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