net: ipa: avoid going past end of resource group array

The minimum and maximum limits for resources assigned to a given
resource group are programmed in pairs, with the limits for two
groups set in a single register.

If the number of supported resource groups is odd, only half of the
register that defines these limits is valid for the last group; that
group has no second group in the pair.

Currently we ignore this constraint, and it turns out to be harmless,
but it is not guaranteed to be.  This patch addresses that, and adds
support for programming the 5th resource group's limits.

Rework how the resource group limit registers are programmed by
having a single function program all group pairs rather than having
one function program each pair.  Add the programming of the 4-5
resource group pair limits to this function.  If a resource group is
not supported, pass a null pointer to ipa_resource_config_common()
for that group and have that function write zeroes in that case.
Tested-by: Sujit Kautkar <sujitka@chromium.org>
Signed-off-by: Alex Elder <elder@linaro.org>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ipa/ipa_main.c

@@ -370,8 +370,11 @@ static bool ipa_resource_limits_valid(struct ipa *ipa,
 	u32 i;
 	u32 j;
 
+	/* We program at most 6 source or destination resource group limits */
+	BUILD_BUG_ON(IPA_RESOURCE_GROUP_SRC_MAX > 6);
+
 	group_count = ipa_resource_group_src_count(ipa->version);
-	if (!group_count)
+	if (!group_count || group_count > IPA_RESOURCE_GROUP_SRC_MAX)
 		return false;
 
 	/* Return an error if a non-zero resource limit is specified
@@ -387,7 +390,7 @@ static bool ipa_resource_limits_valid(struct ipa *ipa,
 	}
 
 	group_count = ipa_resource_group_dst_count(ipa->version);
-	if (!group_count)
+	if (!group_count || group_count > IPA_RESOURCE_GROUP_DST_MAX)
 		return false;
 
 	for (i = 0; i < data->resource_dst_count; i++) {
@@ -421,46 +424,64 @@ ipa_resource_config_common(struct ipa *ipa, u32 offset,
 
 	val = u32_encode_bits(xlimits->min, X_MIN_LIM_FMASK);
 	val |= u32_encode_bits(xlimits->max, X_MAX_LIM_FMASK);
+	if (ylimits) {
 		val |= u32_encode_bits(ylimits->min, Y_MIN_LIM_FMASK);
 		val |= u32_encode_bits(ylimits->max, Y_MAX_LIM_FMASK);
+	}
 
 	iowrite32(val, ipa->reg_virt + offset);
 }
 
-static void ipa_resource_config_src_01(struct ipa *ipa,
+static void ipa_resource_config_src(struct ipa *ipa,
 				    const struct ipa_resource_src *resource)
 {
-	u32 offset = IPA_REG_SRC_RSRC_GRP_01_RSRC_TYPE_N_OFFSET(resource->type);
+	u32 group_count = ipa_resource_group_src_count(ipa->version);
+	const struct ipa_resource_limits *ylimits;
+	u32 offset;
 
-	ipa_resource_config_common(ipa, offset,
-				   &resource->limits[0], &resource->limits[1]);
-}
+	offset = IPA_REG_SRC_RSRC_GRP_01_RSRC_TYPE_N_OFFSET(resource->type);
+	ylimits = group_count == 1 ? NULL : &resource->limits[1];
+	ipa_resource_config_common(ipa, offset, &resource->limits[0], ylimits);
 
-static void ipa_resource_config_src_23(struct ipa *ipa,
-				       const struct ipa_resource_src *resource)
-{
-	u32 offset = IPA_REG_SRC_RSRC_GRP_23_RSRC_TYPE_N_OFFSET(resource->type);
+	if (group_count < 2)
+		return;
 
-	ipa_resource_config_common(ipa, offset,
-				   &resource->limits[2], &resource->limits[3]);
-}
+	offset = IPA_REG_SRC_RSRC_GRP_23_RSRC_TYPE_N_OFFSET(resource->type);
+	ylimits = group_count == 3 ? NULL : &resource->limits[3];
+	ipa_resource_config_common(ipa, offset, &resource->limits[2], ylimits);
 
-static void ipa_resource_config_dst_01(struct ipa *ipa,
-				       const struct ipa_resource_dst *resource)
-{
-	u32 offset = IPA_REG_DST_RSRC_GRP_01_RSRC_TYPE_N_OFFSET(resource->type);
+	if (group_count < 4)
+		return;
 
-	ipa_resource_config_common(ipa, offset,
-				   &resource->limits[0], &resource->limits[1]);
+	offset = IPA_REG_SRC_RSRC_GRP_45_RSRC_TYPE_N_OFFSET(resource->type);
+	ylimits = group_count == 5 ? NULL : &resource->limits[5];
+	ipa_resource_config_common(ipa, offset, &resource->limits[4], ylimits);
 }
 
-static void ipa_resource_config_dst_23(struct ipa *ipa,
+static void ipa_resource_config_dst(struct ipa *ipa,
 				    const struct ipa_resource_dst *resource)
 {
-	u32 offset = IPA_REG_DST_RSRC_GRP_23_RSRC_TYPE_N_OFFSET(resource->type);
+	u32 group_count = ipa_resource_group_dst_count(ipa->version);
+	const struct ipa_resource_limits *ylimits;
+	u32 offset;
+
+	offset = IPA_REG_DST_RSRC_GRP_01_RSRC_TYPE_N_OFFSET(resource->type);
+	ylimits = group_count == 1 ? NULL : &resource->limits[1];
+	ipa_resource_config_common(ipa, offset, &resource->limits[0], ylimits);
+
+	if (group_count < 2)
+		return;
+
+	offset = IPA_REG_DST_RSRC_GRP_23_RSRC_TYPE_N_OFFSET(resource->type);
+	ylimits = group_count == 3 ? NULL : &resource->limits[3];
+	ipa_resource_config_common(ipa, offset, &resource->limits[2], ylimits);
 
-	ipa_resource_config_common(ipa, offset,
-				   &resource->limits[2], &resource->limits[3]);
+	if (group_count < 4)
+		return;
+
+	offset = IPA_REG_DST_RSRC_GRP_45_RSRC_TYPE_N_OFFSET(resource->type);
+	ylimits = group_count == 5 ? NULL : &resource->limits[5];
+	ipa_resource_config_common(ipa, offset, &resource->limits[4], ylimits);
 }
 
 static int
@@ -471,15 +492,11 @@ ipa_resource_config(struct ipa *ipa, const struct ipa_resource_data *data)
 	if (!ipa_resource_limits_valid(ipa, data))
 		return -EINVAL;
 
-	for (i = 0; i < data->resource_src_count; i++) {
-		ipa_resource_config_src_01(ipa, &data->resource_src[i]);
-		ipa_resource_config_src_23(ipa, &data->resource_src[i]);
-	}
+	for (i = 0; i < data->resource_src_count; i++)
+		ipa_resource_config_src(ipa, data->resource_src);
 
-	for (i = 0; i < data->resource_dst_count; i++) {
-		ipa_resource_config_dst_01(ipa, &data->resource_dst[i]);
-		ipa_resource_config_dst_23(ipa, &data->resource_dst[i]);
-	}
+	for (i = 0; i < data->resource_dst_count; i++)
+		ipa_resource_config_dst(ipa, data->resource_dst);
 
 	return 0;
 }