drivers/clk/clk-gpio.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2013 - 2014 Texas Instruments Incorporated - http://www.ti.com
   4  *
   5  * Authors:
   6  *    Jyri Sarha <jsarha@ti.com>
   7  *    Sergej Sawazki <ce3a@gmx.de>
   8  *
   9  * Gpio controlled clock implementation
  10  */
  11
  12 #include <linux/clk-provider.h>
  13 #include <linux/export.h>
  14 #include <linux/slab.h>
  15 #include <linux/gpio/consumer.h>
  16 #include <linux/err.h>
  17 #include <linux/device.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/of_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 static int clk_gpio_gate_enable(struct clk_hw *hw)
  32 {
  33         struct clk_gpio *clk = to_clk_gpio(hw);
  34
  35         gpiod_set_value(clk->gpiod, 1);
  36
  37         return 0;
  38 }
  39
  40 static void clk_gpio_gate_disable(struct clk_hw *hw)
  41 {
  42         struct clk_gpio *clk = to_clk_gpio(hw);
  43
  44         gpiod_set_value(clk->gpiod, 0);
  45 }
  46
  47 static int clk_gpio_gate_is_enabled(struct clk_hw *hw)
  48 {
  49         struct clk_gpio *clk = to_clk_gpio(hw);
  50
  51         return gpiod_get_value(clk->gpiod);
  52 }
  53
  54 const struct clk_ops clk_gpio_gate_ops = {
  55         .enable = clk_gpio_gate_enable,
  56         .disable = clk_gpio_gate_disable,
  57         .is_enabled = clk_gpio_gate_is_enabled,
  58 };
  59 EXPORT_SYMBOL_GPL(clk_gpio_gate_ops);
  60
  61 static int clk_sleeping_gpio_gate_prepare(struct clk_hw *hw)
  62 {
  63         struct clk_gpio *clk = to_clk_gpio(hw);
  64
  65         gpiod_set_value_cansleep(clk->gpiod, 1);
  66
  67         return 0;
  68 }
  69
  70 static void clk_sleeping_gpio_gate_unprepare(struct clk_hw *hw)
  71 {
  72         struct clk_gpio *clk = to_clk_gpio(hw);
  73
  74         gpiod_set_value_cansleep(clk->gpiod, 0);
  75 }
  76
  77 static int clk_sleeping_gpio_gate_is_prepared(struct clk_hw *hw)
  78 {
  79         struct clk_gpio *clk = to_clk_gpio(hw);
  80
  81         return gpiod_get_value_cansleep(clk->gpiod);
  82 }
  83
  84 static const struct clk_ops clk_sleeping_gpio_gate_ops = {
  85         .prepare = clk_sleeping_gpio_gate_prepare,
  86         .unprepare = clk_sleeping_gpio_gate_unprepare,
  87         .is_prepared = clk_sleeping_gpio_gate_is_prepared,
  88 };
  89
  90 /**
  91  * DOC: basic clock multiplexer which can be controlled with a gpio output
  92  * Traits of this clock:
  93  * prepare - clk_prepare only ensures that parents are prepared
  94  * rate - rate is only affected by parent switching.  No clk_set_rate support
  95  * parent - parent is adjustable through clk_set_parent
  96  */
  97
  98 static u8 clk_gpio_mux_get_parent(struct clk_hw *hw)
  99 {
 100         struct clk_gpio *clk = to_clk_gpio(hw);
 101
 102         return gpiod_get_value_cansleep(clk->gpiod);
 103 }
 104
 105 static int clk_gpio_mux_set_parent(struct clk_hw *hw, u8 index)
 106 {
 107         struct clk_gpio *clk = to_clk_gpio(hw);
 108
 109         gpiod_set_value_cansleep(clk->gpiod, index);
 110
 111         return 0;
 112 }
 113
 114 const struct clk_ops clk_gpio_mux_ops = {
 115         .get_parent = clk_gpio_mux_get_parent,
 116         .set_parent = clk_gpio_mux_set_parent,
 117         .determine_rate = __clk_mux_determine_rate,
 118 };
 119 EXPORT_SYMBOL_GPL(clk_gpio_mux_ops);
 120
 121 static struct clk_hw *clk_register_gpio(struct device *dev, const char *name,
