kernel/drivers/counter/counter-sysfs.c, branch 0x221E-v0.0.1-v6.19

counter: i8254: Introduce the Intel 8254 interface library module

2023-06-08T14:11:17Z

Exposes consumer library functions providing support for interfaces compatible with the venerable Intel 8254 Programmable Interval Timer (PIT). The Intel 8254 PIT first appeared in the early 1980s and was used initially in IBM PC compatibles. The popularity of the original Intel 825x family of chips led to many subsequent variants and clones of the interface in various chips and integrated circuits. Although still popular, interfaces compatible with the Intel 8254 PIT are nowdays typically found embedded in larger VLSI processing chips and FPGA components rather than as discrete ICs. A CONFIG_I8254 Kconfig option is introduced by this patch. Modules wanting access to these i8254 library functions should select this Kconfig option, and import the I8254 symbol namespace. Link: https://lore.kernel.org/r/f6fe32c2db9525d816ab1a01f45abad56c081652.1681665189.git.william.gray@linaro.org/ Signed-off-by: William Breathitt Gray

counter: Introduce the COUNTER_COMP_ARRAY component type

2022-09-30T12:32:35Z

The COUNTER_COMP_ARRAY Counter component type is introduced to enable support for Counter array components. With Counter array components, exposure for buffers on counter devices can be defined via new Counter array component macros. This should simplify code for driver authors who would otherwise need to define individual Counter components for each array element. Eight Counter array component macros are introduced:: DEFINE_COUNTER_ARRAY_U64(_name, _length) DEFINE_COUNTER_ARRAY_CAPTURE(_name, _length) DEFINE_COUNTER_ARRAY_POLARITY(_name, _enums, _length) COUNTER_COMP_DEVICE_ARRAY_U64(_name, _read, _write, _array) COUNTER_COMP_COUNT_ARRAY_U64(_name, _read, _write, _array) COUNTER_COMP_SIGNAL_ARRAY_U64(_name, _read, _write, _array) COUNTER_COMP_ARRAY_CAPTURE(_read, _write, _array) COUNTER_COMP_ARRAY_POLARITY(_read, _write, _array) Eight Counter array callbacks are introduced as well:: int (*signal_array_u32_read)(struct counter_device *counter, struct counter_signal *signal, size_t idx, u32 *val); int (*signal_array_u32_write)(struct counter_device *counter, struct counter_signal *signal, size_t idx, u32 val); int (*device_array_u64_read)(struct counter_device *counter, size_t idx, u64 *val); int (*count_array_u64_read)(struct counter_device *counter, struct counter_count *count, size_t idx, u64 *val); int (*signal_array_u64_read)(struct counter_device *counter, struct counter_signal *signal, size_t idx, u64 *val); int (*device_array_u64_write)(struct counter_device *counter, size_t idx, u64 val); int (*count_array_u64_write)(struct counter_device *counter, struct counter_count *count, size_t idx, u64 val); int (*signal_array_u64_write)(struct counter_device *counter, struct counter_signal *signal, size_t idx, u64 val); Driver authors can handle reads/writes for an array component by receiving an element index via the `idx` parameter and processing the respective value via the `val` parameter. For example, suppose a driver wants to expose a Count's read-only capture buffer of four elements using a callback `foobar_capture_read()`:: DEFINE_COUNTER_ARRAY_CAPTURE(foobar_capture_array, 4); COUNTER_COMP_ARRAY_CAPTURE(foobar_capture_read, NULL, foobar_capture_array) Respective sysfs attributes for each array element would appear for the respective Count: * /sys/bus/counter/devices/counterX/countY/capture0 * /sys/bus/counter/devices/counterX/countY/capture1 * /sys/bus/counter/devices/counterX/countY/capture2 * /sys/bus/counter/devices/counterX/countY/capture3 If a user tries to read _capture2_ for example, `idx` will be `2` when passed to the `foobar_capture_read()` callback, and thus the driver knows which array element to handle. Counter arrays for polarity elements can be defined in a similar manner as u64 elements:: const enum counter_signal_polarity foobar_polarity_states[] = { COUNTER_SIGNAL_POLARITY_POSITIVE, COUNTER_SIGNAL_POLARITY_NEGATIVE, }; DEFINE_COUNTER_ARRAY_POLARITY(foobar_polarity_array, foobar_polarity_states, 4); COUNTER_COMP_ARRAY_POLARITY(foobar_polarity_read, foobar_polarity_write, foobar_polarity_array) Tested-by: Julien Panis Link: https://lore.kernel.org/r/5310c22520aeae65b1b74952419f49ac4c8e1ec1.1664204990.git.william.gray@linaro.org/ Signed-off-by: William Breathitt Gray Link: https://lore.kernel.org/r/a51fd608704bdfc5a0efa503fc5481df34241e0a.1664318353.git.william.gray@linaro.org Signed-off-by: Greg Kroah-Hartman

