// SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2013 - 2014 Texas Instruments Incorporated - https://www.ti.com * * Authors: * Jyri Sarha * Sergej Sawazki * * Gpio controlled clock implementation */ #include #include #include #include #include #include #include #include /** * DOC: basic gpio gated clock which can be enabled and disabled * with gpio output * Traits of this clock: * prepare - clk_(un)prepare only ensures parent is (un)prepared * enable - clk_enable and clk_disable are functional & control gpio * rate - inherits rate from parent. No clk_set_rate support * parent - fixed parent. No clk_set_parent support */ /** * struct clk_gpio - gpio gated clock * * @hw: handle between common and hardware-specific interfaces * @gpiod: gpio descriptor * * Clock with a gpio control for enabling and disabling the parent clock * or switching between two parents by asserting or deasserting the gpio. * * Implements .enable, .disable and .is_enabled or * .get_parent, .set_parent and .determine_rate depending on which clk_ops * is used. */ struct clk_gpio { struct clk_hw hw; struct gpio_desc *gpiod; }; #define to_clk_gpio(_hw) container_of(_hw, struct clk_gpio, hw) static int clk_gpio_gate_enable(struct clk_hw *hw) { struct clk_gpio *clk = to_clk_gpio(hw); gpiod_set_value(clk->gpiod, 1); return 0; } static void clk_gpio_gate_disable(struct clk_hw *hw) { struct clk_gpio *clk = to_clk_gpio(hw); gpiod_set_value(clk->gpiod, 0); } static int clk_gpio_gate_is_enabled(struct clk_hw *hw) { struct clk_gpio *clk = to_clk_gpio(hw); return gpiod_get_value(clk->gpiod); } static const struct clk_ops clk_gpio_gate_ops = { .enable = clk_gpio_gate_enable, .disable = clk_gpio_gate_disable, .is_enabled = clk_gpio_gate_is_enabled, }; static int clk_sleeping_gpio_gate_prepare(struct clk_hw *hw) { struct clk_gpio *clk = to_clk_gpio(hw); gpiod_set_value_cansleep(clk->gpiod, 1); return 0; } static void clk_sleeping_gpio_gate_unprepare(struct clk_hw *hw) { struct clk_gpio *clk = to_clk_gpio(hw); gpiod_set_value_cansleep(clk->gpiod, 0); } static int clk_sleeping_gpio_gate_is_prepared(struct clk_hw *hw) { struct clk_gpio *clk = to_clk_gpio(hw); return gpiod_get_value_cansleep(clk->gpiod); } static const struct clk_ops clk_sleeping_gpio_gate_ops = { .prepare = clk_sleeping_gpio_gate_prepare, .unprepare = clk_sleeping_gpio_gate_unprepare, .is_prepared = clk_sleeping_gpio_gate_is_prepared, }; /** * DOC: basic clock multiplexer which can be controlled with a gpio output * Traits of this clock: * prepare - clk_prepare only ensures that parents are prepared * rate - rate is only affected by parent switching. No clk_set_rate support * parent - parent is adjustable through clk_set_parent */ static u8 clk_gpio_mux_get_parent(struct clk_hw *hw) { struct clk_gpio *clk = to_clk_gpio(hw); return gpiod_get_value_cansleep(clk->gpiod); } static int clk_gpio_mux_set_parent(struct clk_hw *hw, u8 index) { struct clk_gpio *clk = to_clk_gpio(hw); gpiod_set_value_cansleep(clk->gpiod, index); return 0; } static const struct clk_ops clk_gpio_mux_ops = { .get_parent = clk_gpio_mux_get_parent, .set_parent = clk_gpio_mux_set_parent, .determine_rate = __clk_mux_determine_rate, }; static struct clk_hw *clk_register_gpio(struct device *dev, u8 num_parents, struct gpio_desc *gpiod, const struct clk_ops *clk_gpio_ops) { struct clk_gpio *clk_gpio; struct clk_hw *hw; struct clk_init_data init = {}; int err; const struct clk_parent_data gpio_parent_data[] = { { .index = 0 }, { .index = 1 }, }; clk_gpio = devm_kzalloc(dev, sizeof(*clk_gpio), GFP_KERNEL); if (!clk_gpio) return ERR_PTR(-ENOMEM); init.name = dev->of_node->name; init.ops = clk_gpio_ops; init.parent_data = gpio_parent_data; init.num_parents = num_parents; init.flags = CLK_SET_RATE_PARENT; clk_gpio->gpiod = gpiod; clk_gpio->hw.init = &init; hw = &clk_gpio->hw; err = devm_clk_hw_register(dev, hw); if (err) return ERR_PTR(err); return hw; } static struct clk_hw *clk_hw_register_gpio_gate(struct device *dev, int num_parents, struct gpio_desc *gpiod) { const struct clk_ops *ops; if (gpiod_cansleep(gpiod)) ops = &clk_sleeping_gpio_gate_ops; else ops = &clk_gpio_gate_ops; return clk_register_gpio(dev, num_parents, gpiod, ops); } static struct clk_hw *clk_hw_register_gpio_mux(struct device *dev, struct gpio_desc *gpiod) { return clk_register_gpio(dev, 2, gpiod, &clk_gpio_mux_ops); } static int gpio_clk_driver_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; struct device_node *node = dev->of_node; const char *gpio_name; unsigned int num_parents; struct gpio_desc *gpiod; struct clk_hw *hw; bool is_mux; int ret; is_mux = of_device_is_compatible(node, "gpio-mux-clock"); num_parents = of_clk_get_parent_count(node); if (is_mux && num_parents != 2) { dev_err(dev, "mux-clock must have 2 parents\n"); return -EINVAL; } gpio_name = is_mux ? "select" : "enable"; gpiod = devm_gpiod_get(dev, gpio_name, GPIOD_OUT_LOW); if (IS_ERR(gpiod)) { ret = PTR_ERR(gpiod); if (ret == -EPROBE_DEFER) pr_debug("%pOFn: %s: GPIOs not yet available, retry later\n", node, __func__); else pr_err("%pOFn: %s: Can't get '%s' named GPIO property\n", node, __func__, gpio_name); return ret; } if (is_mux) hw = clk_hw_register_gpio_mux(dev, gpiod); else hw = clk_hw_register_gpio_gate(dev, num_parents, gpiod); if (IS_ERR(hw)) return PTR_ERR(hw); return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, hw); } static const struct of_device_id gpio_clk_match_table[] = { { .compatible = "gpio-mux-clock" }, { .compatible = "gpio-gate-clock" }, { } }; static struct platform_driver gpio_clk_driver = { .probe = gpio_clk_driver_probe, .driver = { .name = "gpio-clk", .of_match_table = gpio_clk_match_table, }, }; builtin_platform_driver(gpio_clk_driver);