 122                 const char * const *parent_names, u8 num_parents, struct gpio_desc *gpiod,
 123                 unsigned long flags, const struct clk_ops *clk_gpio_ops)
 124 {
 125         struct clk_gpio *clk_gpio;
 126         struct clk_hw *hw;
 127         struct clk_init_data init = {};
 128         int err;
 129
 130         if (dev)
 131                 clk_gpio = devm_kzalloc(dev, sizeof(*clk_gpio), GFP_KERNEL);
 132         else
 133                 clk_gpio = kzalloc(sizeof(*clk_gpio), GFP_KERNEL);
 134
 135         if (!clk_gpio)
 136                 return ERR_PTR(-ENOMEM);
 137
 138         init.name = name;
 139         init.ops = clk_gpio_ops;
 140         init.flags = flags;
 141         init.parent_names = parent_names;
 142         init.num_parents = num_parents;
 143
 144         clk_gpio->gpiod = gpiod;
 145         clk_gpio->hw.init = &init;
 146
 147         hw = &clk_gpio->hw;
 148         if (dev)
 149                 err = devm_clk_hw_register(dev, hw);
 150         else
 151                 err = clk_hw_register(NULL, hw);
 152
 153         if (!err)
 154                 return hw;
 155
 156         if (!dev) {
 157                 kfree(clk_gpio);
 158         }
 159
 160         return ERR_PTR(err);
 161 }
 162
 163 /**
 164  * clk_hw_register_gpio_gate - register a gpio clock gate with the clock
 165  * framework
 166  * @dev: device that is registering this clock
 167  * @name: name of this clock
 168  * @parent_name: name of this clock's parent
 169  * @gpiod: gpio descriptor to gate this clock
 170  * @flags: clock flags
 171  */
 172 struct clk_hw *clk_hw_register_gpio_gate(struct device *dev, const char *name,
 173                 const char *parent_name, struct gpio_desc *gpiod,
 174                 unsigned long flags)
 175 {
 176         const struct clk_ops *ops;
 177
 178         if (gpiod_cansleep(gpiod))
 179                 ops = &clk_sleeping_gpio_gate_ops;
 180         else
 181                 ops = &clk_gpio_gate_ops;
 182
 183         return clk_register_gpio(dev, name,
 184                         (parent_name ? &parent_name : NULL),
 185                         (parent_name ? 1 : 0), gpiod, flags, ops);
 186 }
 187 EXPORT_SYMBOL_GPL(clk_hw_register_gpio_gate);
 188
 189 struct clk *clk_register_gpio_gate(struct device *dev, const char *name,
 190                 const char *parent_name, struct gpio_desc *gpiod,
 191                 unsigned long flags)
 192 {
 193         struct clk_hw *hw;
 194
 195         hw = clk_hw_register_gpio_gate(dev, name, parent_name, gpiod, flags);
 196         if (IS_ERR(hw))
 197                 return ERR_CAST(hw);
 198         return hw->clk;
 199 }
 200 EXPORT_SYMBOL_GPL(clk_register_gpio_gate);
 201
 202 /**
 203  * clk_hw_register_gpio_mux - register a gpio clock mux with the clock framework
 204  * @dev: device that is registering this clock
 205  * @name: name of this clock
 206  * @parent_names: names of this clock's parents
 207  * @num_parents: number of parents listed in @parent_names
 208  * @gpiod: gpio descriptor to gate this clock
 209  * @flags: clock flags
 210  */
 211 struct clk_hw *clk_hw_register_gpio_mux(struct device *dev, const char *name,
 212                 const char * const *parent_names, u8 num_parents, struct gpio_desc *gpiod,
 213                 unsigned long flags)
 214 {
 215         if (num_parents != 2) {
 216                 pr_err("mux-clock %s must have 2 parents\n", name);
