1. Introduction
Debugfs is a simple-to-use RAM-based file system, specially designed for debugging purposes.
It is provided as a simple way for kernel developers to make information available to the user space.
It is part of a pseudo filesystem. Unlike procfs, which is only meant for process information, or sysfs, which has strict one-value-per-file rules, debugfs has no rules at all.
Developers are free to put any information into debugfs.
2. Installing debugfs on your target board
Debugfs is enabled and ready to be used in all STM32MPU Embedded Software distributions, via the Linux® kernel configuration CONFIG_DEBUG_FS, set to yes by default.
Symbol: DEBUG_FS Location: Kernel Hacking ---> Compile-time checks and compiler options --> [*] Debug Filesystem
Please refer to the Menuconfig or how to configure kernel article for instructions on modifying the configuration and recompiling the Linux kernel image in the distribution package context.
3. Getting started
3.1. How to mount debugfs
Debugfs is typically mounted at /sys/kernel/debug with a command such as:
mount -t debugfs none /sys/kernel/debug
3.2. How to use debugfs in Linux kernel drivers
Debugfs is a simple way for kernel drivers to make information available to user space.
It can be manipulated using several calls from the C header file include/linux/debugfs.h , such as:
debugfs_create_file → for creating a file in the debug filesystem.
debugfs_create_dir → for creating a directory in the debug filesystem.
debugfs_create_symlink → for creating a symbolic link in the debug filesystem.
debugfs_create_u32 → for creating a file containing a single 32-bit unsigned integer value
debugfs_remove → for removing a debugfs entry from the debug filesytem.
...
For further details, refer to the Linux kernel documentation for debugfs[1].
For example, you can refer to an OpenSourceForU article: [2].
3.3. How to visualize debugfs information
On the target board, go the debugfs mount directory:
cd /sys/kernel/debug
There you will find all the debugfs entries created by Linux kernel frameworks
ls -l
drwxr-xr-x 2 root root 0 Jan 1 1970 49000000.usb-otg
drwxr-xr-x 4 root root 0 Jan 1 1970 asoc
drwxr-xr-x 40 root root 0 Jan 1 1970 bdi
drwxr-xr-x 10 root root 0 Jan 1 1970 block
drwxr-xr-x 2 root root 0 Jan 1 1970 bluetooth
drwxr-xr-x 3 root root 0 May 28 15:52 cec
drwxr-xr-x 225 root root 0 Jan 1 1970 clk
drwxr-xr-x 2 root root 0 Jan 1 1970 dma_buf
drwxr-xr-x 3 root root 0 Jan 1 1970 dri
drwxr-xr-x 2 root root 0 Jan 1 1970 dynamic_debug
drwxr-xr-x 2 root root 0 Jan 1 1970 extfrag
-rw-r--r-- 1 root root 0 Jan 1 1970 fault_around_bytes
drwxr-xr-x 3 root root 0 May 28 15:52 gc
-r--r--r-- 1 root root 0 Jan 1 1970 gpio
drwxr-xr-x 2 root root 0 Jan 1 1970 hid
drwxr-xr-x 2 root root 0 Jan 1 1970 ieee80211
drwxr-xr-x 7 root root 0 Jan 1 1970 iio
-r--r--r-- 1 root root 0 Jan 1 1970 irq_domain_mapping
drwxr-xr-x 2 root root 0 Jan 1 1970 memblock
drwxr-xr-x 3 root root 0 Jan 1 1970 mmc0
drwxr-xr-x 3 root root 0 Jan 1 1970 mmc1
drwxr-xr-x 11 root root 0 Jan 1 1970 mtd
drwxr-xr-x 4 root root 0 Jan 1 1970 pinctrl
drwxr-xr-x 4 root root 0 Jan 1 1970 pm_genpd
drwxr-xr-x 2 root root 0 Jan 1 1970 pm_qos
-r--r--r-- 1 root root 0 Jan 1 1970 pwm
drwxr-xr-x 2 root root 0 Jan 1 1970 ras
drwxr-xr-x 13 root root 0 Jan 1 1970 regmap
drwxr-xr-x 21 root root 0 Jan 1 1970 regulator
drwxr-xr-x 3 root root 0 Jan 1 1970 remoteproc
-r--r--r-- 1 root root 0 Jan 1 1970 sleep_time
drwxr-xr-x 3 root root 0 Jan 1 1970 stmmaceth
-r--r--r-- 1 root root 0 Jan 1 1970 suspend_stats
dr-xr-xr-x 3 root root 0 Jan 1 1970 tracing
drwxr-xr-x 2 root root 0 Jan 1 1970 ubi
drwxr-xr-x 2 root root 0 Jan 1 1970 ubifs
drwxr-xr-x 4 root root 0 Jan 1 1970 usb
-r--r--r-- 1 root root 0 Jan 1 1970 wakeup_sources
You can then browse to find the requested information.
