From f4cdf7ca9a1fdcca413157df19753f388a5a224e Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Wed, 19 Aug 2026 10:09:22 -0700 Subject: Merge tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media Pull media updates from Mauro Carvalho Chehab: - v4l2-core: added ISP statistics support and per-block validation - v4l2-core: Allow unknown HDR10 white point and luminance - New camera sensors: Sony IMX678 and IMX471m, Himax HM1092 IR sensor - New codec: Milos: VPU v2.0 codec support - isp driver: gained support for Dreamchip RPPX1 ISP framework - vsp1 driver: gained support for RZ/T2H and RZ/N2H - Novalake driver: gained CVS support for new NVL hardware - dvb-core: fix feed leak on failed DMX_ADD_PID - several driver fixes, cleanups and minor improvements * tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (308 commits) media: ipu-bridge: check all DMI entries when overriding sensor rotation media: v4l2-async: avoid deleting unlinked ASC entry on link error media: rzg2l-cru: Align bytesperline to hardware DMA stride requirement media: intel/ipu6: fix async notifier cleanup leak on parse error media: staging/ipu7: fix async notifier UAF on probe error path media: amd: isp4: fix self-deadlock in isp4sd_pwron_and_init() error path media: amd: isp4: release partial allocations in isp4if_alloc_fw_gpumem() media: rcar-isp: Fix VSPX reference leaks media: rcar-isp: Release ISPCORE resources media: i2c: imx415: Release runtime PM reference on VBLANK error media: i2c: imx415: Return test pattern write errors media: renesas: vsp1: Declare index variables in for loop statement media: renesas: vsp1: Make reset control optional to support platforms without a reset line media: dt-bindings: media: renesas,vsp1: Document RZ/T2H and RZ/N2H SoCs media: dt-bindings: media: renesas,fcp: Document RZ/T2H and RZ/N2H SoCs media: nxp: imx8-isi: Add additional 32-bit RGB format support media: nxp: imx8-isi: Add 16-bit raw Bayer format support media: nxp: imx8-isi: Implement per-stream reference counting for multiplexed streams media: nxp: imx8-isi: Use BIT_ULL() for 64-bit stream masks media: nxp: imx8-isi: Correct color map between V4L2 and ISI ... --- Documentation/driver-api/phy/phy.rst | 223 +++++++++++++++++++++++++++++++++++ 1 file changed, 223 insertions(+) create mode 100644 Documentation/driver-api/phy/phy.rst (limited to 'Documentation/driver-api/phy/phy.rst') diff --git a/Documentation/driver-api/phy/phy.rst b/Documentation/driver-api/phy/phy.rst new file mode 100644 index 000000000..0865c2e94 --- /dev/null +++ b/Documentation/driver-api/phy/phy.rst @@ -0,0 +1,223 @@ +============= +PHY subsystem +============= + +:Author: Kishon Vijay Abraham I + +This document explains the Generic PHY Framework along with the APIs provided, +and how-to-use. + +Introduction +============ + +*PHY* is the abbreviation for physical layer. It is used to connect a device +to the physical medium e.g., the USB controller has a PHY to provide functions +such as serialization, de-serialization, encoding, decoding and is responsible +for obtaining the required data transmission rate. Note that some USB +controllers have PHY functionality embedded into it and others use an external +PHY. Other peripherals that use PHY include Wireless LAN, Ethernet, +SATA etc. + +The intention of creating this framework is to bring the PHY drivers spread +all over the Linux kernel to drivers/phy to increase code reuse and for +better code maintainability. + +This framework will be of use only to devices that use external PHY (PHY +functionality is not embedded within the controller). + +Registering/Unregistering the PHY provider +========================================== + +PHY provider refers to an entity that implements one or more PHY instances. +For the simple case where the PHY provider implements only a single instance of +the PHY, the framework provides its own implementation of of_xlate in +of_phy_simple_xlate. If the PHY provider implements multiple instances, it +should provide its own implementation of of_xlate. of_xlate is used only for +dt boot case. + +:: + + #define of_phy_provider_register(dev, xlate) \ + __of_phy_provider_register((dev), NULL, THIS_MODULE, (xlate)) + + #define devm_of_phy_provider_register(dev, xlate) \ + __devm_of_phy_provider_register((dev), NULL, THIS_MODULE, + (xlate)) + +of_phy_provider_register and devm_of_phy_provider_register macros can be used to +register the phy_provider and it takes device and of_xlate as +arguments. For the dt boot case, all PHY providers should use one of the above +2 macros to register the PHY provider. + +Often the device tree nodes associated with a PHY provider will contain a set +of children that each represent a single PHY. Some bindings may nest the child +nodes within extra levels for context and extensibility, in which case the low +level of_phy_provider_register_full() and devm_of_phy_provider_register_full() +macros can be used to override the node containing the children. + +:: + + #define of_phy_provider_register_full(dev, children, xlate) \ + __of_phy_provider_register(dev, children, THIS_MODULE, xlate) + + #define devm_of_phy_provider_register_full(dev, children, xlate) \ + __devm_of_phy_provider_register_full(dev, children, + THIS_MODULE, xlate) + + void devm_of_phy_provider_unregister(struct device *dev, + struct phy_provider *phy_provider); + void of_phy_provider_unregister(struct phy_provider *phy_provider); + +devm_of_phy_provider_unregister and of_phy_provider_unregister can be used to +unregister the PHY. + +Creating the PHY +================ + +The PHY driver should create the PHY in order for other peripheral controllers +to make use of it. The PHY framework provides 