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Date: Sun, 7 Jul 2013 14:46:36 -0500
From: Rob Herring <robherring2@...il.com>
To: Heiko Stübner <heiko@...ech.de>
Cc: Arnd Bergmann <arnd@...db.de>, Olof Johansson <olof@...om.net>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
Grant Likely <grant.likely@...aro.org>,
"devicetree-discuss@...ts.ozlabs.org"
<devicetree-discuss@...ts.ozlabs.org>,
Russell King <linux@....linux.org.uk>,
Philipp Zabel <p.zabel@...gutronix.de>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Ulrich Prinz <ulrich.prinz@...glemail.com>
Subject: Re: [PATCH v3 2/6] misc: sram: add ability to mark sram sections as reserved
On Fri, Jul 5, 2013 at 7:41 AM, Heiko Stübner <heiko@...ech.de> wrote:
> Some SoCs need parts of their sram for special purposes. So while being part
> of the periphal, it should not be part of the genpool controlling the sram.
s/periphal/peripheral/
>
> Threfore add an option mmio-sram-reserved to keep arbitary portions of the
s/Threfore/Therefore/
s/arbitary/arbitrary/
> sram from being part of the pool.
>
> Suggested-by: Rob Herring <robherring2@...il.com>
> Signed-off-by: Heiko Stuebner <heiko@...ech.de>
> Tested-by: Ulrich Prinz <ulrich.prinz@...glemail.com>
> ---
> Documentation/devicetree/bindings/misc/sram.txt | 8 +++
> drivers/misc/sram.c | 80 +++++++++++++++++++++--
> 2 files changed, 82 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/misc/sram.txt b/Documentation/devicetree/bindings/misc/sram.txt
> index 4d0a00e..eae080e 100644
> --- a/Documentation/devicetree/bindings/misc/sram.txt
> +++ b/Documentation/devicetree/bindings/misc/sram.txt
> @@ -8,9 +8,17 @@ Required properties:
>
> - reg : SRAM iomem address range
>
> +Optional properties:
> +
> +- mmio-sram-reserved: ordered list of reserved chunks inside the sram that
> + should not become part of the genalloc pool.
genalloc is linux specific. "should not be used by the OS" would be better.
> + Format is <base size>, <base size>, ...; with base being relative to the
> + reg property base.
> +
> Example:
>
> sram: sram@...00000 {
> compatible = "mmio-sram";
> reg = <0x5c000000 0x40000>; /* 256 KiB SRAM at address 0x5c000000 */
> + mmio-sram-reserved = <0x0 0x100>; /* reserve 0x5c000000-0x5c000100 */
> };
> diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c
> index afe66571..9131e4a 100644
> --- a/drivers/misc/sram.c
> +++ b/drivers/misc/sram.c
> @@ -42,6 +42,13 @@ static int sram_probe(struct platform_device *pdev)
> struct sram_dev *sram;
> struct resource *res;
> unsigned long size;
> + const __be32 *reserved_list = NULL;
> + int reserved_size = 0;
> + unsigned int cur_start = 0;
> + unsigned int cur_size;
> + unsigned int rstart;
> + unsigned int rsize;
Use one line for each type.
> + int i;
> int ret;
>
> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> @@ -65,12 +72,73 @@ 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;
> + if (pdev->dev.of_node) {
> + reserved_list = of_get_property(pdev->dev.of_node,
> + "mmio-sram-reserved",
> + &reserved_size);
> + if (reserved_list) {
> + reserved_size /= sizeof(*reserved_list);
> + if (!reserved_size || reserved_size % 2) {
> + dev_warn(&pdev->dev, "wrong number of arguments in mmio-sram-reserved\n");
> + reserved_list = NULL;
> + }
> + }
> + }
> +
> + if (!reserved_list)
> + reserved_size = 0;
This can be moved to where you set reserved_list to NULL.
> +
> + for (i = 0; i < (reserved_size + 2); i += 2) {
> + if (i < reserved_size) {
This loop is hard to follow. For example, it is not immediate obvious
why you loop an extra time. I think it would be more straight forward
to determine the free regions first and then do the allocations. This
will require a kmalloc or fixed max number of regions, but would
improve readability.
Rob
> + /* get the next reserved block */
> + rstart = be32_to_cpu(*reserved_list++);
> + rsize = be32_to_cpu(*reserved_list++);
> +
> + /* catch unsorted list entries */
> + if (rstart < cur_start) {
> + dev_err(&pdev->dev,
> + "unsorted reserved list (0x%x before current 0x%x)\n",
> + rstart, cur_start);
> + if (sram->clk)
> + clk_disable_unprepare(sram->clk);
> + return -EINVAL;
> + }
> +
> + dev_dbg(&pdev->dev,
> + "found reserved block 0x%x-0x%x\n",
> + rstart, rstart + rsize);
> + } else {
> + /* the last chunk extends to the end of the region */
> + rstart = size;
> + rsize = 0;
> + }
> +
> + /* current start is in a reserved block */
> + if (rstart <= cur_start) {
> + cur_start = rstart + rsize;
> + continue;
> + }
> +
> + /*
> + * allocate the space between the current starting
> + * address and the following reserved block, or the
> + * end of the region.
> + */
> + cur_size = rstart - cur_start;
> +
> + dev_dbg(&pdev->dev, "adding chunk 0x%x-0x%x\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) {
> + if (sram->clk)
> + clk_disable_unprepare(sram->clk);
> + return ret;
> + }
> +
> + /* next allocation after this reserved block */
> + cur_start = rstart + rsize;
> }
>
> platform_set_drvdata(pdev, sram);
> --
> 1.7.10.4
>
--
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