cortexm: Better cache support for Cortex-M7

- On probe, read CTR for cache presence and minimum line length
- Make D-Cache clean a function
- Clean before memory reads
- Clean and invalidate before memory writes
- Flush all I-Cache before resume

src/target/cortexm.c

@@ -78,6 +78,9 @@ struct cortexm_priv {
 	unsigned hw_breakpoint_max;
 	/* Copy of DEMCR for vector-catch */
 	uint32_t demcr;
+	/* Cache parameters */
+	bool has_cache;
+	uint32_t dcache_minline;
 };
 
 /* Register number tables */
@@ -179,45 +182,40 @@ ADIv5_AP_t *cortexm_ap(target *t)
 	return ((struct cortexm_priv *)t->priv)->ap;
 }
 
-static void cortexm_mem_read(target *t, void *dest, target_addr src, size_t len)
+static void cortexm_cache_clean(target *t, target_addr addr, size_t len, bool invalidate)
 {
+	struct cortexm_priv *priv = t->priv;
+	if (!priv->has_cache || (priv->dcache_minline == 0))
+		return;
+	uint32_t cache_reg = invalidate ? CORTEXM_DCCIMVAC : CORTEXM_DCCMVAC;
+	size_t minline = priv->dcache_minline;
+
 	/* flush data cache for RAM regions that intersect requested region */
-	target_addr src_end = src + len; /* following code is NOP if wraparound */
+	target_addr mem_end = addr + len; /* following code is NOP if wraparound */
 	/* requested region is [src, src_end) */
 	for (struct target_ram *r = t->ram; r; r = r->next) {
 		target_addr ram = r->start;
 		target_addr ram_end = r->start + r->length;
 		/* RAM region is [ram, ram_end) */
-                if (src > ram)
+		if (addr > ram)
-			ram = src;
+			ram = addr;
-		if (src_end < ram_end)
+		if (mem_end < ram_end)
-			ram_end = src_end;
+			ram_end = mem_end;
 		/* intersection is [ram, ram_end) */
-		for (ram &= ~0x1f; ram < ram_end; ram += 0x20)
+		for (ram &= ~(minline-1); ram < ram_end; ram += minline)
-			adiv5_mem_write(cortexm_ap(t), CORTEXM_DCCIMVAC, &ram, 4);
+			adiv5_mem_write(cortexm_ap(t), cache_reg, &ram, 4);
+	}
 }
 
+static void cortexm_mem_read(target *t, void *dest, target_addr src, size_t len)
+{
+	cortexm_cache_clean(t, src, len, false);
 	adiv5_mem_read(cortexm_ap(t), dest, src, len);
 }
 
 static void cortexm_mem_write(target *t, target_addr dest, const void *src, size_t len)
 {
-	/* flush data cache for RAM regions that intersect requested region */
+	cortexm_cache_clean(t, dest, len, true);
-	target_addr dest_end = dest + len; /* following code is NOP if wraparound */
-	/* requested region is [dest, dest_end) */
-	for (struct target_ram *r = t->ram; r; r = r->next) {
-		target_addr ram = r->start;
-		target_addr ram_end = r->start + r->length;
-		/* RAM region is [ram, ram_end) */
-                if (dest > ram)
-			ram = dest;
-		if (dest_end < ram_end)
-			ram_end = dest_end;
-		/* intersection is [ram, ram_end) */
-		for (ram &= ~0x1f; ram < ram_end; ram += 0x20)
-			adiv5_mem_write(cortexm_ap(t), CORTEXM_DCCIMVAC, &ram, 4);
-	}
-
 	adiv5_mem_write(cortexm_ap(t), dest, src, len);
 }
 
@@ -283,6 +281,15 @@ bool cortexm_probe(ADIv5_AP_t *ap)
 	priv->demcr = CORTEXM_DEMCR_TRCENA | CORTEXM_DEMCR_VC_HARDERR |
 			CORTEXM_DEMCR_VC_CORERESET;
 
+	/* Check cache type */
+	uint32_t ctr = target_mem_read32(t, CORTEXM_CTR);
+	if ((ctr >> 29) == 4) {
+		priv->has_cache = true;
+		priv->dcache_minline = 4 << (ctr & 0xf);
+	} else {
+		target_check_error(t);
+	}
+
 #define PROBE(x) \
 	do { if ((x)(t)) return true; else target_check_error(t); } while (0)
 
@@ -583,6 +590,9 @@ void cortexm_halt_resume(target *t, bool step)
 			cortexm_pc_write(t, pc + 2);
 	}
 
+	if (priv->has_cache)
+		target_mem_write32(t, CORTEXM_ICIALLU, 0);
+
 	target_mem_write32(t, CORTEXM_DHCSR, dhcsr);
 }
 

src/target/cortexm.h

@@ -37,7 +37,15 @@
 #define CORTEXM_DCRDR		(CORTEXM_SCS_BASE + 0xDF8)
 #define CORTEXM_DEMCR		(CORTEXM_SCS_BASE + 0xDFC)
 
-/* Data cache clean and invalidate by address to the PoC=Point of Coherency */
+/* Cache identification */
+#define CORTEXM_CLIDR		(CORTEXM_SCS_BASE + 0xD78)
+#define CORTEXM_CTR		(CORTEXM_SCS_BASE + 0xD7C)
+#define CORTEXM_CCSIDR		(CORTEXM_SCS_BASE + 0xD80)
+#define CORTEXM_CSSELR		(CORTEXM_SCS_BASE + 0xD84)
+
+/* Cache maintenance operations */
+#define CORTEXM_ICIALLU		(CORTEXM_SCS_BASE + 0xF50)
+#define CORTEXM_DCCMVAC		(CORTEXM_SCS_BASE + 0xF68)
 #define CORTEXM_DCCIMVAC	(CORTEXM_SCS_BASE + 0xF70)
 
 #define CORTEXM_FPB_BASE	(CORTEXM_PPB_BASE + 0x2000)