[PATCH RFC 0/2] clk: implement a new managed helper and add first user

[PATCH RFC 0/2] clk: implement a new managed helper and add first user

[Bartosz Golaszewski]

I'm posting this as RFC to see if there's any interest. I noticed that
some drivers do: clk_get() -> clk_set_rate() -> clk_prepare_enable(). I
was wondering if it's worth factoring this out into dedicated helpers.

This series adds a new such helper for the "optional-enabled" use-case
and the first user. Let me know if this makes sense.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
Bartosz Golaszewski (2):
      clk: provide devm_clk_get_optional_enabled_with_rate()
      Bluetooth: hci_qca: use devm_clk_get_optional_enabled_with_rate()

 drivers/bluetooth/hci_qca.c | 24 ++----------------------
 drivers/clk/clk-devres.c    | 28 ++++++++++++++++++++++++++++
 include/linux/clk.h         | 26 ++++++++++++++++++++++++++
 3 files changed, 56 insertions(+), 22 deletions(-)
---
base-commit: 048d8cb65cde9fe7534eb4440bcfddcf406bb49c
change-id: 20240801-clk-new-helper-7853f662cda1

Best regards,
-- 
Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

[PATCH RFC 1/2] clk: provide devm_clk_get_optional_enabled_with_rate()

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

There are clock users in the kernel that can't use
devm_clk_get_optional_enabled() as they need to set rate after getting
the clock and before enabling it. Provide a managed helper that wraps
these operations in the correct order.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/clk/clk-devres.c | 28 ++++++++++++++++++++++++++++
 include/linux/clk.h      | 26 ++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/drivers/clk/clk-devres.c b/drivers/clk/clk-devres.c
index 90e6078fb6e1..34e800525e21 100644
--- a/drivers/clk/clk-devres.c
+++ b/drivers/clk/clk-devres.c
@@ -99,6 +99,34 @@ struct clk *devm_clk_get_optional_enabled(struct device *dev, const char *id)
 }
 EXPORT_SYMBOL_GPL(devm_clk_get_optional_enabled);
 
+struct clk *devm_clk_get_optional_enabled_with_rate(struct device *dev,
+						    const char *id,
+						    unsigned long rate)
+{
+	struct clk *clk;
+	int ret;
+
+	clk = __devm_clk_get(dev, id, clk_get_optional, NULL,
+			     clk_disable_unprepare);
+	if (IS_ERR(clk))
+		return ERR_CAST(clk);
+
+	ret = clk_set_rate(clk, rate);
+	if (ret)
+		goto out_put_clk;
+
+	ret = clk_prepare_enable(clk);
+	if (ret)
+		goto out_put_clk;
+
+	return clk;
+
+out_put_clk:
+	devm_clk_put(dev, clk);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL(devm_clk_get_optional_enabled_with_rate);
+
 struct clk_bulk_devres {
 	struct clk_bulk_data *clks;
 	int num_clks;
diff --git a/include/linux/clk.h b/include/linux/clk.h
index 0fa56d672532..c8d237e9b8d4 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -640,6 +640,32 @@ struct clk *devm_clk_get_optional_prepared(struct device *dev, const char *id);
  */
 struct clk *devm_clk_get_optional_enabled(struct device *dev, const char *id);
 
+/**
+ * devm_clk_get_optional_enabled_with_rate - devm_clk_get_optional() +
+ *                                           clk_set_rate() +
+ *                                           clk_prepare_enable()
+ * @dev: device for clock "consumer"
+ * @id: clock consumer ID
+ * @rate: new clock rate
+ *
+ * Context: May sleep.
+ *
+ * Return: a struct clk corresponding to the clock producer, or
+ * valid IS_ERR() condition containing errno.  The implementation
+ * uses @dev and @id to determine the clock consumer, and thereby
+ * the clock producer.  If no such clk is found, it returns NULL
+ * which serves as a dummy clk.  That's the only difference compared
+ * to devm_clk_get_enabled().
+ *
+ * The returned clk (if valid) is prepared and enabled and rate was set.
+ *
+ * The clock will automatically be disabled, unprepared and freed
+ * when the device is unbound from the bus.
+ */
+struct clk *devm_clk_get_optional_enabled_with_rate(struct device *dev,
+						    const char *id,
+						    unsigned long rate);
+
 /**
  * devm_get_clk_from_child - lookup and obtain a managed reference to a
  *			     clock producer from child node.

-- 
2.43.0

[PATCH RFC 2/2] Bluetooth: hci_qca: use devm_clk_get_optional_enabled_with_rate()

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Use the new devm_clk_get_optional_enabled_with_rate() clock helper to
shrink the code a bit.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/bluetooth/hci_qca.c | 24 ++----------------------
 1 file changed, 2 insertions(+), 22 deletions(-)

diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index ca6466676902..0670f527909c 100644
--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c
@@ -2297,13 +2297,6 @@ static int qca_init_regulators(struct qca_power *qca,
 	return 0;
 }
 
-static void qca_clk_disable_unprepare(void *data)
-{
-	struct clk *clk = data;
-
-	clk_disable_unprepare(clk);
-}
-
 static int qca_serdev_probe(struct serdev_device *serdev)
 {
 	struct qca_serdev *qcadev;
@@ -2433,25 +2426,12 @@ static int qca_serdev_probe(struct serdev_device *serdev)
 		if (!qcadev->bt_en)
 			power_ctrl_enabled = false;
 
-		qcadev->susclk = devm_clk_get_optional(&serdev->dev, NULL);
+		qcadev->susclk = devm_clk_get_optional_enabled_with_rate(
+					&serdev->dev, NULL, SUSCLK_RATE_32KHZ);
 		if (IS_ERR(qcadev->susclk)) {
 			dev_warn(&serdev->dev, "failed to acquire clk\n");
 			return PTR_ERR(qcadev->susclk);
 		}
-		err = clk_set_rate(qcadev->susclk, SUSCLK_RATE_32KHZ);
-		if (err)
-			return err;
-
-		err = clk_prepare_enable(qcadev->susclk);
-		if (err)
-			return err;
-
-		err = devm_add_action_or_reset(&serdev->dev,
-					       qca_clk_disable_unprepare,
-					       qcadev->susclk);
-		if (err)
-			return err;
-
 	}
 	
 	err = hci_uart_register_device(&qcadev->serdev_hu, &qca_proto);

-- 
2.43.0

Re: [PATCH RFC 1/2] clk: provide devm_clk_get_optional_enabled_with_rate()

[Stephen Boyd]

Quoting Bartosz Golaszewski (2024-08-01 08:58:49)
> diff --git a/drivers/clk/clk-devres.c b/drivers/clk/clk-devres.c
> index 90e6078fb6e1..34e800525e21 100644
> --- a/drivers/clk/clk-devres.c
> +++ b/drivers/clk/clk-devres.c
> @@ -99,6 +99,34 @@ struct clk *devm_clk_get_optional_enabled(struct device *dev, const char *id)
>  }
>  EXPORT_SYMBOL_GPL(devm_clk_get_optional_enabled);
>  
> +struct clk *devm_clk_get_optional_enabled_with_rate(struct device *dev,
> +                                                   const char *id,
> +                                                   unsigned long rate)
> +{
> +       struct clk *clk;
> +       int ret;
> +
> +       clk = __devm_clk_get(dev, id, clk_get_optional, NULL,
> +                            clk_disable_unprepare);
> +       if (IS_ERR(clk))
> +               return ERR_CAST(clk);
> +
> +       ret = clk_set_rate(clk, rate);
> +       if (ret)
> +               goto out_put_clk;
> +
> +       ret = clk_prepare_enable(clk);
> +       if (ret)
> +               goto out_put_clk;
> +
> +       return clk;
> +
> +out_put_clk:
> +       devm_clk_put(dev, clk);
> +       return ERR_PTR(ret);
> +}
> +EXPORT_SYMBOL(devm_clk_get_optional_enabled_with_rate);

GPL