Please note that the different Linux software frameworks available in STM32MP15 Linux kernel overview provide specific trace and debug information in a "How to trace and debug the framework" dedicated chapter, incuding debugfs.
Some examples:
- To list the wakeup sources:
cat /sys/kernel/debug/wakeup_sources
name active_count event_count wakeup_count expire_count active_since total_time max_time last_change prevent_suspend_time
5c002000.i2c:stpmu1@33:onkey 0 0 0 0 0 0 0 4075 0
0-0033 0 0 0 0 0 0 0 3949 0
alarmtimer 0 0 0 0 0 0 0 3901 0
5c004000.rtc 1 1 0 0 0 0 0 5246 0
deleted 0 0 0 0 0 0 0 0 0
- To obtain a summary of the clock settings:
cat /sys/kernel/debug/clk/clk_summary
clock enable_cnt prepare_cnt rate accuracy phase
----------------------------------------------------------------------------------------
ck_usbo_48m 1 1 48000000 0 0
usbo_k 1 1 48000000 0 0
ck_dsi_phy 1 1 0 0 0
dsi_k 1 1 0 0 0
i2s_ckin 0 0 0 0 0
clk-csi 1 1 4000000 0 0
ck_csi 1 1 4000000 0 0
rng2_k 0 0 4000000 0 0
rng1_k 0 0 4000000 0 0
clk-lsi 1 1 32000 0 0
ck_lsi 1 1 32000 0 0
dac12_k 0 0 32000 0 0
clk-lse 1 1 32768 0 0
ck_lse 1 1 32768 0 0
ck_rtc 2 2 32768 0 0
rtc_lsco 1 1 32768 0 0
lptim5_k 0 0 32768 0 0
lptim4_k 0 0 32768 0 0
cec_k 0 0 32768 0 0
clk-hsi 1 1 64000000 0 0
clk-hsi-div 1 1 64000000 0 0
ck_hsi 2 2 64000000 0 0
ck_mco1 0 0 64000000 0 0
uart8_k 0 0 64000000 0 0
uart7_k 0 0 64000000 0 0
uart6_k 0 0 64000000 0 0
uart5_k 0 0 64000000 0 0
uart4_k 1 1 64000000 0 0
usart3_k 0 0 64000000 0 0
usart2_k 1 1 64000000 0 0
usart1_k 0 0 64000000 0 0
i2c6_k 0 0 64000000 0 0
i2c4_k 0 0 64000000 0 0
i2c5_k 0 0 64000000 0 0
i2c3_k 0 0 64000000 0 0
i2c2_k 0 0 64000000 0 0
i2c1_k 0 0 64000000 0 0
spi6_k 0 0 64000000 0 0
spi5_k 0 0 64000000 0 0
spi4_k 0 0 64000000 0 0
clk-hse 1 1 24000000 0 0
ck_hse 7 7 24000000 0 0
ck_hse_rtc 0 0 1000000 0 0
stgen_k 1 1 24000000 0 0
usbphy_k 1 1 24000000 0 0
ck_per 1 1 24000000 0 0
adc12_k 1 1 24000000 0 0
ref4 1 1 24000000 0 0
pll4 1 1 594000000 0 0
pll4_r 0 0 74250000 0 0
pll4_q 1 1 31263158 0 0
ltdc_px 1 1 31263158 0 0
dsi_px 0 0 31263158 0 0
fdcan_k 0 0 31263158 0 0
pll4_p 0 0 74250000 0 0
ref3 1 1 24000000 0 0
pll3 2 3 786431640 0 0
pll3_r 1 1 98303955 0 0
sdmmc3_k 0 0 98303955 0 0
sdmmc2_k 1 1 98303955 0 0
sdmmc1_k 0 0 98303955 0 0
pll3_q 0 1 49151978 0 0
adfsdm_k 0 0 49151978 0 0
sai4_k 0 0 49151978 0 0
sai3_k 0 0 49151978 0 0
sai2_k 0 2 49151978 0 0
sai1_k 0 0 49151978 0 0
spi3_k 0 0 49151978 0 0
spi2_k 0 0 49151978 0 0
spi1_k 0 0 49151978 0 0
spdif_k 0 0 49151978 0 0
pll3_p 1 1 196607910 0 0
ck_mcu 6 16 196607910 0 0
dfsdm_k 0 0 196607910 0 0
gpiok 0 0 196607910 0 0
gpioj 0 0 196607910 0 0
gpioi 0 1 196607910 0 0
