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Commit 529182e2 authored by Kees Cook's avatar Kees Cook
Browse files

ramoops: use DT reserved-memory bindings 



Instead of a ramoops-specific node, use a child node of /reserved-memory.
This requires that of_platform_device_create() be explicitly called
for the node, though, since "/reserved-memory" does not have its own
"compatible" property.

Suggested-by: default avatarRob Herring <robh@kernel.org>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Acked-by: default avatarRob Herring <robh@kernel.org>
parent f38d2e53

Documentation/devicetree/bindings/misc/ramoops.txt→Documentation/devicetree/bindings/reserved-memory/ramoops.txt

+4 −4
Original line number Diff line number Diff line
@@ -2,8 +2,9 @@ Ramoops oops/panic logger 
=========================



ramoops provides persistent RAM storage for oops and panics, so they can be

recovered after a reboot. It is a backend to pstore, so this node is named

"ramoops" after the backend, rather than "pstore" which is the subsystem.

recovered after a reboot. This is a child-node of "/reserved-memory", and

is named "ramoops" after the backend, rather than "pstore" which is the

subsystem.



Parts of this storage may be set aside for other persistent log buffers, such

as kernel log messages, or for optional ECC error-correction data.  The total
@@ -21,8 +22,7 @@ Required properties: 


- compatible: must be "ramoops"



- memory-region: phandle to a region of memory that is preserved between

  reboots

- reg: region of memory that is preserved between reboots





Optional properties:

Documentation/ramoops.txt

+27 −11
Original line number Diff line number Diff line
@@ -45,18 +45,34 @@ corrupt, but usually it is restorable. 


2. Setting the parameters



Setting the ramoops parameters can be done in 3 different manners:

 1. Use the module parameters (which have the names of the variables described

 as before).

 For quick debugging, you can also reserve parts of memory during boot

 and then use the reserved memory for ramoops. For example, assuming a machine

 with > 128 MB of memory, the following kernel command line will tell the

 kernel to use only the first 128 MB of memory, and place ECC-protected ramoops

 region at 128 MB boundary:

Setting the ramoops parameters can be done in several different manners:



 A. Use the module parameters (which have the names of the variables described

 as before). For quick debugging, you can also reserve parts of memory during

 boot and then use the reserved memory for ramoops. For example, assuming a

 machine with > 128 MB of memory, the following kernel command line will tell

 the kernel to use only the first 128 MB of memory, and place ECC-protected

 ramoops region at 128 MB boundary:

 "mem=128M ramoops.mem_address=0x8000000 ramoops.ecc=1"

 2. Use Device Tree bindings, as described in

 Documentation/device-tree/bindings/misc/ramoops.txt.

 3. Use a platform device and set the platform data. The parameters can then



 B. Use Device Tree bindings, as described in

 Documentation/device-tree/bindings/reserved-memory/ramoops.txt.

 For example:



	reserved-memory {

		#address-cells = <2>;

		#size-cells = <2>;

		ranges;



		ramoops@8f000000 {

			compatible = "ramoops";

			reg = <0 0x8f000000 0 0x100000>;

			record-size = <0x4000>;

			console-size = <0x4000>;

		};

	};



 C. Use a platform device and set the platform data. The parameters can then

 be set through that platform data. An example of doing that is:



#include <linux/pstore_ram.h>

drivers/of/platform.c

+18 −2
Original line number Diff line number Diff line
@@ -499,7 +499,23 @@ EXPORT_SYMBOL_GPL(of_platform_default_populate); 


static int __init of_platform_default_populate_init(void)

{

	if (of_have_populated_dt())

	struct device_node *node;



	if (!of_have_populated_dt())

		return -ENODEV;



	/*

	 * Handle ramoops explicitly, since it is inside /reserved-memory,

	 * which lacks a "compatible" property.

	 */

	node = of_find_node_by_path("/reserved-memory");

	if (node) {

		node = of_find_compatible_node(node, NULL, "ramoops");

		if (node)

			of_platform_device_create(node, NULL, NULL);

	}



	/* Populate everything else. */

	of_platform_default_populate(NULL, NULL, NULL);



	return 0;

fs/pstore/ram.c

+7 −16
Original line number Diff line number Diff line
@@ -486,30 +486,21 @@ static int ramoops_parse_dt(struct platform_device *pdev, 
			    struct ramoops_platform_data *pdata)

{

	struct device_node *of_node = pdev->dev.of_node;

	struct device_node *mem_region;

	struct resource res;

	struct resource *res;

	u32 value;

	int ret;



	dev_dbg(&pdev->dev, "using Device Tree\n");



	mem_region = of_parse_phandle(of_node, "memory-region", 0);

	if (!mem_region) {

		dev_err(&pdev->dev, "no memory-region phandle\n");

		return -ENODEV;

	}



	ret = of_address_to_resource(mem_region, 0, &res);

	of_node_put(mem_region);

	if (ret) {

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	if (!res) {

		dev_err(&pdev->dev,

			"failed to translate memory-region to resource: %d\n",

			ret);

		return ret;

			"failed to locate DT /reserved-memory resource\n");

		return -EINVAL;

	}



	pdata->mem_size = resource_size(&res);

	pdata->mem_address = res.start;

	pdata->mem_size = resource_size(res);

	pdata->mem_address = res->start;

	pdata->mem_type = of_property_read_bool(of_node, "unbuffered");

	pdata->dump_oops = !of_property_read_bool(of_node, "no-dump-oops");