Commit 35da6094 authored by Greg Hackmann's avatar Greg Hackmann Committed by Kees Cook
Browse files

pstore/ram: add Device Tree bindings

ramoops is one of the remaining places where ARM vendors still rely on
board-specific shims.  Device Tree lets us replace those shims with
generic code.

These bindings mirror the ramoops module parameters, with two small

(1) dump_oops becomes an optional "no-dump-oops" property, since ramoops
    sets dump_oops=1 by default.

(2) mem_type=1 becomes the more self-explanatory "unbuffered" property.
Signed-off-by: default avatarGreg Hackmann <>
[fixed platform_get_drvdata() crash, thanks to Brian Norris]
[switched from u64 to u32 to simplify code, various whitespace fixes]
[use dev_of_node() to gain code-elimination for CONFIG_OF=n]
Signed-off-by: default avatarKees Cook <>
parent cae73167
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.
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
size of these optional buffers must fit in the reserved region.
Any remaining space will be used for a circular buffer of oops and panic
records. These records have a configurable size, with a size of 0 indicating
that they should be disabled.
At least one of "record-size", "console-size", "ftrace-size", or "pmsg-size"
must be set non-zero, but are otherwise optional as listed below.
Required properties:
- compatible: must be "ramoops"
- memory-region: phandle to a region of memory that is preserved between
Optional properties:
- ecc-size: enables ECC support and specifies ECC buffer size in bytes
(defaults to 0: no ECC)
- record-size: maximum size in bytes of each dump done on oops/panic
(defaults to 0: disabled)
- console-size: size in bytes of log buffer reserved for kernel messages
(defaults to 0: disabled)
- ftrace-size: size in bytes of log buffer reserved for function tracing and
profiling (defaults to 0: disabled)
- pmsg-size: size in bytes of log buffer reserved for userspace messages
(defaults to 0: disabled)
- unbuffered: if present, use unbuffered mappings to map the reserved region
(defaults to buffered mappings)
- no-dump-oops: if present, only dump panics (defaults to panics and oops)
......@@ -45,7 +45,7 @@ corrupt, but usually it is restorable.
2. Setting the parameters
Setting the ramoops parameters can be done in 2 different manners:
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
......@@ -54,7 +54,9 @@ Setting the ramoops parameters can be done in 2 different manners:
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 a platform device and set the platform data. The parameters can then
2. Use Device Tree bindings, as described in
3. 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>
......@@ -34,6 +34,8 @@
#include <linux/slab.h>
#include <linux/compiler.h>
#include <linux/pstore_ram.h>
#include <linux/of.h>
#include <linux/of_address.h>
#define RAMOOPS_KERNMSG_HDR "===="
#define MIN_MEM_SIZE 4096UL
......@@ -458,15 +460,98 @@ static int ramoops_init_prz(struct device *dev, struct ramoops_context *cxt,
return 0;
static int ramoops_parse_dt_size(struct platform_device *pdev,
const char *propname, u32 *value)
u32 val32 = 0;
int ret;
ret = of_property_read_u32(pdev->dev.of_node, propname, &val32);
if (ret < 0 && ret != -EINVAL) {
dev_err(&pdev->dev, "failed to parse property %s: %d\n",
propname, ret);
return ret;
if (val32 > INT_MAX) {
dev_err(&pdev->dev, "%s %u > INT_MAX\n", propname, val32);
return -EOVERFLOW;
*value = val32;
return 0;
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;
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);
if (ret) {
"failed to translate memory-region to resource: %d\n",
return ret;
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");
#define parse_size(name, field) { \
ret = ramoops_parse_dt_size(pdev, name, &value); \
if (ret < 0) \
return ret; \
field = value; \
parse_size("record-size", pdata->record_size);
parse_size("console-size", pdata->console_size);
parse_size("ftrace-size", pdata->ftrace_size);
parse_size("pmsg-size", pdata->pmsg_size);
parse_size("ecc-size", pdata->ecc_info.ecc_size);
#undef parse_size
return 0;
static int ramoops_probe(struct platform_device *pdev)
struct device *dev = &pdev->dev;
struct ramoops_platform_data *pdata = pdev->dev.platform_data;
struct ramoops_platform_data *pdata = dev->platform_data;
struct ramoops_context *cxt = &oops_cxt;
size_t dump_mem_sz;
phys_addr_t paddr;
int err = -EINVAL;
if (dev_of_node(dev) && !pdata) {
pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
if (!pdata) {
err = -ENOMEM;
goto fail_out;
err = ramoops_parse_dt(pdev, pdata);
if (err < 0)
goto fail_out;
/* Only a single ramoops area allowed at a time, so fail extra
* probes.
......@@ -596,11 +681,17 @@ static int ramoops_remove(struct platform_device *pdev)
return 0;
static const struct of_device_id dt_match[] = {
{ .compatible = "ramoops" },
static struct platform_driver ramoops_driver = {
.probe = ramoops_probe,
.remove = ramoops_remove,
.driver = {
.name = "ramoops",
.name = "ramoops",
.of_match_table = dt_match,
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