drivers: ipcbx21a: custom driver for the SIMATIC IPC BX-21A

The BX-21A was unfortunately not designed to either use iTCO or WDAT
as we (Linux folks) are now recommending for SIMATIC IPCs. Their
custom Linux driver was consequently ported over to support this
somewhat recent SIMATIC IPC.

Signed-off-by: Cedric Hombourger <[email protected]>
Signed-off-by: Jan Kiszka <[email protected]>

Makefile.am

@@ -163,13 +163,15 @@ if BOOTLOADER
 
 if ARCH_IS_X86
 # NOTE: wdat.c is placed first so it is tried before any other drivers
+# NOTE: ipcbx21a.c must be *before* itco.c
 # NOTE: ipc4x7e_wdt.c must be *before* itco.c
 # NOTE: ipmi_wdt.c must be *before* itco.c
 efi_sources_watchdogs = \
 	drivers/watchdog/wdat.c \
 	drivers/watchdog/amdfch_wdt.c \
 	drivers/watchdog/i6300esb.c \
 	drivers/watchdog/atom-quark.c \
+	drivers/watchdog/ipcbx21a.c \
 	drivers/watchdog/ipc4x7e_wdt.c \
 	drivers/watchdog/w83627hf_wdt.c \
 	drivers/watchdog/ipmi_wdt.c \

drivers/watchdog/ipcbx21a.c

@@ -0,0 +1,76 @@
+/*
+ * EFI Boot Guard
+ *
+ * Copyright (c) Siemens AG, 2024
+ *
+ * Ported by Cedric Hombourger <[email protected]>
+ * From unpublished code created by XingTong Wu <[email protected]>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ */
+
+#include <efi.h>
+#include <efilib.h>
+#include <pci/header.h>
+#include <sys/io.h>
+#include "simatic.h"
+#include "utils.h"
+
+#define WDT_CTRL_REG_BX_21A			0x1854
+#define TIMEOUT_MIN_BX_21A			(1)
+#define TIMEOUT_DEF_BX_21A			(60)
+#define TIMEOUT_MAX_BX_21A			(1024)
+/* Over-Clocking WDT Timeout Value */
+#define WDT_CTRL_REG_TOV_MASK_BX_21A			(0x3FF)
+/* Over-Clocking WDT ICC Survivability Impact */
+#define WDT_CTRL_REG_ICCSURV_BIT_BX_21A			BIT(13)
+/* Over-Clocking WDT Enable */
+#define WDT_CTRL_REG_EN_BIT_BX_21A			BIT(14)
+/* Over-Clocking WDT Force All */
+#define WDT_CTRL_REG_FORCE_ALL_BIT_BX_21A		BIT(15)
+/* Over-Clocking WDT Non-ICC Survivability Mode Timeout Status */
+#define WDT_CTRL_REG_NO_ICCSURV_STS_BIT_BX_21A		BIT(24)
+/* Over-Clocking WDT ICC Survivability Mode Timeout Status */
+#define WDT_CTRL_REG_ICCSURV_STS_BIT_BX_21A		BIT(25)
+
+static EFI_STATUS init(EFI_PCI_IO __attribute__((unused)) * pci_io,
+		       UINT16 __attribute__((unused)) pci_vendor_id,
+		       UINT16 __attribute__((unused)) pci_device_id,
+		       UINTN timeout)
+{
+	UINT32 regval;
+
+	if (simatic_station_id() != SIMATIC_IPCBX_21A)
+		return EFI_UNSUPPORTED;
+
+	INFO(L"Detected SIMATIC BX-21A watchdog\n");
+
+	if (timeout < TIMEOUT_MIN_BX_21A || timeout > TIMEOUT_MAX_BX_21A) {
+		WARNING(L"Invalid timeout value (%d), default (%ds) is used.\n",
+			timeout, TIMEOUT_DEF_BX_21A);
+		timeout = TIMEOUT_DEF_BX_21A;
+	}
+
+	regval = inl(WDT_CTRL_REG_BX_21A);
+	/* setup timeout value */
+	regval &= (~WDT_CTRL_REG_TOV_MASK_BX_21A);
+	regval |= (timeout - 1);
+	/* get and clear status */
+	regval |= WDT_CTRL_REG_NO_ICCSURV_STS_BIT_BX_21A;
+	regval |= WDT_CTRL_REG_ICCSURV_STS_BIT_BX_21A;
+	outl(regval, WDT_CTRL_REG_BX_21A);
+
+	/* start watchdog */
+	regval = inl(WDT_CTRL_REG_BX_21A);
+	regval |= (WDT_CTRL_REG_EN_BIT_BX_21A |
+			WDT_CTRL_REG_ICCSURV_BIT_BX_21A |
+			WDT_CTRL_REG_FORCE_ALL_BIT_BX_21A);
+	outl(regval, WDT_CTRL_REG_BX_21A);
+
+	return EFI_SUCCESS;
+}
+
+WATCHDOG_REGISTER(init);

include/simatic.h

@@ -25,6 +25,7 @@
 
 #define SIMATIC_IPC427E				0x0a01
 #define SIMATIC_IPC477E				0x0a02
+#define SIMATIC_IPCBX_21A			0x1101
 #define SIMATIC_IPCBX_56A			0x1201
 #define SIMATIC_IPCBX_59A			0x1202