gpioh 0 1 196607910 0 0
gpiog 0 1 196607910 0 0
gpiof 0 1 196607910 0 0
gpioe 0 1 196607910 0 0
gpiod 0 1 196607910 0 0
gpioc 0 1 196607910 0 0
gpiob 0 1 196607910 0 0
gpioa 0 1 196607910 0 0
ipcc 2 2 196607910 0 0
hsem 0 0 196607910 0 0
crc2 0 0 196607910 0 0
rng2 0 0 196607910 0 0
hash2 0 0 196607910 0 0
cryp2 0 0 196607910 0 0
dcmi 0 0 196607910 0 0
sdmmc3 0 0 196607910 0 0
usbo 0 0 196607910 0 0
adc12 1 1 196607910 0 0
dmamux 1 1 196607910 0 0
dma2 0 0 196607910 0 0
dma1 1 1 196607910 0 0
pclk3 1 1 98303955 0 0
lptim3_k 0 0 98303955 0 0
lptim2_k 0 0 98303955 0 0
hdp 0 0 98303955 0 0
pmbctrl 0 0 98303955 0 0
tmpsens 0 0 98303955 0 0
vref 0 0 98303955 0 0
syscfg 1 1 98303955 0 0
sai4 0 0 98303955 0 0
lptim5 0 0 98303955 0 0
lptim4 0 0 98303955 0 0
lptim3 0 0 98303955 0 0
lptim2 0 0 98303955 0 0
pclk2 0 0 98303955 0 0
fdcan 0 0 98303955 0 0
dfsdm 0 0 98303955 0 0
sai3 0 0 98303955 0 0
sai2 0 0 98303955 0 0
sai1 0 0 98303955 0 0
usart6 0 0 98303955 0 0
spi5 0 0 98303955 0 0
spi4 0 0 98303955 0 0
spi1 0 0 98303955 0 0
tim17 0 0 98303955 0 0
tim16 0 0 98303955 0 0
tim15 0 0 98303955 0 0
tim8 0 0 98303955 0 0
tim1 0 0 98303955 0 0
ck2_tim 0 0 196607910 0 0
tim17_k 0 0 196607910 0 0
tim16_k 0 0 196607910 0 0
tim15_k 0 0 196607910 0 0
tim8_k 0 0 196607910 0 0
tim1_k 0 0 196607910 0 0
pclk1 0 2 98303955 0 0
lptim1_k 0 0 98303955 0 0
mdio 0 0 98303955 0 0
dac12 0 0 98303955 0 0
cec 0 0 98303955 0 0
spdif 0 0 98303955 0 0
i2c5 0 0 98303955 0 0
i2c3 0 0 98303955 0 0
i2c2 0 0 98303955 0 0
i2c1 0 0 98303955 0 0
uart8 0 0 98303955 0 0
uart7 0 0 98303955 0 0
uart5 0 0 98303955 0 0
uart4 0 0 98303955 0 0
usart3 0 0 98303955 0 0
usart2 0 0 98303955 0 0
spi3 0 0 98303955 0 0
spi2 0 1 98303955 0 0
lptim1 0 0 98303955 0 0
tim14 0 0 98303955 0 0
tim13 0 0 98303955 0 0
tim12 0 0 98303955 0 0
tim7 0 0 98303955 0 0
tim6 0 0 98303955 0 0
tim5 0 0 98303955 0 0
tim4 0 0 98303955 0 0
tim3 0 0 98303955 0 0
tim2 0 0 98303955 0 0
ck1_tim 0 1 196607910 0 0
tim14_k 0 0 196607910 0 0
tim13_k 0 0 196607910 0 0
tim12_k 0 0 196607910 0 0
tim7_k 0 0 196607910 0 0
tim6_k 0 1 196607910 0 0
tim5_k 0 0 196607910 0 0
tim4_k 0 0 196607910 0 0
tim3_k 0 0 196607910 0 0
tim2_k 0 0 196607910 0 0
ref1 2 2 24000000 0 0
pll2 2 2 533000000 0 0
pll2_r 1 1 533000000 0 0
pll2_q 0 0 533000000 0 0
gpu_k 0 0 533000000 0 0
pll2_p 1 1 266500000 0 0
ck_axi 8 9 266500000 0 0
ck_trace 0 0 133250000 0 0
ck_sys_dbg 0 0 266500000 0 0
qspi_k 0 0 266500000 0 0
fmc_k 0 0 266500000 0 0
ethstp 0 0 266500000 0 0
usbh 1 1 266500000 0 0
crc1 0 0 266500000 0 0
sdmmc2 0 0 266500000 0 0
sdmmc1 0 0 266500000 0 0
qspi 0 0 266500000 0 0
fmc 0 0 266500000 0 0
ethmac 1 1 266500000 0 0
ethrx 1 1 266500000 0 0
