+/*
+ * Copyright (c) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ * Copyright (c) 2016, NVIDIA CORPORATION.
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
#ifndef _CLK_H_
#define _CLK_H_
+#include <linux/errno.h>
+#include <linux/types.h>
+
+/**
+ * A clock is a hardware signal that oscillates autonomously at a specific
+ * frequency and duty cycle. Most hardware modules require one or more clock
+ * signal to drive their operation. Clock signals are typically generated
+ * externally to the HW module consuming them, by an entity this API calls a
+ * clock provider. This API provides a standard means for drivers to enable and
+ * disable clocks, and to set the rate at which they oscillate.
+ *
+ * A driver that implements UCLASS_CLOCK is a clock provider. A provider will
+ * often implement multiple separate clocks, since the hardware it manages
+ * often has this capability. clock_uclass.h describes the interface which
+ * clock providers must implement.
+ *
+ * Clock consumers/clients are the HW modules driven by the clock signals. This
+ * header file describes the API used by drivers for those HW modules.
+ */
+
+struct udevice;
+
+/**
+ * struct clk - A handle to (allowing control of) a single clock.
+ *
+ * Clients provide storage for clock handles. The content of the structure is
+ * managed solely by the clock API and clock drivers. A clock struct is
+ * initialized by "get"ing the clock struct. The clock struct is passed to all
+ * other clock APIs to identify which clock signal to operate upon.
+ *
+ * @dev: The device which implements the clock signal.
+ * @id: The clock signal ID within the provider.
+ *
+ * Currently, the clock API assumes that a single integer ID is enough to
+ * identify and configure any clock signal for any clock provider. If this
+ * assumption becomes invalid in the future, the struct could be expanded to
+ * either (a) add more fields to allow clock providers to store additional
+ * information, or (b) replace the id field with an opaque pointer, which the
+ * provider would dynamically allocated during its .of_xlate op, and process
+ * during is .request op. This may require the addition of an extra op to clean
+ * up the allocation.
+ */
+struct clk {
+ struct udevice *dev;
+ /*
+ * Written by of_xlate. We assume a single id is enough for now. In the
+ * future, we might add more fields here.
+ */
+ unsigned long id;
+};
+
+#if CONFIG_IS_ENABLED(OF_CONTROL) && CONFIG_IS_ENABLED(CLK)
+struct phandle_2_cell;
+int clk_get_by_index_platdata(struct udevice *dev, int index,
+ struct phandle_2_cell *cells, struct clk *clk);
+
+/**
+ * clock_get_by_index - Get/request a clock by integer index.
+ *
+ * This looks up and requests a clock. The index is relative to the client
+ * device; each device is assumed to have n clocks associated with it somehow,
+ * and this function finds and requests one of them. The mapping of client
+ * device clock indices to provider clocks may be via device-tree properties,
+ * board-provided mapping tables, or some other mechanism.
+ *
+ * @dev: The client device.
+ * @index: The index of the clock to request, within the client's list of
+ * clocks.
+ * @clock A pointer to a clock struct to initialize.
+ * @return 0 if OK, or a negative error code.
+ */
+int clk_get_by_index(struct udevice *dev, int index, struct clk *clk);
+
+/**
+ * clock_get_by_name - Get/request a clock by name.
+ *
+ * This looks up and requests a clock. The name is relative to the client
+ * device; each device is assumed to have n clocks associated with it somehow,
+ * and this function finds and requests one of them. The mapping of client
+ * device clock names to provider clocks may be via device-tree properties,
+ * board-provided mapping tables, or some other mechanism.
+ *
+ * @dev: The client device.
+ * @name: The name of the clock to request, within the client's list of
+ * clocks.
+ * @clock: A pointer to a clock struct to initialize.
+ * @return 0 if OK, or a negative error code.
+ */
+int clk_get_by_name(struct udevice *dev, const char *name, struct clk *clk);
+#else
+static inline int clk_get_by_index(struct udevice *dev, int index,
+ struct clk *clk)
+{
+ return -ENOSYS;
+}
+
+static inline int clk_get_by_name(struct udevice *dev, const char *name,
+ struct clk *clk)
+{
+ return -ENOSYS;
+}
+#endif
+
+/**
+ * clk_request - Request a clock by provider-specific ID.
+ *
+ * This requests a clock using a provider-specific ID. Generally, this function
+ * should not be used, since clk_get_by_index/name() provide an interface that
+ * better separates clients from intimate knowledge of clock providers.
+ * However, this function may be useful in core SoC-specific code.
+ *
+ * @dev: The clock provider device.
+ * @clock: A pointer to a clock struct to initialize. The caller must
+ * have already initialized any field in this struct which the
+ * clock provider uses to identify the clock.
+ * @return 0 if OK, or a negative error code.
+ */
+int clk_request(struct udevice *dev, struct clk *clk);
+
+/**
+ * clock_free - Free a previously requested clock.
+ *
+ * @clock: A clock struct that was previously successfully requested by
+ * clk_request/get_by_*().
+ * @return 0 if OK, or a negative error code.
+ */
+int clk_free(struct clk *clk);
+
+/**
+ * clk_get_rate() - Get current clock rate.
+ *
+ * @clk: A clock struct that was previously successfully requested by
+ * clk_request/get_by_*().
+ * @return clock rate in Hz, or -ve error code.
+ */
+ulong clk_get_rate(struct clk *clk);
+
+/**
+ * clk_set_rate() - Set current clock rate.
+ *
+ * @clk: A clock struct that was previously successfully requested by
+ * clk_request/get_by_*().
+ * @rate: New clock rate in Hz.
+ * @return new rate, or -ve error code.
+ */
+ulong clk_set_rate(struct clk *clk, ulong rate);
+
+/**
+ * clk_enable() - Enable (turn on) a clock.
+ *
+ * @clk: A clock struct that was previously successfully requested by
+ * clk_request/get_by_*().
+ * @return zero on success, or -ve error code.
+ */
+int clk_enable(struct clk *clk);
+
+/**
+ * clk_disable() - Disable (turn off) a clock.
+ *
+ * @clk: A clock struct that was previously successfully requested by
+ * clk_request/get_by_*().
+ * @return zero on success, or -ve error code.
+ */
+int clk_disable(struct clk *clk);
+
int soc_clk_dump(void);
-#endif /* _CLK_H_ */
+#endif
projects / people / ms / u-boot.git / blobdiff