2 files changed, 204 insertions, 8 deletions

diff --git a/Documentation/devicetree/bindings/misc/sram.txt b/Documentation/devicetree/bindings/misc/sram.txt
index 36cbe5aea990..42ee9438b771 100644
--- a/Documentation/devicetree/bindings/misc/sram.txt
+++ b/Documentation/devicetree/bindings/misc/sram.txt
@@ -33,6 +33,12 @@ Optional properties in the area nodes:
 
 - compatible : standard definition, should contain a vendor specific string
                in the form <vendor>,[<device>-]<usage>
+- pool : indicates that the particular reserved SRAM area is addressable
+         and in use by another device or devices
+- export : indicates that the reserved SRAM area may be accessed outside
+           of the kernel, e.g. by bootloader or userspace
+- label : the name for the reserved partition, if omitted, the label
+          is taken from the node name excluding the unit address.
 
 Example:
 
@@ -48,4 +54,14 @@ sram: sram@5c000000 {
 		compatible = "socvendor,smp-sram";
 		reg = <0x100 0x50>;
 	};
+
+	device-sram@1000 {
+		reg = <0x1000 0x1000>;
+		pool;
+	};
+
+	exported@20000 {
+		reg = <0x20000 0x20000>;
+		export;
+	};
 };
diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c
index 431e1dd528bc..b0b5e9430bfe 100644
--- a/drivers/misc/sram.c
+++ b/drivers/misc/sram.c
@@ -28,20 +28,144 @@
 
 #define SRAM_GRANULARITY	32
 
+struct sram_partition {
+	void *base;
+
+	struct gen_pool *pool;
+	struct bin_attribute battr;
+	struct mutex lock;
+};
+
 struct sram_dev {
 	struct device *dev;
 	void __iomem *virt_base;
 
 	struct gen_pool *pool;
 	struct clk *clk;
+
+	struct sram_partition *partition;
+	u32 partitions;
 };
 
 struct sram_reserve {
 	struct list_head list;
 	u32 start;
 	u32 size;
+	bool export;
+	bool pool;
+	const char *label;
 };
 
+static ssize_t sram_read(struct file *filp, struct kobject *kobj,
+			 struct bin_attribute *attr,
+			 char *buf, loff_t pos, size_t count)
+{
+	struct sram_partition *part;
+
+	part = container_of(attr, struct sram_partition, battr);
+
+	mutex_lock(&part->lock);
+	memcpy(buf, part->base + pos, count);
+	mutex_unlock(&part->lock);
+
+	return count;
+}
+
+static ssize_t sram_write(struct file *filp, struct kobject *kobj,
+			  struct bin_attribute *attr,
+			  char *buf, loff_t pos, size_t count)
+{
+	struct sram_partition *part;
+
+	part = container_of(attr, struct sram_partition, battr);
+
+	mutex_lock(&part->lock);
+	memcpy(part->base + pos, buf, count);
+	mutex_unlock(&part->lock);
+
+	return count;
+}
+
+static int sram_add_pool(struct sram_dev *sram, struct sram_reserve *block,
+			 phys_addr_t start, struct sram_partition *part)
+{
+	int ret;
+
+	part->pool = devm_gen_pool_create(sram->dev, ilog2(SRAM_GRANULARITY),
+					  NUMA_NO_NODE, block->label);
+	if (IS_ERR(part->pool))
+		return PTR_ERR(part->pool);
+
+	ret = gen_pool_add_virt(part->pool, (unsigned long)part->base, start,
+				block->size, NUMA_NO_NODE);
+	if (ret < 0) {
+		dev_err(sram->dev, "failed to register subpool: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int sram_add_export(struct sram_dev *sram, struct sram_reserve *block,
+			   phys_addr_t start, struct sram_partition *part)
+{
+	sysfs_bin_attr_init(&part->battr);
+	part->battr.attr.name = devm_kasprintf(sram->dev, GFP_KERNEL,
+					       "%llx.sram",
+					       (unsigned long long)start);
+	if (!part->battr.attr.name)
+		return -ENOMEM;
+
+	part->battr.attr.mode = S_IRUSR | S_IWUSR;
+	part->battr.read = sram_read;
+	part->battr.write = sram_write;
+	part->battr.size = block->size;
+
+	return device_create_bin_file(sram->dev, &part->battr);
+}
+
+static int sram_add_partition(struct sram_dev *sram, struct sram_reserve *block,
+			      phys_addr_t start)
+{
+	int ret;
+	struct sram_partition *part = &sram->partition[sram->partitions];
+
+	mutex_init(&part->lock);
+	part->base = sram->virt_base + block->start;
+
+	if (block->pool) {
+		ret = sram_add_pool(sram, block, start, part);
+		if (ret)
+			return ret;
+	}
+	if (block->export) {
+		ret = sram_add_export(sram, block, start, part);
+		if (ret)
+			return ret;
+	}
+	sram->partitions++;
+
+	return 0;
+}
+
+static void sram_free_partitions(struct sram_dev *sram)
+{
+	struct sram_partition *part;
+
+	if (!sram->partitions)
+		return;
+
+	part = &sram->partition[sram->partitions - 1];
+	for (; sram->partitions; sram->partitions--, part--) {
+		if (part->battr.size)
+			device_remove_bin_file(sram->dev, &part->battr);
+
+		if (part->pool &&
+		    gen_pool_avail(part->pool) < gen_pool_size(part->pool))
+			dev_err(sram->dev, "removed pool while SRAM allocated\n");
+	}
+}
+
 static int sram_reserve_cmp(void *priv, struct list_head *a,
 					struct list_head *b)
 {
@@ -57,7 +181,8 @@ static int sram_reserve_regions(struct sram_dev *sram, struct resource *res)
 	unsigned long size, cur_start, cur_size;
 	struct sram_reserve *rblocks, *block;
 	struct list_head reserve_list;
-	unsigned int nblocks;
+	unsigned int nblocks, exports = 0;
+	const char *label;
 	int ret = 0;
 
