ath10k/ath11k/ath12k Coding Style#
Introduction#
This is the coding style document for ath10k, ath11k and ath12k drivers. Read this before writing any code.
Tools#
Use latest GCC which you can download from crosstool. Setting it up is easy, unpack it to a directory and create a GNUmakefile in Linux sources top-level directory:
ARCH=x86
CROSS_COMPILE=/opt/cross/gcc-13.2.0-nolibc/x86_64-linux/bin/x86_64-linux-
export ARCH
export CROSS_COMPILE
include Makefile
You will need the latest sparse from git. Linux distros usually have too old sparse and you will see wrong errors!
Checking code#
For checking the code we have dedicated scripts for each driver:
They run various tests, including sparse and checkpatch. Run the script
with --help to see the installation and usage instructions.
--version shows version information for all dependencies, include
that when reporting a problem.
It is required to run the check script before submitting patches as it can catch common problems. There must not be any warnings!
An example how to run the script:
~$ cd ~/ath
~/ath$ ls
arch/ debian/ include/ lib/ Module.symvers sound/
block/ Documentation/ init/ localversion-wireless-testing net/ tools/
certs/ drivers/ ipc/ localversion-wireless-testing-ath README usr/
COPYING firmware/ Kbuild MAINTAINERS samples/ virt/
CREDITS fs/ Kconfig Makefile scripts/ vmlinux-gdb.py@
crypto/ GNUmakefile kernel/ mm/ security/
~/ath$ ath10k-check
drivers/net/wireless/ath/ath10k/debug.h:207: return is not a function, parentheses are not required
drivers/net/wireless/ath/ath10k/debug.h:209: return is not a function, parentheses are not required
drivers/net/wireless/ath/ath10k/debug.h:210: return is not a function, parentheses are not required
drivers/net/wireless/ath/ath10k/debug.h:214: Alignment should match open parenthesis
drivers/net/wireless/ath/ath10k/debug.h:218: Alignment should match open parenthesis
drivers/net/wireless/ath/ath10k/debug.c:2430: code indent should use tabs where possible
drivers/net/wireless/ath/ath10k/debug.c:2430: please, no spaces at the start of a line
drivers/net/wireless/ath/ath10k/debug.c:2431: code indent should use tabs where possible
drivers/net/wireless/ath/ath10k/debug.c:2431: please, no spaces at the start of a line
drivers/net/wireless/ath/ath10k/debug.c:2464: code indent should use tabs where possible
drivers/net/wireless/ath/ath10k/debug.c:2464: please, no spaces at the start of a line
drivers/net/wireless/ath/ath10k/debug.c:2465: code indent should use tabs where possible
drivers/net/wireless/ath/ath10k/debug.c:2465: please, no spaces at the start of a line
drivers/net/wireless/ath/ath10k/debug.c:2493: Please don't use multiple blank lines
drivers/net/wireless/ath/ath10k/debug.c:2525: Symbolic permissions 'S_IRUSR' are not preferred. Consider using octal permissions '0400'.
drivers/net/wireless/ath/ath10k/debug.c:2527: Symbolic permissions 'S_IRUSR' are not preferred. Consider using octal permissions '0400'.
drivers/net/wireless/ath/ath10k/debug.c:2620: Alignment should match open parenthesis
drivers/net/wireless/ath/ath10k/debug.c:2640: Alignment should match open parenthesis
~/ath$
Linux coding style#
ath10k/ath11k/ath12k mostly follows Linux Coding Style, so read that first.
Status/error variables#
Use a variable named “ret” to store return values or status codes. Also propagate the error code to upper levels.
Example:
int ret;
ret = request_firmware(&fw_entry, filename, ar->dev);
if (ret) {
ath10k_warn("Failed to request firmware '%s': %d\n",
filename, ret);
return ret;
}
return 0;
Name context variables either “ar” or “ar_<hifname>”. Use ath10k_<hifname>_priv() to get access to hif specific context.
Examples:
struct ath10k *ar = ptr;
struct ath10k_pci *ar_pci = ath10k_pci_priv(ar);
For consistency always use the main context (struct ath10k *ar) as function parameter, don’t use hif specific context.
Error path#
Use goto labels err_<action> for handing error path, with <action> giving a clear idea what the label does.
Example:
ret = ath10k_hif_power_on(ar);
if (ret)
return ret;
ret = ath10k_target_start(ar);
if (ret)
goto err_power_off;
ret = ath10k_init_upload(ar);
if (ret)
goto err_target_stop;
return 0;
err_target_stop:
ath10k_target_stop(ar);
err_power_off:
ath10k_hif_power_off(ar);
return ret;
Print error codes after a colon:
ath10k_warn("failed to associate peer STA %pM: %d\n",
sta->addr, ret);
Try to start the warning messages with the verb “failed” if possible. Warning and error messages start with lower case.
ath10k_warn() is used for errors where it might be possible to recover and ath10k_err() for errors when it’s not possible to recover in any way.
Dan Carpenter’s post about error paths: https://staticthinking.wordpress.com/2022/04/28/free-the-last-thing-style/
Locking#
Always document what spinlock/mutex/rcu actually protects. Locks should always protect data, not code flow.
Naming#
Name of symbols and functions follow style <drivername>_<filename>_<symbolname>.
Example:
int ath10k_mac_start(struct ath10k *ar)
For each component use function names create/destroy for allocating and freeing something, register/unregister for initializing and cleaning up them afterwards and start/stop to temporarily pause something.
Example:
int ath10k_cfg80211_create(struct ath10k *ar)
int ath10k_cfg80211_register(struct ath10k *ar)
int ath10k_cfg80211_start(struct ath10k *ar)
void ath10k_cfg80211_stop(struct ath10k *ar)
int ath10k_cfg80211_unregister(struct ath10k *ar)
void ath10k_cfg80211_destroy(struct ath10k *ar)
Error messages#
For warning and error messages we have ath10k_warn() and ath10k_err().
ath10k_warn() should be used when ath10k still continues to work, for example then some limit has been reached or an unknown event has been received. It’s also rate limited.
ath10k_err() should be used when a fatal error has been detected and ath10k will shut itself down, for example during driver initialization or firmware recover fails. It is NOT rate limited.
Examples:
ath10k_warn(ar, "failed to submit frame %d: %d\n", frame_index, ret);
ath10k_err(ar, "failed to wake up the device from sleep: %d\n", ret);
Debug messages#
Use ath10k_dbg() or ath10k_dbg_dump().
The format string for ath10k_dbg() should start with debug level followed by name of the command or event and then parameters. All lowercase and no commas, colons or periods.
Examples:
ath10k_dbg(ar, ATH10K_DBG_BOOT, "boot suspend complete\n");
ath10k_dbg(ar, ATH10K_DBG_WMI, "wmi mgmt tx skb %pK len %d ftype %02x stype %02x\n",
msdu, skb->len, fc & IEEE80211_FCTL_FTYPE,
fc & IEEE80211_FCTL_STYPE);
ath10k_dbg(ar, ATH10K_DBG_MAC, "mac update sta %pM peer bw %d\n",
sta->addr, bw);
Things NOT to do#
Don’t use void pointers.
Don’t use typedef.
Comments#
Multiline comment style is: