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.h> 19 #include <linux/gpio/consumer.h> 20 #include <linux/of_gpio.h> 21 #include <linux/err.h> 22 #include <linux/device.h> 23 #include <linux/platform_device.h> 24 #include <linux/of_device.h> 25 26 /** 27 * DOC: basic gpio gated clock which can be enabled and disabled 28 * with gpio output 29 * Traits of this clock: 30 * prepare - clk_(un)prepare only ensures parent is (un)prepared 31 * enable - clk_enable and clk_disable are functional & control gpio 32 * rate - inherits rate from parent. No clk_set_rate support 33 * parent - fixed parent. No clk_set_parent support 34 */ 35 36 static int clk_gpio_gate_enable(struct clk_hw *hw) 37 { 38 struct clk_gpio *clk = to_clk_gpio(hw); 39 40 gpiod_set_value(clk->gpiod, 1); 41 42 return 0; 43 } 44 45 static void clk_gpio_gate_disable(struct clk_hw *hw) 46 { 47 struct clk_gpio *clk = to_clk_gpio(hw); 48 49 gpiod_set_value(clk->gpiod, 0); 50 } 51 52 static int clk_gpio_gate_is_enabled(struct clk_hw *hw) 53 { 54 struct clk_gpio *clk = to_clk_gpio(hw); 55 56 return gpiod_get_value(clk->gpiod); 57 } 58 59 const struct clk_ops clk_gpio_gate_ops = { 60 .enable = clk_gpio_gate_enable, 61 .disable = clk_gpio_gate_disable, 62 .is_enabled = clk_gpio_gate_is_enabled, 63 }; 64 EXPORT_SYMBOL_GPL(clk_gpio_gate_ops); 65 66 /** 67 * DOC: basic clock multiplexer which can be controlled with a gpio output 68 * Traits of this clock: 69 * prepare - clk_prepare only ensures that parents are prepared 70 * rate - rate is only affected by parent switching. No clk_set_rate support 71 * parent - parent is adjustable through clk_set_parent 72 */ 73 74 static u8 clk_gpio_mux_get_parent(struct clk_hw *hw) 75 { 76 struct clk_gpio *clk = to_clk_gpio(hw); 77 78 return gpiod_get_value(clk->gpiod); 79 } 80 81 static int clk_gpio_mux_set_parent(struct clk_hw *hw, u8 index) 82 { 83 struct clk_gpio *clk = to_clk_gpio(hw); 84 85 gpiod_set_value(clk->gpiod, index); 86 87 return 0; 88 } 89 90 const struct clk_ops clk_gpio_mux_ops = { 91 .get_parent = clk_gpio_mux_get_parent, 92 .set_parent = clk_gpio_mux_set_parent, 93 .determine_rate = __clk_mux_determine_rate, 94 }; 95 EXPORT_SYMBOL_GPL(clk_gpio_mux_ops); 96 97 static struct clk *clk_register_gpio(struct device *dev, const char *name, 98 const char * const *parent_names, u8 num_parents, unsigned gpio, 99 bool active_low, unsigned long flags, 100 const struct clk_ops *clk_gpio_ops) 101 { 102 struct clk_gpio *clk_gpio; 103 struct clk *clk; 104 struct clk_init_data init = {}; 105 unsigned long gpio_flags; 106 int err; 107 108 if (dev) 109 clk_gpio = devm_kzalloc(dev, sizeof(*clk_gpio), GFP_KERNEL); 110 else 111 clk_gpio = kzalloc(sizeof(*clk_gpio), GFP_KERNEL); 112 113 if (!clk_gpio) 114 return ERR_PTR(-ENOMEM); 115 116 if (active_low) 117 gpio_flags = GPIOF_ACTIVE_LOW | GPIOF_OUT_INIT_HIGH; 118 else 119 gpio_flags = GPIOF_OUT_INIT_LOW; 120 121 if (dev) 122 err = devm_gpio_request_one(dev, gpio, gpio_flags, name); 123 else 124 err = gpio_request_one(gpio, gpio_flags, name); 125 if (err) { 126 if (err != -EPROBE_DEFER) 127 pr_err("%s: %s: Error requesting clock control gpio %u\n", 128 __func__, name, gpio); 129 if (!dev) 130 kfree(clk_gpio); 131 132 return ERR_PTR(err); 133 } 134 135 init.name = name; 136 init.ops = clk_gpio_ops; 137 init.flags = flags | CLK_IS_BASIC; 138 init.parent_names = parent_names; 139 init.num_parents = num_parents; 140 141 clk_gpio->gpiod = gpio_to_desc(gpio); 142 clk_gpio->hw.init = &init; 143 144 if (dev) 145 clk = devm_clk_register(dev, &clk_gpio->hw); 146 else 147 clk = clk_register(NULL, &clk_gpio->hw); 148 149 if (!IS_ERR(clk)) 150 return clk; 151 152 if (!dev) { 