drivers/misc/sram.c - linux/kernel/git/bpf/bpf-next - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Generic on-chip SRAM allocation driver
  *
  * Copyright (C) 2012 Philipp Zabel, Pengutronix
  */

 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/genalloc.h>
 #include <linux/io.h>
 #include <linux/list_sort.h>
 #include <linux/of_address.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
 #include <linux/mfd/syscon.h>
 #include <soc/at91/atmel-secumod.h>

 #include "sram.h"

 #define SRAM_GRANULARITY	32

 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_fromio(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_toio(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;
 	}
 	if (block->protect_exec) {
 		ret = sram_check_protect_exec(sram, block, part);
 		if (ret)
 			return ret;

 		ret = sram_add_pool(sram, block, start, part);
 		if (ret)
 			return ret;

 		sram_add_protect_exec(part);
 	}

 	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)
 {
 	struct sram_reserve *ra = list_entry(a, struct sram_reserve, list);
 	struct sram_reserve *rb = list_entry(b, struct sram_reserve, list);

 	return ra->start - rb->start;
 }

 static int sram_reserve_regions(struct sram_dev *sram, struct resource *res)
 {
 	struct device_node *np = sram->dev->of_node, *child;
 	unsigned long size, cur_start, cur_size;
 	struct sram_reserve *rblocks, *block;
 	struct list_head reserve_list;
 	unsigned int nblocks, exports = 0;
 	const char *label;
 	int ret = 0;

 	INIT_LIST_HEAD(&reserve_list);

 	size = resource_size(res);

 	/*
 	 * We need an additional block to mark the end of the memory region
 	 * after the reserved blocks from the dt are processed.
 	 */
 	nblocks = (np) ? of_get_available_child_count(np) + 1 : 1;
 	rblocks = kcalloc(nblocks, sizeof(*rblocks), GFP_KERNEL);
 	if (!rblocks)
 		return -ENOMEM;

 	block = &rblocks[0];
 	for_each_available_child_of_node(np, child) {
 		struct resource child_res;

 		ret = of_address_to_resource(child, 0, &child_res);
 		if (ret < 0) {
 			dev_err(sram->dev,
 				"could not get address for node %pOF\n",
 				child);
 			goto err_chunks;
 		}

 		if (child_res.start < res->start || child_res.end > res->end) {
 			dev_err(sram->dev,
 				"reserved block %pOF outside the sram area\n",
 				child);
 			ret = -EINVAL;
 			goto err_chunks;
 		}

 		block->start = child_res.start - res->start;
 		block->size = resource_size(&child_res);
 		list_add_tail(&block->list, &reserve_list);

 		if (of_find_property(child, "export", NULL))
 			block->export = true;

 		if (of_find_property(child, "pool", NULL))
 			block->pool = true;

 		if (of_find_property(child, "protect-exec", NULL))
 			block->protect_exec = true;

 		if ((block->export || block->pool || block->protect_exec) &&
 		    block->size) {
 			exports++;

 			label = NULL;
 			ret = of_property_read_string(child, "label", &label);
 			if (ret && ret != -EINVAL) {
 				dev_err(sram->dev,
 					"%pOF has invalid label name\n",
 					child);
 				goto err_chunks;
 			}
 			if (!label)
 				label = child->name;

 			block->label = devm_kstrdup(sram->dev,
 						    label, GFP_KERNEL);
 			if (!block->label) {
 				ret = -ENOMEM;
 				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;
 	rblocks[nblocks - 1].size = 0;
 	list_add_tail(&rblocks[nblocks - 1].list, &reserve_list);

 	list_sort(NULL, &reserve_list, sram_reserve_cmp);

 	if (exports) {
 		sram->partition = devm_kcalloc(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) {
 			dev_err(sram->dev,
 				"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->protect_exec) &&
 		    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;
 			continue;
 		}

 		/*
 		 * allocate the space between the current starting
 		 * address and the following reserved block, or the
 		 * end of the region.
 		 */
 		cur_size = block->start - cur_start;

 		dev_dbg(sram->dev, "adding chunk 0x%lx-0x%lx\n",
 			cur_start, cur_start + cur_size);

 		ret = gen_pool_add_virt(sram->pool,
 				(unsigned long)sram->virt_base + cur_start,
 				res->start + cur_start, cur_size, -1);
 		if (ret < 0) {
 			sram_free_partitions(sram);
 			goto err_chunks;
 		}

