In contrast to fixed clocks that are described as ungateable, boards
sometimes use additional oscillators for things like PCIe reference
clocks, that need actual supplies to get enabled and enable-gpios to be
toggled for them to work.
This adds a driver for those generic voltage controlled oscillators,
that can show up in schematics looking like
----------------
Enable - | 100MHz,3.3V, | - VDD
| 3225 |
GND - | | - OUT
----------------
Signed-off-by: Heiko Stuebner <heiko@xxxxxxxxx>
---
drivers/clk/Kconfig | 10 ++++
drivers/clk/Makefile | 1 +
drivers/clk/clk-vco.c | 133 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 144 insertions(+)
create mode 100644 drivers/clk/clk-vco.c
diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index 3e9099504fad4..e93a380b6ee47 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -414,6 +414,16 @@ config COMMON_CLK_VC7
Renesas Versaclock7 is a family of configurable clock generator
and jitter attenuator ICs with fractional and integer dividers.
+config COMMON_CLK_VCO
+ tristate "Clock driver for voltage controlled oscillators"
+ depends on GPIOLIB && REGULATOR
+ help
+ This driver supports generic voltage controlled oscillators that
+ are not configurable but need supplies to be enabled to run.
+ Generally they need a supply voltage to be enabled and may also
+ require a separate enable pin, though in a lot of cases, vdd
+ and enable control might be tied to the same supply.
+
config COMMON_CLK_STM32F
def_bool COMMON_CLK && (MACH_STM32F429 || MACH_STM32F469 || MACH_STM32F746)
help
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index 4abe16c8ccdfe..ca7b7b7ddfd8d 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -79,6 +79,7 @@ obj-$(CONFIG_COMMON_CLK_SI521XX) += clk-si521xx.o
obj-$(CONFIG_COMMON_CLK_VC3) += clk-versaclock3.o
obj-$(CONFIG_COMMON_CLK_VC5) += clk-versaclock5.o
obj-$(CONFIG_COMMON_CLK_VC7) += clk-versaclock7.o
+obj-$(CONFIG_COMMON_CLK_VCO) += clk-vco.o
obj-$(CONFIG_COMMON_CLK_WM831X) += clk-wm831x.o
obj-$(CONFIG_COMMON_CLK_XGENE) += clk-xgene.o
diff --git a/drivers/clk/clk-vco.c b/drivers/clk/clk-vco.c
new file mode 100644
index 0000000000000..f7fe2bc627f36
--- /dev/null
+++ b/drivers/clk/clk-vco.c
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 Heiko Stuebner <heiko@xxxxxxxxx>
+ *
+ * Generic voltage controlled oscillator
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+
+struct clk_vco {
+ struct device *dev;
+ struct clk_hw hw;
+ u32 rate;
+ struct regulator *supply;
+ struct gpio_desc *enable_gpio;
+};
+
+#define to_clk_vco(_hw) container_of(_hw, struct clk_vco, hw)
+
+static int clk_vco_prepare(struct clk_hw *hw)
+{
+ return regulator_enable(to_clk_vco(hw)->supply);
+}
+
+static void clk_vco_unprepare(struct clk_hw *hw)
+{
+ regulator_disable(to_clk_vco(hw)->supply);
+}
+
+static int clk_vco_enable(struct clk_hw *hw)
+{
+ gpiod_set_value(to_clk_vco(hw)->enable_gpio, 1);
+ return 0;
+}
+
+static void clk_vco_disable(struct clk_hw *hw)
+{
+ gpiod_set_value(to_clk_vco(hw)->enable_gpio, 0);
+}
+
+static unsigned long clk_vco_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ return to_clk_vco(hw)->rate;
+}
+
+const struct clk_ops clk_vco_ops = {
+ .prepare = clk_vco_prepare,
+ .unprepare = clk_vco_unprepare,
+ .enable = clk_vco_enable,
+ .disable = clk_vco_disable,
+ .recalc_rate = clk_vco_recalc_rate,
+};
+
+static int clk_vco_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct clk_vco *clkgen;
+ const char *clk_name;
+ int ret;
+
+ clkgen = devm_kzalloc(dev, sizeof(*clkgen), GFP_KERNEL);
+ if (!clkgen)
+ return -ENOMEM;
+
+ clkgen->dev = dev;
+
+ if (device_property_read_u32(dev, "clock-frequency", &clkgen->rate))
+ return dev_err_probe(dev, -EIO, "failed to get clock-frequency");
+
+ ret = device_property_read_string(dev, "clock-output-names", &clk_name);
+ if (ret)
+ clk_name = fwnode_get_name(dev->fwnode);
+
+ clkgen->supply = devm_regulator_get_optional(dev, "vdd");
+ if (IS_ERR(clkgen->supply)) {
+ if (PTR_ERR(clkgen->supply) != -ENODEV)
+ return dev_err_probe(dev, PTR_ERR(clkgen->supply),
+ "failed to get regulator\n");
+ clkgen->supply = NULL;
+ }
+
+ clkgen->enable_gpio = devm_gpiod_get_optional(dev, "enable",
+ GPIOD_OUT_LOW);
+ if (IS_ERR(clkgen->enable_gpio))
+ return dev_err_probe(dev, PTR_ERR(clkgen->enable_gpio),
+ "failed to get gpio\n");
+
+ ret = gpiod_direction_output(clkgen->enable_gpio, 0);
+ if (ret < 0)
+ return dev_err_probe(dev, ret, "failed to set gpio output");
+
+ clkgen->hw.init = CLK_HW_INIT_NO_PARENT(clk_name, &clk_vco_ops, 0);
+
+ /* register the clock */
+ ret = devm_clk_hw_register(dev, &clkgen->hw);
+ if (ret)
+ return dev_err_probe(dev, ret,
+ "failed to register clock\n");
+
+ ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
+ &clkgen->hw);
+ if (ret)
+ return dev_err_probe(dev, ret,
+ "failed to register clock provider\n");
+
+ return 0;
+}
+
+static const struct of_device_id clk_vco_ids[] = {
+ { .compatible = "voltage-oscillator" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, clk_vco_ids);
+
+static struct platform_driver clk_vco_driver = {
+ .driver = {
+ .name = "clk_vco",
+ .of_match_table = clk_vco_ids,
+ },
+ .probe = clk_vco_probe,
+};
+module_platform_driver(clk_vco_driver);
+
+MODULE_AUTHOR("Heiko Stuebner <heiko@xxxxxxxxx>");
+MODULE_DESCRIPTION("Voltage controlled oscillator driver");
+MODULE_LICENSE("GPL");
--
2.39.2
