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Message-ID: <20250521104115.176950-1-mehdi.djait@linux.intel.com>
Date: Wed, 21 May 2025 12:41:15 +0200
From: Mehdi Djait <mehdi.djait@...ux.intel.com>
To: sakari.ailus@...ux.intel.com,
laurent.pinchart@...asonboard.com
Cc: tomi.valkeinen@...asonboard.com,
jacopo.mondi@...asonboard.com,
hverkuil@...all.nl,
kieran.bingham@...asonboard.com,
naush@...pberrypi.com,
mchehab@...nel.org,
hdegoede@...hat.com,
dave.stevenson@...pberrypi.com,
arnd@...db.de,
linux-media@...r.kernel.org,
linux-kernel@...r.kernel.org,
Mehdi Djait <mehdi.djait@...ux.intel.com>
Subject: [RFC PATCH v5] media: v4l2-common: Add a helper for obtaining the clock producer
Introduce a helper for v4l2 sensor drivers on both DT- and ACPI-based
platforms to retrieve a reference to the clock producer from firmware.
This helper behaves the same as clk_get_optional() except where there is
no clock producer like in ACPI-based platforms.
For ACPI-based platforms the function will read the "clock-frequency"
ACPI _DSD property and register a fixed frequency clock with the frequency
indicated in the property.
This function also handles the special ACPI-based system case where:
The clock-frequency _DSD property is present.
A reference to the clock producer is present, where the clock is provided
by a camera sensor PMIC driver (e.g. int3472/tps68470.c).
In this case try to set the clock-frequency value to the provided clock.
Signed-off-by: Mehdi Djait <mehdi.djait@...ux.intel.com>
---
v4 -> v5:
Suggested by Arnd Bergmann:
- removed IS_REACHABLE(CONFIG_COMMON_CLK). IS_REACHABLE() is actually
discouraged [1]. COFIG_COMMON_CLK is a bool, so IS_ENABLED() will be the
right solution here
Suggested by Hans de Goede:
- added handling for the special ACPI-based system case, where
both a reference to the clock-provider and the _DSD
clock-frequency are present.
- updated the function's kernel-doc and the commit msg
to mention this special case.
Link v4: https://lore.kernel.org/linux-media/20250321130329.342236-1-mehdi.djait@linux.intel.com/
[1] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/Documentation/kbuild/kconfig-language.rst?h=next-20250513&id=700bd25bd4f47a0f4e02e0a25dde05f1a6b16eea
v3 -> v4:
Suggested by Laurent:
- removed the #ifdef to use IS_REACHABLE(CONFIG_COMMON_CLK)
- changed to kasprintf() to allocate the clk name when id is NULL and
used the __free(kfree) scope-based cleanup helper when
defining the variable to hold the allocated name
Link v3: https://lore.kernel.org/linux-media/20250321093814.18159-1-mehdi.djait@linux.intel.com/
v2 -> v3:
- Added #ifdef CONFIG_COMMON_CLK for the ACPI case
Link v2: https://lore.kernel.org/linux-media/20250310122305.209534-1-mehdi.djait@linux.intel.com/
v1 -> v2:
Suggested by Sakari:
- removed clk_name
- removed the IS_ERR() check
- improved the kernel-doc comment and commit msg
Link v1: https://lore.kernel.org/linux-media/20250227092643.113939-1-mehdi.djait@linux.intel.com
drivers/media/v4l2-core/v4l2-common.c | 46 +++++++++++++++++++++++++++
include/media/v4l2-common.h | 25 +++++++++++++++
2 files changed, 71 insertions(+)
diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c
index 4ee4aa19efe6..6099acd339ad 100644
--- a/drivers/media/v4l2-core/v4l2-common.c
+++ b/drivers/media/v4l2-core/v4l2-common.c
@@ -34,6 +34,9 @@
* Added Gerd Knorrs v4l1 enhancements (Justin Schoeman)
*/
+#include <linux/clk.h>
+#include <linux/clkdev.h>
+#include <linux/clk-provider.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
@@ -665,3 +668,46 @@ int v4l2_link_freq_to_bitmap(struct device *dev, const u64 *fw_link_freqs,
return 0;
}
EXPORT_SYMBOL_GPL(v4l2_link_freq_to_bitmap);
+
+struct clk *devm_v4l2_sensor_clk_get(struct device *dev, const char *id)
+{
+ const char *clk_id __free(kfree) = NULL;
+ struct clk_hw *clk_hw;
+ struct clk *clk;
+ u32 rate;
+ int ret;
+
+ clk = devm_clk_get_optional(dev, id);
+ ret = device_property_read_u32(dev, "clock-frequency", &rate);
+
+ if (clk) {
+ if (!ret) {
+ ret = clk_set_rate(clk, rate);
+ if (ret)
+ dev_warn(dev, "Failed to set clock rate: %u\n",
+ rate);
+ }
+
+ return clk;
+ }
+
+ if (ret)
+ return ERR_PTR(ret);
+
+ if (!IS_ENABLED(CONFIG_COMMON_CLK) || !is_acpi_node(dev_fwnode(dev)))
+ return ERR_PTR(-ENOENT);
+
+ if (!id) {
+ clk_id = kasprintf(GFP_KERNEL, "clk-%s", dev_name(dev));
+ if (!clk_id)
+ return ERR_PTR(-ENOMEM);
+ id = clk_id;
+ }
+
+ clk_hw = devm_clk_hw_register_fixed_rate(dev, id, NULL, 0, rate);
+ if (IS_ERR(clk_hw))
+ return ERR_CAST(clk_hw);
+
+ return clk_hw->clk;
+}
+EXPORT_SYMBOL_GPL(devm_v4l2_sensor_clk_get);
diff --git a/include/media/v4l2-common.h b/include/media/v4l2-common.h
index fda903bb3674..5ddbf7b3d9c3 100644
--- a/include/media/v4l2-common.h
+++ b/include/media/v4l2-common.h
@@ -586,6 +586,31 @@ int v4l2_link_freq_to_bitmap(struct device *dev, const u64 *fw_link_freqs,
unsigned int num_of_driver_link_freqs,
unsigned long *bitmap);
+/**
+ * devm_v4l2_sensor_clk_get - lookup and obtain a reference to an optional clock
+ * producer for a camera sensor.
+ *
+ * @dev: device for v4l2 sensor clock "consumer"
+ * @id: clock consumer ID
+ *
+ * This function behaves the same way as clk_get_optional() except where there
+ * is no clock producer like in ACPI-based platforms.
+ *
+ * For ACPI-based platforms, the function will read the "clock-frequency"
+ * ACPI _DSD property and register a fixed-clock with the frequency indicated
+ * in the property.
+ *
+ * This function also handles the special ACPI-based system case where:
+ * The clock-frequency _DSD property is present.
+ * A reference to the clock producer is present, where the clock is provided by
+ * a camera sensor PMIC driver (e.g. int3472/tps68470.c)
+ * In this case try to set the clock-frequency value to the provided clock.
+ *
+ * Return:
+ * * pointer to a struct clk on success or an error code on failure.
+ */
+struct clk *devm_v4l2_sensor_clk_get(struct device *dev, const char *id);
+
static inline u64 v4l2_buffer_get_timestamp(const struct v4l2_buffer *buf)
{
/*
--
2.49.0
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