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  * @gpiod: gpio descriptor to gate this clock
  69  */
  70 struct clk *clk_register_gpio_gate(struct device *dev, const char *name,
  71                 const char *parent_name, struct gpio_desc *gpiod,
  72                 unsigned long flags)
  73 {
  74         struct clk_gpio *clk_gpio = NULL;
  75         struct clk *clk = ERR_PTR(-EINVAL);
  76         struct clk_init_data init = { NULL };
  77         unsigned long gpio_flags;
  78         int err;
  79
  80         if (gpiod_is_active_low(gpiod))
  81                 gpio_flags = GPIOF_OUT_INIT_HIGH;
  82         else
  83                 gpio_flags = GPIOF_OUT_INIT_LOW;
  84
  85         if (dev)
  86                 err = devm_gpio_request_one(dev, desc_to_gpio(gpiod),
  87                                             gpio_flags, name);
  88         else
  89                 err = gpio_request_one(desc_to_gpio(gpiod), gpio_flags, name);
  90
  91         if (err) {
  92                 pr_err("%s: %s: Error requesting clock control gpio %u\n",
  93                        __func__, name, desc_to_gpio(gpiod));
  94                 return ERR_PTR(err);
  95         }
  96
  97         if (dev)
  98                 clk_gpio = devm_kzalloc(dev, sizeof(struct clk_gpio),
  99                                         GFP_KERNEL);
 100         else
 101                 clk_gpio = kzalloc(sizeof(struct clk_gpio), GFP_KERNEL);
 102
 103         if (!clk_gpio) {
 104                 clk = ERR_PTR(-ENOMEM);
 105                 goto clk_register_gpio_gate_err;
 106         }
 107
 108         init.name = name;
 109         init.ops = &clk_gpio_gate_ops;
 110         init.flags = flags | CLK_IS_BASIC;
 111         init.parent_names = (parent_name ? &parent_name : NULL);
 112         init.num_parents = (parent_name ? 1 : 0);
 113
 114         clk_gpio->gpiod = gpiod;
 115         clk_gpio->hw.init = &init;
 116
 117         clk = clk_register(dev, &clk_gpio->hw);
 118
 119         if (!IS_ERR(clk))
 120                 return clk;
 121
 122         if (!dev)
 123                 kfree(clk_gpio);
 124
 125 clk_register_gpio_gate_err:
 126         gpiod_put(gpiod);
 127
 128         return clk;
 129 }
 130 EXPORT_SYMBOL_GPL(clk_register_gpio_gate);
 131
 132 #ifdef CONFIG_OF
 133 /**
 134  * The clk_register_gpio_gate has to be delayed, because the EPROBE_DEFER
 135  * can not be handled properly at of_clk_init() call time.
 136  */
 137
 138 struct clk_gpio_gate_delayed_register_data {
 139         struct device_node *node;
 140         struct mutex lock;
 141         struct clk *clk;
 142 };
 143
 144 static struct clk *of_clk_gpio_gate_delayed_register_get(
 145                 struct of_phandle_args *clkspec,
 146                 void *_data)
 147 {
 148         struct clk_gpio_gate_delayed_register_data *data = _data;
 149         struct clk *clk;
 150         const char *clk_name = data->node->name;
 151         const char *parent_name;
 152         struct gpio_desc *gpiod;
 153         int gpio;
 154
 155         mutex_lock(&data->lock);
 156
 157         if (data->clk) {
 158                 mutex_unlock(&data->lock);
 159                 return data->clk;
 160         }
 161
 162         gpio = of_get_named_gpio_flags(data->node, "enable-gpios", 0, NULL);
 163         if (gpio < 0) {
 164                 mutex_unlock(&data->lock);
 165                 if (gpio != -EPROBE_DEFER)
 166                         pr_err("%s: %s: Can't get 'enable-gpios' DT property\n",
 167                                __func__, clk_name);
 168                 return ERR_PTR(gpio);
 169         }
 170         gpiod = gpio_to_desc(gpio);
 171
 172         parent_name = of_clk_get_parent_name(data->node, 0);
 173
 174         clk = clk_register_gpio_gate(NULL, clk_name, parent_name, gpiod, 0);
 175         if (IS_ERR(clk)) {
 176                 mutex_unlock(&data->lock);
 177                 return clk;
 178         }
 179
 180         data->clk = clk;
 181         mutex_unlock(&data->lock);
 182
 183         return clk;
 184 }
 185
 186 /**
 187  * of_gpio_gate_clk_setup() - Setup function for gpio controlled clock
 188  */
 189 void __init of_gpio_gate_clk_setup(struct device_node *node)
 190 {
 191         struct clk_gpio_gate_delayed_register_data *data;
 192
 193         data = kzalloc(sizeof(struct clk_gpio_gate_delayed_register_data),
 194                        GFP_KERNEL);
 195         if (!data)
 196                 return;
 197
 198         data->node = node;
 199         mutex_init(&data->lock);
 200
 201         of_clk_add_provider(node, of_clk_gpio_gate_delayed_register_get, data);
 202 }
 203 EXPORT_SYMBOL_GPL(of_gpio_gate_clk_setup);
 204 CLK_OF_DECLARE(gpio_gate_clk, "gpio-gate-clock", of_gpio_gate_clk_setup);
 205 #endif