 		/* next allocation after this reserved block */
 		cur_start = block->start + block->size;
 	}

 err_chunks:
 	of_node_put(child);
 	kfree(rblocks);

 	return ret;
 }

 static int atmel_securam_wait(void)
 {
 	struct regmap *regmap;
 	u32 val;

 	regmap = syscon_regmap_lookup_by_compatible("atmel,sama5d2-secumod");
 	if (IS_ERR(regmap))
 		return -ENODEV;

 	return regmap_read_poll_timeout(regmap, AT91_SECUMOD_RAMRDY, val,
 					val & AT91_SECUMOD_RAMRDY_READY,
 					10000, 500000);
 }

 static const struct of_device_id sram_dt_ids[] = {
 	{ .compatible = "mmio-sram" },
 	{ .compatible = "atmel,sama5d2-securam", .data = atmel_securam_wait },
 	{}
 };

 static int sram_probe(struct platform_device *pdev)
 {
 	struct sram_dev *sram;
 	int ret;
 	int (*init_func)(void);

 	sram = devm_kzalloc(&pdev->dev, sizeof(*sram), GFP_KERNEL);
 	if (!sram)
 		return -ENOMEM;

 	sram->dev = &pdev->dev;

 	if (of_property_read_bool(pdev->dev.of_node, "no-memory-wc"))
 		sram->virt_base = devm_platform_ioremap_resource(pdev, 0);
 	else
 		sram->virt_base = devm_platform_ioremap_resource_wc(pdev, 0);
 	if (IS_ERR(sram->virt_base)) {
 		dev_err(&pdev->dev, "could not map SRAM registers\n");
 		return PTR_ERR(sram->virt_base);
 	}

 	sram->pool = devm_gen_pool_create(sram->dev, ilog2(SRAM_GRANULARITY),
 					  NUMA_NO_NODE, NULL);
 	if (IS_ERR(sram->pool))
 		return PTR_ERR(sram->pool);

 	sram->clk = devm_clk_get(sram->dev, NULL);
 	if (IS_ERR(sram->clk))
 		sram->clk = NULL;
 	else
 		clk_prepare_enable(sram->clk);

 	ret = sram_reserve_regions(sram,
 			platform_get_resource(pdev, IORESOURCE_MEM, 0));
 	if (ret)
 		goto err_disable_clk;

 	platform_set_drvdata(pdev, sram);

 	init_func = of_device_get_match_data(&pdev->dev);
 	if (init_func) {
 		ret = init_func();
 		if (ret)
 			goto err_free_partitions;
 	}

 	dev_dbg(sram->dev, "SRAM pool: %zu KiB @ 0x%p\n",
 		gen_pool_size(sram->pool) / 1024, sram->virt_base);

 	return 0;

 err_free_partitions:
 	sram_free_partitions(sram);
 err_disable_clk:
 	if (sram->clk)
 		clk_disable_unprepare(sram->clk);

 	return ret;
 }

 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");

 	if (sram->clk)
 		clk_disable_unprepare(sram->clk);

 	return 0;
 }

 static struct platform_driver sram_driver = {
 	.driver = {
 		.name = "sram",
 		.of_match_table = sram_dt_ids,
 	},
 	.probe = sram_probe,
 	.remove = sram_remove,
 };

 static int __init sram_init(void)
 {
 	return platform_driver_register(&sram_driver);
 }

 postcore_initcall(sram_init);
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* Generic on-chip SRAM allocation driver
	*
	* Copyright (C) 2012 Philipp Zabel, Pengutronix
	*/

	#include <linux/clk.h>
	#include <linux/delay.h>
	#include <linux/genalloc.h>
	#include <linux/io.h>
	#include <linux/list_sort.h>
	#include <linux/of_address.h>
	#include <linux/of_device.h>
	#include <linux/platform_device.h>
	#include <linux/regmap.h>
	#include <linux/slab.h>
	#include <linux/mfd/syscon.h>
	#include <soc/at91/atmel-secumod.h>

	#include "sram.h"

	#define SRAM_GRANULARITY 32

	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_fromio(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_toio(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;
	}
	if (block->protect_exec) {
	ret = sram_check_protect_exec(sram, block, part);
	if (ret)
	return ret;

	ret = sram_add_pool(sram, block, start, part);
	if (ret)
	return ret;

	sram_add_protect_exec(part);
	}

	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)
	{
	struct sram_reserve *ra = list_entry(a, struct sram_reserve, list);
	struct sram_reserve *rb = list_entry(b, struct sram_reserve, list);

	return ra->start - rb->start;
	}

	static int sram_reserve_regions(struct sram_dev sram, struct resource res)
	{
	struct device_node np = sram->dev->of_node, child;
	unsigned long size, cur_start, cur_size;
	struct sram_reserve rblocks, block;
	struct list_head reserve_list;
	unsigned int nblocks, exports = 0;
	const char *label;
	int ret = 0;

	INIT_LIST_HEAD(&reserve_list);

	size = resource_size(res);

	/*
	* We need an additional block to mark the end of the memory region
	* after the reserved blocks from the dt are processed.
	*/
	nblocks = (np) ? of_get_available_child_count(np) + 1 : 1;
	rblocks = kcalloc(nblocks, sizeof(*rblocks), GFP_KERNEL);
	if (!rblocks)
	return -ENOMEM;

	block = &rblocks[0];
	for_each_available_child_of_node(np, child) {
	struct resource child_res;

	ret = of_address_to_resource(child, 0, &child_res);
	if (ret < 0) {
	dev_err(sram->dev,
	"could not get address for node %pOF\n",
	child);
	goto err_chunks;
	}

	if (child_res.start < res->start \|\| child_res.end > res->end) {
	dev_err(sram->dev,
	"reserved block %pOF outside the sram area\n",
	child);
	ret = -EINVAL;
	goto err_chunks;
	}