ethtx 1 1 266500000 0 0
gpu 0 0 266500000 0 0
mdma 1 1 266500000 0 0
bkpsram 0 0 266500000 0 0
rng1 0 0 266500000 0 0
hash1 0 0 266500000 0 0
cryp1 0 0 266500000 0 0
gpioz 0 1 266500000 0 0
tzc2 0 0 266500000 0 0
tzc1 0 0 266500000 0 0
pclk5 1 1 66625000 0 0
stgen 0 0 66625000 0 0
bsec 0 0 66625000 0 0
iwdg1 0 0 66625000 0 0
tzpc 0 0 66625000 0 0
rtcapb 2 2 66625000 0 0
usart1 0 0 66625000 0 0
i2c6 0 0 66625000 0 0
i2c4 0 0 66625000 0 0
spi6 0 0 66625000 0 0
pclk4 1 1 133250000 0 0
stgenro 0 0 133250000 0 0
usbphy 0 0 133250000 0 0
iwdg2 1 1 133250000 0 0
dsi 0 0 133250000 0 0
ltdc 0 0 133250000 0 0
pll1 1 1 650000000 0 0
pll1_p 1 1 650000000 0 0
ck_mpu 1 1 650000000 0 0
ck_mco2 0 0 650000000 0 0
clk-hse-div2 0 0 12000000 0 0
ethptp_k 0 0 0 0 0
ethck_k 0 0 0 0 0
- To obtain a summary of the regulator settings:
cat /sys/kernel/debug/regulator/regulator_summary
regulator use open bypass voltage current min max
-------------------------------------------------------------------------------
regulator-dummy 0 11 0 0mV 0mA 0mV 0mV
49000000.usb-otg 0mV 0mV
49000000.usb-otg 0mV 0mV
5a000000.dsi.0 0mV 0mV
vddcore 0 0 0 1200mV 0mA 800mV 1350mV
vdd_ddr 0 1 0 1350mV 0mA 1350mV 1350mV
vtt_ddr 0 0 0 675mV 0mA 675mV 675mV
vdd 0 1 0 3300mV 0mA 3300mV 3300mV
vref 1 1 0 2500mV 0mA 2500mV 2500mV
48003000.adc 0mV 0mV
v3v3 0 5 0 3300mV 0mA 3300mV 3300mV
0-004a 0mV 0mV
58007000.sdmmc 3300mV 3300mV
58005000.sdmmc 3300mV 3300mV
v1v8_audio 0 3 0 1800mV 0mA 1800mV 1800mV
0-004a 0mV 0mV
0-004a 0mV 0mV
0-004a 0mV 0mV
v1v2_hdmi 0 1 0 1200mV 0mA 1200mV 1200mV
0-0039 0mV 0mV
v3v3_hdmi 0 1 0 3300mV 0mA 3300mV 3300mV
0-0039 0mV 0mV
vdd_usb 2 2 0 3300mV 0mA 3300mV 3300mV
phy-5a006000.usbphyc.1 0mV 0mV
phy-5a006000.usbphyc.0 0mV 0mV
vdda 0 0 0 2900mV 0mA 2900mV 2900mV
bst_out 0 2 0 5000mV 0mA 0mV 0mV
vbus_otg 0 0 0 5000mV 0mA 0mV 0mV
vbus_sw 0 0 0 5000mV 0mA 0mV 0mV
reg11 1 1 0 1100mV 0mA 1100mV 1100mV
5a006000.usbphyc 0mV 0mV
reg18 2 2 0 1800mV 0mA 1800mV 1800mV
5a006000.usbphyc 0mV 0mV
5a000000.dsi 0mV 0mV
usb33 1 1 0 3300mV 0mA 3300mV 3300mV
49000000.usb-otg 0mV 0mV
vref_ddr 0 0 0 675mV 0mA 0mV 0mV
- To list the pin control settings:
cat /sys/kernel/debug/pinctrl/soc\:pin-controller@50002000/pinconf-pins
Pin config settings per pin
Format: pin (name): configs
pin 0 (PA0): analog
pin 1 (PA1): alternate 11 (ETH1_GMII_RX_CLK ETH1_MII_RX_CLK ETH1_RGMII_RX_CLK ETH1_RMII_REF_CLK) - push pull - floating - low speed
pin 2 (PA2): alternate 11 (ETH1_MDIO) - push pull - floating - very high speed
pin 3 (PA3): alternate 14 (LCD_B5) - push pull - floating - high speed
pin 4 (PA4): analog
pin 5 (PA5): analog
pin 6 (PA6): analog
