Add a reset driver framework/uclass

A reset controller is a hardware module that controls reset signals that
affect other hardware modules or chips.

This patch defines a standard API that connects reset clients (i.e. the
drivers for devices affected by reset signals) to drivers for reset
controllers/providers. Initially, DT is the only supported method for
connecting the two.

The DT binding specification (reset.txt) was taken from Linux kernel
v4.5's Documentation/devicetree/bindings/reset/reset.txt.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Simon Glass <sjg@chromium.org>

1 files changed, 81 insertions, 0 deletions

diff --git a/include/reset-uclass.h b/include/reset-uclass.h
new file mode 100644
index 00000000000..50adeca7579
--- /dev/null
+++ b/include/reset-uclass.h
@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2016, NVIDIA CORPORATION.
+ *
+ * SPDX-License-Identifier: GPL-2.0
+ */
+
+#ifndef _RESET_UCLASS_H
+#define _RESET_UCLASS_H
+
+/* See reset.h for background documentation. */
+
+#include <reset.h>
+
+struct udevice;
+
+/**
+ * struct reset_ops - The functions that a reset controller driver must
+ * implement.
+ */
+struct reset_ops {
+	/**
+	 * of_xlate - Translate a client's device-tree (OF) reset specifier.
+	 *
+	 * The reset core calls this function as the first step in implementing
+	 * a client's reset_get_by_*() call.
+	 *
+	 * If this function pointer is set to NULL, the reset core will use a
+	 * default implementation, which assumes #reset-cells = <1>, and that
+	 * the DT cell contains a simple integer reset signal ID.
+	 *
+	 * At present, the reset API solely supports device-tree. If this
+	 * changes, other xxx_xlate() functions may be added to support those
+	 * other mechanisms.
+	 *
+	 * @reset_ctl:	The reset control struct to hold the translation result.
+	 * @args:	The reset specifier values from device tree.
+	 * @return 0 if OK, or a negative error code.
+	 */
+	int (*of_xlate)(struct reset_ctl *reset_ctl,
+			struct fdtdec_phandle_args *args);
+	/**
+	 * request - Request a translated reset control.
+	 *
+	 * The reset core calls this function as the second step in
+	 * implementing a client's reset_get_by_*() call, following a
+	 * successful xxx_xlate() call.
+	 *
+	 * @reset_ctl:	The reset control struct to request; this has been
+	 *		filled in by a previoux xxx_xlate() function call.
+	 * @return 0 if OK, or a negative error code.
+	 */
+	int (*request)(struct reset_ctl *reset_ctl);
+	/**
+	 * free - Free a previously requested reset control.
+	 *
+	 * This is the implementation of the client reset_free() API.
+	 *
+	 * @reset_ctl:	The reset control to free.
+	 * @return 0 if OK, or a negative error code.
+	 */
+	int (*free)(struct reset_ctl *reset_ctl);
+	/**
+	 * rst_assert - Assert a reset signal.
+	 *
+	 * Note: This function is named rst_assert not assert to avoid
+	 * conflicting with global macro assert().
+	 *
+	 * @reset_ctl:	The reset signal to assert.
+	 * @return 0 if OK, or a negative error code.
+	 */
+	int (*rst_assert)(struct reset_ctl *reset_ctl);
+	/**
+	 * rst_deassert - Deassert a reset signal.
+	 *
+	 * @reset_ctl:	The reset signal to deassert.
+	 * @return 0 if OK, or a negative error code.
+	 */
+	int (*rst_deassert)(struct reset_ctl *reset_ctl);
+};
+
+#endif