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
differences:

(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: Greg Hackmann <ghackmann@google.com>
[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: Kees Cook <keescook@chromium.org>

1 files changed, 93 insertions, 2 deletions

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,
 	},
 };