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Diffstat (limited to 'Documentation/driver-api')
20 files changed, 1327 insertions, 24 deletions
diff --git a/Documentation/driver-api/clk.rst b/Documentation/driver-api/clk.rst new file mode 100644 index 000000000000..511628bb3d3a --- /dev/null +++ b/Documentation/driver-api/clk.rst @@ -0,0 +1,307 @@ +======================== +The Common Clk Framework +======================== + +:Author: Mike Turquette <mturquette@ti.com> + +This document endeavours to explain the common clk framework details, +and how to port a platform over to this framework. It is not yet a +detailed explanation of the clock api in include/linux/clk.h, but +perhaps someday it will include that information. + +Introduction and interface split +================================ + +The common clk framework is an interface to control the clock nodes +available on various devices today. This may come in the form of clock +gating, rate adjustment, muxing or other operations. This framework is +enabled with the CONFIG_COMMON_CLK option. + +The interface itself is divided into two halves, each shielded from the +details of its counterpart. First is the common definition of struct +clk which unifies the framework-level accounting and infrastructure that +has traditionally been duplicated across a variety of platforms. Second +is a common implementation of the clk.h api, defined in +drivers/clk/clk.c. Finally there is struct clk_ops, whose operations +are invoked by the clk api implementation. + +The second half of the interface is comprised of the hardware-specific +callbacks registered with struct clk_ops and the corresponding +hardware-specific structures needed to model a particular clock. For +the remainder of this document any reference to a callback in struct +clk_ops, such as .enable or .set_rate, implies the hardware-specific +implementation of that code. Likewise, references to struct clk_foo +serve as a convenient shorthand for the implementation of the +hardware-specific bits for the hypothetical "foo" hardware. + +Tying the two halves of this interface together is struct clk_hw, which +is defined in struct clk_foo and pointed to within struct clk_core. This +allows for easy navigation between the two discrete halves of the common +clock interface. + +Common data structures and api +============================== + +Below is the common struct clk_core definition from +drivers/clk/clk.c, modified for brevity:: + + struct clk_core { + const char *name; + const struct clk_ops *ops; + struct clk_hw *hw; + struct module *owner; + struct clk_core *parent; + const char **parent_names; + struct clk_core **parents; + u8 num_parents; + u8 new_parent_index; + ... + }; + +The members above make up the core of the clk tree topology. The clk +api itself defines several driver-facing functions which operate on +struct clk. That api is documented in include/linux/clk.h. + +Platforms and devices utilizing the common struct clk_core use the struct +clk_ops pointer in struct clk_core to perform the hardware-specific parts of +the operations defined in clk-provider.h:: + + struct clk_ops { + int (*prepare)(struct clk_hw *hw); + void (*unprepare)(struct clk_hw *hw); + int (*is_prepared)(struct clk_hw *hw); + void (*unprepare_unused)(struct clk_hw *hw); + int (*enable)(struct clk_hw *hw); + void (*disable)(struct clk_hw *hw); + int (*is_enabled)(struct clk_hw *hw); + void (*disable_unused)(struct clk_hw *hw); + unsigned long (*recalc_rate)(struct clk_hw *hw, + unsigned long parent_rate); + long (*round_rate)(struct clk_hw *hw, + unsigned long rate, + unsigned long *parent_rate); + int (*determine_rate)(struct clk_hw *hw, + struct clk_rate_request *req); + int (*set_parent)(struct clk_hw *hw, u8 index); + u8 (*get_parent)(struct clk_hw *hw); + int (*set_rate)(struct clk_hw *hw, + unsigned long rate, + unsigned long parent_rate); + int (*set_rate_and_parent)(struct clk_hw *hw, + unsigned long rate, + unsigned long parent_rate, + u8 index); + unsigned long (*recalc_accuracy)(struct clk_hw *hw, + unsigned long parent_accuracy); + int (*get_phase)(struct clk_hw *hw); + int (*set_phase)(struct clk_hw *hw, int degrees); + void (*init)(struct clk_hw *hw); + int (*debug_init)(struct clk_hw *hw, + struct dentry *dentry); + }; + +Hardware clk implementations +============================ + +The strength of the common struct clk_core comes from its .ops and .hw pointers +which abstract the details of struct clk from the hardware-specific bits, and +vice versa. To illustrate consider the simple gateable clk implementation in +drivers/clk/clk-gate.c:: + + struct clk_gate { + struct clk_hw hw; + void __iomem *reg; + u8 bit_idx; + ... + }; + +struct clk_gate contains struct clk_hw hw as well as hardware-specific +knowledge about which register and bit controls this clk's gating. +Nothing about clock topology or accounting, such as enable_count or +notifier_count, is needed here. That is all handled by the common +framework code and struct clk_core. + +Let's walk through enabling this clk from driver code:: + + struct clk *clk; + clk = clk_get(NULL, "my_gateable_clk"); + + clk_prepare(clk); + clk_enable(clk); + +The call graph for clk_enable is very simple:: + + clk_enable(clk); + clk->ops->enable(clk->hw); + [resolves to...] + clk_gate_enable(hw); + [resolves struct clk gate with to_clk_gate(hw)] + clk_gate_set_bit(gate); + +And the definition of clk_gate_set_bit:: + + static void clk_gate_set_bit(struct clk_gate *gate) + { + u32 reg; + + reg = __raw_readl(gate->reg); + reg |= BIT(gate->bit_idx); + writel(reg, gate->reg); + } + +Note that to_clk_gate is defined as:: + + #define to_clk_gate(_hw) container_of(_hw, struct clk_gate, hw) + +This pattern of abstraction is used for every clock hardware +representation. + +Supporting your own clk hardware +================================ + +When implementing support for a new type of clock it is only necessary to +include the following header:: + + #include <linux/clk-provider.h> + +To construct a clk hardware structure for your platform you must define +the following:: + + struct clk_foo { + struct clk_hw hw; + ... hardware specific data goes here ... + }; + +To take advantage of your data you'll need to support valid operations +for your clk:: + + struct clk_ops clk_foo_ops { + .enable = &clk_foo_enable; + .disable = &clk_foo_disable; + }; + +Implement the above functions using container_of:: + + #define to_clk_foo(_hw) container_of(_hw, struct clk_foo, hw) + + int clk_foo_enable(struct clk_hw *hw) + { + struct clk_foo *foo; + + foo = to_clk_foo(hw); + + ... perform magic on foo ... + + return 0; + }; + +Below is a matrix detailing which clk_ops are mandatory based upon the +hardware capabilities of that clock. A cell marked as "y" means +mandatory, a cell marked as "n" implies that either including that +callback is invalid or otherwise unnecessary. Empty cells are either +optional or must be evaluated on a case-by-case basis. + +.. table:: clock hardware characteristics + + +----------------+------+-------------+---------------+-------------+------+ + | | gate | change rate | single parent | multiplexer | root | + +================+======+=============+===============+=============+======+ + |.prepare | | | | | | + +----------------+------+-------------+---------------+-------------+------+ + |.unprepare | | | | | | + +----------------+------+-------------+---------------+-------------+------+ + +----------------+------+-------------+---------------+-------------+------+ + |.enable | y | | | | | + +----------------+------+-------------+---------------+-------------+------+ + |.disable | y | | | | | + +----------------+------+-------------+---------------+-------------+------+ + |.is_enabled | y | | | | | + +----------------+------+-------------+---------------+-------------+------+ + +----------------+------+-------------+---------------+-------------+------+ + |.recalc_rate | | y | | | | + +----------------+------+-------------+---------------+-------------+------+ + |.round_rate | | y [1]_ | | | | + +----------------+------+-------------+---------------+-------------+------+ + |.determine_rate | | y [1]_ | | | | + +----------------+------+-------------+---------------+-------------+------+ + |.set_rate | | y | | | | + +----------------+------+-------------+---------------+-------------+------+ + +----------------+------+-------------+---------------+-------------+------+ + |.set_parent | | | n | y | n | + +----------------+------+-------------+---------------+-------------+------+ + |.get_parent | | | n | y | n | + +----------------+------+-------------+---------------+-------------+------+ + +----------------+------+-------------+---------------+-------------+------+ + |.recalc_accuracy| | | | | | + +----------------+------+-------------+---------------+-------------+------+ + +----------------+------+-------------+---------------+-------------+------+ + |.init | | | | | | + +----------------+------+-------------+---------------+-------------+------+ + +.. [1] either one of round_rate or determine_rate is required. + +Finally, register your clock at run-time with a hardware-specific +registration function. This function simply populates struct clk_foo's +data and then passes the common struct clk parameters to the framework +with a call to:: + + clk_register(...) + +See the basic clock types in ``drivers/clk/clk-*.c`` for examples. + +Disabling clock gating of unused clocks +======================================= + +Sometimes during development it can be useful to be able to bypass the +default disabling of unused clocks. For example, if drivers aren't enabling +clocks properly but rely on them being on from the bootloader, bypassing +the disabling means that the driver will remain functional while the issues +are sorted out. + +To bypass this disabling, include "clk_ignore_unused" in the bootargs to the +kernel. + +Locking +======= + +The common clock framework uses two global locks, the prepare lock and the +enable lock. + +The enable lock is a spinlock and is held across calls to the .enable, +.disable operations. Those operations are thus not allowed to sleep, +and calls to the clk_enable(), clk_disable() API functions are allowed in +atomic context. + +For clk_is_enabled() API, it is also designed to be allowed to be used in +atomic context. However, it doesn't really make any sense to hold the enable +lock in core, unless you want to do something else with the information of +the enable state with that lock held. Otherwise, seeing if a clk is enabled is +a one-shot read of the enabled state, which could just as easily change after +the function returns because the lock is released. Thus the user of this API +needs to handle synchronizing the read of the state with whatever they're +using it for to make sure that the enable state doesn't change during that +time. + +The prepare lock is a mutex and is held across calls to all other operations. +All those operations are allowed to sleep, and calls to the corresponding API +functions are not allowed in atomic context. + +This effectively divides operations in two groups from a locking perspective. + +Drivers don't need to manually protect resources shared between the operations +of one group, regardless of whether those resources are shared by multiple +clocks or not. However, access to resources that are shared between operations +of the two groups needs to be protected by the drivers. An example of such a +resource would be a register that controls both the clock rate and the clock +enable/disable state. + +The clock framework is reentrant, in that a driver is allowed to call clock +framework functions from within its implementation of clock operations. This +can for instance cause a .set_rate operation of one clock being called from +within the .set_rate operation of another clock. This case must be considered +in the driver implementations, but the code flow is usually controlled by the +driver in that case. + +Note that locking must also be considered when code outside of the common +clock framework needs to access resources used by the clock operations. This +is considered out of scope of this document. diff --git a/Documentation/driver-api/device_connection.rst b/Documentation/driver-api/device_connection.rst index affbc5566ab0..ba364224c349 100644 --- a/Documentation/driver-api/device_connection.rst +++ b/Documentation/driver-api/device_connection.rst @@ -40,4 +40,4 @@ API --- .. kernel-doc:: drivers/base/devcon.c - : functions: device_connection_find_match device_connection_find device_connection_add device_connection_remove + :functions: device_connection_find_match device_connection_find device_connection_add device_connection_remove diff --git a/Documentation/driver-api/firmware/fallback-mechanisms.rst b/Documentation/driver-api/firmware/fallback-mechanisms.rst index f353783ae0be..d35fed65eae9 100644 --- a/Documentation/driver-api/firmware/fallback-mechanisms.rst +++ b/Documentation/driver-api/firmware/fallback-mechanisms.rst @@ -72,9 +72,12 @@ the firmware requested, and establishes it in the device hierarchy by associating the device used to make the request as the device's parent. The sysfs directory's file attributes are defined and controlled through the new device's class (firmware_class) and group (fw_dev_attr_groups). -This is actually where the original firmware_class.c file name comes from, -as originally the only firmware loading mechanism available was the -mechanism we now use as a fallback mechanism. +This is actually where the original firmware_class module name came from, +given that originally the only firmware loading mechanism available was the +mechanism we now use as a fallback mechanism, which registers a struct class +firmware_class. Because the attributes exposed are part of the module name, the +module name firmware_class cannot be renamed in the future, to ensure backward +compatibility with old userspace. To load firmware using the sysfs interface we expose a loading indicator, and a file upload firmware into: @@ -83,7 +86,7 @@ and a file upload firmware into: * /sys/$DEVPATH/data To upload firmware you will echo 1 onto the loading file to indicate -you are loading firmware. You then cat the firmware into the data file, +you are loading firmware. You then write the firmware into the data file, and you notify the kernel the firmware is ready by echo'ing 0 onto the loading file. @@ -136,7 +139,8 @@ by kobject uevents. This is specially exacerbated due to the fact that most distributions today disable CONFIG_FW_LOADER_USER_HELPER_FALLBACK. Refer to do_firmware_uevent() for details of the kobject event variables -setup. Variables passwdd with a kobject add event: +setup. The variables currently passed to userspace with a "kobject add" +event are: * FIRMWARE=firmware name * TIMEOUT=timeout value diff --git a/Documentation/driver-api/firmware/firmware_cache.rst b/Documentation/driver-api/firmware/firmware_cache.rst index 2210e5bfb332..c2e69d9c6bf1 100644 --- a/Documentation/driver-api/firmware/firmware_cache.rst +++ b/Documentation/driver-api/firmware/firmware_cache.rst @@ -29,8 +29,8 @@ Some implementation details about the firmware cache setup: * If an asynchronous call is used the firmware cache is only set up for a device if if the second argument (uevent) to request_firmware_nowait() is true. When uevent is true it requests that a kobject uevent be sent to - userspace for the firmware request. For details refer to the Fackback - mechanism documented below. + userspace for the firmware request through the sysfs fallback mechanism + if the firmware file is not found. * If the firmware cache is determined to be needed as per the above two criteria the firmware cache is setup by adding a devres entry for the diff --git a/Documentation/driver-api/firmware/request_firmware.rst b/Documentation/driver-api/firmware/request_firmware.rst index cf4516dfbf96..f62bdcbfed5b 100644 --- a/Documentation/driver-api/firmware/request_firmware.rst +++ b/Documentation/driver-api/firmware/request_firmware.rst @@ -17,17 +17,22 @@ an error is returned. request_firmware ---------------- -.. kernel-doc:: drivers/base/firmware_class.c +.. kernel-doc:: drivers/base/firmware_loader/main.c :functions: request_firmware +firmware_request_nowarn +----------------------- +.. kernel-doc:: drivers/base/firmware_loader/main.c + :functions: firmware_request_nowarn + request_firmware_direct ----------------------- -.. kernel-doc:: drivers/base/firmware_class.c +.. kernel-doc:: drivers/base/firmware_loader/main.c :functions: request_firmware_direct request_firmware_into_buf ------------------------- -.. kernel-doc:: drivers/base/firmware_class.c +.. kernel-doc:: drivers/base/firmware_loader/main.c :functions: request_firmware_into_buf Asynchronous firmware requests @@ -41,7 +46,7 @@ in atomic contexts. request_firmware_nowait ----------------------- -.. kernel-doc:: drivers/base/firmware_class.c +.. kernel-doc:: drivers/base/firmware_loader/main.c :functions: request_firmware_nowait Special optimizations on reboot @@ -50,12 +55,12 @@ Special optimizations on reboot Some devices have an optimization in place to enable the firmware to be retained during system reboot. When such optimizations are used the driver author must ensure the firmware is still available on resume from suspend, -this can be done with firmware_request_cache() insted of requesting for the -firmare to be loaded. +this can be done with firmware_request_cache() instead of requesting for the +firmware to be loaded. firmware_request_cache() ------------------------ -.. kernel-doc:: drivers/base/firmware_class.c +------------------------ +.. kernel-doc:: drivers/base/firmware_loader/main.c :functions: firmware_request_cache request firmware API expected driver use diff --git a/Documentation/driver-api/fpga/fpga-bridge.rst b/Documentation/driver-api/fpga/fpga-bridge.rst new file mode 100644 index 000000000000..2c2aaca894bf --- /dev/null +++ b/Documentation/driver-api/fpga/fpga-bridge.rst @@ -0,0 +1,49 @@ +FPGA Bridge +=========== + +API to implement a new FPGA bridge +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: include/linux/fpga/fpga-bridge.h + :functions: fpga_bridge + +.. kernel-doc:: include/linux/fpga/fpga-bridge.h + :functions: fpga_bridge_ops + +.. kernel-doc:: drivers/fpga/fpga-bridge.c + :functions: fpga_bridge_create + +.. kernel-doc:: drivers/fpga/fpga-bridge.c + :functions: fpga_bridge_free + +.. kernel-doc:: drivers/fpga/fpga-bridge.c + :functions: fpga_bridge_register + +.. kernel-doc:: drivers/fpga/fpga-bridge.c + :functions: fpga_bridge_unregister + +API to control an FPGA bridge +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +You probably won't need these directly. FPGA regions should handle this. + +.. kernel-doc:: drivers/fpga/fpga-bridge.c + :functions: of_fpga_bridge_get + +.. kernel-doc:: drivers/fpga/fpga-bridge.c + :functions: fpga_bridge_get + +.. kernel-doc:: drivers/fpga/fpga-bridge.c + :functions: fpga_bridge_put + +.. kernel-doc:: drivers/fpga/fpga-bridge.c + :functions: fpga_bridge_get_to_list + +.. kernel-doc:: drivers/fpga/fpga-bridge.c + :functions: of_fpga_bridge_get_to_list + +.. kernel-doc:: drivers/fpga/fpga-bridge.c + :functions: fpga_bridge_enable + +.. kernel-doc:: drivers/fpga/fpga-bridge.c + :functions: fpga_bridge_disable diff --git a/Documentation/driver-api/fpga/fpga-mgr.rst b/Documentation/driver-api/fpga/fpga-mgr.rst new file mode 100644 index 000000000000..bcf2dd24e179 --- /dev/null +++ b/Documentation/driver-api/fpga/fpga-mgr.rst @@ -0,0 +1,220 @@ +FPGA Manager +============ + +Overview +-------- + +The FPGA manager core exports a set of functions for programming an FPGA with +an image. The API is manufacturer agnostic. All manufacturer specifics are +hidden away in a low level driver which registers a set of ops with the core. +The FPGA image data itself is very manufacturer specific, but for our purposes +it's just binary data. The FPGA manager core won't parse it. + +The FPGA image to be programmed can be in a scatter gather list, a single +contiguous buffer, or a firmware file. Because allocating contiguous kernel +memory for the buffer should be avoided, users are encouraged to use a scatter +gather list instead if possible. + +The particulars for programming the image are presented in a structure (struct +fpga_image_info). This struct contains parameters such as pointers to the +FPGA image as well as image-specific particulars such as whether the image was +built for full or partial reconfiguration. + +How to support a new FPGA device +-------------------------------- + +To add another FPGA manager, write a driver that implements a set of ops. The +probe function calls fpga_mgr_register(), such as:: + + static const struct fpga_manager_ops socfpga_fpga_ops = { + .write_init = socfpga_fpga_ops_configure_init, + .write = socfpga_fpga_ops_configure_write, + .write_complete = socfpga_fpga_ops_configure_complete, + .state = socfpga_fpga_ops_state, + }; + + static int socfpga_fpga_probe(struct platform_device *pdev) + { + struct device *dev = &pdev->dev; + struct socfpga_fpga_priv *priv; + struct fpga_manager *mgr; + int ret; + + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + /* + * do ioremaps, get interrupts, etc. and save + * them in priv + */ + + mgr = fpga_mgr_create(dev, "Altera SOCFPGA FPGA Manager", + &socfpga_fpga_ops, priv); + if (!mgr) + return -ENOMEM; + + platform_set_drvdata(pdev, mgr); + + ret = fpga_mgr_register(mgr); + if (ret) + fpga_mgr_free(mgr); + + return ret; + } + + static int socfpga_fpga_remove(struct platform_device *pdev) + { + struct fpga_manager *mgr = platform_get_drvdata(pdev); + + fpga_mgr_unregister(mgr); + + return 0; + } + + +The ops will implement whatever device specific register writes are needed to +do the programming sequence for this particular FPGA. These ops return 0 for +success or negative error codes otherwise. + +The programming sequence is:: + 1. .write_init + 2. .write or .write_sg (may be called once or multiple times) + 3. .write_complete + +The .write_init function will prepare the FPGA to receive the image data. The +buffer passed into .write_init will be atmost .initial_header_size bytes long, +if the whole bitstream is not immediately available then the core code will +buffer up at least this much before starting. + +The .write function writes a buffer to the FPGA. The buffer may be contain the +whole FPGA image or may be a smaller chunk of an FPGA image. In the latter +case, this function is called multiple times for successive chunks. This interface +is suitable for drivers which use PIO. + +The .write_sg version behaves the same as .write except the input is a sg_table +scatter list. This interface is suitable for drivers which use DMA. + +The .write_complete function is called after all the image has been written +to put the FPGA into operating mode. + +The ops include a .state function which will read the hardware FPGA manager and +return a code of type enum fpga_mgr_states. It doesn't result in a change in +hardware state. + +How to write an image buffer to a supported FPGA +------------------------------------------------ + +Some sample code:: + + #include <linux/fpga/fpga-mgr.h> + + struct fpga_manager *mgr; + struct fpga_image_info *info; + int ret; + + /* + * Get a reference to FPGA manager. The manager is not locked, so you can + * hold onto this reference without it preventing programming. + * + * This example uses the device node of the manager. Alternatively, use + * fpga_mgr_get(dev) instead if you have the device. + */ + mgr = of_fpga_mgr_get(mgr_node); + + /* struct with information about the FPGA image to program. */ + info = fpga_image_info_alloc(dev); + + /* flags indicates whether to do full or partial reconfiguration */ + info->flags = FPGA_MGR_PARTIAL_RECONFIG; + + /* + * At this point, indicate where the image is. This is pseudo-code; you're + * going to use one of these three. + */ + if (image is in a scatter gather table) { + + info->sgt = [your scatter gather table] + + } else if (image is in a buffer) { + + info->buf = [your image buffer] + info->count = [image buffer size] + + } else if (image is in a firmware file) { + + info->firmware_name = devm_kstrdup(dev, firmware_name, GFP_KERNEL); + + } + + /* Get exclusive control of FPGA manager */ + ret = fpga_mgr_lock(mgr); + + /* Load the buffer to the FPGA */ + ret = fpga_mgr_buf_load(mgr, &info, buf, count); + + /* Release the FPGA manager */ + fpga_mgr_unlock(mgr); + fpga_mgr_put(mgr); + + /* Deallocate the image info if you're done with it */ + fpga_image_info_free(info); + +API for implementing a new FPGA Manager driver +---------------------------------------------- + +.. kernel-doc:: include/linux/fpga/fpga-mgr.h + :functions: fpga_manager + +.. kernel-doc:: include/linux/fpga/fpga-mgr.h + :functions: fpga_manager_ops + +.. kernel-doc:: drivers/fpga/fpga-mgr.c + :functions: fpga_mgr_create + +.. kernel-doc:: drivers/fpga/fpga-mgr.c + :functions: fpga_mgr_free + +.. kernel-doc:: drivers/fpga/fpga-mgr.c + :functions: fpga_mgr_register + +.. kernel-doc:: drivers/fpga/fpga-mgr.c + :functions: fpga_mgr_unregister + +API for programming a FPGA +-------------------------- + +.. kernel-doc:: include/linux/fpga/fpga-mgr.h + :functions: fpga_image_info + +.. kernel-doc:: include/linux/fpga/fpga-mgr.h + :functions: fpga_mgr_states + +.. kernel-doc:: drivers/fpga/fpga-mgr.c + :functions: fpga_image_info_alloc + +.. kernel-doc:: drivers/fpga/fpga-mgr.c + :functions: fpga_image_info_free + +.. kernel-doc:: drivers/fpga/fpga-mgr.c + :functions: of_fpga_mgr_get + +.. kernel-doc:: drivers/fpga/fpga-mgr.c + :functions: fpga_mgr_get + +.. kernel-doc:: drivers/fpga/fpga-mgr.c + :functions: fpga_mgr_put + +.. kernel-doc:: drivers/fpga/fpga-mgr.c + :functions: fpga_mgr_lock + +.. kernel-doc:: drivers/fpga/fpga-mgr.c + :functions: fpga_mgr_unlock + +.. kernel-doc:: include/linux/fpga/fpga-mgr.h + :functions: fpga_mgr_states + +Note - use :c:func:`fpga_region_program_fpga()` instead of :c:func:`fpga_mgr_load()` + +.. kernel-doc:: drivers/fpga/fpga-mgr.c + :functions: fpga_mgr_load diff --git a/Documentation/driver-api/fpga/fpga-region.rst b/Documentation/driver-api/fpga/fpga-region.rst new file mode 100644 index 000000000000..f89e4a311722 --- /dev/null +++ b/Documentation/driver-api/fpga/fpga-region.rst @@ -0,0 +1,102 @@ +FPGA Region +=========== + +Overview +-------- + +This document is meant to be an brief overview of the FPGA region API usage. A +more conceptual look at regions can be found in the Device Tree binding +document [#f1]_. + +For the purposes of this API document, let's just say that a region associates +an FPGA Manager and a bridge (or bridges) with a reprogrammable region of an +FPGA or the whole FPGA. The API provides a way to register a region and to +program a region. + +Currently the only layer above fpga-region.c in the kernel is the Device Tree +support (of-fpga-region.c) described in [#f1]_. The DT support layer uses regions +to program the FPGA and then DT to handle enumeration. The common region code +is intended to be used by other schemes that have other ways of accomplishing +enumeration after programming. + +An fpga-region can be set up to know the following things: + + * which FPGA manager to use to do the programming + + * which bridges to disable before programming and enable afterwards. + +Additional info needed to program the FPGA image is passed in the struct +fpga_image_info including: + + * pointers to the image as either a scatter-gather buffer, a contiguous + buffer, or the name of firmware file + + * flags indicating specifics such as whether the image if for partial + reconfiguration. + +How to program a FPGA using a region +------------------------------------ + +First, allocate the info struct:: + + info = fpga_image_info_alloc(dev); + if (!info) + return -ENOMEM; + +Set flags as needed, i.e.:: + + info->flags |= FPGA_MGR_PARTIAL_RECONFIG; + +Point to your FPGA image, such as:: + + info->sgt = &sgt; + +Add info to region and do the programming:: + + region->info = info; + ret = fpga_region_program_fpga(region); + +:c:func:`fpga_region_program_fpga()` operates on info passed in the +fpga_image_info (region->info). This function will attempt to: + + * lock the region's mutex + * lock the region's FPGA manager + * build a list of FPGA bridges if a method has been specified to do so + * disable the bridges + * program the FPGA + * re-enable the bridges + * release the locks + +Then you will want to enumerate whatever hardware has appeared in the FPGA. + +How to