diff options
Diffstat (limited to 'drivers/clk/clk-gpio-gate.c')
| -rw-r--r-- | drivers/clk/clk-gpio-gate.c | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/drivers/clk/clk-gpio-gate.c b/drivers/clk/clk-gpio-gate.c new file mode 100644 index 000000000..a71cabedd --- /dev/null +++ b/drivers/clk/clk-gpio-gate.c @@ -0,0 +1,208 @@ +/* + * Copyright (C) 2013 - 2014 Texas Instruments Incorporated - http://www.ti.com + * Author: Jyri Sarha <jsarha@ti.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * Gpio gated clock implementation + */ + +#include <linux/clk-provider.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/gpio.h> +#include <linux/gpio/consumer.h> +#include <linux/of_gpio.h> +#include <linux/err.h> +#include <linux/device.h> + +/** + * 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 + */ + +#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); +} + +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, +}; +EXPORT_SYMBOL_GPL(clk_gpio_gate_ops); + +/** + * clk_register_gpio - register a gpip clock with the clock framework + * @dev: device that is registering this clock + * @name: name of this clock + * @parent_name: name of this clock's parent + * @gpio: gpio number to gate this clock + * @active_low: true if gpio should be set to 0 to enable clock + * @flags: clock flags + */ +struct clk *clk_register_gpio_gate(struct device *dev, const char *name, + const char *parent_name, unsigned gpio, bool active_low, + unsigned long flags) +{ + struct clk_gpio *clk_gpio = NULL; + struct clk *clk = ERR_PTR(-EINVAL); + struct clk_init_data init = { NULL }; + unsigned long gpio_flags; + int err; + + if (active_low) + gpio_flags = GPIOF_ACTIVE_LOW | GPIOF_OUT_INIT_HIGH; + else + gpio_flags = GPIOF_OUT_INIT_LOW; + + if (dev) + err = devm_gpio_request_one(dev, gpio, gpio_flags, name); + else + err = gpio_request_one(gpio, gpio_flags, name); + + if (err) { + pr_err("%s: %s: Error requesting clock control gpio %u\n", + __func__, name, gpio); + return ERR_PTR(err); + } + + if (dev) + clk_gpio = devm_kzalloc(dev, sizeof(struct clk_gpio), + GFP_KERNEL); + else + clk_gpio = kzalloc(sizeof(struct clk_gpio), GFP_KERNEL); + + if (!clk_gpio) { + clk = ERR_PTR(-ENOMEM); + goto clk_register_gpio_gate_err; + } + + init.name = name; + init.ops = &clk_gpio_gate_ops; + init.flags = flags | CLK_IS_BASIC; + init.parent_names = (parent_name ? &parent_name : NULL); + init.num_parents = (parent_name ? 1 : 0); + + clk_gpio->gpiod = gpio_to_desc(gpio); + clk_gpio->hw.init = &init; + + clk = clk_register(dev, &clk_gpio->hw); + + if (!IS_ERR(clk)) + return clk; + + if (!dev) + kfree(clk_gpio); + +clk_register_gpio_gate_err: + if (!dev) + gpio_free(gpio); + + return clk; +} +EXPORT_SYMBOL_GPL(clk_register_gpio_gate); + +#ifdef CONFIG_OF +/** + * The clk_register_gpio_gate has to be delayed, because the EPROBE_DEFER + * can not be handled properly at of_clk_init() call time. + */ + +struct clk_gpio_gate_delayed_register_data { + struct device_node *node; + struct mutex lock; + struct clk *clk; +}; + +static struct clk *of_clk_gpio_gate_delayed_register_get( + struct of_phandle_args *clkspec, + void *_data) +{ + struct clk_gpio_gate_delayed_register_data *data = _data; + struct clk *clk; + const char *clk_name = data->node->name; + const char *parent_name; + int gpio; + enum of_gpio_flags of_flags; + + mutex_lock(&data->lock); + + if (data->clk) { + mutex_unlock(&data->lock); + return data->clk; + } + + gpio = of_get_named_gpio_flags(data->node, "enable-gpios", 0, + &of_flags); + if (gpio < 0) { + mutex_unlock(&data->lock); + if (gpio != -EPROBE_DEFER) + pr_err("%s: %s: Can't get 'enable-gpios' DT property\n", + __func__, clk_name); + return ERR_PTR(gpio); + } + + parent_name = of_clk_get_parent_name(data->node, 0); + + clk = clk_register_gpio_gate(NULL, clk_name, parent_name, gpio, + of_flags & OF_GPIO_ACTIVE_LOW, 0); + if (IS_ERR(clk)) { + mutex_unlock(&data->lock); + return clk; + } + + data->clk = clk; + mutex_unlock(&data->lock); + + return clk; +} + +/** + * of_gpio_gate_clk_setup() - Setup function for gpio controlled clock + */ +void __init of_gpio_gate_clk_setup(struct device_node *node) +{ + struct clk_gpio_gate_delayed_register_data *data; + + data = kzalloc(sizeof(struct clk_gpio_gate_delayed_register_data), + GFP_KERNEL); + if (!data) + return; + + data->node = node; + mutex_init(&data->lock); + + of_clk_add_provider(node, of_clk_gpio_gate_delayed_register_get, data); +} +EXPORT_SYMBOL_GPL(of_gpio_gate_clk_setup); +CLK_OF_DECLARE(gpio_gate_clk, "gpio-gate-clock", of_gpio_gate_clk_setup); +#endif |