cxl: Parse device tree and create cxl device(s) at boot

BugLink: http://bugs.launchpad.net/bugs/1588468

Add new entry point to scan the device tree at boot in a guest,
looking for cxl devices.
Co-authored-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
Signed-off-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: Manoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
(cherry picked from commit b40844aa)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

drivers/misc/cxl/base.c

@@ -11,6 +11,7 @@
 #include <linux/rcupdate.h>
 #include <asm/errno.h>
 #include <misc/cxl-base.h>
+#include <linux/of_platform.h>
 #include "cxl.h"
 
 /* protected by rcu */
@@ -91,3 +92,27 @@ int cxl_update_properties(struct device_node *dn,
 	return of_update_property(dn, new_prop);
 }
 EXPORT_SYMBOL_GPL(cxl_update_properties);
+
+static int __init cxl_base_init(void)
+{
+	struct device_node *np = NULL;
+	struct platform_device *dev;
+	int count = 0;
+
+	/*
+	 * Scan for compatible devices in guest only
+	 */
+	if (cpu_has_feature(CPU_FTR_HVMODE))
+		return 0;
+
+	while ((np = of_find_compatible_node(np, NULL,
+				     "ibm,coherent-platform-facility"))) {
+		dev = of_platform_device_create(np, NULL, NULL);
+		if (dev)
+			count++;
+	}
+	pr_devel("Found %d cxl device(s)\n", count);
+	return 0;
+}
+
+module_init(cxl_base_init);