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Subject[PATCH v8 2/6] misc: sram: implement reserved sram areas
Date
This implements support for defining reserved areas as subnodes,
to keep the genpool from using these.

Suggested-by: Rob Herring <robherring2@gmail.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Ulrich Prinz <ulrich.prinz@googlemail.com>
---
drivers/misc/sram.c | 125 +++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 118 insertions(+), 7 deletions(-)

diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c
index afe66571..674b0cd 100644
--- a/drivers/misc/sram.c
+++ b/drivers/misc/sram.c
@@ -24,6 +24,9 @@
#include <linux/err.h>
#include <linux/io.h>
#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/list.h>
+#include <linux/list_sort.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
@@ -36,14 +39,35 @@ struct sram_dev {
struct clk *clk;
};

+struct sram_reserve {
+ struct list_head list;
+ u32 start;
+ u32 size;
+};
+
+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_probe(struct platform_device *pdev)
{
void __iomem *virt_base;
struct sram_dev *sram;
struct resource *res;
- unsigned long size;
+ struct device_node *np = pdev->dev.of_node, *child;
+ unsigned long size, cur_start, cur_size;
+ struct sram_reserve *rblocks, *block;
+ struct list_head reserve_list;
+ unsigned int nblocks;
int ret;

+ INIT_LIST_HEAD(&reserve_list);
+
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
virt_base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(virt_base))
@@ -65,19 +89,106 @@ static int sram_probe(struct platform_device *pdev)
if (!sram->pool)
return -ENOMEM;

- ret = gen_pool_add_virt(sram->pool, (unsigned long)virt_base,
- res->start, size, -1);
- if (ret < 0) {
- if (sram->clk)
- clk_disable_unprepare(sram->clk);
- return ret;
+ /*
+ * 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 = kmalloc((nblocks) * sizeof(*rblocks), GFP_KERNEL);
+ if (!rblocks) {
+ ret = -ENOMEM;
+ goto err_alloc;
}

+ 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(&pdev->dev,
+ "could not get address for node %s\n",
+ child->full_name);
+ goto err_chunks;
+ }
+
+ if (child_res.start < res->start || child_res.end > res->end) {
+ dev_err(&pdev->dev,
+ "reserved block %s outside the sram area\n",
+ child->full_name);
+ 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);
+
+ dev_dbg(&pdev->dev, "found reserved block 0x%x-0x%x\n",
+ block->start,
+ block->start + block->size);
+
+ block++;
+ }
+
+ /* 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);
+
+ cur_start = 0;
+
+ list_for_each_entry(block, &reserve_list, list) {
+ /* can only happen if sections overlap */
+ if (block->start < cur_start) {
+ dev_err(&pdev->dev,
+ "block at 0x%x starts after current offset 0x%lx\n",
+ block->start, cur_start);
+ ret = -EINVAL;
+ 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(&pdev->dev, "adding chunk 0x%lx-0x%lx\n",
+ cur_start, cur_start + cur_size);
+ ret = gen_pool_add_virt(sram->pool,
+ (unsigned long)virt_base + cur_start,
+ res->start + cur_start, cur_size, -1);
+ if (ret < 0)
+ goto err_chunks;
+
+ /* next allocation after this reserved block */
+ cur_start = block->start + block->size;
+ }
+
+ kfree(rblocks);
+
platform_set_drvdata(pdev, sram);

dev_dbg(&pdev->dev, "SRAM pool: %ld KiB @ 0x%p\n", size / 1024, virt_base);

return 0;
+
+err_chunks:
+ kfree(rblocks);
+err_alloc:
+ if (sram->clk)
+ clk_disable_unprepare(sram->clk);
+ return ret;
}

static int sram_remove(struct platform_device *pdev)
--
1.8.5.3



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