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+/*
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+ * Copyright (c) 2016, NVIDIA CORPORATION.
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+ *
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+ * SPDX-License-Identifier: GPL-2.0
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+ */
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+
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+#ifndef _RESET_H
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+#define _RESET_H
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+
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+/**
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+ * A reset is a hardware signal indicating that a HW module (or IP block, or
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+ * sometimes an entire off-CPU chip) reset all of its internal state to some
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+ * known-good initial state. Drivers will often reset HW modules when they
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+ * begin execution to ensure that hardware correctly responds to all requests,
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+ * or in response to some error condition. Reset signals are often controlled
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+ * externally to the HW module being reset, by an entity this API calls a reset
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+ * controller. This API provides a standard means for drivers to request that
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+ * reset controllers set or clear reset signals.
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+ *
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+ * A driver that implements UCLASS_RESET is a reset controller or provider. A
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+ * controller will often implement multiple separate reset signals, since the
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+ * hardware it manages often has this capability. reset-uclass.h describes the
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+ * interface which reset controllers must implement.
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+ *
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+ * Reset consumers/clients are the HW modules affected by reset signals. This
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+ * header file describes the API used by drivers for those HW modules.
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+ */
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+
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+struct udevice;
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+
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+/**
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+ * struct reset_ctl - A handle to (allowing control of) a single reset signal.
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+ *
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+ * Clients provide storage for reset control handles. The content of the
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+ * structure is managed solely by the reset API and reset drivers. A reset
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+ * control struct is initialized by "get"ing the reset control struct. The
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+ * reset control struct is passed to all other reset APIs to identify which
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+ * reset signal to operate upon.
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+ *
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+ * @dev: The device which implements the reset signal.
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+ * @id: The reset signal ID within the provider.
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+ *
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+ * Currently, the reset API assumes that a single integer ID is enough to
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+ * identify and configure any reset signal for any reset provider. If this
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+ * assumption becomes invalid in the future, the struct could be expanded to
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+ * either (a) add more fields to allow reset providers to store additional
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+ * information, or (b) replace the id field with an opaque pointer, which the
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+ * provider would dynamically allocated during its .of_xlate op, and process
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+ * during is .request op. This may require the addition of an extra op to clean
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+ * up the allocation.
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+ */
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+struct reset_ctl {
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+ struct udevice *dev;
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+ /*
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+ * Written by of_xlate. We assume a single id is enough for now. In the
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+ * future, we might add more fields here.
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+ */
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+ unsigned long id;
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+};
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+
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+/**
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+ * reset_get_by_index - Get/request a reset signal by integer index.
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+ *
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+ * This looks up and requests a reset signal. The index is relative to the
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+ * client device; each device is assumed to have n reset signals associated
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+ * with it somehow, and this function finds and requests one of them. The
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+ * mapping of client device reset signal indices to provider reset signals may
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+ * be via device-tree properties, board-provided mapping tables, or some other
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+ * mechanism.
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+ *
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+ * @dev: The client device.
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+ * @index: The index of the reset signal to request, within the client's
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+ * list of reset signals.
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+ * @reset_ctl A pointer to a reset control struct to initialize.
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+ * @return 0 if OK, or a negative error code.
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+ */
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+int reset_get_by_index(struct udevice *dev, int index,
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+ struct reset_ctl *reset_ctl);
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+
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+/**
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+ * reset_get_by_name - Get/request a reset signal by name.
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+ *
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+ * This looks up and requests a reset signal. The name is relative to the
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+ * client device; each device is assumed to have n reset signals associated
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+ * with it somehow, and this function finds and requests one of them. The
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+ * mapping of client device reset signal names to provider reset signal may be
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+ * via device-tree properties, board-provided mapping tables, or some other
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+ * mechanism.
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+ *
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+ * @dev: The client device.
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+ * @name: The name of the reset signal to request, within the client's
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+ * list of reset signals.
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+ * @reset_ctl: A pointer to a reset control struct to initialize.
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+ * @return 0 if OK, or a negative error code.
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+ */
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+int reset_get_by_name(struct udevice *dev, const char *name,
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+ struct reset_ctl *reset_ctl);
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+
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+/**
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+ * reset_free - Free a previously requested reset signal.
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+ *
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+ * @reset_ctl: A reset control struct that was previously successfully
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+ * requested by reset_get_by_*().
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+ * @return 0 if OK, or a negative error code.
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+ */
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+int reset_free(struct reset_ctl *reset_ctl);
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+
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+/**
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+ * reset_assert - Assert a reset signal.
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+ *
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+ * This function will assert the specified reset signal, thus resetting the
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+ * affected HW module(s). Depending on the reset controller hardware, the reset
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+ * signal will either stay asserted until reset_deassert() is called, or the
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+ * hardware may autonomously clear the reset signal itself.
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+ *
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+ * @reset_ctl: A reset control struct that was previously successfully
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+ * requested by reset_get_by_*().
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+ * @return 0 if OK, or a negative error code.
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+ */
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+int reset_assert(struct reset_ctl *reset_ctl);
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+
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+/**
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+ * reset_deassert - Deassert a reset signal.
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+ *
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+ * This function will deassert the specified reset signal, thus releasing the
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+ * affected HW modules() from reset, and allowing them to continue normal
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+ * operation.
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+ *
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+ * @reset_ctl: A reset control struct that was previously successfully
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+ * requested by reset_get_by_*().
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+ * @return 0 if OK, or a negative error code.
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+ */
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+int reset_deassert(struct reset_ctl *reset_ctl);
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+
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+#endif
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