1 files changed, 22 insertions, 3 deletions

diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
index 415efc3bee0d..e99a0ffd22d1 100644
--- a/arch/arm/mm/cache-l2x0.c
+++ b/arch/arm/mm/cache-l2x0.c
@@ -755,13 +755,24 @@ static void __init __l2c_init(const struct l2c_init_data *data,
 {
         struct outer_cache_fns fns;
         unsigned way_size_bits, ways;
-        u32 aux;
+        u32 aux, old_aux;
 
-        aux = readl_relaxed(l2x0_base + L2X0_AUX_CTRL);
+        /*
+         * Sanity check the aux values.  aux_mask is the bits we preserve
+         * from reading the hardware register, and aux_val is the bits we
+         * set.
+         */
+        if (aux_val & aux_mask)
+                pr_alert("L2C: platform provided aux values permit register corruption.\n");
 
+        old_aux = aux = readl_relaxed(l2x0_base + L2X0_AUX_CTRL);
         aux &= aux_mask;
         aux |= aux_val;
 
+        if (old_aux != aux)
+                pr_warn("L2C: DT/platform modifies aux control register: 0x%08x -> 0x%08x\n",
+                        old_aux, aux);
+
         /* Determine the number of ways */
         switch (cache_id & L2X0_CACHE_ID_PART_MASK) {
         case L2X0_CACHE_ID_PART_L310:
@@ -1392,7 +1403,7 @@ int __init l2x0_of_init(u32 aux_val, u32 aux_mask)
         const struct l2c_init_data *data;
         struct device_node *np;
         struct resource res;
-        u32 cache_id;
+        u32 cache_id, old_aux;
 
         np = of_find_matching_node(NULL, l2x0_ids);
         if (!np)
@@ -1409,6 +1420,14 @@ int __init l2x0_of_init(u32 aux_val, u32 aux_mask)
 
         data = of_match_node(l2x0_ids, np)->data;
 
+        old_aux = readl_relaxed(l2x0_base + L2X0_AUX_CTRL);
+        if (old_aux != ((old_aux & aux_mask) | aux_val)) {
+                pr_warn("L2C: platform modifies aux control register: 0x%08x -> 0x%08x\n",
+                        old_aux, (old_aux & aux_mask) | aux_val);
+        } else if (aux_mask != ~0U && aux_val != 0) {
+                pr_alert("L2C: platform provided aux values match the hardware, so have no effect.  Please remove them.\n");
+        }
+
         /* All L2 caches are unified, so this property should be specified */
         if (!of_property_read_bool(np, "cache-unified"))
                 pr_err("L2C: device tree omits to specify unified cache\n");