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 gated-fixed-clocks
that can show up in schematics looking like
----------------
Enable - | 100MHz,3.3V, | - VDD
| 3225 |
GND - | | - OUT
----------------
The new driver gets grouped together with the existing gpio-gate and
gpio-mux, as it for one re-uses a lot of the gpio-gate functions
and also in it's core it's just another gpio-controlled clock, just
with a fixed rate and a regulator-supply added in.
The regulator-API provides function stubs for the !CONFIG_REGULATOR case,
so no special handling is necessary.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
---
drivers/clk/clk-gpio.c | 182 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 182 insertions(+)
diff --git a/drivers/clk/clk-gpio.c b/drivers/clk/clk-gpio.c
index cda362a2eca0..8bcdef340b4c 100644
--- a/drivers/clk/clk-gpio.c
+++ b/drivers/clk/clk-gpio.c
@@ -17,6 +17,7 @@
#include <linux/device.h>
#include <linux/of.h>
#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
/**
* DOC: basic gpio gated clock which can be enabled and disabled
@@ -239,3 +240,184 @@ static struct platform_driver gpio_clk_driver = {
},
};
builtin_platform_driver(gpio_clk_driver);
+
+/**
+ * DOC: gated fixed clock, controlled with a gpio output and a regulator
+ * Traits of this clock:
+ * prepare - clk_prepare and clk_unprepare are function & control regulator
+ * optionally a gpio that can sleep
+ * enable - clk_enable and clk_disable are functional & control gpio
+ * rate - rate is fixed and set on clock generation
+ * parent - fixed clock is a root clock and has no parent.
+ */
+
+/**
+ * struct clk_gate_fixed - gated-fixed-clock
+ *
+ * clk_gpio: instance of clk_gpio for gate-gpio
+ * supply: supply regulator
+ * rate: fixed rate
+ */
+struct clk_gated_fixed {
+ struct clk_gpio clk_gpio;
+ struct regulator *supply;
+ u32 rate;
+};
+
+#define to_clk_gated_fixed(_clk_gpio) container_of(_clk_gpio, struct clk_gated_fixed, clk_gpio)
+
+static unsigned long clk_gated_fixed_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ return to_clk_gated_fixed(to_clk_gpio(hw))->rate;
+}
+
+static int clk_gated_fixed_prepare(struct clk_hw *hw)
+{
+ struct clk_gated_fixed *clk = to_clk_gated_fixed(to_clk_gpio(hw));
+
+ if (!clk->supply)
+ return 0;
+
+ return regulator_enable(clk->supply);
+}
+
+static void clk_gated_fixed_unprepare(struct clk_hw *hw)
+{
+ struct clk_gated_fixed *clk = to_clk_gated_fixed(to_clk_gpio(hw));
+
+ if (!clk->supply)
+ return;
+
+ regulator_disable(clk->supply);
+}
+
+static int clk_gated_fixed_is_prepared(struct clk_hw *hw)
+{
+ struct clk_gated_fixed *clk = to_clk_gated_fixed(to_clk_gpio(hw));
+
+ if (!clk->supply)
+ return true;
+
+ return regulator_is_enabled(clk->supply);
+}
+
+/*
+ * Fixed gated clock with non-sleeping gpio.
+ *
+ * Prepare operation turns on the supply regulator
+ * and the enable operation switches the enable-gpio.
+ */
+const struct clk_ops clk_gated_fixed_ops = {
+ .prepare = clk_gated_fixed_prepare,
+ .unprepare = clk_gated_fixed_unprepare,
+ .is_prepared = clk_gated_fixed_is_prepared,
+ .enable = clk_gpio_gate_enable,
+ .disable = clk_gpio_gate_disable,
+ .is_enabled = clk_gpio_gate_is_enabled,
+ .recalc_rate = clk_gated_fixed_recalc_rate,
+};
+
+static int clk_sleeping_gated_fixed_prepare(struct clk_hw *hw)
+{
+ int ret;
+
+ ret = clk_gated_fixed_prepare(hw);
+ if (ret)
+ return ret;
+
+ ret = clk_sleeping_gpio_gate_prepare(hw);
+ if (ret)
+ clk_gated_fixed_unprepare(hw);
+
+ return ret;
+}
+
+static void clk_sleeping_gated_fixed_unprepare(struct clk_hw *hw)
+{
+ clk_gated_fixed_unprepare(hw);
+ clk_sleeping_gpio_gate_unprepare(hw);
+}
+
+/*
+ * Fixed gated clock with non-sleeping gpio.
