ARC: Cache: Add more HW configuration checks

Add additional cache configuration checks and note about
supported configurations.

It is unlikely to face some configuration in real life but
it's better to be prepared and refuse to work on those.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

diff --git a/arch/arc/lib/cache.c b/arch/arc/lib/cache.c
index 5d7583d86897967f5355aa0da3d66b045ac35d4f..fd70ce8efe86ac62401f74c50fc9cd7630904f63 100644 (file)
--- a/arch/arc/lib/cache.c
+++ b/arch/arc/lib/cache.c
@@ -85,6 +85,66 @@
  * enabling force function inline with '__attribute__((always_inline))' gcc
  * attribute to avoid any function call (and BLINK store) between cache flush
  * and disable.
+ *
+ *
+ * [ NOTE 2 ]:
+ * As of today we only support the following cache configurations on ARC.
+ * Other configurations may exist in HW (for example, since version 3.0 HS
+ * supports SL$ (L2 system level cache) disable) but we don't support it in SW.
+ * Configuration 1:
+ *        ______________________
+ *       |                      |
+ *       |   ARC CPU            |
+ *       |______________________|
+ *        ___|___        ___|___
+ *       |       |      |       |
+ *       | L1 I$ |      | L1 D$ |
+ *       |_______|      |_______|
+ *        on/off         on/off
+ *        ___|______________|____
+ *       |                      |
+ *       |   main memory        |
+ *       |______________________|
+ *
+ * Configuration 2:
+ *        ______________________
+ *       |                      |
+ *       |   ARC CPU            |
+ *       |______________________|
+ *        ___|___        ___|___
+ *       |       |      |       |
+ *       | L1 I$ |      | L1 D$ |
+ *       |_______|      |_______|
+ *        on/off         on/off
+ *        ___|______________|____
+ *       |                      |
+ *       |   L2 (SL$)           |
+ *       |______________________|
+ *          always must be on
+ *        ___|______________|____
+ *       |                      |
+ *       |   main memory        |
+ *       |______________________|
+ *
+ * Configuration 3:
+ *        ______________________
+ *       |                      |
+ *       |   ARC CPU            |
+ *       |______________________|
+ *        ___|___        ___|___
+ *       |       |      |       |
+ *       | L1 I$ |      | L1 D$ |
+ *       |_______|      |_______|
+ *        on/off        must be on
+ *        ___|______________|____      _______
+ *       |                      |     |       |
+ *       |   L2 (SL$)           |-----|  IOC  |
+ *       |______________________|     |_______|
+ *          always must be on          on/off
+ *        ___|______________|____
+ *       |                      |
+ *       |   main memory        |
+ *       |______________________|
  */
 
 DECLARE_GLOBAL_DATA_PTR;
@@ -308,6 +368,14 @@ static void arc_ioc_setup(void)
        /* IOC Aperture size is equal to DDR size */
        long ap_size = CONFIG_SYS_SDRAM_SIZE;
 
+       /* Unsupported configuration. See [ NOTE 2 ] for more details. */
+       if (!slc_exists())
+               panic("Try to enable IOC but SLC is not present");
+
+       /* Unsupported configuration. See [ NOTE 2 ] for more details. */
+       if (!dcache_enabled())
+               panic("Try to enable IOC but L1 D$ is disabled");
+
        flush_n_invalidate_dcache_all();
 
        if (!is_power_of_2(ap_size) || ap_size < 4096)
@@ -338,6 +406,13 @@ static void read_decode_cache_bcr_arcv2(void)
        if (slc_exists()) {
                slc_cfg.word = read_aux_reg(ARC_AUX_SLC_CONFIG);
                gd->arch.slc_line_sz = (slc_cfg.fields.lsz == 0) ? 128 : 64;
+
+               /*
+                * We don't support configuration where L1 I$ or L1 D$ is
+                * absent but SL$ exists. See [ NOTE 2 ] for more details.
+                */
+               if (!icache_exists() || !dcache_exists())
+                       panic("Unsupported cache configuration: SLC exists but one of L1 caches is absent");
        }
 
 #endif /* CONFIG_ISA_ARCV2 */