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authorLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
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Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linuxgrafted
Pull I3C updates from Alexandre Belloni: "A new driver this cycle, for the AMD AXI I3C controller. There are also new features such as IBI wakeup support, SETAASA device discovery and ACPI support for the the DAA methods, meaning we can now communicate with the SPD devices on DDR5 modules. New driver: - AMD AXI I3C master controller Subsystem: - I3C Common Command Code (CCC) handling improvements, especially around GET CCCs - SETAASA device discovery support - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as well as I2C devices on I3C bus - IBI-based wakeup support Drivers: - dw: SETAASA support - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C controller support, PIO queue management support for HCI v1.2 - renesas: improve suspend to RAM support, add runtime PM support" * tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits) i3c: dw: reduce do_daa time if there's no client i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2 i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode i3c: dw: rename "pclk" to "apb" to match dt-binding i3c: dw: make struct dw_i3c_cmd smaller i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding i3c: renesas: Don't register devices when ENTDAA times out i3c: master: dw-i3c-master: fix OD timing for first broadcast i3c: mipi-i3c-hci: Advertise IBI wakeup capability i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev() i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI i3c: master: Reject IBI requests from non-IBI-capable devices i3c: master: Add helper to query bus wakeup requirements i3c: master: Report wakeup events for IBIs i3c: master: Support IBI-based wakeup capability i3c: master: Fix potential UAF in i3c_device_match() i3c: master: Fix potential UAF in i3c_device_uevent() i3c: Make dev->desc locking assumptions explicit i3c: master: Fix use-after-free of master->this ...
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+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Programming gameport drivers
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A basic classic gameport
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+If the gameport doesn't provide more than the inb()/outb() functionality,
+the code needed to register it with the joystick drivers is simple::
+
+ struct gameport gameport;
+
+ gameport.io = MY_IO_ADDRESS;
+ gameport_register_port(&gameport);
+
+Make sure struct gameport is initialized to 0 in all other fields. The
+gameport generic code will take care of the rest.
+
+If your hardware supports more than one io address, and your driver can
+choose which one to program the hardware to, starting from the more exotic
+addresses is preferred, because the likelihood of clashing with the standard
+0x201 address is smaller.
+
+E.g. if your driver supports addresses 0x200, 0x208, 0x210 and 0x218, then
+0x218 would be the address of first choice.
+
+If your hardware supports a gameport address that is not mapped to ISA io
+space (is above 0x1000), use that one, and don't map the ISA mirror.
+
+Also, always request_region() on the whole io space occupied by the
+gameport. Although only one ioport is really used, the gameport usually
+occupies from one to sixteen addresses in the io space.
+
+Please also consider enabling the gameport on the card in the ->open()
+callback if the io is mapped to ISA space - this way it'll occupy the io
+space only when something really is using it. Disable it again in the
+->close() callback. You also can select the io address in the ->open()
+callback, so that it doesn't fail if some of the possible addresses are
+already occupied by other gameports.
+
+Memory mapped gameport
+~~~~~~~~~~~~~~~~~~~~~~
+
+When a gameport can be accessed through MMIO, this way is preferred, because
+it is faster, allowing more reads per second. Registering such a gameport
+isn't as easy as a basic IO one, but not so much complex::
+
+ struct gameport gameport;
+
+ void my_trigger(struct gameport *gameport)
+ {
+ my_mmio = 0xff;
+ }
+
+ unsigned char my_read(struct gameport *gameport)
+ {
+ return my_mmio;
+ }
+
+ gameport.read = my_read;
+ gameport.trigger = my_trigger;
+ gameport_register_port(&gameport);
+
+.. _gameport_pgm_cooked_mode:
+
+Cooked mode gameport
+~~~~~~~~~~~~~~~~~~~~
+
+There are gameports that can report the axis values as numbers, that means
+the driver doesn't have to measure them the old way - an ADC is built into
+the gameport. To register a cooked gameport::
+
+ struct gameport gameport;
+
+ int my_cooked_read(struct gameport *gameport, int *axes, int *buttons)
+ {
+ int i;
+
+ for (i = 0; i < 4; i++)
+ axes[i] = my_mmio[i];
+ buttons[0] = my_mmio[4];
+ }
+
+ int my_open(struct gameport *gameport, int mode)
+ {
+ return -(mode != GAMEPORT_MODE_COOKED);
+ }
+
+ gameport.cooked_read = my_cooked_read;
+ gameport.open = my_open;
+ gameport.fuzz = 8;
+ gameport_register_port(&gameport);
+
+The only confusing thing here is the fuzz value. Best determined by
+experimentation, it is the amount of noise in the ADC data. Perfect
+gameports can set this to zero, most common have fuzz between 8 and 32.
