misc: sram: implement reserved sram areas

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c
index e3e421d97ad4b7be5d9be9c2b8ad5ddd192f4f9a..21181fa243dfd8705f10e113f4293c990b231c37 100644 (file)
--- 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)