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From 8142c4554ffaa927529f24427a35f7ee2861793a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
Date: Thu, 16 Jun 2022 20:59:03 +0200
Subject: [PATCH] fw_env: add fallback to Linux's NVMEM based access
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
A new DT binding for describing environment data block has been added in
Linux's commit 5db1c2dbc04c ("dt-bindings: nvmem: add U-Boot environment
variables binding"). Once we get a proper Linux NVMEM driver it'll be
possible to use Linux's binary interface for user-space as documented
in the:
https://www.kernel.org/doc/html/latest/driver-api/nvmem.html
This commits makes fw_env fallback to looking for a compatible NVMEM
device in case config file isn't present. In a long term this may make
config files redundant and avoid code (info) duplication.
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
tools/env/fw_env.c | 70 ++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 67 insertions(+), 3 deletions(-)
--- a/tools/env/fw_env.c
+++ b/tools/env/fw_env.c
@@ -1713,6 +1713,67 @@ static int check_device_config(int dev)
return rc;
}
+static int find_nvmem_device(void)
+{
+ const char *path = "/sys/bus/nvmem/devices";
+ struct dirent *dent;
+ char *nvmem = NULL;
+ char comp[256];
+ char buf[32];
+ int bytes;
+ DIR *dir;
+
+ dir = opendir(path);
+ if (!dir) {
+ return -EIO;
+ }
+
+ while (!nvmem && (dent = readdir(dir))) {
+ FILE *fp;
+
+ if (!strcmp(dent->d_name, ".") || !strcmp(dent->d_name, "..")) {
+ continue;
+ }
+
+ bytes = snprintf(comp, sizeof(comp), "%s/%s/of_node/compatible", path, dent->d_name);
+ if (bytes < 0 || bytes == sizeof(comp)) {
+ continue;
+ }
+
+ fp = fopen(comp, "r");
+ if (!fp) {
+ continue;
+ }
+
+ fread(buf, sizeof(buf), 1, fp);
+
+ if (!strcmp(buf, "u-boot,env")) {
+ bytes = asprintf(&nvmem, "%s/%s/nvmem", path, dent->d_name);
+ if (bytes < 0) {
+ nvmem = NULL;
+ }
+ }
+
+ fclose(fp);
+ }
+
+ closedir(dir);
+
+ if (nvmem) {
+ struct stat s;
+
+ stat(nvmem, &s);
+
+ DEVNAME(0) = nvmem;
+ DEVOFFSET(0) = 0;
+ ENVSIZE(0) = s.st_size;
+
+ return 0;
+ }
+
+ return -ENOENT;
+}
+
static int parse_config(struct env_opts *opts)
{
int rc;
@@ -1723,9 +1784,12 @@ static int parse_config(struct env_opts
#if defined(CONFIG_FILE)
/* Fills in DEVNAME(), ENVSIZE(), DEVESIZE(). Or don't. */
if (get_config(opts->config_file)) {
- fprintf(stderr, "Cannot parse config file '%s': %m\n",
- opts->config_file);
- return -1;
+ if (find_nvmem_device()) {
+ fprintf(stderr, "Cannot parse config file '%s': %m\n",
+ opts->config_file);
+ fprintf(stderr, "Failed to find NVMEM device\n");
+ return -1;
+ }
}
#else
DEVNAME(0) = DEVICE1_NAME;
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