add a new FPGA region +---------------------------- + +An example of usage can be seen in the probe function of [#f2]_. + +.. [#f1] ../devicetree/bindings/fpga/fpga-region.txt +.. [#f2] ../../drivers/fpga/of-fpga-region.c + +API to program a FGPA +--------------------- + +.. kernel-doc:: drivers/fpga/fpga-region.c + :functions: fpga_region_program_fpga + +API to add a new FPGA region +---------------------------- + +.. kernel-doc:: include/linux/fpga/fpga-region.h + :functions: fpga_region + +.. kernel-doc:: drivers/fpga/fpga-region.c + :functions: fpga_region_create + +.. kernel-doc:: drivers/fpga/fpga-region.c + :functions: fpga_region_free + +.. kernel-doc:: drivers/fpga/fpga-region.c + :functions: fpga_region_register + +.. kernel-doc:: drivers/fpga/fpga-region.c + :functions: fpga_region_unregister diff --git a/Documentation/driver-api/fpga/index.rst b/Documentation/driver-api/fpga/index.rst new file mode 100644 index 000000000000..c51e5ebd544a --- /dev/null +++ b/Documentation/driver-api/fpga/index.rst @@ -0,0 +1,13 @@ +============== +FPGA Subsystem +============== + +:Author: Alan Tull + +.. toctree:: + :maxdepth: 2 + + intro + fpga-mgr + fpga-bridge + fpga-region diff --git a/Documentation/driver-api/fpga/intro.rst b/Documentation/driver-api/fpga/intro.rst new file mode 100644 index 000000000000..51cd81dbb4dc --- /dev/null +++ b/Documentation/driver-api/fpga/intro.rst @@ -0,0 +1,54 @@ +Introduction +============ + +The FPGA subsystem supports reprogramming FPGAs dynamically under +Linux. Some of the core intentions of the FPGA subsystems are: + +* The FPGA subsystem is vendor agnostic. + +* The FPGA subsystem separates upper layers (userspace interfaces and + enumeration) from lower layers that know how to program a specific + FPGA. + +* Code should not be shared between upper and lower layers. This + should go without saying. If that seems necessary, there's probably + framework functionality that that can be added that will benefit + other users. Write the linux-fpga mailing list and maintainers and + seek out a solution that expands the framework for broad reuse. + +* Generally, when adding code, think of the future. Plan for re-use. + +The framework in the kernel is divided into: + +FPGA Manager +------------ + +If you are adding a new FPGA or a new method of programming a FPGA, +this is the subsystem for you. Low level FPGA manager drivers contain +the knowledge of how to program a specific device. This subsystem +includes the framework in fpga-mgr.c and the low level drivers that +are registered with it. + +FPGA Bridge +----------- + +FPGA Bridges prevent spurious signals from going out of a FPGA or a +region of a FPGA during programming. They are disabled before +programming begins and re-enabled afterwards. An FPGA bridge may be +actual hard hardware that gates a bus to a cpu or a soft ("freeze") +bridge in FPGA fabric that surrounds a partial reconfiguration region +of an FPGA. This subsystem includes fpga-bridge.c and the low level +drivers that are registered with it. + +FPGA Region +----------- + +If you are adding a new interface to the FPGA framework, add it on top +of a FPGA region to allow the most reuse of your interface. + +The FPGA Region framework (fpga-region.c) associates managers and +bridges as reconfigurable regions. A region may refer to the whole +FPGA in full reconfiguration or to a partial reconfiguration region. + +The Device Tree FPGA Region support (of-fpga-region.c) handles +reprogramming FPGAs when device tree overlays are applied. diff --git a/Documentation/driver-api/gpio/driver.rst b/Documentation/driver-api/gpio/driver.rst index 505ee906d7d9..cbe0242842d1 100644 --- a/Documentation/driver-api/gpio/driver.rst +++ b/Documentation/driver-api/gpio/driver.rst @@ -44,7 +44,7 @@ common to each controller of that type: - methods to establish GPIO line direction - methods used to access GPIO line values - - method to set electrical configuration to a a given GPIO line + - method to set electrical configuration for a given GPIO line - method to return the IRQ number associated to a given GPIO line - flag saying whether calls to its methods may sleep - optional line names array to identify lines @@ -143,7 +143,7 @@ resistor will make the line tend to high level unless one of the transistors on the rail actively pulls it down. The level on the line will go as high as the VDD on the pull-up resistor, which -may be higher than the level supported by the transistor, achieveing a +may be higher than the level supported by the transistor, achieving a level-shift to the higher VDD. Integrated electronics often have an output driver stage in the form of a CMOS @@ -382,7 +382,7 @@ Real-Time compliance for GPIO IRQ chips Any provider of irqchips needs to be carefully tailored to support Real Time preemption. It is desirable that all irqchips in the GPIO subsystem keep this -in mind and does the proper testing to assure they are real time-enabled. +in mind and do the proper testing to assure they are real time-enabled. So, pay attention on above " RT_FULL:" notes, please. The following is a checklist to follow when preparing a driver for real time-compliance: diff --git a/Documentation/driver-api/index.rst b/Documentation/driver-api/index.rst index 6d8352c0f354..f4180e7c7ed5 100644 --- a/Documentation/driver-api/index.rst +++ b/Documentation/driver-api/index.rst @@ -17,7 +17,9 @@ available subsections can be seen below. basics infrastructure pm/index + clk device-io + device_connection dma-buf device_link message-based @@ -49,6 +51,7 @@ available subsections can be seen below. dmaengine/index slimbus soundwire/index + fpga/index .. only:: subproject and html diff --git a/Documentation/driver-api/infrastructure.rst b/Documentation/driver-api/infrastructure.rst index 6d9ff316b608..bee1b9a1702f 100644 --- a/Documentation/driver-api/infrastructure.rst +++ b/Documentation/driver-api/infrastructure.rst @@ -28,7 +28,7 @@ Device Drivers Base .. kernel-doc:: drivers/base/node.c :internal: -.. kernel-doc:: drivers/base/firmware_class.c +.. kernel-doc:: drivers/base/firmware_loader/main.c :export: .. kernel-doc:: drivers/base/transport_class.c diff --git a/Documentation/driver-api/soundwire/error_handling.rst b/Documentation/driver-api/soundwire/error_handling.rst new file mode 100644 index 000000000000..aa3a0a23a066 --- /dev/null +++ b/Documentation/driver-api/soundwire/error_handling.rst @@ -0,0 +1,65 @@ +======================== +SoundWire Error Handling +======================== + +The SoundWire PHY was designed with care and errors on the bus are going to +be very unlikely, and if they happen it should be limited to single bit +errors. Examples of this design can be found in the synchronization +mechanism (sync loss after two errors) and short CRCs used for the Bulk +Register Access. + +The errors can be detected with multiple mechanisms: + +1. Bus clash or parity errors: This mechanism relies on low-level detectors + that are independent of the payload and usages, and they cover both control + and audio data. The current implementation only logs such errors. + Improvements could be invalidating an entire programming