+See analog.c and input.c for handling of fuzz - the fuzz value determines
+the size of a gaussian filter window that is used to eliminate the noise
+in the data.
+
+More complex gameports
+~~~~~~~~~~~~~~~~~~~~~~
+
+Gameports can support both raw and cooked modes. In that case combine either
+examples 1+2 or 1+3. Gameports can support internal calibration - see below,
+and also lightning.c and analog.c on how that works. If your driver supports
+more than one gameport instance simultaneously, use the ->private member of
+the gameport struct to point to your data.
+
+Unregistering a gameport
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+Simple::
+
+ gameport_unregister_port(&gameport);
+
+The gameport structure
+~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ struct gameport {
+
+ void *port_data;
+
+A private pointer for free use in the gameport driver. (Not the joystick
+driver!)
+
+::
+
+ char name[32];
+
+Driver's name as set by driver calling gameport_set_name(). Informational
+purpose only.
+
+::
+
+ char phys[32];
+
+gameport's physical name/description as set by driver calling gameport_set_phys().
+Informational purpose only.
+
+::
+
+ int io;
+
+I/O address for use with raw mode. You have to either set this, or ->read()
+to some value if your gameport supports raw mode.
+
+::
+
+ int speed;
+
+Raw mode speed of the gameport reads in thousands of reads per second.
+
+::
+
+ int fuzz;
+
+If the gameport supports cooked mode, this should be set to a value that
+represents the amount of noise in the data. See
+:ref:`gameport_pgm_cooked_mode`.
+
+::
+
+ void (*trigger)(struct gameport *);
+
+Trigger. This function should trigger the ns558 oneshots. If set to NULL,
+outb(0xff, io) will be used.
+
+::
+
+ unsigned char (*read)(struct gameport *);
+
+Read the buttons and ns558 oneshot bits. If set to NULL, inb(io) will be
+used instead.
+
+::
+
+ int (*cooked_read)(struct gameport *, int *axes, int *buttons);
+
+If the gameport supports cooked mode, it should point this to its cooked
+read function. It should fill axes[0..3] with four values of the joystick axes
+and buttons[0] with four bits representing the buttons.
+
+::
+
+ int (*calibrate)(struct gameport *, int *axes, int *max);
+
+Function for calibrating the ADC hardware. When called, axes[0..3] should be
+pre-filled by cooked data by the caller, max[0..3] should be pre-filled with
+expected maximums for each axis. The calibrate() function should set the
+sensitivity of the ADC hardware so that the maximums fit in its range and
+recompute the axes[] values to match the new sensitivity or re-read them from
+the hardware so that they give valid values.
+
+::
+
+ int (*open)(struct gameport *, int mode);
+
+Open() serves two purposes. First a driver either opens the port in raw or
+in cooked mode, the open() callback can decide which modes are supported.
+Second, resource allocation can happen here. The port can also be enabled
+here. Prior to this call, other fields of the gameport struct (namely the io
+member) need not to be valid.
+
+::
+
+ void (*close)(struct gameport *);
+
+Close() should free the resources allocated by open, possibly disabling the
+gameport.
+
+::
+
+ struct timer_list poll_timer;
+ unsigned int poll_interval; /* in msecs */
+ spinlock_t timer_lock;
+ unsigned int poll_cnt;
+ void (*poll_handler)(struct gameport *);
+ struct gameport *parent, *child;
+ struct gameport_driver *drv;
+ struct mutex drv_mutex; /* protects serio->drv so attributes can pin driver */
+ struct device dev;
+ struct list_head node;
+
+For internal use by the gameport layer.
+
+::
+
+ };
+
+Enjoy!