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Message-ID: <1375106520.4223.24.camel@pizza.hi.pengutronix.de>
Subject: Re: [PATCH v4 2/6] misc: sram: add ability to mark sram sections as
 reserved
From: Philipp Zabel <p.zabel@pengutronix.de>
To: Heiko =?ISO-8859-1?Q?St=FCbner?= <heiko@sntech.de>
Cc: Arnd Bergmann <arnd@arndb.de>, Olof Johansson <olof@lixom.net>,
        "linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
        Grant Likely <grant.likely@linaro.org>,
        Rob Herring <robherring2@gmail.com>,
        devicetree-discuss@lists.ozlabs.org,
        Russell King <linux@arm.linux.org.uk>, linux-kernel@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Ulrich Prinz <ulrich.prinz@googlemail.com>
Date: Mon, 29 Jul 2013 16:02:00 +0200
In-Reply-To: <201307291512.25126.heiko@sntech.de>
References: <201307291510.31679.heiko@sntech.de>
	 <201307291512.25126.heiko@sntech.de>
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Hi Heiko,

Am Montag, den 29.07.2013, 15:12 +0200 schrieb Heiko Stübner:
> Some SoCs need parts of their sram for special purposes. So while being part
> of the peripheral, it should not be part of the genpool controlling the sram.
> 
> Therefore add an option mmio-sram-reserved to keep arbitrary portions of the
> sram from being part of the pool.
> 
> Suggested-by: Rob Herring <robherring2@gmail.com>
> Signed-off-by: Heiko Stuebner <heiko@sntech.de>
> Tested-by: Ulrich Prinz <ulrich.prinz@googlemail.com>
> ---
> Philipp: I didn't carry the ack, because the loop changed significantly again.
> So if it looks ok, could you re-ack it please?

I'd prefer the first loop to contain the magic and produce a list of
useable chunks, instead of a list of reserved blocks. The second loop
could then iterate over the array and just call gen_pool_add_virt
repeatedly.

regards
Philipp

>  Documentation/devicetree/bindings/misc/sram.txt |    8 ++
>  drivers/misc/sram.c                             |  101 +++++++++++++++++++++--
>  2 files changed, 101 insertions(+), 8 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/misc/sram.txt b/Documentation/devicetree/bindings/misc/sram.txt
> index 4d0a00e..3b7a5c1 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 be used by the OS.
> +  Format is <base size>, <base size>, ...; with base being relative to the
> +  reg property base.
> +
>  Example:
>  
>  sram: sram@5c000000 {
>  	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..b3ceefb 100644
> --- a/drivers/misc/sram.c
> +++ b/drivers/misc/sram.c
> @@ -36,13 +36,23 @@ struct sram_dev {
>  	struct clk *clk;
>  };
>  
> +struct sram_reserve {
> +	unsigned long start;
> +	unsigned long size;
> +};
> +
>  static int sram_probe(struct platform_device *pdev)
>  {
>  	void __iomem *virt_base;
>  	struct sram_dev *sram;
>  	struct resource *res;
> -	unsigned long size;
> -	int ret;
> +	unsigned long size, cur_start, cur_size;
> +	const __be32 *reserved_list = NULL;
> +	int reserved_size = 0;
> +	struct sram_reserve *rblocks;
> +	unsigned int nblocks;
> +	int ret = 0;
> +	int i;
>  
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>  	virt_base = devm_ioremap_resource(&pdev->dev, res);
> @@ -65,19 +75,94 @@ 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;
> +				reserved_size = 0;
> +			}
> +		}
>  	}
>  
> +	/*
> +	 * We need an additional block to mark the end of the memory region
> +	 * after the reserved blocks from the dt are processed.
> +	 */
> +	nblocks = reserved_size / 2 + 1;
> +	rblocks = kmalloc((nblocks) * sizeof(*rblocks), GFP_KERNEL);
> +	if (!rblocks) {
> +		ret = -ENOMEM;
> +		goto err_alloc;
> +	}
> +
> +	for (i = 0; i < nblocks - 1; i++) {
> +		rblocks[i].start = be32_to_cpu(*reserved_list++);
> +		rblocks[i].size = be32_to_cpu(*reserved_list++);
> +
> +		dev_dbg(&pdev->dev, "found reserved block 0x%lx-0x%lx\n",
> +			rblocks[i].start,
> +			rblocks[i].start + rblocks[i].size);
> +	}
> +
> +	/* the last chunk marks the end of the region */
> +	rblocks[nblocks - 1].start = size;
> +	rblocks[nblocks - 1].size = 0;
> +
> +	cur_start = 0;
> +	for (i = 0; i < nblocks; i++) {
> +		/* catch unsorted list entries */
> +		if (rblocks[i].start < cur_start) {
> +			dev_err(&pdev->dev,
> +				"unsorted reserved list (0x%lx before current 0x%lx)\n",
> +				rblocks[i].start, cur_start);
> +			ret = -EINVAL;
> +			goto err_chunks;
> +		}
> +
> +		/* current start is in a reserved block, so continue after it */
> +		if (rblocks[i].start == cur_start) {
> +			cur_start = rblocks[i].start + rblocks[i].size;
> +			continue;
> +		}
> +
> +		/*
> +		 * allocate the space between the current starting
> +		 * address and the following reserved block, or the
> +		 * end of the region.
> +		 */
> +		cur_size = rblocks[i].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 = rblocks[i].start + rblocks[i].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)


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