 	INIT_LIST_HEAD(&reserve_list);
@@ -69,7 +194,7 @@ static int sram_reserve_regions(struct sram_dev *sram, struct resource *res)
 	 * after the reserved blocks from the dt are processed.
 	 */
 	nblocks = (np) ? of_get_available_child_count(np) + 1 : 1;
-	rblocks = kmalloc((nblocks) * sizeof(*rblocks), GFP_KERNEL);
+	rblocks = kzalloc((nblocks) * sizeof(*rblocks), GFP_KERNEL);
 	if (!rblocks)
 		return -ENOMEM;
 
@@ -82,7 +207,6 @@ static int sram_reserve_regions(struct sram_dev *sram, struct resource *res)
 			dev_err(sram->dev,
 				"could not get address for node %s\n",
 				child->full_name);
-			of_node_put(child);
 			goto err_chunks;
 		}
 
@@ -91,7 +215,6 @@ static int sram_reserve_regions(struct sram_dev *sram, struct resource *res)
 				"reserved block %s outside the sram area\n",
 				child->full_name);
 			ret = -EINVAL;
-			of_node_put(child);
 			goto err_chunks;
 		}
 
@@ -99,11 +222,42 @@ static int sram_reserve_regions(struct sram_dev *sram, struct resource *res)
 		block->size = resource_size(&child_res);
 		list_add_tail(&block->list, &reserve_list);
 
-		dev_dbg(sram->dev, "found reserved block 0x%x-0x%x\n",
-			block->start, block->start + block->size);
+		if (of_find_property(child, "export", NULL))
+			block->export = true;
+
+		if (of_find_property(child, "pool", NULL))
+			block->pool = true;
+
+		if ((block->export || block->pool) && block->size) {
+			exports++;
+
+			label = NULL;
+			ret = of_property_read_string(child, "label", &label);
+			if (ret && ret != -EINVAL) {
+				dev_err(sram->dev,
+					"%s has invalid label name\n",
+					child->full_name);
+				goto err_chunks;
+			}
+			if (!label)
+				label = child->name;
+
+			block->label = devm_kstrdup(sram->dev,
+						    label, GFP_KERNEL);
+			if (!block->label)
+				goto err_chunks;
+
+			dev_dbg(sram->dev, "found %sblock '%s' 0x%x-0x%x\n",
+				block->export ? "exported " : "", block->label,
+				block->start, block->start + block->size);
+		} else {
+			dev_dbg(sram->dev, "found reserved block 0x%x-0x%x\n",
+				block->start, block->start + block->size);
+		}
 
 		block++;
 	}
+	child = NULL;
 
 	/* the last chunk marks the end of the region */
 	rblocks[nblocks - 1].start = size;
@@ -112,8 +266,17 @@ static int sram_reserve_regions(struct sram_dev *sram, struct resource *res)
 
 	list_sort(NULL, &reserve_list, sram_reserve_cmp);
 
-	cur_start = 0;
+	if (exports) {
+		sram->partition = devm_kzalloc(sram->dev,
+				       exports * sizeof(*sram->partition),
+				       GFP_KERNEL);
+		if (!sram->partition) {
+			ret = -ENOMEM;
+			goto err_chunks;
+		}
+	}
 
+	cur_start = 0;
 	list_for_each_entry(block, &reserve_list, list) {
 		/* can only happen if sections overlap */
 		if (block->start < cur_start) {
@@ -121,9 +284,19 @@ static int sram_reserve_regions(struct sram_dev *sram, struct resource *res)
 				"block at 0x%x starts after current offset 0x%lx\n",
 				block->start, cur_start);
 			ret = -EINVAL;
+			sram_free_partitions(sram);
 			goto err_chunks;
 		}
 
+		if ((block->export || block->pool) && block->size) {
+			ret = sram_add_partition(sram, block,
+						 res->start + block->start);
+			if (ret) {
+				sram_free_partitions(sram);
+				goto err_chunks;
+			}
+		}
+
 		/* current start is in a reserved block, so continue after it */
 		if (block->start == cur_start) {
 			cur_start = block->start + block->size;
@@ -143,14 +316,19 @@ static int sram_reserve_regions(struct sram_dev *sram, struct resource *res)
 		ret = gen_pool_add_virt(sram->pool,
 				(unsigned long)sram->virt_base + cur_start,
 				res->start + cur_start, cur_size, -1);
-		if (ret < 0)
+		if (ret < 0) {
+			sram_free_partitions(sram);
 			goto err_chunks;
+		}
 
 		/* next allocation after this reserved block */
 		cur_start = block->start + block->size;
 	}
 
  err_chunks:
+	if (child)
+		of_node_put(child);
+
 	kfree(rblocks);
 
 	return ret;
@@ -213,6 +391,8 @@ static int sram_remove(struct platform_device *pdev)
 {
 	struct sram_dev *sram = platform_get_drvdata(pdev);
 
+	sram_free_partitions(sram);
+
 	if (gen_pool_avail(sram->pool) < gen_pool_size(sram->pool))
 		dev_err(sram->dev, "removed while SRAM allocated\n");