[PARISC] Ensure Space ID hashing is turned off

Check PDC_CACHE to see if spaceid hashing is turned on, and fail to
boot if that is the case.

However, some old machines do not implement the PDC_CACHE_RET_SPID
firmware call, so continue to boot if the call fails because of
PDC_BAD_OPTION (but fail in all other error returns).
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>

arch/parisc/kernel/cache.c

@@ -236,7 +236,8 @@ parisc_cache_init(void)
 
 void disable_sr_hashing(void)
 {
-	int srhash_type;
+	int srhash_type, retval;
+	unsigned long space_bits;
 
 	switch (boot_cpu_data.cpu_type) {
 	case pcx: /* We shouldn't get this far.  setup.c should prevent it. */
@@ -262,6 +263,13 @@ void disable_sr_hashing(void)
 	}
 
 	disable_sr_hashing_asm(srhash_type);
+
+	retval = pdc_spaceid_bits(&space_bits);
+	/* If this procedure isn't implemented, don't panic. */
+	if (retval < 0 && retval != PDC_BAD_OPTION)
+		panic("pdc_spaceid_bits call failed.\n");
+	if (space_bits != 0)
+		panic("SpaceID hashing is still on!\n");
 }
 
 void flush_dcache_page(struct page *page)

arch/parisc/kernel/firmware.c

@@ -512,6 +512,26 @@ int pdc_cache_info(struct pdc_cache_info *cache_info)
         return retval;
 }
 
+/**
+ * pdc_spaceid_bits - Return whether Space ID hashing is turned on.
+ * @space_bits: Should be 0, if not, bad mojo!
+ *
+ * Returns information about Space ID hashing.
+ */
+int pdc_spaceid_bits(unsigned long *space_bits)
+{
+	int retval;
+
+	spin_lock_irq(&pdc_lock);
+	pdc_result[0] = 0;
+	retval = mem_pdc_call(PDC_CACHE, PDC_CACHE_RET_SPID, __pa(pdc_result), 0);
+	convert_to_wide(pdc_result);
+	*space_bits = pdc_result[0];
+	spin_unlock_irq(&pdc_lock);
+
+	return retval;
+}
+
 #ifndef CONFIG_PA20
 /**
  * pdc_btlb_info - Return block TLB information.

include/asm-parisc/pdc.h

@@ -733,6 +733,7 @@ int pdc_model_cpuid(unsigned long *cpu_id);
 int pdc_model_versions(unsigned long *versions, int id);
 int pdc_model_capabilities(unsigned long *capabilities);
 int pdc_cache_info(struct pdc_cache_info *cache);
+int pdc_spaceid_bits(unsigned long *space_bits);
 #ifndef CONFIG_PA20
 int pdc_btlb_info(struct pdc_btlb_info *btlb);
 int pdc_mem_map_hpa(struct pdc_memory_map *r_addr, struct pdc_module_path *mod_path);