sequence and + restarting from a known position. In the case of such errors outside of a + control/command sequence, there is no concealment or recovery for audio + data enabled by the SoundWire protocol, the location of the error will also + impact its audibility (most-significant bits will be more impacted in PCM), + and after a number of such errors are detected the bus might be reset. Note + that bus clashes due to programming errors (two streams using the same bit + slots) or electrical issues during the transmit/receive transition cannot + be distinguished, although a recurring bus clash when audio is enabled is a + indication of a bus allocation issue. The interrupt mechanism can also help + identify Slaves which detected a Bus Clash or a Parity Error, but they may + not be responsible for the errors so resetting them individually is not a + viable recovery strategy. + +2. Command status: Each command is associated with a status, which only + covers transmission of the data between devices. The ACK status indicates + that the command was received and will be executed by the end of the + current frame. A NAK indicates that the command was in error and will not + be applied. In case of a bad programming (command sent to non-existent + Slave or to a non-implemented register) or electrical issue, no response + signals the command was ignored. Some Master implementations allow for a + command to be retransmitted several times. If the retransmission fails, + backtracking and restarting the entire programming sequence might be a + solution. Alternatively some implementations might directly issue a bus + reset and re-enumerate all devices. + +3. Timeouts: In a number of cases such as ChannelPrepare or + ClockStopPrepare, the bus driver is supposed to poll a register field until + it transitions to a NotFinished value of zero. The MIPI SoundWire spec 1.1 + does not define timeouts but the MIPI SoundWire DisCo document adds + recommendation on timeouts. If such configurations do not complete, the + driver will return a -ETIMEOUT. Such timeouts are symptoms of a faulty + Slave device and are likely impossible to recover from. + +Errors during global reconfiguration sequences are extremely difficult to +handle: + +1. BankSwitch: An error during the last command issuing a BankSwitch is + difficult to backtrack from. Retransmitting the Bank Switch command may be + possible in a single segment setup, but this can lead to synchronization + problems when enabling multiple bus segments (a command with side effects + such as frame reconfiguration would be handled at different times). A global + hard-reset might be the best solution. + +Note that SoundWire does not provide a mechanism to detect illegal values +written in valid registers. In a number of cases the standard even mentions +that the Slave might behave in implementation-defined ways. The bus +implementation does not provide a recovery mechanism for such errors, Slave +or Master driver implementers are responsible for writing valid values in +valid registers and implement additional range checking if needed. diff --git a/Documentation/driver-api/soundwire/index.rst b/Documentation/driver-api/soundwire/index.rst index 647e94654752..6db026028f27 100644 --- a/Documentation/driver-api/soundwire/index.rst +++ b/Documentation/driver-api/soundwire/index.rst @@ -6,6 +6,9 @@ SoundWire Documentation :maxdepth: 1 summary + stream + error_handling + locking .. only:: subproject diff --git a/Documentation/driver-api/soundwire/locking.rst b/Documentation/driver-api/soundwire/locking.rst new file mode 100644 index 000000000000..253f73555255 --- /dev/null +++ b/Documentation/driver-api/soundwire/locking.rst @@ -0,0 +1,106 @@ +================= +SoundWire Locking +================= + +This document explains locking mechanism of the SoundWire Bus. Bus uses +following locks in order to avoid race conditions in Bus operations on +shared resources. + + - Bus lock + + - Message lock + +Bus lock +======== + +SoundWire Bus lock is a mutex and is part of Bus data structure +(sdw_bus) which is used for every Bus instance. This lock is used to +serialize each of the following operations(s) within SoundWire Bus instance. + + - Addition and removal of Slave(s), changing Slave status. + + - Prepare, Enable, Disable and De-prepare stream operations. + + - Access of Stream data structure. + +Message lock +============ + +SoundWire message transfer lock. This mutex is part of +Bus data structure (sdw_bus). This lock is used to serialize the message +transfers (read/write) within a SoundWire Bus instance. + +Below examples show how locks are acquired. + +Example 1 +--------- + +Message transfer. + + 1. For every message transfer + + a. Acquire Message lock. + + b. Transfer message (Read/Write) to Slave1 or broadcast message on + Bus in case of bank switch. + + c. Release Message lock :: + + +----------+ +---------+ + | | | | + | Bus | | Master | + | | | Driver | + | | | | + +----+-----+ +----+----+ + | | + | bus->ops->xfer_msg() | + <-------------------------------+ a. Acquire Message lock + | | b. Transfer message + | | + +-------------------------------> c. Release Message lock + | return success/error | d. Return success/error + | | + + + + +Example 2 +--------- + +Prepare operation. + + 1. Acquire lock for Bus instance associated with Master 1. + + 2. For every message transfer in Prepare operation + + a. Acquire Message lock. + + b. Transfer message (Read/Write) to Slave1 or broadcast message on + Bus in case of bank switch. + + c. Release Message lock. + + 3. Release lock for Bus instance associated with Master 1 :: + + +----------+ +---------+ + | | | | + | Bus | | Master | + | | | Driver | + | | | | + +----+-----+ +----+----+ + | | + | sdw_prepare_stream() | + <-------------------------------+ 1. Acquire bus lock + | | 2. Perform stream prepare + | | + | | + | bus->ops->xfer_msg() | + <-------------------------------+ a. Acquire Message lock + | | b. Transfer message + | | + +-------------------------------> c. Release Message lock + | return success/error | d. Return success/error + | | + | | + | return success/error | 3. Release bus lock + +-------------------------------> 4. Return success/error + | | + + + diff --git a/Documentation/driver-api/soundwire/stream.rst b/Documentation/driver-api/soundwire/stream.rst new file mode 100644 index 000000000000..29121aa55fb9 --- /dev/null +++ b/Documentation/driver-api/soundwire/stream.rst @@ -0,0 +1,372 @@ +========================= +Audio Stream in SoundWire +========================= + +An audio stream is a logical or virtual connection created between + + (1) System memory buffer(s) and Codec(s) + + (2) DSP memory buffer(s) and Codec(s) + + (3) FIFO(s) and Codec(s) + + (4) Codec(s) and Codec(s) + +which is typically driven by a DMA(s) channel through the data link. An +audio stream contains one or more channels of data. All channels within +stream must have same sample rate and same sample size. + +Assume a stream with two channels (Left & Right) is opened using SoundWire +interface. Below are some ways a stream can be represented in SoundWire. + +Stream Sample in memory (System memory, DSP memory or FIFOs) :: + + ------------------------- + | L | R | L | R | L | R | + ------------------------- + +Example 1: Stereo Stream with L and R channels is rendered from Master to +Slave. Both Master and Slave is using single port. :: + + +---------------+ Clock Signal +---------------+ + | Master +----------------------------------+ Slave | + | Interface | | Interface | + | | | 1 | + | | Data Signal | | + | L + R +----------------------------------+ L + R | + | (Data) | Data Direction | (Data) | + +---------------+ +-----------------------> +---------------+ + + +Example 2: Stereo Stream with L and R channels is captured from Slave to +Master. Both Master and Slave is using single port. :: + + + +---------------+ Clock Signal +---------------+ + | Master +----------------------------------+ Slave | + | Interface | | Interface | + | | | 1 | + | | Data Signal | | + | L + R +----------------------------------+ L + R | + | (Data) | Data Direction | (Data) | + +---------------+ <-----------------------+ +---------------+ + + +Example 3: Stereo Stream with L and R channels is rendered by Master. Each +of the L and R channel is received by two different Slaves. Master and both +Slaves are using single port. :: + + +---------------+ Clock Signal +---------------+ + | Master +---------+------------------------+ Slave | + | Interface | | | Interface | + | | | | 1 | + | | | Data Signal | | + | L + R +---+------------------------------+ L | + | (Data) | | | Data Direction | (Data) | + +---------------+ | | +-------------> +---------------+ + | | + | | + | | +---------------+ + | +----------------------> | Slave | + | | Interface | + | | 2 | + | | | + +----------------------------> | R | + | (Data) | + +---------------+ + + +Example 4: Stereo Stream with L and R channel is rendered by two different +Ports of the Master and is received by only single Port of the Slave +interface. :: + + +--------------------+ + | | + | +--------------+ +----------------+ + | | || | | + | | Data Port || L Channel | | + | | 1 |------------+ | | + | | L Channel || | +-----+----+ | + | | (Data) || | L + R Channel || Data | | + | Master +----------+ | +---+---------> || Port | | + | Interface | | || 1 | | + | +--------------+ | || | | + | | || | +----------+ | + | | Data Port |------------+ | | + | | 2 || R Channel | Slave | + | | R Channel || | Interface | + | | (Data) || | 1 | + | +--------------+ Clock Signal | L + R | + | +---------------------------> | (Data) | + +--------------------+ | | + +----------------+ + +SoundWire Stream Management flow +================================ + +Stream definitions +------------------ + + (1) Current stream: This is classified as the stream on which operation has + to be performed like prepare, enable, disable, de-prepare etc. + + (2) Active stream: This is classified as the stream which is already active + on Bus other than current stream. There can be multiple active streams + on the Bus. + +SoundWire Bus manages stream operations for each stream getting +rendered/captured on the SoundWire Bus. This section explains Bus operations +done for each of the stream allocated/released on Bus. Following are the +stream states maintained by the Bus for each of the audio stream. + + +SoundWire stream states +----------------------- + +Below shows the SoundWire stream states and state transition diagram. :: + + +-----------+ +------------+ +----------+ +----------+ + | ALLOCATED +---->| CONFIGURED +---->| PREPARED +---->| ENABLED | + | STATE | | STATE | | STATE | | STATE | + +-----------+ +------------+ +----------+ +----+-----+ + ^ + | + | + v + +----------+ +------------+ +----+-----+ + | RELEASED |<----------+ DEPREPARED |<-------+ DISABLED | + | STATE | | STATE | | STATE | + +----------+ +------------+ +----------+ + +NOTE: State transition between prepare and deprepare is supported in Spec +but not in the software (subsystem) + +NOTE2: Stream state transition checks need to be handled by caller +framework, for example ALSA/ASoC. No checks for stream transition exist in +SoundWire subsystem. + +Stream State Operations +----------------------- + +Below section explains the operations done by the Bus on Master(s) and +Slave(s) as part of stream state transitions. + +SDW_STREAM_ALLOCATED +~~~~~~~~~~~~~~~~~~~~ + +Allocation state for stream. This is the entry state +of the stream. Operations performed before entering in this state: + + (1) A stream runtime is allocated for the stream. This stream + runtime is used as a reference for all the operations performed + on the stream. + + (2) The resources required for holding stream runtime information are + allocated and initialized. This holds all stream related information + such as stream type (PCM/PDM) and parameters, Master and Slave + interface associated with the stream, stream state etc. + +After all above operations are successful, stream state is set to +``SDW_STREAM_ALLOCATED``. + +Bus implements below API for allocate a stream which needs to be called once +per stream. From ASoC DPCM framework, this stream state maybe linked to +.startup() operation. + + .. code-block:: c + int sdw_alloc_stream(char * stream_name); + + +SDW_STREAM_CONFIGURED +~~~~~~~~~~~~~~~~~~~~~ + +Configuration state of stream. Operations performed before entering in +this state: + + (1) The resources allocated for stream information in SDW_STREAM_ALLOCATED + state are updated here. This includes stream parameters, Master(s) + and Slave(s) runtime information associated with current stream. + + (2) All the Master(s) and Slave(s) associated with current stream provide + the port information to Bus which includes port numbers allocated by + Master(s) and Slave(s) for current stream and their channel mask. + +After all above operations are successful, stream state is set to +``SDW_STREAM_CONFIGURED``. + +Bus implements below APIs for CONFIG state which needs to be called by +the respective Master(s) and Slave(s) associated with stream. These APIs can +only be invoked once by respective Master(s) and Slave(s). From ASoC DPCM +framework, this stream state is linked to .hw_params() operation. + + .. code-block:: c + int sdw_stream_add_master(struct sdw_bus * bus, + struct sdw_stream_config * stream_config, + struct sdw_ports_config * ports_config, + struct sdw_stream_runtime * stream); + + int sdw_stream_add_slave(struct sdw_slave * slave, + struct sdw_stream_config * stream_config, + struct sdw_ports_config * ports_config, + struct sdw_stream_runtime * stream); + + +SDW_STREAM_PREPARED +~~~~~~~~~~~~~~~~~~~ + +Prepare state of stream. Operations performed before entering in this state: + + (1) Bus parameters such as bandwidth, frame shape, clock frequency, + are computed based on current stream as well as already active + stream(s) on Bus. Re-computation is required to accommodate current + stream on the Bus. + + (2) Transport and port parameters of all Master(s) and Slave(s) port(s) are + computed for the current as well as already active stream based on frame + shape and clock frequency computed in step 1. + + (3) Computed Bus and transport parameters are programmed in Master(s) and + Slave(s) registers. The