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_cansleep(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_cansleep(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 init.name = name; 113 init.ops = clk_gpio_ops; 114 init.flags = flags | CLK_IS_BASIC; 115 init.parent_names = parent_names; 116 init.num_parents = num_parents; 117 118 clk_gpio->gpiod = gpiod; 119 clk_gpio->hw.init = &init; 120 121 hw = &clk_gpio->hw; 122 if (dev) 123 err = devm_clk_hw_register(dev, hw); 124 else 125 err = clk_hw_register(NULL, hw); 126 127 if (!err) 128 return hw; 129 130 if (!dev) { 131 kfree(clk_gpio); 132 } 133 134 return ERR_PTR(err); 135 } 136 137 /** 138 * clk_hw_register_gpio_gate - register a gpio clock gate with the clock 139 * framework 140 * @dev: device that is registering this clock 141 * @name: name of this clock 142 * @parent_name: name of this clock's parent 143 * @gpiod: gpio descriptor to gate this clock 144 * @flags: clock flags 145 */ 146 struct clk_hw *clk_hw_register_gpio_gate(struct device *dev, const char *name, 147 const char *parent_name, struct gpio_desc *gpiod, 148 unsigned long flags) 149 { 150 return clk_register_gpio(dev, name, 151 (parent_name ? &parent_name : NULL), 152 (parent_name ? 1 : 0), gpiod, flags, 153 &clk_gpio_gate_ops); 154 } 155 EXPORT_SYMBOL_GPL(clk_hw_register_gpio_gate); 156 157 struct clk *clk_register_gpio_gate(struct device *dev, const char *name, 158 const char *parent_name, struct gpio_desc *gpiod, 159 unsigned long flags) 160 { 161 struct clk_hw *hw; 162 163 hw = clk_hw_register_gpio_gate(dev, name, parent_name, gpiod, flags); 164 if (IS_ERR(hw)) 165 return ERR_CAST(hw); 166 return hw->clk; 167 } 168 EXPORT_SYMBOL_GPL(clk_register_gpio_gate); 169 170 /** 171 * clk_hw_register_gpio_mux - register a gpio clock mux with the clock framework 172 * @dev: device that is registering this clock 173 * @name: name of this clock 174 * @parent_names: names of this clock's parents 175 * @num_parents: number of parents listed in @parent_names 176 * @gpiod: gpio descriptor to gate this clock 177 * @flags: clock flags 178 */ 179 struct clk_hw *clk_hw_register_gpio_mux(struct device *dev, const char *name, 180 const char * const *parent_names, u8 num_parents, struct gpio_desc *gpiod, 181 unsigned long flags) 182 { 183 if (num_parents != 2) { 184 pr_err("mux-clock %s must have 2 parents\n", name); 185 return ERR_PTR(-EINVAL); 186 } 187 188 return clk_register_gpio(dev, name, parent_names, num_parents, 189 gpiod, flags, &clk_gpio_mux_ops); 190 } 191 EXPORT_SYMBOL_GPL(clk_hw_register_gpio_mux); 192 193 struct clk *clk_register_gpio_mux(struct device *dev, const char *name, 194 const char * const *parent_names, u8 num_parents, struct gpio_desc *gpiod, 195 unsigned long flags) 196 { 197 struct clk_hw *hw; 198 199 hw = clk_hw_register_gpio_mux(dev, name, parent_names, num_parents, 200 gpiod, flags); 201 if (IS_ERR(hw)) 202 return ERR_CAST(hw); 203 return hw->clk; 204 } 205 EXPORT_SYMBOL_GPL(clk_register_gpio_mux); 206 207 static int gpio_clk_driver_probe(struct platform_device *pdev) 208 { 209 struct device_node *node = pdev->dev.of_node; 210 const char **parent_names, *gpio_name; 211 unsigned int num_parents; 212 struct gpio_desc *gpiod; 213 struct clk *clk; 214 bool is_mux; 215 int ret; 216 217 num_parents = of_clk_get_parent_count(node); 218 if (num_parents) { 219 parent_names = devm_kcalloc(&pdev->dev, num_parents, 220 sizeof(char *), GFP_KERNEL); 221 if (!parent_names) 222 return -ENOMEM; 223 224 of_clk_parent_fill(node, parent_names, num_parents); 225 } else { 226 parent_names = NULL; 227 } 228 229 is_mux = of_device_is_compatible(node, "gpio-mux-clock"); 230 231 gpio_name = is_mux ? "select" : "enable"; 232 gpiod = devm_gpiod_get(&pdev->dev, gpio_name, GPIOD_OUT_LOW); 233 if (IS_ERR(gpiod)) { 234 ret = PTR_ERR(gpiod); 235 if (ret == -EPROBE_DEFER) 236 pr_debug("%s: %s: GPIOs not yet available, retry later\n", 237 node->name, __func__); 238 else 239 pr_err("%s: %s: Can't get '%s' named GPIO property\n", 240 node->name, __func__, 241 gpio_name); 242 return ret; 243 } 244 245 if (is_mux) 246 clk = clk_register_gpio_mux(&pdev->dev, node->name, 247 parent_names, num_parents, gpiod, 0); 248 else 249 clk = clk_register_gpio_gate(&pdev->dev, node->name, 250 parent_names ? parent_names[0] : NULL, gpiod, 251 0); 252 if (IS_ERR(clk)) 253 return PTR_ERR(clk); 254 255 return of_clk_add_provider(node, of_clk_src_simple_get, clk); 256 } 257 258 static const struct of_device_id gpio_clk_match_table[] = { 259 { .compatible = "gpio-mux-clock" }, 260 { .compatible = "gpio-gate-clock" }, 261 { } 262 }; 263 264 static struct platform_driver gpio_clk_driver = { 265 .probe = gpio_clk_driver_probe, 266 .driver = { 267 .name = "gpio-clk", 268 .of_match_table = gpio_clk_match_table, 269 }, 270 }; 271 builtin_platform_driver(gpio_clk_driver); 272