hw/watchdog: Allwinner WDT emulation for system reset

This patch adds basic support for Allwinner WDT.
Both sun4i and sun6i variants are supported.
However, interrupt generation is not supported, so WDT can be used only to trigger system reset.

Signed-off-by: Strahinja Jankovic <strahinja.p.jankovic@gmail.com>
Reviewed-by: Niek Linnenbank <nieklinnenbank@gmail.com>
Tested-by: Niek Linnenbank <nieklinnenbank@gmail.com>
Message-id: 20230326202256.22980-2-strahinja.p.jankovic@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 123 insertions, 0 deletions

diff --git a/include/hw/watchdog/allwinner-wdt.h b/include/hw/watchdog/allwinner-wdt.h
new file mode 100644
index 0000000..7fe41e2
--- /dev/null
+++ b/include/hw/watchdog/allwinner-wdt.h
@@ -0,0 +1,123 @@
+/*
+ * Allwinner Watchdog emulation
+ *
+ * Copyright (C) 2023 Strahinja Jankovic <strahinja.p.jankovic@gmail.com>
+ *
+ *  This file is derived from Allwinner RTC,
+ *  by Niek Linnenbank.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef HW_WATCHDOG_ALLWINNER_WDT_H
+#define HW_WATCHDOG_ALLWINNER_WDT_H
+
+#include "qom/object.h"
+#include "hw/ptimer.h"
+#include "hw/sysbus.h"
+
+/*
+ * This is a model of the Allwinner watchdog.
+ * Since watchdog registers belong to the timer module (and are shared with the
+ * RTC module), the interrupt line from watchdog is not handled right now.
+ * In QEMU, we just wire up the watchdog reset to watchdog_perform_action(),
+ * at least for the moment.
+ */
+
+#define TYPE_AW_WDT    "allwinner-wdt"
+
+/** Allwinner WDT sun4i family (A10, A12), also sun7i (A20) */
+#define TYPE_AW_WDT_SUN4I    TYPE_AW_WDT "-sun4i"
+
+/** Allwinner WDT sun6i family and newer (A31, H2+, H3, etc) */
+#define TYPE_AW_WDT_SUN6I    TYPE_AW_WDT "-sun6i"
+
+/** Number of WDT registers */
+#define AW_WDT_REGS_NUM      (5)
+
+OBJECT_DECLARE_TYPE(AwWdtState, AwWdtClass, AW_WDT)
+
+/**
+ * Allwinner WDT object instance state.
+ */
+struct AwWdtState {
+    /*< private >*/
+    SysBusDevice parent_obj;
+
+    /*< public >*/
+    MemoryRegion iomem;
+    struct ptimer_state *timer;
+
+    uint32_t regs[AW_WDT_REGS_NUM];
+};
+
+/**
+ * Allwinner WDT class-level struct.
+ *
+ * This struct is filled by each sunxi device specific code
+ * such that the generic code can use this struct to support
+ * all devices.
+ */
+struct AwWdtClass {
+    /*< private >*/
+    SysBusDeviceClass parent_class;
+    /*< public >*/
+
+    /** Defines device specific register map */
+    const uint8_t *regmap;
+
+    /** Size of the regmap in bytes */
+    size_t regmap_size;
+
+    /**
+     * Read device specific register
+     *
+     * @offset: register offset to read
+     * @return true if register read successful, false otherwise
+     */
+    bool (*read)(AwWdtState *s, uint32_t offset);
+
+    /**
+     * Write device specific register
+     *
+     * @offset: register offset to write
+     * @data: value to set in register
+     * @return true if register write successful, false otherwise
+     */
+    bool (*write)(AwWdtState *s, uint32_t offset, uint32_t data);
+
+    /**
+     * Check if watchdog can generate system reset
+     *
+     * @return true if watchdog can generate system reset
+     */
+    bool (*can_reset_system)(AwWdtState *s);
+
+    /**
+     * Check if provided key is valid
+     *
+     * @value: value written to register
+     * @return true if key is valid, false otherwise
+     */
+    bool (*is_key_valid)(AwWdtState *s, uint32_t val);
+
+    /**
+     * Get current INTV_VALUE setting
+     *
+     * @return current INTV_VALUE (0-15)
+     */
+    uint8_t (*get_intv_value)(AwWdtState *s);
+};
+
+#endif /* HW_WATCHDOG_ALLWINNER_WDT_H */