From 578030bfe117060bf86c81aaa7b3faead4589810 Mon Sep 17 00:00:00 2001
From: Scott Cheloha <cheloha@linux.ibm.com>
Date: Wed, 13 Jul 2022 15:23:34 -0500
Subject: [PATCH] powerpc/pseries: register pseries-wdt device with platform
 bus

References: jsc#PED-549
Patch-mainline: v6.0-rc1
Git-commit: 578030bfe117060bf86c81aaa7b3faead4589810

PAPR v2.12 defines a new hypercall, H_WATCHDOG.  The hypercall permits
guest control of one or more virtual watchdog timers.

These timers do not conform to PowerPC device conventions.  They are
not affixed to any extant bus, nor do they have full representation in
the device tree.

As a workaround we represent them as platform devices.

This patch registers a single platform device, "pseries-wdt", with the
platform bus if the FW_FEATURE_WATCHDOG flag is set.

A driver for this device, "pseries-wdt", will be introduced in a
subsequent patch.

Signed-off-by: Scott Cheloha <cheloha@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220713202335.1217647-4-cheloha@linux.ibm.com
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/platforms/pseries/setup.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index a74c425be624..489f4c4df468 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -14,6 +14,7 @@
 
 #include <linux/cpu.h>
 #include <linux/errno.h>
+#include <linux/platform_device.h>
 #include <linux/sched.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
@@ -170,6 +171,18 @@ static void __init fwnmi_init(void)
 #endif
 }
 
+/*
+ * Affix a device for the first timer to the platform bus if
+ * we have firmware support for the H_WATCHDOG hypercall.
+ */
+static __init int pseries_wdt_init(void)
+{
+	if (firmware_has_feature(FW_FEATURE_WATCHDOG))
+		platform_device_register_simple("pseries-wdt", 0, NULL, 0);
+	return 0;
+}
+machine_subsys_initcall(pseries, pseries_wdt_init);
+
 static void pseries_8259_cascade(struct irq_desc *desc)
 {
 	struct irq_chip *chip = irq_desc_get_chip(desc);
-- 
2.35.3