pin 7 (PA7): alternate 11 (ETH1_GMII_RX_DV ETH1_MII_RX_DV ETH1_RGMII_RX_CTL ETH1_RMII_CRS_DV) - push pull - floating - low speed
pin 8 (PA8): analog
pin 9 (PA9): analog
pin 10 (PA10): output - high - push pull - floating - low speed
pin 11 (PA11): analog
pin 12 (PA12): analog
pin 13 (PA13): output - low - open drain - floating - very high speed
pin 14 (PA14): input - high - floating
pin 15 (PA15): analog
pin 16 (PB0): alternate 11 (ETH1_GMII_RXD2 ETH1_MII_RXD2 ETH1_RGMII_RXD2) - push pull - floating - low speed
pin 17 (PB1): alternate 11 (ETH1_GMII_RXD3 ETH1_MII_RXD3 ETH1_RGMII_RXD3) - push pull - floating - low speed
pin 18 (PB2): alternate 8 (UART4_RX) - push pull - floating - low speed
pin 19 (PB3): alternate 9 (SDMMC2_D2) - push pull - pull up - very high speed
pin 20 (PB4): alternate 9 (SDMMC2_D3) - push pull - pull up - very high speed
pin 21 (PB5): analog
pin 22 (PB6): alternate 5 (CEC) - open drain - floating - low speed
pin 23 (PB7): analog
pin 24 (PB8): alternate 14 (LCD_B6) - push pull - floating - high speed
pin 25 (PB9): analog
pin 26 (PB10): analog
pin 27 (PB11): alternate 11 (ETH1_GMII_TX_EN ETH1_MII_TX_EN ETH1_RGMII_TX_CTL ETH1_RMII_TX_EN) - push pull - floating - very high speed
pin 28 (PB12): analog
pin 29 (PB13): analog
pin 30 (PB14): alternate 9 (SDMMC2_D0) - push pull - pull up - very high speed
pin 31 (PB15): alternate 9 (SDMMC2_D1) - push pull - pull up - very high speed
pin 32 (PC0): alternate 14 (LCD_R5) - push pull - floating - high speed
pin 33 (PC1): alternate 11 (ETH1_MDC) - push pull - floating - very high speed
pin 34 (PC2): alternate 11 (ETH1_GMII_TXD2 ETH1_MII_TXD2 ETH1_RGMII_TXD2) - push pull - floating - very high speed
pin 35 (PC3): analog
pin 36 (PC4): alternate 11 (ETH1_GMII_RXD0 ETH1_MII_RXD0 ETH1_RGMII_RXD0 ETH1_RMII_RXD0) - push pull - floating - low speed
pin 37 (PC5): alternate 11 (ETH1_GMII_RXD1 ETH1_MII_RXD1 ETH1_RGMII_RXD1 ETH1_RMII_RXD1) - push pull - floating - low speed
pin 38 (PC6): analog
pin 39 (PC7): analog
pin 40 (PC8): analog
pin 41 (PC9): analog
pin 42 (PC10): analog
pin 43 (PC11): analog
pin 44 (PC12): analog
pin 45 (PC13): analog
pin 46 (PC14): analog
pin 47 (PC15): analog
pin 48 (PD0): analog
pin 49 (PD1): analog
pin 50 (PD2): analog
pin 51 (PD3): alternate 7 (USART2_CTS USART2_NSS) - push pull - floating - low speed
pin 52 (PD4): alternate 7 (USART2_RTS USART2_DE) - push pull - floating - very high speed
pin 53 (PD5): alternate 7 (USART2_TX) - push pull - floating - very high speed
pin 54 (PD6): alternate 7 (USART2_RX) - push pull - floating - low speed
pin 55 (PD7): analog
pin 56 (PD8): alternate 14 (LCD_B7) - push pull - floating - high speed
pin 57 (PD9): alternate 14 (LCD_B0) - push pull - floating - high speed
