[PATCH v2 10/19] cache: andes_llcache: register cache ops only when the errata needs them

[Mina Hui-Min Chou]

The driver registers its CCTL-based cache ops whenever
riscv_cbom_block_size is non-zero. On Andes cores with Zicbom, it holds
the Zicbom block size, so the CCTL ops would override the standard
Zicbom CMO.

Only register them when riscv_cbom_block_size is 1, the value the Andes
errata sets when the core needs CCTL-based cache maintenance.

Do this check before looking up the LLC node, so the driver does
nothing on platforms that do not need it. Once the errata has asked for
the CCTL ops, the LLC node is required to provide them, so report a
missing node with an error instead of failing silently.

Signed-off-by: Mina Hui-Min Chou <minachou at andestech.com>
---
 drivers/cache/andes_llcache.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/drivers/cache/andes_llcache.c b/drivers/cache/andes_llcache.c
index bf49dbcb080b..80c55616ab10 100644
--- a/drivers/cache/andes_llcache.c
+++ b/drivers/cache/andes_llcache.c
@@ -176,25 +176,25 @@ static int __init andes_cache_init(void)
 	struct resource res;
 	int ret;
 
+	/*
+	 * The Andes errata sets riscv_cbom_block_size to 1 only when the
+	 * core needs CCTL-based cache maintenance. Otherwise this driver is
+	 * not needed, so return without probing it any further.
+	 */
+	if (riscv_cbom_block_size != 1)
+		return 0;
+
 	struct device_node *np __free(device_node) =
 		of_find_matching_node(NULL, andes_cache_ids);
-	if (!of_device_is_available(np))
+	if (!of_device_is_available(np)) {
+		pr_err("No Andes LLC node found, cache ops not registered\n");
 		return -ENODEV;
+	}
 
 	ret = of_address_to_resource(np, 0, &res);
 	if (ret)
 		return ret;
 
-	/*
-	 * If IOCP is present on the Andes core riscv_cbom_block_size
-	 * will be 0 for sure, so we can definitely rely on it. If
-	 * riscv_cbom_block_size = 0 we don't need to handle CMO using SW any
-	 * more so we just return success here and only if its being set we
-	 * continue further in the probe path.
-	 */
-	if (!riscv_cbom_block_size)
-		return 0;
-
 	andes_priv.llc_base = ioremap(res.start, resource_size(&res));
 	if (!andes_priv.llc_base)
 		return -ENOMEM;
-- 
2.34.1