powerpc/powernv: Add opal details to the hardware description

Add OPAL version details to the hardware description, which is printed
at boot and in case of an oops.

eg: Hardware name: ... opal:v6.2
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220930082709.55830-5-mpe@ellerman.id.au

arch/powerpc/platforms/powernv/setup.c

@@ -17,6 +17,7 @@
 #include <linux/console.h>
 #include <linux/delay.h>
 #include <linux/irq.h>
+#include <linux/seq_buf.h>
 #include <linux/seq_file.h>
 #include <linux/of.h>
 #include <linux/of_fdt.h>
@@ -207,8 +208,29 @@ static void __init pnv_setup_arch(void)
 	pnv_rng_init();
 }
 
+static void __init pnv_add_hw_description(void)
+{
+	struct device_node *dn;
+	const char *s;
+
+	dn = of_find_node_by_path("/ibm,opal/firmware");
+	if (!dn)
+		return;
+
+	if (of_property_read_string(dn, "version", &s) == 0 ||
+	    of_property_read_string(dn, "git-id", &s) == 0)
+		seq_buf_printf(&ppc_hw_desc, "opal:%s ", s);
+
+	if (of_property_read_string(dn, "mi-version", &s) == 0)
+		seq_buf_printf(&ppc_hw_desc, "mi:%s ", s);
+
+	of_node_put(dn);
+}
+
 static void __init pnv_init(void)
 {
+	pnv_add_hw_description();
+
 	/*
 	 * Initialize the LPC bus now so that legacy serial
 	 * ports can be found on it