pin 58 (PD10): alternate 14 (LCD_B3) - push pull - floating - high speed
pin 59 (PD11): output - low - push pull - floating - low speed
pin 60 (PD12): alternate 5 (I2C1_SCL) - open drain - floating - low speed
pin 61 (PD13): analog
pin 62 (PD14): analog
pin 63 (PD15): analog
pin 64 (PE0): alternate 10 (SAI2_MCLK_A) - push pull - floating - high speed
pin 65 (PE1): analog
pin 66 (PE2): alternate 11 (ETH1_GMII_TXD3 ETH1_MII_TXD3 ETH1_RGMII_TXD3) - push pull - floating - very high speed
pin 67 (PE3): alternate 9 (SDMMC2_CK) - push pull - pull up - very high speed
pin 68 (PE4): output - high - push pull - floating - low speed
pin 69 (PE5): alternate 14 (LCD_G0) - push pull - floating - high speed
pin 70 (PE6): alternate 14 (LCD_G1) - push pull - floating - high speed
pin 71 (PE7): analog
pin 72 (PE8): analog
pin 73 (PE9): analog
pin 74 (PE10): analog
pin 75 (PE11): analog
pin 76 (PE12): analog
pin 77 (PE13): analog
pin 78 (PE14): analog
pin 79 (PE15): alternate 14 (LCD_R7) - push pull - floating - high speed
pin 80 (PF0): analog
pin 81 (PF1): analog
pin 82 (PF2): input - high - floating
pin 83 (PF3): analog
pin 84 (PF4): analog
pin 85 (PF5): analog
pin 86 (PF6): analog
pin 87 (PF7): analog
pin 88 (PF8): analog
pin 89 (PF9): analog
pin 90 (PF10): alternate 14 (LCD_DE) - push pull - floating - high speed
pin 91 (PF11): alternate 10 (SAI2_SD_B) - push pull - floating - low speed
pin 92 (PF12): analog
pin 93 (PF13): analog
pin 94 (PF14): analog
pin 95 (PF15): alternate 5 (I2C1_SDA) - open drain - floating - low speed
pin 96 (PG0): analog
pin 97 (PG1): input - high - floating
pin 98 (PG2): analog
pin 99 (PG3): analog
pin 100 (PG4): alternate 11 (ETH1_GMII_GTX_CLK ETH1_RGMII_GTX_CLK) - push pull - floating - very high speed
pin 101 (PG5): alternate 11 (ETH1_GMII_CLK125 ETH1_RGMII_CLK125) - push pull - floating - very high speed
pin 102 (PG6): alternate 10 (SDMMC2_CMD) - push pull - pull up - very high speed
pin 103 (PG7): alternate 14 (LCD_CLK) - push pull - floating - high speed
pin 104 (PG8): analog
pin 105 (PG9): output - high - push pull - floating - low speed
pin 106 (PG10): alternate 14 (LCD_B2) - push pull - floating - high speed
pin 107 (PG11): alternate 6 (UART4_TX) - push pull - floating - low speed
pin 108 (PG12): alternate 14 (LCD_B1) - push pull - floating - high speed
pin 109 (PG13): alternate 11 (ETH1_GMII_TXD0 ETH1_MII_TXD0 ETH1_RGMII_TXD0 ETH1_RMII_TXD0) - push pull - floating - very high speed
pin 110 (PG14): alternate 11 (ETH1_GMII_TXD1 ETH1_MII_TXD1 ETH1_RGMII_TXD1 ETH1_RMII_TXD1) - push pull - floating - very high speed
pin 111 (PG15): analog
pin 112 (PH0): analog
pin 113 (PH1): analog
