include/clk.h

   1 /*
   2  * Copyright (c) 2015 Google, Inc
   3  * Written by Simon Glass <sjg@chromium.org>
   4  * Copyright (c) 2016, NVIDIA CORPORATION.
   5  *
   6  * SPDX-License-Identifier:     GPL-2.0+
   7  */
   8
   9 #ifndef _CLK_H_
  10 #define _CLK_H_
  11
  12 #include <linux/errno.h>
  13 #include <linux/types.h>
  14
  15 /**
  16  * A clock is a hardware signal that oscillates autonomously at a specific
  17  * frequency and duty cycle. Most hardware modules require one or more clock
  18  * signal to drive their operation. Clock signals are typically generated
  19  * externally to the HW module consuming them, by an entity this API calls a
  20  * clock provider. This API provides a standard means for drivers to enable and
  21  * disable clocks, and to set the rate at which they oscillate.
  22  *
  23  * A driver that implements UCLASS_CLOCK is a clock provider. A provider will
  24  * often implement multiple separate clocks, since the hardware it manages
  25  * often has this capability. clock_uclass.h describes the interface which
  26  * clock providers must implement.
  27  *
  28  * Clock consumers/clients are the HW modules driven by the clock signals. This
  29  * header file describes the API used by drivers for those HW modules.
  30  */
  31
  32 struct udevice;
  33
  34 /**
  35  * struct clk - A handle to (allowing control of) a single clock.
  36  *
  37  * Clients provide storage for clock handles. The content of the structure is
  38  * managed solely by the clock API and clock drivers. A clock struct is
  39  * initialized by "get"ing the clock struct. The clock struct is passed to all
  40  * other clock APIs to identify which clock signal to operate upon.
  41  *
  42  * @dev: The device which implements the clock signal.
  43  * @id: The clock signal ID within the provider.
  44  *
  45  * Currently, the clock API assumes that a single integer ID is enough to
  46  * identify and configure any clock signal for any clock provider. If this
  47  * assumption becomes invalid in the future, the struct could be expanded to
  48  * either (a) add more fields to allow clock providers to store additional
  49  * information, or (b) replace the id field with an opaque pointer, which the
  50  * provider would dynamically allocated during its .of_xlate op, and process
  51  * during is .request op. This may require the addition of an extra op to clean
  52  * up the allocation.
  53  */
  54 struct clk {
  55         struct udevice *dev;
  56         /*
  57          * Written by of_xlate. We assume a single id is enough for now. In the
  58          * future, we might add more fields here.
  59          */
  60         unsigned long id;
  61 };
  62
  63 #if CONFIG_IS_ENABLED(OF_CONTROL) && CONFIG_IS_ENABLED(CLK)
  64 struct phandle_2_cell;
  65 int clk_get_by_index_platdata(struct udevice *dev, int index,
  66                               struct phandle_2_cell *cells, struct clk *clk);
  67
  68 /**
  69  * clock_get_by_index - Get/request a clock by integer index.
  70  *
  71  * This looks up and requests a clock. The index is relative to the client
  72  * device; each device is assumed to have n clocks associated with it somehow,
  73  * and this function finds and requests one of them. The mapping of client
  74  * device clock indices to provider clocks may be via device-tree properties,
  75  * board-provided mapping tables, or some other mechanism.
  76  *
  77  * @dev:        The client device.
  78  * @index:      The index of the clock to request, within the client's list of
  79  *              clocks.
  80  * @clock       A pointer to a clock struct to initialize.
  81  * @return 0 if OK, or a negative error code.
  82  */
  83 int clk_get_by_index(struct udevice *dev, int index, struct clk *clk);
  84
  85 /**
  86  * clock_get_by_name - Get/request a clock by name.
  87  *
  88  * This looks up and requests a clock. The name is relative to the client
  89  * device; each device is assumed to have n clocks associated with it somehow,
  90  * and this function finds and requests one of them. The mapping of client
  91  * device clock names to provider clocks may be via device-tree properties,
  92  * board-provided mapping tables, or some other mechanism.
  93  *
  94  * @dev:        The client device.
  95  * @name:       The name of the clock to request, within the client's list of
  96  *              clocks.
  97  * @clock:      A pointer to a clock struct to initialize.
  98  * @return 0 if OK, or a negative error code.
  99  */
 100 int clk_get_by_name(struct udevice *dev, const char *name, struct clk *clk);
 101 #else
 102 static inline int clk_get_by_index(struct udevice *dev, int index,
 103                                    struct clk *clk)
 104 {
 105         return -ENOSYS;
 106 }
 107
 108 static inline int clk_get_by_name(struct udevice *dev, const char *name,
 109                            struct clk *clk)
 110 {
 111         return -ENOSYS;
 112 }
 113 #endif
 114
 115 /**
 116  * clk_request - Request a clock by provider-specific ID.
 117  *
 118  * This requests a clock using a provider-specific ID. Generally, this function
 119  * should not be used, since clk_get_by_index/name() provide an interface that
 120  * better separates clients from intimate knowledge of clock providers.
 121  * However, this function may be useful in core SoC-specific code.
 122  *
 123  * @dev:        The clock provider device.
 124  * @clock:      A pointer to a clock struct to initialize. The caller must
 125  *              have already initialized any field in this struct which the
 126  *              clock provider uses to identify the clock.
 127  * @return 0 if OK, or a negative error code.
 128  */
 129 int clk_request(struct udevice *dev, struct clk *clk);
 130
 131 /**
 132  * clock_free - Free a previously requested clock.
 133  *
 134  * @clock:      A clock struct that was previously successfully requested by
 135  *              clk_request/get_by_*().
 136  * @return 0 if OK, or a negative error code.
 137  */
 138 int clk_free(struct clk *clk);
 139
 140 /**
 141  * clk_get_rate() - Get current clock rate.
 142  *
 143  * @clk:        A clock struct that was previously successfully requested by
 144  *              clk_request/get_by_*().
 145  * @return clock rate in Hz, or -ve error code.
 146  */
 147 ulong clk_get_rate(struct clk *clk);
 148
 149 /**
 150  * clk_set_rate() - Set current clock rate.
 151  *
 152  * @clk:        A clock struct that was previously successfully requested by
 153  *              clk_request/get_by_*().
 154  * @rate:       New clock rate in Hz.
 155  * @return new rate, or -ve error code.
 156  */
 157 ulong clk_set_rate(struct clk *clk, ulong rate);
 158
 159 /**
 160  * clk_enable() - Enable (turn on) a clock.
 161  *
 162  * @clk:        A clock struct that was previously successfully requested by
 163  *              clk_request/get_by_*().
 164  * @return zero on success, or -ve error code.
 165  */
 166 int clk_enable(struct clk *clk);
 167
 168 /**
 169  * clk_disable() - Disable (turn off) a clock.
 170  *
 171  * @clk:        A clock struct that was previously successfully requested by
 172  *              clk_request/get_by_*().
 173  * @return zero on success, or -ve error code.
 174  */
 175 int clk_disable(struct clk *clk);
 176
 177 int soc_clk_dump(void);
 178
 179 #endif