drivers/clk/clk-gpio.c

   1 /*
   2  * Copyright (C) 2013 - 2014 Texas Instruments Incorporated - http://www.ti.com
   3  *
   4  * Authors:
   5  *    Jyri Sarha <jsarha@ti.com>
   6  *    Sergej Sawazki <ce3a@gmx.de>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  * Gpio controlled clock implementation
  13  */
  14
  15 #include <linux/clk-provider.h>
  16 #include <linux/export.h>
  17 #include <linux/slab.h>
  18 #include <linux/gpio/consumer.h>
  19 #include <linux/err.h>
  20 #include <linux/device.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/of_device.h>
  23
  24 /**
  25  * DOC: basic gpio gated clock which can be enabled and disabled
  26  *      with gpio output
  27  * Traits of this clock:
  28  * prepare - clk_(un)prepare only ensures parent is (un)prepared
  29  * enable - clk_enable and clk_disable are functional & control gpio
  30  * rate - inherits rate from parent.  No clk_set_rate support
  31  * parent - fixed parent.  No clk_set_parent support
  32  */
  33
  34 static int clk_gpio_gate_enable(struct clk_hw *hw)
  35 {
  36         struct clk_gpio *clk = to_clk_gpio(hw);
  37
  38         gpiod_set_value(clk->gpiod, 1);
  39
  40         return 0;
  41 }
  42
  43 static void clk_gpio_gate_disable(struct clk_hw *hw)
  44 {
  45         struct clk_gpio *clk = to_clk_gpio(hw);
  46
  47         gpiod_set_value(clk->gpiod, 0);
  48 }
  49
  50 static int clk_gpio_gate_is_enabled(struct clk_hw *hw)
  51 {
  52         struct clk_gpio *clk = to_clk_gpio(hw);
  53
  54         return gpiod_get_value(clk->gpiod);
  55 }
  56
  57 const struct clk_ops clk_gpio_gate_ops = {
  58         .enable = clk_gpio_gate_enable,
  59         .disable = clk_gpio_gate_disable,
  60         .is_enabled = clk_gpio_gate_is_enabled,
  61 };
  62 EXPORT_SYMBOL_GPL(clk_gpio_gate_ops);
  63
  64 /**
  65  * DOC: basic clock multiplexer which can be controlled with a gpio output
  66  * Traits of this clock:
  67  * prepare - clk_prepare only ensures that parents are prepared
  68  * rate - rate is only affected by parent switching.  No clk_set_rate support
  69  * parent - parent is adjustable through clk_set_parent
  70  */
  71
  72 static u8 clk_gpio_mux_get_parent(struct clk_hw *hw)
  73 {
  74         struct clk_gpio *clk = to_clk_gpio(hw);
  75
  76         return gpiod_get_value(clk->gpiod);
  77 }
  78
  79 static int clk_gpio_mux_set_parent(struct clk_hw *hw, u8 index)
  80 {
  81         struct clk_gpio *clk = to_clk_gpio(hw);
  82
  83         gpiod_set_value(clk->gpiod, index);
  84
  85         return 0;
  86 }
  87
  88 const struct clk_ops clk_gpio_mux_ops = {
  89         .get_parent = clk_gpio_mux_get_parent,
  90         .set_parent = clk_gpio_mux_set_parent,
  91         .determine_rate = __clk_mux_determine_rate,
  92 };
  93 EXPORT_SYMBOL_GPL(clk_gpio_mux_ops);
  94
  95 static struct clk_hw *clk_register_gpio(struct device *dev, const char *name,
  96                 const char * const *parent_names, u8 num_parents, struct gpio_desc *gpiod,
  97                 unsigned long flags, const struct clk_ops *clk_gpio_ops)
  98 {
  99         struct clk_gpio *clk_gpio;
 100         struct clk_hw *hw;
 101         struct clk_init_data init = {};
 102         int err;
 103
 104         if (dev)
 105                 clk_gpio = devm_kzalloc(dev, sizeof(*clk_gpio), GFP_KERNEL);
 106         else
 107                 clk_gpio = kzalloc(sizeof(*clk_gpio), GFP_KERNEL);
 108
 109         if (!clk_gpio)
 110                 return ERR_PTR(-ENOMEM);
 111
 112         /*
 113          * Set to disabled no matter what: NOTE if the GPIO line is active low
 114          * the GPIO descriptor knows this and will set it high to deassert the
 115          * line. This assumes the GPIO descriptor has been requested using
 116          * GPIOD_ASIS by the callers so we need to initialize it as disabled here.
