summaryrefslogtreecommitdiffstats
path: root/drivers/clk/clk-gpio.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/clk/clk-gpio.c')
-rw-r--r--drivers/clk/clk-gpio.c249
1 files changed, 249 insertions, 0 deletions
diff --git a/drivers/clk/clk-gpio.c b/drivers/clk/clk-gpio.c
new file mode 100644
index 000000000..38755a241
--- /dev/null
+++ b/drivers/clk/clk-gpio.c
@@ -0,0 +1,249 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2013 - 2014 Texas Instruments Incorporated - https://www.ti.com
+ *
+ * Authors:
+ * Jyri Sarha <jsarha@ti.com>
+ * Sergej Sawazki <ce3a@gmx.de>
+ *
+ * Gpio controlled clock implementation
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/gpio/consumer.h>
+#include <linux/err.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/of_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
+ */
+
+/**
+ * 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);