X-Git-Url: https://git.sur5r.net/?a=blobdiff_plain;f=include%2Fclk.h;h=5a5c2ff1e674875dfd6ba999addf73baae231d3a;hb=6a34af5b411ed316b66547ac575d2669df223dc6;hp=df4570c6f54abb0f5e6aac166b8096c19becdf69;hpb=e7538fee991308c16f76f7eca2517089f2a30ff4;p=u-boot diff --git a/include/clk.h b/include/clk.h index df4570c6f5..5a5c2ff1e6 100644 --- a/include/clk.h +++ b/include/clk.h @@ -1,6 +1,179 @@ +/* + * Copyright (c) 2015 Google, Inc + * Written by Simon Glass + * Copyright (c) 2016, NVIDIA CORPORATION. + * + * SPDX-License-Identifier: GPL-2.0+ + */ + #ifndef _CLK_H_ #define _CLK_H_ +#include +#include + +/** + * 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