 117          */
 118         gpiod_set_value(gpiod, 0);
 119
 120         init.name = name;
 121         init.ops = clk_gpio_ops;
 122         init.flags = flags | CLK_IS_BASIC;
 123         init.parent_names = parent_names;
 124         init.num_parents = num_parents;
 125
 126         clk_gpio->gpiod = gpiod;
 127         clk_gpio->hw.init = &init;
 128
 129         hw = &clk_gpio->hw;
 130         if (dev)
 131                 err = devm_clk_hw_register(dev, hw);
 132         else
 133                 err = clk_hw_register(NULL, hw);
 134
 135         if (!err)
 136                 return hw;
 137
 138         if (!dev) {
 139                 kfree(clk_gpio);
 140         }
 141
 142         return ERR_PTR(err);
 143 }
 144
 145 /**
 146  * clk_hw_register_gpio_gate - register a gpio clock gate with the clock
 147  * framework
 148  * @dev: device that is registering this clock
 149  * @name: name of this clock
 150  * @parent_name: name of this clock's parent
 151  * @gpiod: gpio descriptor to gate this clock
 152  * @flags: clock flags
 153  */
 154 struct clk_hw *clk_hw_register_gpio_gate(struct device *dev, const char *name,
 155                 const char *parent_name, struct gpio_desc *gpiod,
 156                 unsigned long flags)
 157 {
 158         return clk_register_gpio(dev, name,
 159                         (parent_name ? &parent_name : NULL),
 160                         (parent_name ? 1 : 0), gpiod, flags,
 161                         &clk_gpio_gate_ops);
 162 }
 163 EXPORT_SYMBOL_GPL(clk_hw_register_gpio_gate);
 164
 165 struct clk *clk_register_gpio_gate(struct device *dev, const char *name,
 166                 const char *parent_name, struct gpio_desc *gpiod,
 167                 unsigned long flags)
 168 {
 169         struct clk_hw *hw;
 170
 171         hw = clk_hw_register_gpio_gate(dev, name, parent_name, gpiod, flags);
 172         if (IS_ERR(hw))
 173                 return ERR_CAST(hw);
 174         return hw->clk;
 175 }
 176 EXPORT_SYMBOL_GPL(clk_register_gpio_gate);
 177
 178 /**
 179  * clk_hw_register_gpio_mux - register a gpio clock mux with the clock framework
 180  * @dev: device that is registering this clock
 181  * @name: name of this clock
 182  * @parent_names: names of this clock's parents
 183  * @num_parents: number of parents listed in @parent_names
 184  * @gpiod: gpio descriptor to gate this clock
 185  * @flags: clock flags
 186  */
 187 struct clk_hw *clk_hw_register_gpio_mux(struct device *dev, const char *name,
 188                 const char * const *parent_names, u8 num_parents, struct gpio_desc *gpiod,
 189                 unsigned long flags)
 190 {
 191         if (num_parents != 2) {
 192                 pr_err("mux-clock %s must have 2 parents\n", name);
 193                 return ERR_PTR(-EINVAL);
 194         }
 195
 196         return clk_register_gpio(dev, name, parent_names, num_parents,
 197                         gpiod, flags, &clk_gpio_mux_ops);
 198 }
 199 EXPORT_SYMBOL_GPL(clk_hw_register_gpio_mux);
 200
 201 struct clk *clk_register_gpio_mux(struct device *dev, const char *name,
 202                 const char * const *parent_names, u8 num_parents, struct gpio_desc *gpiod,
 203                 unsigned long flags)
 204 {
 205         struct clk_hw *hw;
 206
 207         hw = clk_hw_register_gpio_mux(dev, name, parent_names, num_parents,
 208                         gpiod, flags);
 209         if (IS_ERR(hw))
 210                 return ERR_CAST(hw);
 211         return hw->clk;
 212 }
 213 EXPORT_SYMBOL_GPL(clk_register_gpio_mux);
 214
 215 static int gpio_clk_driver_probe(struct platform_device *pdev)
 216 {
 217         struct device_node *node = pdev->dev.of_node;
 218         const char **parent_names, *gpio_name;
 219         unsigned int num_parents;
 220         struct gpio_desc *gpiod;
 221         struct clk *clk;
 222         bool is_mux;
 223         int ret;
 224
 225         num_parents = of_clk_get_parent_count(node);
 226         if (num_parents) {
 227                 parent_names = devm_kcalloc(&pdev->dev, num_parents,
 228                                             sizeof(char *), GFP_KERNEL);
 229                 if (!parent_names)
 230                         return -ENOMEM;
 231
 232                 of_clk_parent_fill(node, parent_names, num_parents);
 233         } else {
 234                 parent_names = NULL;
 235         }
 236
 237         is_mux = of_device_is_compatible(node, "gpio-mux-clock");
 238
 239         gpio_name = is_mux ? "select" : "enable";
 240         gpiod = devm_gpiod_get(&pdev->dev, gpio_name, GPIOD_ASIS);
 241         if (IS_ERR(gpiod)) {
 242                 ret = PTR_ERR(gpiod);
 243                 if (ret == -EPROBE_DEFER)
 244                         pr_debug("%s: %s: GPIOs not yet available, retry later\n",
 245                                         node->name, __func__);
 246                 else
 247                         pr_err("%s: %s: Can't get '%s' named GPIO property\n",
 248                                         node->name, __func__,
 249                                         gpio_name);
 250                 return ret;
 251         }
 252
 253         if (is_mux)
 254                 clk = clk_register_gpio_mux(&pdev->dev, node->name,
 255                                 parent_names, num_parents, gpiod, 0);
 256         else
 257                 clk = clk_register_gpio_gate(&pdev->dev, node->name,
 258                                 parent_names ?  parent_names[0] : NULL, gpiod,
 259                                 0);
 260         if (IS_ERR(clk))
 261                 return PTR_ERR(clk);
 262
 263         return of_clk_add_provider(node, of_clk_src_simple_get, clk);
 264 }
 265
 266 static const struct of_device_id gpio_clk_match_table[] = {
 267         { .compatible = "gpio-mux-clock" },
 268         { .compatible = "gpio-gate-clock" },
 269         { }
 270 };
 271
 272 static struct platform_driver gpio_clk_driver = {
 273         .probe          = gpio_clk_driver_probe,
 274         .driver         = {
 275                 .name   = "gpio-clk",
 276                 .of_match_table = gpio_clk_match_table,
 277         },
 278 };
 279 builtin_platform_driver(gpio_clk_driver);