banked registers programming is done on the + alternate bank (bank currently unused). Port(s) are enabled for the + already active stream(s) on the alternate bank (bank currently unused). + This is done in order to not disrupt already active stream(s). + + (4) Once all the values are programmed, Bus initiates switch to alternate + bank where all new values programmed gets into effect. + + (5) Ports of Master(s) and Slave(s) for current stream are prepared by + programming PrepareCtrl register. + +After all above operations are successful, stream state is set to +``SDW_STREAM_PREPARED``. + +Bus implements below API for PREPARE state which needs to be called once per +stream. From ASoC DPCM framework, this stream state is linked to +.prepare() operation. + + .. code-block:: c + int sdw_prepare_stream(struct sdw_stream_runtime * stream); + + +SDW_STREAM_ENABLED +~~~~~~~~~~~~~~~~~~ + +Enable state of stream. The data port(s) are enabled upon entering this state. +Operations performed before entering in this state: + + (1) All the values computed in SDW_STREAM_PREPARED state are programmed + in alternate bank (bank currently unused). It includes programming of + already active stream(s) as well. + + (2) All the Master(s) and Slave(s) port(s) for the current stream are + enabled on alternate bank (bank currently unused) by programming + ChannelEn register. + + (3) Once all the values are programmed, Bus initiates switch to alternate + bank where all new values programmed gets into effect and port(s) + associated with current stream are enabled. + +After all above operations are successful, stream state is set to +``SDW_STREAM_ENABLED``. + +Bus implements below API for ENABLE state which needs to be called once per +stream. From ASoC DPCM framework, this stream state is linked to +.trigger() start operation. + + .. code-block:: c + int sdw_enable_stream(struct sdw_stream_runtime * stream); + +SDW_STREAM_DISABLED +~~~~~~~~~~~~~~~~~~~ + +Disable state of stream. The data port(s) are disabled upon exiting this state. +Operations performed before entering in this state: + + (1) All the Master(s) and Slave(s) port(s) for the current stream are + disabled on alternate bank (bank currently unused) by programming + ChannelEn register. + + (2) All the current configuration of Bus and active stream(s) are programmed + into alternate bank (bank currently unused). + + (3) Once all the values are programmed, Bus initiates switch to alternate + bank where all new values programmed gets into effect and port(s) associated + with current stream are disabled. + +After all above operations are successful, stream state is set to +``SDW_STREAM_DISABLED``. + +Bus implements below API for DISABLED state which needs to be called once +per stream. From ASoC DPCM framework, this stream state is linked to +.trigger() stop operation. + + .. code-block:: c + int sdw_disable_stream(struct sdw_stream_runtime * stream); + + +SDW_STREAM_DEPREPARED +~~~~~~~~~~~~~~~~~~~~~ + +De-prepare state of stream. Operations performed before entering in this +state: + + (1) All the port(s) of Master(s) and Slave(s) for current stream are + de-prepared by programming PrepareCtrl register. + + (2) The payload bandwidth of current stream is reduced from the total + bandwidth requirement of bus and new parameters calculated and + applied by performing bank switch etc. + +After all above operations are successful, stream state is set to +``SDW_STREAM_DEPREPARED``. + +Bus implements below API for DEPREPARED state which needs to be called once +per stream. From ASoC DPCM framework, this stream state is linked to +.trigger() stop operation. + + .. code-block:: c + int sdw_deprepare_stream(struct sdw_stream_runtime * stream); + + +SDW_STREAM_RELEASED +~~~~~~~~~~~~~~~~~~~ + +Release state of stream. Operations performed before entering in this state: + + (1) Release port resources for all Master(s) and Slave(s) port(s) + associated with current stream. + + (2) Release Master(s) and Slave(s) runtime resources associated with + current stream. + + (3) Release stream runtime resources associated with current stream. + +After all above operations are successful, stream state is set to +``SDW_STREAM_RELEASED``. + +Bus implements below APIs for RELEASE state which needs to be called by +all the Master(s) and Slave(s) associated with stream. From ASoC DPCM +framework, this stream state is linked to .hw_free() operation. + + .. code-block:: c + int sdw_stream_remove_master(struct sdw_bus * bus, + struct sdw_stream_runtime * stream); + int sdw_stream_remove_slave(struct sdw_slave * slave, + struct sdw_stream_runtime * stream); + + +The .shutdown() ASoC DPCM operation calls below Bus API to release +stream assigned as part of ALLOCATED state. + +In .shutdown() the data structure maintaining stream state are freed up. + + .. code-block:: c + void sdw_release_stream(struct sdw_stream_runtime * stream); + +Not Supported +============= + +1. A single port with multiple channels supported cannot be used between two +streams or across stream. For example a port with 4 channels cannot be used +to handle 2 independent stereo streams even though it's possible in theory +in SoundWire. diff --git a/Documentation/driver-api/uio-howto.rst b/Documentation/driver-api/uio-howto.rst index 92056c20e070..fb2eb73be4a3 100644 --- a/Documentation/driver-api/uio-howto.rst +++ b/Documentation/driver-api/uio-howto.rst @@ -711,7 +711,8 @@ The vmbus device regions are mapped into uio device resources: If a subchannel is created by a request to host, then the uio_hv_generic device driver will create a sysfs binary file for the per-channel ring buffer. -For example: +For example:: + /sys/bus/vmbus/devices/3811fe4d-0fa0-4b62-981a-74fc1084c757/channels/21/ring Further information diff --git a/Documentation/driver-api/usb/dwc3.rst b/Documentation/driver-api/usb/dwc3.rst index c3dc84a50ce5..8b36ff11cef9 100644 --- a/Documentation/driver-api/usb/dwc3.rst +++ b/Documentation/driver-api/usb/dwc3.rst @@ -674,9 +674,8 @@ operations, both of which can be traced. Format is:: __entry->flags & DWC3_EP_ENABLED ? 'E' : 'e', __entry->flags & DWC3_EP_STALL ? 'S' : 's', __entry->flags & DWC3_EP_WEDGE ? 'W' : 'w', - __entry->flags & DWC3_EP_BUSY ? 'B' : 'b', + __entry->flags & DWC3_EP_TRANSFER_STARTED ? 'B' : 'b', __entry->flags & DWC3_EP_PENDING_REQUEST ? 'P' : 'p', - __entry->flags & DWC3_EP_MISSED_ISOC ? 'M' : 'm', __entry->flags & DWC3_EP_END_TRANSFER_PENDING ? 'E' : 'e', __entry->direction ? '<' : '>' ) diff --git a/Documentation/driver-api/usb/typec.rst b/Documentation/driver-api/usb/typec.rst index feb31946490b..48ff58095f11 100644 --- a/Documentation/driver-api/usb/typec.rst +++ b/Documentation/driver-api/usb/typec.rst @@ -210,7 +210,7 @@ If the connector is dual-role capable, there may also be a switch for the data role. USB Type-C Connector Class does not supply separate API for them. The port drivers can use USB Role Class API with those. -Illustration of the muxes behind a connector that supports an alternate mode: +Illustration of the muxes behind a connector that supports an alternate mode:: ------------------------ | Connector | |