drivers/clk/clk-gpio.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2013 - 2014 Texas Instruments Incorporated - https://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/of.h>
  19 #include <linux/platform_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 /**
  32  * struct clk_gpio - gpio gated clock
  33  *
  34  * @hw:         handle between common and hardware-specific interfaces
  35  * @gpiod:      gpio descriptor
  36  *
  37  * Clock with a gpio control for enabling and disabling the parent clock
  38  * or switching between two parents by asserting or deasserting the gpio.
  39  *
  40  * Implements .enable, .disable and .is_enabled or
  41  * .get_parent, .set_parent and .determine_rate depending on which clk_ops
  42  * is used.
  43  */
  44 struct clk_gpio {
  45         struct clk_hw   hw;
  46         struct gpio_desc *gpiod;
  47 };
  48
  49 #define to_clk_gpio(_hw) container_of(_hw, struct clk_gpio, hw)
  50
  51 static int clk_gpio_gate_enable(struct clk_hw *hw)
  52 {
  53         struct clk_gpio *clk = to_clk_gpio(hw);
  54
  55         gpiod_set_value(clk->gpiod, 1);
  56
  57         return 0;
  58 }
  59
  60 static void clk_gpio_gate_disable(struct clk_hw *hw)
  61 {
  62         struct clk_gpio *clk = to_clk_gpio(hw);
  63
  64         gpiod_set_value(clk->gpiod, 0);
  65 }
  66
  67 static int clk_gpio_gate_is_enabled(struct clk_hw *hw)
  68 {
  69         struct clk_gpio *clk = to_clk_gpio(hw);
  70
  71         return gpiod_get_value(clk->gpiod);
  72 }
  73
  74 static const struct clk_ops clk_gpio_gate_ops = {
  75         .enable = clk_gpio_gate_enable,
  76         .disable = clk_gpio_gate_disable,
  77         .is_enabled = clk_gpio_gate_is_enabled,
  78 };
  79
  80 static int clk_sleeping_gpio_gate_prepare(struct clk_hw *hw)
  81 {
  82         struct clk_gpio *clk = to_clk_gpio(hw);
  83
  84         gpiod_set_value_cansleep(clk->gpiod, 1);
  85
  86         return 0;
  87 }
  88
  89 static void clk_sleeping_gpio_gate_unprepare(struct clk_hw *hw)
  90 {
  91         struct clk_gpio *clk = to_clk_gpio(hw);
  92
  93         gpiod_set_value_cansleep(clk->gpiod, 0);
  94 }
  95
  96 static int clk_sleeping_gpio_gate_is_prepared(struct clk_hw *hw)
  97 {
  98         struct clk_gpio *clk = to_clk_gpio(hw);
  99
 100         return gpiod_get_value_cansleep(clk->gpiod);
 101 }
 102
 103 static const struct clk_ops clk_sleeping_gpio_gate_ops = {
 104         .prepare = clk_sleeping_gpio_gate_prepare,
 105         .unprepare = clk_sleeping_gpio_gate_unprepare,
 106         .is_prepared = clk_sleeping_gpio_gate_is_prepared,
 107 };
 108
 109 /**
 110  * DOC: basic clock multiplexer which can be controlled with a gpio output
 111  * Traits of this clock:
 112  * prepare - clk_prepare only ensures that parents are prepared
 113  * rate - rate is only affected by parent switching.  No clk_set_rate support
 114  * parent - parent is adjustable through clk_set_parent
 115  */
 116
 117 static u8 clk_gpio_mux_get_parent(struct clk_hw *hw)
 118 {
 119         struct clk_gpio *clk = to_clk_gpio(hw);
 120
 121         return gpiod_get_value_cansleep(clk->gpiod);
 122 }
 123
 124 static int clk_gpio_mux_set_parent(struct clk_hw *hw, u8 index)
 125 {
 126         struct clk_gpio *clk = to_clk_gpio(hw);
 127
 128         gpiod_set_value_cansleep(clk->gpiod, index);
 129
 130         return 0;
 131 }
 132
 133 static const struct clk_ops clk_gpio_mux_ops = {
 134         .get_parent = clk_gpio_mux_get_parent,
 135         .set_parent = clk_gpio_mux_set_parent,
 136         .determine_rate = __clk_mux_determine_rate,
 137 };
 138
 139 static struct clk_hw *clk_register_gpio(struct device *dev, u8 num_parents,
 140                                         struct gpio_desc *gpiod,
 141                                         const struct clk_ops *clk_gpio_ops)
 142 {
 143         struct clk_gpio *clk_gpio;