counter: Consolidate Counter extension sysfs attribute creation

2022-09-30T12:32:35Z

Counter extensions are handled for the Device, Counts, and Signals. The code loops through each Counter extension and creates the expected sysfs attributes. This patch consolidates that code into functions to reduce redundancy and make the intention of the code clearer. Link: https://lore.kernel.org/r/6f2121cf52073028c119dbf981a8b72f3eb625d2.1664204990.git.william.gray@linaro.org/ Signed-off-by: William Breathitt Gray Link: https://lore.kernel.org/r/0469c3ae3fbccbca908993c78d94f221761a6a3a.1664318353.git.william.gray@linaro.org Signed-off-by: Greg Kroah-Hartman

counter: Introduce the Signal polarity component

2022-09-30T12:32:35Z

The Signal polarity component represents the active level of a respective Signal. There are two possible states: positive (rising edge) and negative (falling edge); enum counter_signal_polarity represents these states. A convenience macro COUNTER_COMP_POLARITY() is provided for driver authors to declare a Signal polarity component. Cc: Julien Panis Link: https://lore.kernel.org/r/8f47d6e1db71a11bb1e2666f8e2a6e9d256d4131.1664204990.git.william.gray@linaro.org/ Signed-off-by: William Breathitt Gray Link: https://lore.kernel.org/r/b6e53438badcb6318997d13dd2fc052f97d808ac.1664318353.git.william.gray@linaro.org Signed-off-by: Greg Kroah-Hartman

counter: Stop using dev_get_drvdata() to get the counter device

2022-03-15T18:24:13Z

dev_get_drvdata() returns NULL since commit b56346ddbd82 ("counter: Use container_of instead of drvdata to track counter_device") which wrongly claimed there were no users of drvdata. Convert to container_of() to fix a null pointer dereference. Reported-by: Oleksij Rempel Fixes: b56346ddbd82 ("counter: Use container_of instead of drvdata to track counter_device") Signed-off-by: Uwe Kleine-König Tested-by: Jarkko Nikula Link: https://lore.kernel.org/all/20220204082556.370348-1-u.kleine-koenig@pengutronix.de/ Signed-off-by: William Breathitt Gray Link: https://lore.kernel.org/r/4a14311a3b935b62b33e665a97ecaaf2f078228a.1646957732.git.vilhelm.gray@gmail.com Signed-off-by: Greg Kroah-Hartman

counter: Fix use-after-free race condition for events_queue_size write

2021-10-21T11:02:47Z

A race condition is possible when writing to events_queue_size where the events kfifo is freed during the execution of a kfifo_in(), resulting in a use-after-free. This patch prevents such a scenario by protecting the events queue in operation with a spinlock and locking before performing the events queue size adjustment. The existing events_lock mutex is renamed to events_out_lock to reflect that it only protects events queue out operations. Because the events queue in operations can occur in an interrupt context, a new events_in_lock spinlock is introduced and utilized. Fixes: feff17a550c7 ("counter: Implement events_queue_size sysfs attribute") Cc: David Lechner Signed-off-by: William Breathitt Gray Link: https://lore.kernel.org/r/20211021103540.955639-1-vilhelm.gray@gmail.com Signed-off-by: Greg Kroah-Hartman

counter: Cleanup lingering atomic.h includes

2021-10-21T11:02:45Z

With the removal of the chrdev_lock atomic flag, the counter-sysfs.c and counter-chrdev.c no longer needs to include the atomic.h header file. Signed-off-by: William Breathitt Gray Link: https://lore.kernel.org/r/20211021103514.955622-1-vilhelm.gray@gmail.com Signed-off-by: Greg Kroah-Hartman

counter: drop chrdev_lock

2021-10-19T09:36:28Z

This removes the chrdev_lock from the counter subsystem. This was intended to prevent opening the chrdev more than once. However, this doesn't work in practice since userspace can duplicate file descriptors and pass file descriptors to other processes. Since this protection can't be relied on, it is best to just remove it. Suggested-by: Greg KH Acked-by: William Breathitt Gray Signed-off-by: David Lechner Link: https://lore.kernel.org/r/20211017185521.3468640-1-david@lechnology.com Signed-off-by: Greg Kroah-Hartman

counter/counter-sysfs: use sysfs_emit everywhere

2021-10-19T07:40:49Z

In the counter subsystem, we are already using sysfs_emit(), but there were a few places where we were still using sprintf() in *_show() functions. For consistency and added protections, use sysfs_emit() everywhere. Suggested-by: Greg KH Acked-by: William Breathitt Gray Signed-off-by: David Lechner Link: https://lore.kernel.org/r/20211017190106.3472645-1-david@lechnology.com Signed-off-by: Greg Kroah-Hartman

counter: Implement events_queue_size sysfs attribute

2021-10-17T09:55:01Z

The events_queue_size sysfs attribute provides a way for users to dynamically configure the Counter events queue size for the Counter character device interface. The size is in number of struct counter_event data structures. The number of elements will be rounded-up to a power of 2 due to a requirement of the kfifo_alloc function called during reallocation of the queue. Cc: Oleksij Rempel Signed-off-by: William Breathitt Gray Link: https://lore.kernel.org/r/c914b2db2ea0a2637633bcc3e86ded3c94783f2e.1632884256.git.vilhelm.gray@gmail.com Signed-off-by: Jonathan Cameron