+ *
+ * Enabling the supply regulator and switching the enable-gpio happens
+ * both in the prepare step.
+ * is_prepared only needs to check the gpio state, as toggling the
+ * gpio is the last step when preparing.
+ */
+const struct clk_ops clk_sleeping_gated_fixed_ops = {
+ .prepare = clk_sleeping_gated_fixed_prepare,
+ .unprepare = clk_sleeping_gated_fixed_unprepare,
+ .is_prepared = clk_sleeping_gpio_gate_is_prepared,
+ .recalc_rate = clk_gated_fixed_recalc_rate,
+};
+
+static int clk_gated_fixed_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct clk_gated_fixed *clk;
+ const struct clk_ops *ops;
+ const char *clk_name;
+ int ret;
+
+ clk = devm_kzalloc(dev, sizeof(*clk), GFP_KERNEL);
+ if (!clk)
+ return -ENOMEM;
+
+ if (device_property_read_u32(dev, "clock-frequency", &clk->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);
+
+ clk->supply = devm_regulator_get_optional(dev, "vdd");
+ if (IS_ERR(clk->supply)) {
+ if (PTR_ERR(clk->supply) != -ENODEV)
+ return dev_err_probe(dev, PTR_ERR(clk->supply),
+ "failed to get regulator\n");
+ clk->supply = NULL;
+ }
+
+ clk->clk_gpio.gpiod = devm_gpiod_get_optional(dev, "enable",
+ GPIOD_OUT_LOW);
+ if (IS_ERR(clk->clk_gpio.gpiod))
+ return dev_err_probe(dev, PTR_ERR(clk->clk_gpio.gpiod),
+ "failed to get gpio\n");
+
+ if (gpiod_cansleep(clk->clk_gpio.gpiod))
+ ops = &clk_sleeping_gated_fixed_ops;
+ else
+ ops = &clk_gated_fixed_ops;
+
+ clk->clk_gpio.hw.init = CLK_HW_INIT_NO_PARENT(clk_name, ops, 0);
+
+ /* register the clock */
+ ret = devm_clk_hw_register(dev, &clk->clk_gpio.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,
+ &clk->clk_gpio.hw);
+ if (ret)
+ return dev_err_probe(dev, ret,
+ "failed to register clock provider\n");
+
+ return 0;
+}
+
+static const struct of_device_id gated_fixed_clk_match_table[] = {
+ { .compatible = "gated-fixed-clock" },
+};
+
+static struct platform_driver gated_fixed_clk_driver = {
+ .probe = clk_gated_fixed_probe,
+ .driver = {
+ .name = "gated-fixed-clk",
+ .of_match_table = gated_fixed_clk_match_table,
+ },
+};
+builtin_platform_driver(gated_fixed_clk_driver);
--
2.43.0Quoting Heiko Stuebner (2024-08-28 03:15:02)
> diff --git a/drivers/clk/clk-gpio.c b/drivers/clk/clk-gpio.c
> index cda362a2eca0..8bcdef340b4c 100644
> --- a/drivers/clk/clk-gpio.c
> +++ b/drivers/clk/clk-gpio.c
> @@ -239,3 +240,184 @@ static struct platform_driver gpio_clk_driver = {
> },
> };
> builtin_platform_driver(gpio_clk_driver);
> +
> +/**
> + * DOC: gated fixed clock, controlled with a gpio output and a regulator
> + * Traits of this clock:
> + * prepare - clk_prepare and clk_unprepare are function & control regulator
> + * optionally a gpio that can sleep
> + * enable - clk_enable and clk_disable are functional & control gpio
> + * rate - rate is fixed and set on clock generation
Maybe 'clock registration'
> + * parent - fixed clock is a root clock and has no parent.
Not sure why this one gets the period while other lines above don't.
> + */
> +
> +/**
> + * struct clk_gate_fixed - gated-fixed-clock
> + *
> + * clk_gpio: instance of clk_gpio for gate-gpio
> + * supply: supply regulator
> + * rate: fixed rate
> + */
> +struct clk_gated_fixed {
> + struct clk_gpio clk_gpio;
> + struct regulator *supply;
> + u32 rate;
unsigned long rate to match the CCF type please.