	block->start = child_res.start - res->start;
	block->size = resource_size(&child_res);
	list_add_tail(&block->list, &reserve_list);

	if (of_find_property(child, "export", NULL))
	block->export = true;

	if (of_find_property(child, "pool", NULL))
	block->pool = true;

	if (of_find_property(child, "protect-exec", NULL))
	block->protect_exec = true;

	if ((block->export \|\| block->pool \|\| block->protect_exec) &&
	block->size) {
	exports++;

	label = NULL;
	ret = of_property_read_string(child, "label", &label);
	if (ret && ret != -EINVAL) {
	dev_err(sram->dev,
	"%pOF has invalid label name\n",
	child);
	goto err_chunks;
	}
	if (!label)
	label = child->name;

	block->label = devm_kstrdup(sram->dev,
	label, GFP_KERNEL);
	if (!block->label) {
	ret = -ENOMEM;
	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;
	rblocks[nblocks - 1].size = 0;
	list_add_tail(&rblocks[nblocks - 1].list, &reserve_list);

	list_sort(NULL, &reserve_list, sram_reserve_cmp);

	if (exports) {
	sram->partition = devm_kcalloc(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) {
	dev_err(sram->dev,
	"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->protect_exec) &&
	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;
	continue;
	}

	/*
	* allocate the space between the current starting
	* address and the following reserved block, or the
	* end of the region.
	*/
	cur_size = block->start - cur_start;

	dev_dbg(sram->dev, "adding chunk 0x%lx-0x%lx\n",
	cur_start, cur_start + cur_size);

	ret = gen_pool_add_virt(sram->pool,
	(unsigned long)sram->virt_base + cur_start,
	res->start + cur_start, cur_size, -1);
	if (ret < 0) {
	sram_free_partitions(sram);
	goto err_chunks;
	}

	/* next allocation after this reserved block */
	cur_start = block->start + block->size;
	}

	err_chunks:
	of_node_put(child);
	kfree(rblocks);

	return ret;
	}

	static int atmel_securam_wait(void)
	{
	struct regmap *regmap;
	u32 val;

	regmap = syscon_regmap_lookup_by_compatible("atmel,sama5d2-secumod");
	if (IS_ERR(regmap))
	return -ENODEV;

	return regmap_read_poll_timeout(regmap, AT91_SECUMOD_RAMRDY, val,
	val & AT91_SECUMOD_RAMRDY_READY,
	10000, 500000);
	}

	static const struct of_device_id sram_dt_ids[] = {
	{ .compatible = "mmio-sram" },
	{ .compatible = "atmel,sama5d2-securam", .data = atmel_securam_wait },
	{}
	};

	static int sram_probe(struct platform_device *pdev)
	{
	struct sram_dev *sram;
	int ret;
	int (*init_func)(void);

	sram = devm_kzalloc(&pdev->dev, sizeof(*sram), GFP_KERNEL);
	if (!sram)
	return -ENOMEM;

	sram->dev = &pdev->dev;

	if (of_property_read_bool(pdev->dev.of_node, "no-memory-wc"))
	sram->virt_base = devm_platform_ioremap_resource(pdev, 0);
	else
	sram->virt_base = devm_platform_ioremap_resource_wc(pdev, 0);
	if (IS_ERR(sram->virt_base)) {
	dev_err(&pdev->dev, "could not map SRAM registers\n");
	return PTR_ERR(sram->virt_base);
	}

	sram->pool = devm_gen_pool_create(sram->dev, ilog2(SRAM_GRANULARITY),
	NUMA_NO_NODE, NULL);
	if (IS_ERR(sram->pool))
	return PTR_ERR(sram->pool);

	sram->clk = devm_clk_get(sram->dev, NULL);
	if (IS_ERR(sram->clk))
	sram->clk = NULL;
	else
	clk_prepare_enable(sram->clk);

	ret = sram_reserve_regions(sram,
	platform_get_resource(pdev, IORESOURCE_MEM, 0));
	if (ret)
	goto err_disable_clk;

	platform_set_drvdata(pdev, sram);

	init_func = of_device_get_match_data(&pdev->dev);
	if (init_func) {
	ret = init_func();
	if (ret)
	goto err_free_partitions;
	}

	dev_dbg(sram->dev, "SRAM pool: %zu KiB @ 0x%p\n",
	gen_pool_size(sram->pool) / 1024, sram->virt_base);

	return 0;

	err_free_partitions:
	sram_free_partitions(sram);
	err_disable_clk:
	if (sram->clk)
	clk_disable_unprepare(sram->clk);

	return ret;
	}

	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");

	if (sram->clk)
	clk_disable_unprepare(sram->clk);

	return 0;
	}

	static struct platform_driver sram_driver = {
	.driver = {
	.name = "sram",
	.of_match_table = sram_dt_ids,
	},
	.probe = sram_probe,
	.remove = sram_remove,
	};

	static int __init sram_init(void)
	{
	return platform_driver_register(&sram_driver);
	}

	postcore_initcall(sram_init);