153 gpiod_put(clk_gpio->gpiod); 154 kfree(clk_gpio); 155 } 156 157 return clk; 158 } 159 160 /** 161 * clk_register_gpio_gate - register a gpio clock gate with the clock framework 162 * @dev: device that is registering this clock 163 * @name: name of this clock 164 * @parent_name: name of this clock's parent 165 * @gpio: gpio number to gate this clock 166 * @active_low: true if gpio should be set to 0 to enable clock 167 * @flags: clock flags 168 */ 169 struct clk *clk_register_gpio_gate(struct device *dev, const char *name, 170 const char *parent_name, unsigned gpio, bool active_low, 171 unsigned long flags) 172 { 173 return clk_register_gpio(dev, name, 174 (parent_name ? &parent_name : NULL), 175 (parent_name ? 1 : 0), gpio, active_low, flags, 176 &clk_gpio_gate_ops); 177 } 178 EXPORT_SYMBOL_GPL(clk_register_gpio_gate); 179 180 /** 181 * clk_register_gpio_mux - register a gpio clock mux with the clock framework 182 * @dev: device that is registering this clock 183 * @name: name of this clock 184 * @parent_names: names of this clock's parents 185 * @num_parents: number of parents listed in @parent_names 186 * @gpio: gpio number to gate this clock 187 * @active_low: true if gpio should be set to 0 to enable clock 188 * @flags: clock flags 189 */ 190 struct clk *clk_register_gpio_mux(struct device *dev, const char *name, 191 const char * const *parent_names, u8 num_parents, unsigned gpio, 192 bool active_low, unsigned long flags) 193 { 194 if (num_parents != 2) { 195 pr_err("mux-clock %s must have 2 parents\n", name); 196 return ERR_PTR(-EINVAL); 197 } 198 199 return clk_register_gpio(dev, name, parent_names, num_parents, 200 gpio, active_low, flags, &clk_gpio_mux_ops); 201 } 202 EXPORT_SYMBOL_GPL(clk_register_gpio_mux); 203 204 static int gpio_clk_driver_probe(struct platform_device *pdev) 205 { 206 struct device_node *node = pdev->dev.of_node; 207 const char **parent_names, *gpio_name; 208 unsigned int num_parents; 209 int gpio; 210 enum of_gpio_flags of_flags; 211 struct clk *clk; 212 bool active_low, is_mux; 213 214 num_parents = of_clk_get_parent_count(node); 215 if (num_parents) { 216 parent_names = devm_kcalloc(&pdev->dev, num_parents, 217 sizeof(char *), GFP_KERNEL); 218 if (!parent_names) 219 return -ENOMEM; 220 221 of_clk_parent_fill(node, parent_names, num_parents); 222 } else { 223 parent_names = NULL; 224 } 225 226 is_mux = of_device_is_compatible(node, "gpio-mux-clock"); 227 228 gpio_name = is_mux ? "select-gpios" : "enable-gpios"; 229 gpio = of_get_named_gpio_flags(node, gpio_name, 0, &of_flags); 230 if (gpio < 0) { 231 if (gpio == -EPROBE_DEFER) 232 pr_debug("%s: %s: GPIOs not yet available, retry later\n", 233 node->name, __func__); 234 else 235 pr_err("%s: %s: Can't get '%s' DT property\n", 236 node->name, __func__, 237 gpio_name); 238 return gpio; 239 } 240 241 active_low = of_flags & OF_GPIO_ACTIVE_LOW; 242 243 if (is_mux) 244 clk = clk_register_gpio_mux(&pdev->dev, node->name, 245 parent_names, num_parents, gpio, active_low, 0); 246 else 247 clk = clk_register_gpio_gate(&pdev->dev, node->name, 248 parent_names ? parent_names[0] : NULL, gpio, 249 active_low, 0); 250 if (IS_ERR(clk)) 251 return PTR_ERR(clk); 252 253 return of_clk_add_provider(node, of_clk_src_simple_get, clk); 254 } 255 256 static const struct of_device_id gpio_clk_match_table[] = { 257 { .compatible = "gpio-mux-clock" }, 258 { .compatible = "gpio-gate-clock" }, 259 { } 260 }; 261 262 static struct platform_driver gpio_clk_driver = { 263 .probe = gpio_clk_driver_probe, 264 .driver = { 265 .name = "gpio-clk", 266 .of_match_table = gpio_clk_match_table, 267 }, 268 }; 269 builtin_platform_driver(gpio_clk_driver); 270