Merge pull request #342 from sifive/add-l2lim

Add support for L2 LIM.

Makefile.am

@@ -78,6 +78,7 @@ nobase_include_HEADERS += \
 	metal/io.h \
 	metal/itim.h \
 	metal/led.h \
+	metal/lim.h \
 	metal/lock.h \
 	metal/memory.h \
 	metal/pmp.h \

gloss/crt0.S

@@ -108,6 +108,36 @@ _start:
      complete */
   fence.i
 
+2:
+
+  /* Copy the LIM section */
+  la t0, metal_segment_lim_source_start
+  la t1, metal_segment_lim_target_start
+  la t2, metal_segment_lim_target_end
+
+  beq t0, t1, 2f
+  bge t1, t2, 2f
+
+1:
+#if __riscv_xlen == 32
+  lw   a0, 0(t0)
+  addi t0, t0, 4
+  sw   a0, 0(t1)
+  addi t1, t1, 4
+  blt  t1, t2, 1b
+#else
+  ld   a0, 0(t0)
+  addi t0, t0, 8
+  sd   a0, 0(t1)
+  addi t1, t1, 8
+  blt  t1, t2, 1b
+#endif
+2:
+
+  /* Fence all subsequent instruction fetches until after the LIM writes
+     complete */
+  fence.i
+
   /* Zero the BSS segment. */
   la t1, metal_segment_bss_target_start
   la t2, metal_segment_bss_target_end

metal/drivers/sifive_ccache0.h

@@ -29,6 +29,7 @@ typedef enum {
 
 /*! @brief Initialize cache controller, enables all available
  *         cache-ways.
+ *         Note: If LIM is in use, corresponding cache ways are not enabled.
  * @param None.
  * @return 0 If no error.*/
 int sifive_ccache0_init(void);

metal/lim.h

@@ -0,0 +1,20 @@
+/* Copyright 2020 SiFive, Inc */
+/* SPDX-License-Identifier: Apache-2.0 */
+
+#ifndef METAL__LIM_H
+#define METAL__LIM_H
+
+/*! @file lim.h
+ *
+ * API for manipulating LIM allocation
+ */
+
+/*! @def METAL_PLACE_IN_LIM
+ * @brief Link a function into the LIM
+ *
+ * Link a function into the LIM (Loosely Integrated
+ * Memory) if the LIM is present on the target device.
+ */
+#define METAL_PLACE_IN_LIM __attribute__((section(".lim")))
+
+#endif

src/drivers/sifive_ccache0.c

@@ -21,19 +21,16 @@
 #define REG_SHIFT_16 16
 #define REG_SHIFT_24 24
 
-/* Masks to get cache configuration data */
-#define SIFIVE_CCACHE0_CONFIG_BANKS_MASK 0x000000FFUL
-#define SIFIVE_CCACHE0_CONFIG_WAYS_MASK 0x0000FF00UL
-#define SIFIVE_CCACHE0_CONFIG_SETS_MASK 0x00FF0000UL
-#define SIFIVE_CCACHE0_CONFIG_BLOCKS_MASK 0xFF000000UL
-
-#define SIFIVE_CCACHE0_WAY_ENABLE_MASK 0x000000FFUL
+#define SIFIVE_CCACHE0_BYTE_MASK 0xFFUL
 
 static int sifive_ccache0_interrupts[] = METAL_SIFIVE_CCACHE0_INTERRUPTS;
 
 /* Initialize cache at start-up via metal constructors */
 METAL_CONSTRUCTOR(_sifive_ccache0_init) { sifive_ccache0_init(); }
 
+/* Linker symbols to calculate LIM allocated size */
+extern char metal_segment_lim_target_start, metal_segment_lim_target_end;
+
 int sifive_ccache0_init(void) {
     int ret;
 
@@ -42,6 +39,17 @@ int sifive_ccache0_init(void) {
     /* Get cache configuration data */
     sifive_ccache0_get_config(&config);
 
+    int lim_size =
+        &metal_segment_lim_target_end - &metal_segment_lim_target_start;
+
+    if (lim_size) { /* Do not enable cache ways, corresponding to LIM area in
+                       use. */
+        while (lim_size > 0) {
+            lim_size -= (config.block_size * config.num_sets * config.num_bank);
+            config.num_ways--;
+        }
+    }
+
     /* Enable ways */
     ret = sifive_ccache0_set_enabled_ways(config.num_ways);
 
@@ -56,21 +64,20 @@ void sifive_ccache0_get_config(sifive_ccache0_config *config) {
         val = REGW(METAL_SIFIVE_CCACHE0_CONFIG);
 
         /* Populate cache configuration data */
-        config->num_bank = (val & SIFIVE_CCACHE0_CONFIG_BANKS_MASK);
-        config->num_ways =
-            (val & SIFIVE_CCACHE0_CONFIG_WAYS_MASK) >> REG_SHIFT_8;
+        config->num_bank = (val & SIFIVE_CCACHE0_BYTE_MASK);
+        config->num_ways = ((val >> REG_SHIFT_8) & SIFIVE_CCACHE0_BYTE_MASK);
         config->num_sets =
-            2 ^ ((val & SIFIVE_CCACHE0_CONFIG_SETS_MASK) >> REG_SHIFT_16);
+            2 << (((val >> REG_SHIFT_16) & SIFIVE_CCACHE0_BYTE_MASK) - 1);
         config->block_size =
-            2 ^ ((val & SIFIVE_CCACHE0_CONFIG_BLOCKS_MASK) >> REG_SHIFT_24);
+            2 << (((val >> REG_SHIFT_24) & SIFIVE_CCACHE0_BYTE_MASK) - 1);
     }
 }
 
 uint32_t sifive_ccache0_get_enabled_ways(void) {
 
     uint32_t val = 0;
 
-    val = SIFIVE_CCACHE0_WAY_ENABLE_MASK & REGW(METAL_SIFIVE_CCACHE0_WAYENABLE);
+    val = SIFIVE_CCACHE0_BYTE_MASK & REGW(METAL_SIFIVE_CCACHE0_WAYENABLE);
 
     /* The stored number is the way index, so increment by 1 */
     val++;