2 APIs to create the PHY. + +:: + + struct phy *phy_create(struct device *dev, struct device_node *node, + const struct phy_ops *ops); + struct phy *devm_phy_create(struct device *dev, + struct device_node *node, + const struct phy_ops *ops); + +The PHY drivers can use one of the above 2 APIs to create the PHY by passing +the device pointer and phy ops. +phy_ops is a set of function pointers for performing PHY operations such as +init, exit, power_on and power_off. + +Inorder to dereference the private data (in phy_ops), the phy provider driver +can use phy_set_drvdata() after creating the PHY and use phy_get_drvdata() in +phy_ops to get back the private data. + +Getting a reference to the PHY +============================== + +Before the controller can make use of the PHY, it has to get a reference to +it. This framework provides the following APIs to get a reference to the PHY. + +:: + + struct phy *phy_get(struct device *dev, const char *string); + struct phy *devm_phy_get(struct device *dev, const char *string); + struct phy *devm_phy_optional_get(struct device *dev, + const char *string); + struct phy *devm_of_phy_get(struct device *dev, struct device_node *np, + const char *con_id); + struct phy *devm_of_phy_optional_get(struct device *dev, + struct device_node *np, + const char *con_id); + struct phy *devm_of_phy_get_by_index(struct device *dev, + struct device_node *np, + int index); + +phy_get, devm_phy_get and devm_phy_optional_get can be used to get the PHY. +In the case of dt boot, the string arguments +should contain the phy name as given in the dt data and in the case of +non-dt boot, it should contain the label of the PHY. The two +devm_phy_get associates the device with the PHY using devres on +successful PHY get. On driver detach, release function is invoked on +the devres data and devres data is freed. +The _optional_get variants should be used when the phy is optional. These +functions will never return -ENODEV, but instead return NULL when +the phy cannot be found. +Some generic drivers, such as ehci, may use multiple phys. In this case, +devm_of_phy_get or devm_of_phy_get_by_index can be used to get a phy +reference based on name or index. + +It should be noted that NULL is a valid phy reference. All phy +consumer calls on the NULL phy become NOPs. That is the release calls, +the phy_init() and phy_exit() calls, and phy_power_on() and +phy_power_off() calls are all NOP when applied to a NULL phy. The NULL +phy is useful in devices for handling optional phy devices. + +Order of API calls +================== + +The general order of calls should be:: + + [devm_][of_]phy_get() + phy_init() + phy_power_on() + [phy_set_mode[_ext]()] + ... + phy_power_off() + phy_exit() + [[of_]phy_put()] + +Some PHY drivers may not implement :c:func:`phy_init` or :c:func:`phy_power_on`, +but controllers should always call these functions to be compatible with other +PHYs. Some PHYs may require :c:func:`phy_set_mode `, while +others may use a default mode (typically configured via devicetree or other +firmware). For compatibility, you should always call this function if you know +what mode you will be using. Generally, this function should be called after +:c:func:`phy_power_on`, although some PHY drivers may allow it at any time. + +Releasing a reference to the PHY +================================ + +When the controller no longer needs the PHY, it has to release the reference +to the PHY it has obtained using the APIs mentioned in the above section. The +PHY framework provides 2 APIs to release a reference to the PHY. + +:: + + void phy_put(struct phy *phy); + void devm_phy_put(struct device *dev, struct phy *phy); + +Both these APIs are used to release a reference to the PHY and devm_phy_put +destroys the devres associated with this PHY. + +Destroying the PHY +================== + +When the driver that created the PHY is unloaded, it should destroy the PHY it +created using one of the following 2 APIs:: + + void phy_destroy(struct phy *phy); + void devm_phy_destroy(struct device *dev, struct phy *phy); + +Both these APIs destroy the PHY and devm_phy_destroy destroys the devres +associated with this PHY. + +PM Runtime +========== + +This subsystem is pm runtime enabled. So while creating the PHY, +pm_runtime_enable of the phy device created by this subsystem is called and +while destroying the PHY, pm_runtime_disable is called. Note that the phy +device created by this subsystem will be a child of the device that calls +phy_create (PHY provider device). + +So pm_runtime_get_sync of the phy_device created by this subsystem will invoke +pm_runtime_get_sync of PHY provider device because of parent-child relationship. +It should also be noted that phy_power_on and phy_power_off performs +phy_pm_runtime_get_sync and phy_pm_runtime_put respectively. +There are exported APIs like phy_pm_runtime_get, phy_pm_runtime_get_sync, +phy_pm_runtime_put and phy_pm_runtime_put_sync for performing PM operations. + +PHY Mappings +============ + +In order to get reference to a PHY without help from DeviceTree, the framework +offers lookups which can be compared to clkdev that allow clk structures to be +bound to devices. A lookup can be made during runtime when a handle to the +struct phy already exists. + +The framework offers the following API for registering and unregistering the +lookups:: + + int phy_create_lookup(struct phy *phy, const char *con_id, + const char *dev_id); + void phy_remove_lookup(struct phy *phy, const char *con_id, + const char *dev_id); + +DeviceTree Binding +================== + +The documentation for PHY dt binding can be found @ +Documentation/devicetree/bindings/phy/phy-bindings.txt -- cgit v1.3.1