3 files changed, 145 insertions, 4 deletions

diff --git a/Documentation/devicetree/bindings/misc/ramoops.txt b/Documentation/devicetree/bindings/misc/ramoops.txt
new file mode 100644
index 000000000000..cd02cec67d38
--- /dev/null
+++ b/Documentation/devicetree/bindings/misc/ramoops.txt
@@ -0,0 +1,48 @@
+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
+  reboots
+
+
+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)
diff --git a/Documentation/ramoops.txt b/Documentation/ramoops.txt
index 5d8675615e59..9264bcab4099 100644
--- a/Documentation/ramoops.txt
+++ b/Documentation/ramoops.txt
@@ -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
+ Documentation/device-tree/bindings/misc/ramoops.txt.
+ 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>
diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index d9668c2b43cb..47516a794011 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -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);
+        of_node_put(mem_region);
+        if (ret) {
+                dev_err(&pdev->dev,
+                        "failed to translate memory-region to resource: %d\n",
+                        ret);
+                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,
         },
 };