rtc: goldfish: Support platform data for non-DT probing

Currently, the Goldfish RTC driver exclusively relies on device tree
to retrieve the base address, failing immediately if dev_read_addr()
returns FDT_ADDR_T_NONE. This restriction prevents the driver from
being used on platforms that instantiate devices via U_BOOT_DRVINFO()
instead of device tree, such as the QEMU m68k virt machine.

Add support for platform data to address this limitation. Introduce a
new .of_to_plat hook to handle device tree parsing and populate the
platform data. Update the probe function to rely exclusively on this
platform data, enabling support for both Device Tree and manual
instantiation.

Introduce a new header file include/goldfish_rtc.h to define the
platform data structure.

Signed-off-by: Kuan-Wei Chiu <[email protected]>
Reviewed-by: Heinrich Schuchardt <[email protected]>

1 files changed, 15 insertions, 0 deletions

diff --git a/include/goldfish_rtc.h b/include/goldfish_rtc.h
new file mode 100644
index 00000000000..f0e6ba3d543
--- /dev/null
+++ b/include/goldfish_rtc.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2025, Kuan-Wei Chiu <[email protected]>
+ */
+
+#ifndef _GOLDFISH_RTC_H_
+#define _GOLDFISH_RTC_H_
+
+#include <linux/types.h>
+
+struct goldfish_rtc_plat {
+	phys_addr_t reg;
+};
+
+#endif /* _GOLDFISH_RTC_H_ */