> +};
> +
> +#define to_clk_gated_fixed(_clk_gpio) container_of(_clk_gpio, struct clk_gated_fixed, clk_gpio)
> +
> +static unsigned long clk_gated_fixed_recalc_rate(struct clk_hw *hw,
> + unsigned long parent_rate)
> +{
> + return to_clk_gated_fixed(to_clk_gpio(hw))->rate;
> +}
> +
> +static int clk_gated_fixed_prepare(struct clk_hw *hw)
> +{
> + struct clk_gated_fixed *clk = to_clk_gated_fixed(to_clk_gpio(hw));
> +
> + if (!clk->supply)
> + return 0;
> +
> + return regulator_enable(clk->supply);
> +}
> +
> +static void clk_gated_fixed_unprepare(struct clk_hw *hw)
> +{
> + struct clk_gated_fixed *clk = to_clk_gated_fixed(to_clk_gpio(hw));
> +
> + if (!clk->supply)
> + return;
> +
> + regulator_disable(clk->supply);
> +}
> +
> +static int clk_gated_fixed_is_prepared(struct clk_hw *hw)
> +{
> + struct clk_gated_fixed *clk = to_clk_gated_fixed(to_clk_gpio(hw));
> +
> + if (!clk->supply)
> + return true;
> +
> + return regulator_is_enabled(clk->supply);
> +}
> +
> +/*
> + * Fixed gated clock with non-sleeping gpio.
> + *
> + * Prepare operation turns on the supply regulator
> + * and the enable operation switches the enable-gpio.
> + */
> +const struct clk_ops clk_gated_fixed_ops = {
static
> + .prepare = clk_gated_fixed_prepare,
> + .unprepare = clk_gated_fixed_unprepare,
> + .is_prepared = clk_gated_fixed_is_prepared,
> + .enable = clk_gpio_gate_enable,
> + .disable = clk_gpio_gate_disable,
> + .is_enabled = clk_gpio_gate_is_enabled,
> + .recalc_rate = clk_gated_fixed_recalc_rate,
> +};
> +
> +static int clk_sleeping_gated_fixed_prepare(struct clk_hw *hw)
> +{
> + int ret;
> +
> + ret = clk_gated_fixed_prepare(hw);
> + if (ret)
> + return ret;
> +
> + ret = clk_sleeping_gpio_gate_prepare(hw);
> + if (ret)
> + clk_gated_fixed_unprepare(hw);
> +
> + return ret;
> +}
> +
> +static void clk_sleeping_gated_fixed_unprepare(struct clk_hw *hw)
> +{
> + clk_gated_fixed_unprepare(hw);
> + clk_sleeping_gpio_gate_unprepare(hw);
> +}
> +
> +/*
> + * Fixed gated clock with non-sleeping gpio.
> + *
> + * Enabling the supply regulator and switching the enable-gpio happens
> + * both in the prepare step.
> + * is_prepared only needs to check the gpio state, as toggling the
> + * gpio is the last step when preparing.
> + */
> +const struct clk_ops clk_sleeping_gated_fixed_ops = {
static
> + .prepare = clk_sleeping_gated_fixed_prepare,
> + .unprepare = clk_sleeping_gated_fixed_unprepare,
> + .is_prepared = clk_sleeping_gpio_gate_is_prepared,
> + .recalc_rate = clk_gated_fixed_recalc_rate,
> +};
> +
> +static int clk_gated_fixed_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct clk_gated_fixed *clk;
> + const struct clk_ops *ops;
> + const char *clk_name;
> + int ret;
> +
> + clk = devm_kzalloc(dev, sizeof(*clk), GFP_KERNEL);
> + if (!clk)
> + return -ENOMEM;
> +
> + if (device_property_read_u32(dev, "clock-frequency", &clk->rate))
Why not return the error code?
> + return dev_err_probe(dev, -EIO, "failed to get clock-frequency");
Missing newline on printk.
