# I2C
Source: [https://docs.qualcomm.com/doc/80-70030-8/topic/i2c.html](https://docs.qualcomm.com/doc/80-70030-8/topic/i2c.html)
Interintegrated circuit (I2C) is a bidirectional 2-wire bus for an efficient inter‑IC
control bus developed by Philips in the 1980s. Every device on the bus has its own
unique address (registered with the I2C general body headed by Philips). The I2C core
supports a multicontroller mode and 10‑bit target address and 10‑bit extendable address.
For more information about I2C, see [https://www.i2c-bus.org/fileadmin/ftp/i2c_bus_specification_1995.pdf](https://www.i2c-bus.org/fileadmin/ftp/i2c_bus_specification_1995.pdf).
### I2C communication sequence overview
The following figure shows the communication sequence between the controller and
targets in I2C.
Figure : I2C controller and target communication sequence
For example, no device can use 1111-0XX listed in the I2C specification and
high-speed mode with 3.4 MHz clock frequency.
Following are the I2C modes and supported speeds.
- Standard mode: 100 kbps
- Fast mode: 400 kbps
- Fast mode plus: 1 Mbps
The maximum supported bandwidth is 1 MHz.
### I2C data packet format
The controller sends a 7‑bit or 10‑bit address as shown in the following figure.
Along with the address, a 1‑bit read/write indicating the type of operation is also
sent. Data is transferred in sequences of 8 bits placed on an SDA line. For every
byte transferred, the device receiving the data sends back an ACK bit (totaling nine
clock pulses).
- ACK bit LOW: receives the data and is ready to accept the next byte.
- ACK bit HIGH: receives the data and can't accept further data. The
controller then terminates the transmission with the STOP sequence.
Figure : I2C data packet
### I2C sequences
When the SCL is high, the SDA must remain stable and can't change. Only when the
clock line is low can the data line change. However, there are two exceptions: START
and STOP sequences.
Figure : I2C sequence
## I2C features
Source: [https://docs.qualcomm.com/doc/80-70030-8/topic/i2c.html](https://docs.qualcomm.com/doc/80-70030-8/topic/i2c.html)
This section explains the I2C serial engine transfer modes and the different scenarios
where each mode is used. The following table lists the transfer modes enabled in the
various I2C subsystem drivers.
| Subsystem | Transfer mode | Description |
| --- | --- | --- |
| Linux |
FIFO (low speed)
CPU DMA (high speed)
GSI
|
Supports 100 kHz, 400 kHz, and 1000 kHz bus speeds
Supports 7‑bit target address according to the I2C specification
Supports 100 kHz, 400 kHz, and 1000 kHz bus speeds
Supports 7‑bit target address according to the I2C specification
|
| Boot | FIFO |
Supports 100 kHz, 400 kHz, and 1000 kHz bus speeds
Supports 7‑bit target address according to the I2C specification
Supports 100 kHz, 400 kHz, and 1000 kHz bus speeds
Supports 7‑bit target address according to the I2C specification
|
| aDSP/Qualcomm TEE/SDC | FIFO |
Supports 100 kHz, 400 kHz, and 1000 kHz bus speeds
Supports 7‑bit target address according to the I2C specification
Supports 100 kHz, 400 kHz, and 1000 kHz bus speeds
Supports 7‑bit target address according to the I2C specification
|
| | | |
| | | |
## I2C interface components
Source: [https://docs.qualcomm.com/doc/80-70030-8/topic/i2c.html](https://docs.qualcomm.com/doc/80-70030-8/topic/i2c.html)
This section provides information about the subsystem driver, kernel device tree nodes,
and related documentation.
Table : I2C interface: Linux
| File type | Description |
| --- | --- |
| Device tree source |
QUP v3 serial engine: /firmware/qualcomm-linux-spf-1-0_ap_standard_oem_nomodem/BOOT.MXF.1.0.c1/boot_images/boot/Settings/Soc/<chipset>/Core/Buses/qup_common/<chipset>-qupv3.dtsi
|
### I2C APIs
Source: [https://docs.qualcomm.com/doc/80-70030-8/topic/i2c.html](https://docs.qualcomm.com/doc/80-70030-8/topic/i2c.html)
I2C APIs for the following subsystems are listed in this section.