 217                 return ERR_PTR(-EINVAL);
 218         }
 219
 220         return clk_register_gpio(dev, name, parent_names, num_parents,
 221                         gpiod, flags, &clk_gpio_mux_ops);
 222 }
 223 EXPORT_SYMBOL_GPL(clk_hw_register_gpio_mux);
 224
 225 struct clk *clk_register_gpio_mux(struct device *dev, const char *name,
 226                 const char * const *parent_names, u8 num_parents, struct gpio_desc *gpiod,
 227                 unsigned long flags)
 228 {
 229         struct clk_hw *hw;
 230
 231         hw = clk_hw_register_gpio_mux(dev, name, parent_names, num_parents,
 232                         gpiod, flags);
 233         if (IS_ERR(hw))
 234                 return ERR_CAST(hw);
 235         return hw->clk;
 236 }
 237 EXPORT_SYMBOL_GPL(clk_register_gpio_mux);
 238
 239 static int gpio_clk_driver_probe(struct platform_device *pdev)
 240 {
 241         struct device_node *node = pdev->dev.of_node;
 242         const char **parent_names, *gpio_name;
 243         unsigned int num_parents;
 244         struct gpio_desc *gpiod;
 245         struct clk *clk;
 246         bool is_mux;
 247         int ret;
 248
 249         num_parents = of_clk_get_parent_count(node);
 250         if (num_parents) {
 251                 parent_names = devm_kcalloc(&pdev->dev, num_parents,
 252                                             sizeof(char *), GFP_KERNEL);
 253                 if (!parent_names)
 254                         return -ENOMEM;
 255
 256                 of_clk_parent_fill(node, parent_names, num_parents);
 257         } else {
 258                 parent_names = NULL;
 259         }
 260
 261         is_mux = of_device_is_compatible(node, "gpio-mux-clock");
 262
 263         gpio_name = is_mux ? "select" : "enable";
 264         gpiod = devm_gpiod_get(&pdev->dev, gpio_name, GPIOD_OUT_LOW);
 265         if (IS_ERR(gpiod)) {
 266                 ret = PTR_ERR(gpiod);
 267                 if (ret == -EPROBE_DEFER)
 268                         pr_debug("%pOFn: %s: GPIOs not yet available, retry later\n",
 269                                         node, __func__);
 270                 else
 271                         pr_err("%pOFn: %s: Can't get '%s' named GPIO property\n",
 272                                         node, __func__,
 273                                         gpio_name);
 274                 return ret;
 275         }
 276
 277         if (is_mux)
 278                 clk = clk_register_gpio_mux(&pdev->dev, node->name,
 279                                 parent_names, num_parents, gpiod, 0);
 280         else
 281                 clk = clk_register_gpio_gate(&pdev->dev, node->name,
 282                                 parent_names ?  parent_names[0] : NULL, gpiod,
 283                                 0);
 284         if (IS_ERR(clk))
 285                 return PTR_ERR(clk);
 286
 287         return of_clk_add_provider(node, of_clk_src_simple_get, clk);
 288 }
 289
 290 static const struct of_device_id gpio_clk_match_table[] = {
 291         { .compatible = "gpio-mux-clock" },
 292         { .compatible = "gpio-gate-clock" },
 293         { }
 294 };
 295
 296 static struct platform_driver gpio_clk_driver = {
 297         .probe          = gpio_clk_driver_probe,
 298         .driver         = {
 299                 .name   = "gpio-clk",
 300                 .of_match_table = gpio_clk_match_table,
 301         },
 302 };
 303 builtin_platform_driver(gpio_clk_driver);