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/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 /** 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); 250