diff options
Diffstat (limited to 'include/clk.h')
| -rw-r--r-- | include/clk.h | 220 |
1 files changed, 131 insertions, 89 deletions
diff --git a/include/clk.h b/include/clk.h index ca20c3d..2f31cf7 100644 --- a/include/clk.h +++ b/include/clk.h @@ -1,6 +1,7 @@ /* * Copyright (c) 2015 Google, Inc * Written by Simon Glass <sjg@chromium.org> + * Copyright (c) 2016, NVIDIA CORPORATION. * * SPDX-License-Identifier: GPL-2.0+ */ @@ -8,125 +9,166 @@ #ifndef _CLK_H_ #define _CLK_H_ -#include <errno.h> #include <linux/types.h> -struct udevice; +/** + * 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. + */ -int soc_clk_dump(void); +struct udevice; -struct clk_ops { - /** - * get_rate() - Get current clock rate - * - * @dev: Device to check (UCLASS_CLK) - * @return clock rate in Hz, or -ve error code - */ - ulong (*get_rate)(struct udevice *dev); - - /** - * set_rate() - Set current clock rate - * - * @dev: Device to adjust - * @rate: New clock rate in Hz - * @return new rate, or -ve error code - */ - ulong (*set_rate)(struct udevice *dev, ulong rate); - - /** - * enable() - Enable the clock for a peripheral - * - * @dev: clock provider - * @periph: Peripheral ID to enable - * @return zero on success, or -ve error code - */ - int (*enable)(struct udevice *dev, int periph); - - /** - * get_periph_rate() - Get clock rate for a peripheral - * - * @dev: Device to check (UCLASS_CLK) - * @periph: Peripheral ID to check - * @return clock rate in Hz, or -ve error code - */ - ulong (*get_periph_rate)(struct udevice *dev, int periph); - - /** - * set_periph_rate() - Set current clock rate for a peripheral - * - * @dev: Device to update (UCLASS_CLK) - * @periph: Peripheral ID to update - * @return new clock rate in Hz, or -ve error code +/** + * 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. */ - ulong (*set_periph_rate)(struct udevice *dev, int periph, ulong rate); + unsigned long id; }; -#define clk_get_ops(dev) ((struct clk_ops *)(dev)->driver->ops) +#if CONFIG_IS_ENABLED(OF_CONTROL) +/** + * 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); /** - * clk_get_rate() - Get current clock rate + * clock_get_by_name - Get/request a clock by name. * - * @dev: Device to check (UCLASS_CLK) - * @return clock rate in Hz, or -ve error code + * 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. */ -ulong clk_get_rate(struct udevice *dev); +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 int clk_get_by_name(struct udevice *dev, const char *name, + struct clk *clk) +{ + return -ENOSYS; +} +#endif /** - * clk_set_rate() - Set current clock rate + * clk_request - Request a clock by provider-specific ID. * - * @dev: Device to adjust - * @rate: New clock rate in Hz - * @return new rate, or -ve error code + * 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. */ -ulong clk_set_rate(struct udevice *dev, ulong rate); +int clk_request(struct udevice *dev, struct clk *clk); /** - * clk_enable() - Enable the clock for a peripheral + * clock_free - Free a previously requested clock. * - * @dev: clock provider - * @periph: Peripheral ID to enable - * @return zero on success, or -ve error code + * @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_enable(struct udevice *dev, int periph); +int clk_free(struct clk *clk); /** - * clk_get_periph_rate() - Get current clock rate for a peripheral + * clk_get_rate() - Get current clock rate. * - * @dev: Device to check (UCLASS_CLK) - * @return clock rate in Hz, -ve error code + * @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_periph_rate(struct udevice *dev, int periph); +ulong clk_get_rate(struct clk *clk); /** - * clk_set_periph_rate() - Set current clock rate for a peripheral + * clk_set_rate() - Set current clock rate. * - * @dev: Device to update (UCLASS_CLK) - * @periph: Peripheral ID to update - * @return new clock rate in Hz, or -ve error code + * @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_periph_rate(struct udevice *dev, int periph, ulong rate); +ulong clk_set_rate(struct clk *clk, ulong rate); -#if CONFIG_IS_ENABLED(OF_CONTROL) /** - * clk_get_by_index() - look up a clock referenced by a device + * clk_enable() - Enable (turn on) a clock. * - * Parse a device's 'clocks' list, returning information on the indexed clock, - * ensuring that it is activated. + * @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. * - * @dev: Device containing the clock reference - * @index: Clock index to return (0 = first) - * @clk_devp: Returns clock device - * @return: Peripheral ID for the device to control. This is the first - * argument after the clock node phandle. If there is no arguemnt, - * returns 0. Return -ve error code on any error + * @clk: A clock struct that was previously successfully requested by + * clk_request/get_by_*(). + * @return zero on success, or -ve error code. */ -int clk_get_by_index(struct udevice *dev, int index, struct udevice **clk_devp); -#else -static inline int clk_get_by_index(struct udevice *dev, int index, - struct udevice **clk_devp) -{ - return -ENOSYS; -} -#endif +int clk_disable(struct clk *clk); -#endif /* _CLK_H_ */ +int soc_clk_dump(void); + +#endif |