pin 114 (PH2): alternate 14 (LCD_R0) - push pull - floating - high speed
pin 115 (PH3): alternate 14 (LCD_R1) - push pull - floating - high speed
pin 116 (PH4): output - high - push pull - floating - low speed
pin 117 (PH5): analog
pin 118 (PH6): analog
pin 119 (PH7): analog
pin 120 (PH8): alternate 14 (LCD_R2) - push pull - floating - high speed
pin 121 (PH9): alternate 14 (LCD_R3) - push pull - floating - high speed
pin 122 (PH10): alternate 14 (LCD_R4) - push pull - floating - high speed
pin 123 (PH11): analog
pin 124 (PH12): alternate 14 (LCD_R6) - push pull - floating - high speed
pin 125 (PH13): alternate 14 (LCD_G2) - push pull - floating - high speed
pin 126 (PH14): alternate 14 (LCD_G3) - push pull - floating - high speed
pin 127 (PH15): alternate 14 (LCD_G4) - push pull - floating - high speed
pin 128 (PI0): alternate 14 (LCD_G5) - push pull - floating - high speed
pin 129 (PI1): alternate 14 (LCD_G6) - push pull - floating - high speed
pin 130 (PI2): alternate 14 (LCD_G7) - push pull - floating - high speed
pin 131 (PI3): analog
pin 132 (PI4): alternate 14 (LCD_B4) - push pull - floating - high speed
pin 133 (PI5): alternate 10 (SAI2_SCK_A) - push pull - floating - medium speed
pin 134 (PI6): alternate 10 (SAI2_SD_A) - push pull - floating - medium speed
pin 135 (PI7): alternate 10 (SAI2_FS_A) - push pull - floating - medium speed
pin 136 (PI8): analog
pin 137 (PI9): alternate 14 (LCD_VSYNC) - push pull - floating - high speed
pin 138 (PI10): alternate 14 (LCD_HSYNC) - push pull - floating - high speed
pin 139 (PI11): analog
- To obtain the GPIO settings:
cat /sys/kernel/debug/gpio
gpiochip0: GPIOs 0-15, parent: platform/soc:pin-controller@50002000, GPIOA:
gpio-10 ( |reset ) out lo
gpiochip1: GPIOs 16-31, parent: platform/soc:pin-controller@50002000, GPIOB:
gpiochip2: GPIOs 32-47, parent: platform/soc:pin-controller@50002000, GPIOC:
gpiochip3: GPIOs 48-63, parent: platform/soc:pin-controller@50002000, GPIOD:
gpio-59 ( |heartbeat ) out lo
gpiochip4: GPIOs 64-79, parent: platform/soc:pin-controller@50002000, GPIOE:
gpio-68 ( |reset ) out hi
gpiochip5: GPIOs 80-95, parent: platform/soc:pin-controller@50002000, GPIOF:
gpiochip6: GPIOs 96-111, parent: platform/soc:pin-controller@50002000, GPIOG:
gpio-105 ( |reset ) out hi
gpiochip7: GPIOs 112-127, parent: platform/soc:pin-controller@50002000, GPIOH:
gpio-116 ( |reset ) out hi
gpiochip8: GPIOs 128-143, parent: platform/soc:pin-controller@50002000, GPIOI:
gpiochip9: GPIOs 400-415, parent: platform/soc:pin-controller-z@54004000, GPIOZ:
4. To go further
4.1. Regmap (register map) cache
Debugfs contains a register cache (mirror) for drivers/peripherals based on regmap API[3].