> +
> + ret = device_property_read_string(dev, "clock-output-names", &clk_name);
> + if (ret)
> + clk_name = fwnode_get_name(dev->fwnode);
> +
> + clk->supply = devm_regulator_get_optional(dev, "vdd");
> + if (IS_ERR(clk->supply)) {
> + if (PTR_ERR(clk->supply) != -ENODEV)
> + return dev_err_probe(dev, PTR_ERR(clk->supply),
> + "failed to get regulator\n");
> + clk->supply = NULL;
> + }
> +
> + clk->clk_gpio.gpiod = devm_gpiod_get_optional(dev, "enable",
> + GPIOD_OUT_LOW);
> + if (IS_ERR(clk->clk_gpio.gpiod))
> + return dev_err_probe(dev, PTR_ERR(clk->clk_gpio.gpiod),
> + "failed to get gpio\n");
> +
> + if (gpiod_cansleep(clk->clk_gpio.gpiod))
> + ops = &clk_sleeping_gated_fixed_ops;
> + else
> + ops = &clk_gated_fixed_ops;
> +
> + clk->clk_gpio.hw.init = CLK_HW_INIT_NO_PARENT(clk_name, ops, 0);
> +
> + /* register the clock */
> + ret = devm_clk_hw_register(dev, &clk->clk_gpio.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,
> + &clk->clk_gpio.hw);
> + if (ret)
> + return dev_err_probe(dev, ret,
> + "failed to register clock provider\n");
> +
> + return 0;
> +}
> +
> +static const struct of_device_id gated_fixed_clk_match_table[] = {
> + { .compatible = "gated-fixed-clock" },
Add a sentinel.
> +};
> +
> +static struct platform_driver gated_fixed_clk_driver = {
> + .probe = clk_gated_fixed_probe,
> + .driver = {
> + .name = "gated-fixed-clk",
> + .of_match_table = gated_fixed_clk_match_table,
> + },
> +};
> +builtin_platform_driver(gated_fixed_clk_driver);
The comment above builtin_platform_driver says "Each driver may only use
this macro once". Seems that we need to expand the macro.
Am Mittwoch, 28. August 2024, 20:30:51 CEST schrieb Stephen Boyd:
> Quoting Heiko Stuebner (2024-08-28 03:15:02)
[leaving out all the "will fix" parts :-) ]
> > +static struct platform_driver gated_fixed_clk_driver = {
> > + .probe = clk_gated_fixed_probe,
> > + .driver = {
> > + .name = "gated-fixed-clk",
> > + .of_match_table = gated_fixed_clk_match_table,
> > + },
> > +};
> > +builtin_platform_driver(gated_fixed_clk_driver);
>
> The comment above builtin_platform_driver says "Each driver may only use
> this macro once". Seems that we need to expand the macro.
each _driver_, not each file is the important point I think.
Looking at the code generation, it just wants to use the name of the
driver struct for generating the init functions.
So in the builtin_driver macro [0] it wants to use the
gated_fixed_clk_driver to create the init-function as
gated_fixed_clk_driver_init() hence anybody using the macro a second time
for the same driver would create that function two times.
Also as can be seen with the imx gpc driver [1], the two-drivers in the
same file is already in use.
I've also done a practical test with that and did [2], which resulted in
both drivers getting registered as expected:
[ 0.132087] ----init gpio_clk_driver
[ 0.132160] ----init gated_fixed_clk_driver
So not sure, if I misinterpreted your comment, but I don't think changes
are necessary for this portion.
Heiko
[0] https://elixir.bootlin.com/linux/v6.10.8/source/include/linux/device/driver.h#L284
[1]
https://elixir.bootlin.com/linux/v6.10.8/source/drivers/pmdomain/imx/gpc.c#L239
https://elixir.bootlin.com/linux/v6.10.8/source/drivers/pmdomain/imx/gpc.c#L556
[2]
diff --git a/include/linux/device/driver.h b/include/linux/device/driver.h
index 1fc8b68786de..e306f554cd0f 100644
--- a/include/linux/device/driver.h
+++ b/include/linux/device/driver.h
@@ -284,6 +284,7 @@ module_exit(__driver##_exit);
#define builtin_driver(__driver, __register, ...) \
static int __init __driver##_init(void) \
{ \
+ printk("----init %s\n", __stringify(__driver)); \
return __register(&(__driver) , ##__VA_ARGS__); \
} \
device_initcall(__driver##_init);
Quoting Heiko Stübner (2024-09-05 15:48:35)
> Am Mittwoch, 28. August 2024, 20:30:51 CEST schrieb Stephen Boyd:
> > Quoting Heiko Stuebner (2024-08-28 03:15:02)
>
> [leaving out all the "will fix" parts :-) ]
>
> > > +static struct platform_driver gated_fixed_clk_driver = {
> > > + .probe = clk_gated_fixed_probe,
> > > + .driver = {
> > > + .name = "gated-fixed-clk",
> > > + .of_match_table = gated_fixed_clk_match_table,
> > > + },
> > > +};
> > > +builtin_platform_driver(gated_fixed_clk_driver);
> >
> > The comment above builtin_platform_driver says "Each driver may only use
> > this macro once". Seems that we need to expand the macro.
>
> each _driver_, not each file is the important point I think.
Ok!
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