- Linux:
- [https://github.com/torvalds/linux/blob/master/include/linux/i2c.h](https://github.com/torvalds/linux/blob/master/include/linux/i2c.h).
- [https://github.com/torvalds/linux/blob/master/include/linux/i2c-dev.h](https://github.com/torvalds/linux/blob/master/include/linux/i2c-dev.h).
- Boot: boot\_images/boot/QcomPkg/Include/i2c\_api.h
- aDSP/SDC/SLPI: adsp\_proc/core/api/buses/i2c\_api.h
- Qualcomm TEE:
trustzone\_images/core/buses/api/i2c/qupv3/i2c\_api.h
## I2C software device tree configuration
Source: [https://docs.qualcomm.com/doc/80-70030-8/topic/i2c.html](https://docs.qualcomm.com/doc/80-70030-8/topic/i2c.html)
This section provides information on the I2C device tree configuration, and documentation
for the device nodes.
### Linux
For the configuration settings file, see the following DTSI files.
- QCS6490 and QCS5430: [https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/qcom/kodiak.dtsi](https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/qcom/kodiak.dtsi)
- Dragonwing IQ-9075: [https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/qcom/lemans.dtsi](https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/qcom/lemans.dtsi)
- Dragonwing IQ-615: [https://git.kernel.org/pub/scm/linux/kernel/git/qcom/linux.git/tree/arch/arm64/boot/dts/qcom/qcs615.dtsi?h=arm64-for-6.16](https://git.kernel.org/pub/scm/linux/kernel/git/qcom/linux.git/tree/arch/arm64/boot/dts/qcom/qcs615.dtsi?h=arm64-for-6.16)
For more details, see the i2c-geni-qcom.yaml file
at [https://github.com/torvalds/linux/blob/master/Documentation/devicetree/bindings/i2c/qcom%2Ci2c-geni-qcom.yaml](https://github.com/torvalds/linux/blob/master/Documentation/devicetree/bindings/i2c/qcom%2Ci2c-geni-qcom.yaml), and the I2C driver at the [https://github.com/torvalds/linux/blob/master/drivers/i2c/busses/i2c-qcom-geni.c](https://github.com/torvalds/linux/blob/master/drivers/i2c/busses/i2c-qcom-geni.c) files.
i2c1: i2c@984000 {
compatible = "qcom,geni-i2c";
reg = <0 0x00984000 0 0x4000>;
clocks = <&gcc GCC_QUPV3_WRAP0_S1_CLK>;
clock-names = "se";
pinctrl-names = "default";
pinctrl-0 = <&qup_i2c1_data_clk>;
interrupts = ;
#address-cells = <1>;
#size-cells = <0>;
interconnects = <&clk_virt MASTER_QUP_CORE_0 0 &clk_virt SLAVE_QUP_CORE_0 0>, <&gem_noc MASTER_APPSS_PROC 0 &cnoc2 SLAVE_QUP_0 0>, <&aggre1_noc MASTER_QUP_0 0 &mc_virt SLAVE_EBI1 0>;
interconnect-names = "qup-core", "qup-config", "qup-memory";
power-domains = <&rpmhpd SC7280_CX>;
required-opps = <&rpmhpd_opp_low_svs>; dmas = <&gpi_dma0 0 1 QCOM_GPI_I2C>, <&gpi_dma0 1 1 QCOM_GPI_I2C>;
dma-names = "tx", "rx";
status = "disabled"; };Copy to clipboard
For kernel documentation specific to the GPIO `pinctrl`configuration,
see the following files.
- QCS6490 and QCS5430: [https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/qcom/kodiak.dtsi](https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/qcom/kodiak.dtsi)
- Dragonwing IQ-9075: [https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/qcom/lemans.dtsi](https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/qcom/lemans.dtsi)
- Dragonwing IQ-615: [https://git.kernel.org/pub/scm/linux/kernel/git/qcom/linux.git/tree/arch/arm64/boot/dts/qcom/qcs615.dtsi?h=arm64-for-6.16](https://git.kernel.org/pub/scm/linux/kernel/git/qcom/linux.git/tree/arch/arm64/boot/dts/qcom/qcs615.dtsi?h=arm64-for-6.16)
- Documentation/devicetree/bindings/pinctrl/qcom,<chipset>-tlmm.yaml
The corresponding configurations of the QUP v3 serial engine GPIOs are present
and mapped in the pinctrl.dtsi file.
qup_i2c1_data_clk: qup-i2c1-data-clk-state { pins = "gpio4", "gpio5"; function = "qup01"; };Copy to clipboard
In the QUPAC\_Access.c file, ensure that the particular serial
engine configuration for the specified protocol is for the I2C protocol. Qualcomm
TEE
build: /firmware/qualcomm-linux-spf-1-0\_ap\_standard\_oem\_nomodem/TZ.XF.5.0/trustzone\_images/core/settings/buses/qup\_accesscontrol/qupv3/config/<chipset>/QUPAC\_Access.c.
