intel/common: Implement preferred SLM encode

Preferred SLM has a different encode than SLM allocation size so
adding a function just to encode it, functions call to this new
function will be added in the next patches.

BSpec: 64042
BSpec: 68700
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/28910>

src/intel/common/intel_compute_slm.c

@@ -112,3 +112,44 @@ intel_compute_slm_encode_size(unsigned gen, uint32_t bytes)
 
    return slm_size;
 }
+
+/* encode = 0 sets to largest SLM size supported in subslice */
+static struct slm_encode preferred_slm_allocation_size_table[] = {
+   { .encode = 0x8, .size_in_kb = 0, },
+   { .encode = 0x9, .size_in_kb = 16, },
+   { .encode = 0xa, .size_in_kb = 32, },
+   { .encode = 0xb, .size_in_kb = 64, },
+   { .encode = 0xc, .size_in_kb = 96, },
+   { .encode = 0xd, .size_in_kb = 128, },
+};
+
+static struct slm_encode xe2_preferred_slm_allocation_size_table[] = {
+  { .encode = 0x0, .size_in_kb = 0, },
+  { .encode = 0x1, .size_in_kb = 16, },
+  { .encode = 0x2, .size_in_kb = 32, },
+  { .encode = 0x3, .size_in_kb = 64, },
+  { .encode = 0x4, .size_in_kb = 96, },
+  { .encode = 0x5, .size_in_kb = 128, },
+  { .encode = 0x6, .size_in_kb = 160, },
+  { .encode = 0x7, .size_in_kb = 192, },
+  { .encode = 0x8, .size_in_kb = 224, },
+  { .encode = 0x9, .size_in_kb = 256, },
+  { .encode = 0xA, .size_in_kb = 384, },
+};
+
+uint32_t
+intel_compute_preferred_slm_encode_size(unsigned gen, uint32_t bytes)
+{
+   struct slm_encode *table;
+   unsigned int table_len;
+
+   if (gen >= 20) {
+      table = xe2_preferred_slm_allocation_size_table;
+      table_len = ARRAY_SIZE(xe2_preferred_slm_allocation_size_table);
+   } else {
+      table = preferred_slm_allocation_size_table;
+      table_len = ARRAY_SIZE(preferred_slm_allocation_size_table);
+   }
+
+   return slm_encode_lookup(table, table_len, bytes)->encode;
+}

src/intel/common/intel_compute_slm.h

@@ -9,3 +9,4 @@
 
 uint32_t intel_compute_slm_calculate_size(unsigned gen, uint32_t bytes);
 uint32_t intel_compute_slm_encode_size(unsigned gen, uint32_t bytes);
+uint32_t intel_compute_preferred_slm_encode_size(unsigned gen, uint32_t bytes);