cache
+        * register RAC_CONFIG0_REG will be restored to its default value, make
+        * sure we re-enable it and set the enable flag, we are also guaranteed
+        * to run on the boot CPU, so not racy again.
+        */
+       __b15_rac_enable(rac_config0_reg);
+       clear_bit(RAC_SUSPENDED, &b15_rac_flags);
+}
+
+static struct syscore_ops b15_rac_syscore_ops = {
+       .suspend        = b15_rac_suspend,
+       .resume         = b15_rac_resume,
+};
+#endif
+
 static int __init b15_rac_init(void)
 {
        struct device_node *dn;
@@ -242,6 +286,10 @@ static int __init b15_rac_init(void)
                goto out_cpu_dead;
 #endif
 
+#ifdef CONFIG_PM_SLEEP
+       register_syscore_ops(&b15_rac_syscore_ops);
+#endif
+
        spin_lock(&rac_lock);
        reg = __raw_readl(b15_rac_base + RAC_CONFIG0_REG);
        for_each_possible_cpu(cpu)