drivers/clk/clk-gpio-gate.c

   1 /*
   2  * Copyright (C) 2013 - 2014 Texas Instruments Incorporated - http://www.ti.com
   3  * Author: Jyri Sarha <jsarha@ti.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  *
   9  * Gpio gated clock implementation
  10  */
  11
  12 #include <linux/clk-provider.h>
  13 #include <linux/module.h>
  14 #include <linux/slab.h>
  15 #include <linux/gpio.h>
  16 #include <linux/gpio/consumer.h>
  17 #include <linux/of_gpio.h>
  18 #include <linux/err.h>
  19 #include <linux/device.h>
  20
  21 /**
  22  * DOC: basic gpio gated clock which can be enabled and disabled
  23  *      with gpio output
  24  * Traits of this clock:
  25  * prepare - clk_(un)prepare only ensures parent is (un)prepared
  26  * enable - clk_enable and clk_disable are functional & control gpio
  27  * rate - inherits rate from parent.  No clk_set_rate support
  28  * parent - fixed parent.  No clk_set_parent support
  29  */
  30
  31 #define to_clk_gpio(_hw) container_of(_hw, struct clk_gpio, hw)
  32
  33 static int clk_gpio_gate_enable(struct clk_hw *hw)
  34 {
  35         struct clk_gpio *clk = to_clk_gpio(hw);
  36
  37         gpiod_set_value(clk->gpiod, 1);
  38
  39         return 0;
  40 }
  41
  42 static void clk_gpio_gate_disable(struct clk_hw *hw)
  43 {
  44         struct clk_gpio *clk = to_clk_gpio(hw);
  45
  46         gpiod_set_value(clk->gpiod, 0);
  47 }
  48
  49 static int clk_gpio_gate_is_enabled(struct clk_hw *hw)
  50 {
  51         struct clk_gpio *clk = to_clk_gpio(hw);
  52
  53         return gpiod_get_value(clk->gpiod);
  54 }
  55
  56 const struct clk_ops clk_gpio_gate_ops = {
  57         .enable = clk_gpio_gate_enable,
  58         .disable = clk_gpio_gate_disable,
  59         .is_enabled = clk_gpio_gate_is_enabled,
  60 };
  61 EXPORT_SYMBOL_GPL(clk_gpio_gate_ops);
  62
  63 /**
  64  * clk_register_gpio - register a gpip clock with the clock framework
  65  * @dev: device that is registering this clock
  66  * @name: name of this clock
  67  * @parent_name: name of this clock's parent
  68  * @gpio: gpio number to gate this clock
  69  * @active_low: true if gpio should be set to 0 to enable clock
  70  * @flags: clock flags
  71  */
  72 struct clk *clk_register_gpio_gate(struct device *dev, const char *name,
  73                 const char *parent_name, unsigned gpio, bool active_low,
  74                 unsigned long flags)
  75 {
  76         struct clk_gpio *clk_gpio = NULL;
  77         struct clk *clk = ERR_PTR(-EINVAL);
  78         struct clk_init_data init = { NULL };
  79         unsigned long gpio_flags;
  80         int err;
  81
  82         if (active_low)
  83                 gpio_flags = GPIOF_ACTIVE_LOW | GPIOF_OUT_INIT_HIGH;
  84         else
  85                 gpio_flags = GPIOF_OUT_INIT_LOW;
  86
  87         if (dev)
  88                 err = devm_gpio_request_one(dev, gpio, gpio_flags, name);
  89         else
  90                 err = gpio_request_one(gpio, gpio_flags, name);
  91
  92         if (err) {
  93                 pr_err("%s: %s: Error requesting clock control gpio %u\n",
  94                        __func__, name, gpio);
  95                 return ERR_PTR(err);
  96         }
  97
  98         if (dev)
  99                 clk_gpio = devm_kzalloc(dev, sizeof(struct clk_gpio),
 100                                         GFP_KERNEL);
 101         else
 102                 clk_gpio = kzalloc(sizeof(struct clk_gpio), GFP_KERNEL);
 103