Regmap is a register map abstraction API of the Linux kernel. It is mainly used for serial bus device drivers (I2C and SPI), but can also be used for internal peripheral drivers.
Many of these drivers contain some very similar code for accessing connected-hardware device registers.
The regmap kernel API proposes a solution which factors out this code from the drivers, saving code and making it much easier to share infrastructure.
- Path of the regmap register cache in debugfs
cd /sys/kernel/debug/regmap
- List of devices for which drivers are based on regmap API:
ls -la .
total 0
drwxr-xr-x 18 root root 0 Jan 1 1970 .
drwx------ 32 root root 0 Jan 1 1970 ..
drwxr-xr-x 2 root root 0 Jan 1 1970 0-001b
drwxr-xr-x 2 root root 0 Jan 1 1970 0-0042
drwxr-xr-x 2 root root 0 Jan 1 1970 2-0033
drwxr-xr-x 2 root root 0 Jan 1 1970 40004000.timer
drwxr-xr-x 2 root root 0 Jan 1 1970 4000d000.audio-controller
drwxr-xr-x 2 root root 0 Nov 30 12:19 40016000.cec
drwxr-xr-x 2 root root 0 Jan 1 1970 40017000.dac
drwxr-xr-x 2 root root 0 Jan 1 1970 4400b004.audio-controller
drwxr-xr-x 2 root root 0 Jan 1 1970 4400b024.audio-controller
drwxr-xr-x 2 root root 0 Jan 1 1970 4400d000.dfsdm
drwxr-xr-x 2 root root 0 Jan 1 1970 50027004.audio-controller
drwxr-xr-x 2 root root 0 Jan 1 1970 dummy-interrupt-controller@5000d000
drwxr-xr-x 2 root root 0 Jan 1 1970 dummy-pwr@50001000
drwxr-xr-x 2 root root 0 Jan 1 1970 dummy-rcc@50000000
drwxr-xr-x 2 root root 0 Jan 1 1970 dummy-syscon@50020000
drwxr-xr-x 2 root root 0 Jan 1 1970 dummy-tamp@5c00a000
- Check for the corresponding driver: example for 2-0033 regmap entry
cat 2-0033/name
stpmic1
Then, on the STM32MPU device tree files, you can check for the device, and the corresponding driver
pmic: stpmic@33 { compatible = "st,stpmic1"; reg = <0x33>; interrupts-extended = <&exti_pwr 55 IRQ_TYPE_EDGE_FALLING>; interrupt-controller; #interrupt-cells = <2>; status = "okay";
- Regmap entries stating by dummy-
This kind of entry is set when there are no associated /dev entries (devtmpfs).
To find the corresponding node in the device tree, you can look for the suffix name after dummy-:
Example for dummy-interrupt-controller@5000d000
exti: interrupt-controller@5000d000 { compatible = "st,stm32mp1-exti", "syscon"; interrupt-controller; #interrupt-cells = <2>; reg = <0x5000d000 0x400>; };
- List of registers: example for 2-0033 regmap entry
cat 2-0033/registers 01: 10 02: 00 03: 00 04: 00 05: 60 06: 10 10: 04 11: 00 12: 00 13: 00 14: 00 15: c0 16: 00 17: 00 18: 04 19: 00 1a: 00 1b: 00 1c: 00 1d: 0f 1e: 04 20: 61 21: 79 22: d9 23: d9 24: 01 25: 51 26: 4c 27: 7d 28: 01 29: 51 2a: 25 30: 61 31: 50 32: d9 33: d9 34: 00 35: 24 36: 24 37: 24 38: 01 39: 51 3a: 04 40: 35 50: 00 51: 00 52: 00 53: 80 60: 00 61: 00 62: 00 63: 00 70: 00 71: 00 72: 00 73: 00 80: fc 81: 8f 82: c4 83: cf 90: fc 91: 8f 92: c4 93: cf a0: 03 a1: 70 a2: 3b a3: 00 b0: 00 b1: 00 b2: 00 b3: 80
The first column representes the register address, and the second column the register value.
For register definitions, please refer to the device specification.
5. References
- Useful external links
| Document link | Document Type | Description |
|---|---|---|
| Wikipedia debugfs | Standard | Wikipedia |
| Guide to debugfs | Standard | Guide |
| regmap: Reducing the Redundancy in Linux Code | Article | Guide |