The added ti,gpio-gate-clock is a basic clock that can be enabled and disabled trough a gpio output. The DT binding document for the clock is also added. For EPROBE_DEFER handling the registering of the clock has to be delayed until of_clk_get() call time.
Signed-off-by: Jyri Sarha jsarha@ti.com --- .../bindings/clock/ti/gpio-gate-clock.txt | 21 ++ drivers/clk/ti/Makefile | 2 +- drivers/clk/ti/gpio.c | 202 ++++++++++++++++++++ 3 files changed, 224 insertions(+), 1 deletion(-) create mode 100644 Documentation/devicetree/bindings/clock/ti/gpio-gate-clock.txt create mode 100644 drivers/clk/ti/gpio.c
diff --git a/Documentation/devicetree/bindings/clock/ti/gpio-gate-clock.txt b/Documentation/devicetree/bindings/clock/ti/gpio-gate-clock.txt new file mode 100644 index 0000000..6156f82 --- /dev/null +++ b/Documentation/devicetree/bindings/clock/ti/gpio-gate-clock.txt @@ -0,0 +1,21 @@ +Binding for simple gpio controlled clock. + +This binding uses the common clock binding[1]. + +[1] Documentation/devicetree/bindings/clock/clock-bindings.txt + +Required properties: +- compatible : shall be "ti,gpio-gate-clock". +- #clock-cells : from common clock binding; shall be set to 0. +- enable-gpios : GPIO reference for enabling and disabling the clock. + +Optional properties: +- clocks: Maximum of one parent clock is supported. + +Example: + clock { + compatible = "ti,gpio-gate-clock"; + clocks = <&parentclk>; + #clock-cells = <0>; + enable-gpios = <&gpio 1 GPIO_ACTIVE_HIGH>; + }; diff --git a/drivers/clk/ti/Makefile b/drivers/clk/ti/Makefile index ed4d0aa..88074d3 100644 --- a/drivers/clk/ti/Makefile +++ b/drivers/clk/ti/Makefile @@ -1,7 +1,7 @@ ifneq ($(CONFIG_OF),) obj-y += clk.o autoidle.o clockdomain.o clk-common = dpll.o composite.o divider.o gate.o \ - fixed-factor.o mux.o apll.o + fixed-factor.o mux.o apll.o gpio.o obj-$(CONFIG_SOC_AM33XX) += $(clk-common) clk-33xx.o obj-$(CONFIG_ARCH_OMAP2) += $(clk-common) interface.o clk-2xxx.o obj-$(CONFIG_ARCH_OMAP3) += $(clk-common) interface.o clk-3xxx.o diff --git a/drivers/clk/ti/gpio.c b/drivers/clk/ti/gpio.c new file mode 100644 index 0000000..b973801 --- /dev/null +++ b/drivers/clk/ti/gpio.c @@ -0,0 +1,202 @@ +/* + * Copyright (C) 2012 - 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 controlled clock implementation + */ + +#include <linux/clk-provider.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/gpio.h> +#include <linux/of_gpio.h> +#include <linux/err.h> +#include <linux/device.h> + +struct clk_gpio { + struct clk_hw hw; + struct gpio_desc *gpiod; +}; + +/** + * DOC: basic gpio controlled 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_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_disable(struct clk_hw *hw) +{ + struct clk_gpio *clk = to_clk_gpio(hw); + + gpiod_set_value(clk->gpiod, 0); +} + +static int clk_gpio_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_ops = { + .enable = clk_gpio_enable, + .disable = clk_gpio_disable, + .is_enabled = clk_gpio_is_enabled, +}; + +/** + * 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 + * @gpiod: gpio descriptor to control this clock + */ +static struct clk *clk_register_gpio(struct device *dev, const char *name, + const char *parent_name, struct gpio_desc *gpiod, + 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 (gpiod_is_active_low(gpiod)) + gpio_flags = GPIOF_OUT_INIT_HIGH; + else + gpio_flags = GPIOF_OUT_INIT_LOW; + + if (dev) + err = devm_gpio_request_one(dev, desc_to_gpio(gpiod), + gpio_flags, name); + else + err = gpio_request_one(desc_to_gpio(gpiod), gpio_flags, name); + + if (err) { + pr_err("%s: %s: Error requesting clock control gpio %u\n", + __func__, name, desc_to_gpio(gpiod)); + 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) + goto clk_register_gpio_err; + + init.name = name; + init.ops = &clk_gpio_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 = gpiod; + 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_err: + gpiod_put(gpiod); + + return clk; +} + +/** + * The clk_register_gpio has to be delayed, because the EPROBE_DEFER + * can not be handled properly at of_clk_init() call time. + */ + +struct clk_gpio_delayed_register_data { + struct device_node *node; + struct mutex lock; + struct clk *clk; +}; + +static +struct clk *of_clk_gpio_delayed_register_get(struct of_phandle_args *clkspec, + void *_data) +{ + struct clk_gpio_delayed_register_data *data = _data; + struct clk *clk; + const char *clk_name = data->node->name; + const char *parent_name; + struct gpio_desc *gpiod; + int gpio; + + 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, NULL); + 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); + } + gpiod = gpio_to_desc(gpio); + + parent_name = of_clk_get_parent_name(data->node, 0); + + clk = clk_register_gpio(NULL, clk_name, parent_name, gpiod, 0); + if (IS_ERR(clk)) { + mutex_unlock(&data->lock); + return clk; + } + + data->clk = clk; + mutex_unlock(&data->lock); + + return clk; +} + +/** + * of_gpio_clk_setup() - Setup function for gpio controlled clock + */ +static void __init of_gpio_clk_setup(struct device_node *node) +{ + struct clk_gpio_delayed_register_data *data; + + data = kzalloc(sizeof(struct clk_gpio_delayed_register_data), + GFP_KERNEL); + if (!data) + return; + + data->node = node; + mutex_init(&data->lock); + + of_clk_add_provider(node, of_clk_gpio_delayed_register_get, data); +} +CLK_OF_DECLARE(gpio_clk, "ti,gpio-gate-clock", of_gpio_clk_setup);