[Skiboot] [PATCH v2] opal-prd: display explicit message on IBM Power systems

[Cédric Le Goater]

Today, when run on an IBM Power systems, opal-prd complains in syslog
with a set of messages similar to these :

	opal-prd: CTRL: Starting PRD daemon
	opal-prd: I2C: Found Chip: 00000000 engine 1 port 0
	opal-prd: I2C: Found Chip: 00000010 engine 1 port 0
	opal-prd: CTRL: Listening on control socket /run/opal-prd-control
	opal-prd: FW: Can't open PRD device /dev/opal-prd: No such file or directory
	opal-prd: FW: Error initialising PRD channel
	opal-prd: CTRL: stopping PRD daemon

Which are difficult to interpret for a person not initiated to Power
firmware.

The patch below detects if the platform has support for PRD by looking
at the device tree property :

	/sys/firmware/devicetree/base/ibm,opal/diagnostics/compatible

and stops opal-prd early in the main routine with an explicit
message for the user.

Signed-off-by: Cédric Le Goater <clg at fr.ibm.com>
---

 Changes since v2:

 - use ibm,opal/diagnostics/compatible property to detect PRD support

 external/opal-prd/opal-prd.c |   51 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

Index: skiboot.git/external/opal-prd/opal-prd.c
===================================================================
--- skiboot.git.orig/external/opal-prd/opal-prd.c
+++ skiboot.git/external/opal-prd/opal-prd.c
@@ -1032,6 +1032,51 @@ out_free:
 	return rc;
 }
 
+bool find_string(const char *buffer, size_t len, const char *s)
+{
+	const char *c, *end;
+
+	if (!buffer)
+		return false;
+	c = buffer;
+	end = c + len;
+
+	while (c < end) {
+		if (!strcasecmp(s, c))
+			return true;
+		c += strlen(c) + 1;
+	}
+	return false;
+}
+
+static int is_prd_supported(void)
+{
+	char *path;
+	int rc;
+	int len;
+	char *buf;
+
+	rc = asprintf(&path, "%s/ibm,opal/diagnostics/compatible",
+		      devicetree_base);
+	if (rc < 0) {
+		pr_log(LOG_ERR, "FW: error creating 'compatible' node path: %m");
+		return -1;
+	}
+
+	rc = open_and_read(path, (void *) &buf, &len);
+	if (rc)
+		return -1;
+
+	if (buf[len - 1] != '\0')
+		pr_log(LOG_INFO, "FW: node %s is not nul-terminated", path);
+
+	rc = find_string(buf, len, "ibm,opal-prd") ? 0 : -1;
+
+	free(buf);
+
+	return rc;
+}
+
 static int prd_init(struct opal_prd_ctx *ctx)
 {
 	int rc;
@@ -1963,6 +2008,12 @@ int main(int argc, char *argv[])
 		action = ACTION_RUN_DAEMON;
 	}
 
+	if (is_prd_supported() < 0) {
+		pr_log(LOG_ERR, "CTRL: PowerNV OPAL runtime diagnostic "
+				"is not supported on this system");
+		return -1;
+	}
+
 	switch (action) {
 	case ACTION_RUN_DAEMON:
 		rc = run_prd_daemon(ctx);