 144         struct clk_hw *hw;
 145         struct clk_init_data init = {};
 146         int err;
 147         const struct clk_parent_data gpio_parent_data[] = {
 148                 { .index = 0 },
 149                 { .index = 1 },
 150         };
 151
 152         clk_gpio = devm_kzalloc(dev, sizeof(*clk_gpio), GFP_KERNEL);
 153         if (!clk_gpio)
 154                 return ERR_PTR(-ENOMEM);
 155
 156         init.name = dev->of_node->name;
 157         init.ops = clk_gpio_ops;
 158         init.parent_data = gpio_parent_data;
 159         init.num_parents = num_parents;
 160         init.flags = CLK_SET_RATE_PARENT;
 161
 162         clk_gpio->gpiod = gpiod;
 163         clk_gpio->hw.init = &init;
 164
 165         hw = &clk_gpio->hw;
 166         err = devm_clk_hw_register(dev, hw);
 167         if (err)
 168                 return ERR_PTR(err);
 169
 170         return hw;
 171 }
 172
 173 static struct clk_hw *clk_hw_register_gpio_gate(struct device *dev,
 174                                                 int num_parents,
 175                                                 struct gpio_desc *gpiod)
 176 {
 177         const struct clk_ops *ops;
 178
 179         if (gpiod_cansleep(gpiod))
 180                 ops = &clk_sleeping_gpio_gate_ops;
 181         else
 182                 ops = &clk_gpio_gate_ops;
 183
 184         return clk_register_gpio(dev, num_parents, gpiod, ops);
 185 }
 186
 187 static struct clk_hw *clk_hw_register_gpio_mux(struct device *dev,
 188                                                struct gpio_desc *gpiod)
 189 {
 190         return clk_register_gpio(dev, 2, gpiod, &clk_gpio_mux_ops);
 191 }
 192
 193 static int gpio_clk_driver_probe(struct platform_device *pdev)
 194 {
 195         struct device *dev = &pdev->dev;
 196         struct device_node *node = dev->of_node;
 197         const char *gpio_name;
 198         unsigned int num_parents;
 199         struct gpio_desc *gpiod;
 200         struct clk_hw *hw;
 201         bool is_mux;
 202         int ret;
 203
 204         is_mux = of_device_is_compatible(node, "gpio-mux-clock");
 205
 206         num_parents = of_clk_get_parent_count(node);
 207         if (is_mux && num_parents != 2) {
 208                 dev_err(dev, "mux-clock must have 2 parents\n");
 209                 return -EINVAL;
 210         }
 211
 212         gpio_name = is_mux ? "select" : "enable";
 213         gpiod = devm_gpiod_get(dev, gpio_name, GPIOD_OUT_LOW);
 214         if (IS_ERR(gpiod)) {
 215                 ret = PTR_ERR(gpiod);
 216                 if (ret == -EPROBE_DEFER)
 217                         pr_debug("%pOFn: %s: GPIOs not yet available, retry later\n",
 218                                         node, __func__);
 219                 else
 220                         pr_err("%pOFn: %s: Can't get '%s' named GPIO property\n",
 221                                         node, __func__,
 222                                         gpio_name);
 223                 return ret;
 224         }
 225
 226         if (is_mux)
 227                 hw = clk_hw_register_gpio_mux(dev, gpiod);
 228         else
 229                 hw = clk_hw_register_gpio_gate(dev, num_parents, gpiod);
 230         if (IS_ERR(hw))
 231                 return PTR_ERR(hw);
 232
 233         return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, hw);
 234 }
 235
 236 static const struct of_device_id gpio_clk_match_table[] = {
 237         { .compatible = "gpio-mux-clock" },
 238         { .compatible = "gpio-gate-clock" },
 239         { }
 240 };
 241
 242 static struct platform_driver gpio_clk_driver = {
 243         .probe          = gpio_clk_driver_probe,
 244         .driver         = {
 245                 .name   = "gpio-clk",
 246                 .of_match_table = gpio_clk_match_table,
 247         },
 248 };
 249 builtin_platform_driver(gpio_clk_driver);