 104         if (!clk_gpio) {
 105                 clk = ERR_PTR(-ENOMEM);
 106                 goto clk_register_gpio_gate_err;
 107         }
 108
 109         init.name = name;
 110         init.ops = &clk_gpio_gate_ops;
 111         init.flags = flags | CLK_IS_BASIC;
 112         init.parent_names = (parent_name ? &parent_name : NULL);
 113         init.num_parents = (parent_name ? 1 : 0);
 114
 115         clk_gpio->gpiod = gpio_to_desc(gpio);
 116         clk_gpio->hw.init = &init;
 117
 118         clk = clk_register(dev, &clk_gpio->hw);
 119
 120         if (!IS_ERR(clk))
 121                 return clk;
 122
 123         if (!dev)
 124                 kfree(clk_gpio);
 125
 126 clk_register_gpio_gate_err:
 127         if (!dev)
 128                 gpio_free(gpio);
 129
 130         return clk;
 131 }
 132 EXPORT_SYMBOL_GPL(clk_register_gpio_gate);
 133
 134 #ifdef CONFIG_OF
 135 /**
 136  * The clk_register_gpio_gate has to be delayed, because the EPROBE_DEFER
 137  * can not be handled properly at of_clk_init() call time.
 138  */
 139
 140 struct clk_gpio_gate_delayed_register_data {
 141         struct device_node *node;
 142         struct mutex lock;
 143         struct clk *clk;
 144 };
 145
 146 static struct clk *of_clk_gpio_gate_delayed_register_get(
 147                 struct of_phandle_args *clkspec,
 148                 void *_data)
 149 {
 150         struct clk_gpio_gate_delayed_register_data *data = _data;
 151         struct clk *clk;
 152         const char *clk_name = data->node->name;
 153         const char *parent_name;
 154         int gpio;
 155         enum of_gpio_flags of_flags;
 156
 157         mutex_lock(&data->lock);
 158
 159         if (data->clk) {
 160                 mutex_unlock(&data->lock);
 161                 return data->clk;
 162         }
 163
 164         gpio = of_get_named_gpio_flags(data->node, "enable-gpios", 0,
 165                                                 &of_flags);
 166         if (gpio < 0) {
 167                 mutex_unlock(&data->lock);
 168                 if (gpio != -EPROBE_DEFER)
 169                         pr_err("%s: %s: Can't get 'enable-gpios' DT property\n",
 170                                __func__, clk_name);
 171                 return ERR_PTR(gpio);
 172         }
 173
 174         parent_name = of_clk_get_parent_name(data->node, 0);
 175
 176         clk = clk_register_gpio_gate(NULL, clk_name, parent_name, gpio,
 177                                         of_flags & OF_GPIO_ACTIVE_LOW, 0);
 178         if (IS_ERR(clk)) {
 179                 mutex_unlock(&data->lock);
 180                 return clk;
 181         }
 182
 183         data->clk = clk;
 184         mutex_unlock(&data->lock);
 185
 186         return clk;
 187 }
 188
 189 /**
 190  * of_gpio_gate_clk_setup() - Setup function for gpio controlled clock
 191  */
 192 void __init of_gpio_gate_clk_setup(struct device_node *node)
 193 {
 194         struct clk_gpio_gate_delayed_register_data *data;
 195
 196         data = kzalloc(sizeof(struct clk_gpio_gate_delayed_register_data),
 197                        GFP_KERNEL);
 198         if (!data)
 199                 return;
 200
 201         data->node = node;
 202         mutex_init(&data->lock);
 203
 204         of_clk_add_provider(node, of_clk_gpio_gate_delayed_register_get, data);
 205 }
 206 EXPORT_SYMBOL_GPL(of_gpio_gate_clk_setup);
 207 CLK_OF_DECLARE(gpio_gate_clk, "gpio-gate-clock", of_gpio_gate_clk_setup);
 208 #endif