Modify the required settings or refer to the default settings assigned for the QUP
v3 serial engine instances. The following sample configuration is enabled by default
in
I2C.
/* PeriphID, ProtocolID, Mode, NsOwner, bAllowFifo, bLoad, bModExcl */
{ QUPV3_0_SE0, QUPV3_PROTOCOL_I2C, QUPV3_MODE_FIFO, AC_HLOS, TRUE, TRUE, FALSE }, // LT9611 and QPS615 I2C
{ QUPV3_0_SE1, QUPV3_PROTOCOL_I2C, QUPV3_MODE_FIFO, AC_HLOS, TRUE, TRUE, FALSE }, // APPS I2C - PCIE/ USB Type C
{ QUPV3_0_SE2, QUPV3_PROTOCOL_I2C, QUPV3_MODE_FIFO, AC_HLOS, TRUE, TRUE, FALSE }, // SMB / LS1 I2C
{ QUPV3_1_SE1, QUPV3_PROTOCOL_I2C, QUPV3_MODE_FIFO, AC_HLOS, TRUE, TRUE, FALSE }, // NFC I2C
{ QUPV3_1_SE2, QUPV3_PROTOCOL_I2C, QUPV3_MODE_FIFO, AC_HLOS, TRUE, TRUE, FALSE }, // HDMI OUT for
{ QUPV3_1_SE5, QUPV3_PROTOCOL_I2C, QUPV3_MODE_GSI, AC_HLOS, FALSE, TRUE, FALSE}, // Legacy TouchCopy to clipboard
### Boot
1. Configure I2C in the UEFI. The configuration files can be accessed from the
following locations.
- QUP v3 serial engine:
/firmware/qualcomm-linux-spf-1-0\_ap\_standard\_oem\_nomodem/BOOT.MXF.1.0.c1/boot\_images/boot/Settings/Soc/<chipset>/Core/Buses/qup\_common/<chipset>-qupv3.dtsi
- Qualcomm TEE settings:
/firmware/qualcomm-linux-spf-1-0\_ap\_standard\_oem\_nomodem/TZ.XF.5.0/trustzone\_images/core/settings/buses/qup\_accesscontrol/qupv3/config/<chipset>/QUPAC\_Access.c
Note: For configuration settings in boot, see [Boot](https://docs.qualcomm.com/doc/80-70030-8/topic/spi.html#spi_software__section_ibv_tfb_r1c).
2. Enable the I2C protocol in UEFI at
/QcomPkg/SocPkg/<chipset>/LAA/Core.fdf.
-#INF QcomPkg/Drivers/I2CDxe/I2CDxe.inf
+INF QcomPkg/Drivers/I2CDxe/I2CDxe.inf
Copy to clipboard
3. The application enables the I2C interface. The application then performs the
read and write operation through the I2C interface. For information about I2C
function usage, see
boot\_images/QcomPkg/QcomTestPkg/I2CApp/I2Ceeprom.c.
4. Add i2c\_open->i2c\_read/i2c\_write->i2c\_close sequentially in
code.
5. Ensure that the GpiDxe.inf and I2C.efi
files are loaded by verifying the device/UEFI bootup logs before you call
`I2c_open`.
### aDSP/SDC
Firmware loading with SSC QUP is performed during the bootup sequence of the aDSP
subsystem. The configuration files are present in the aDSP build at /firmware/qualcomm-linux-spf-1-0\_ap\_standard\_oem\_nomodem/ADSP.HT.5.5.c8/adsp\_proc/core/settings/buses/qup\_fw/config/<chipset>/fw\_devcfg.c
and /firmware/qualcomm-linux-spf-1-0\_ap\_standard\_oem\_nomodem/ADSP.HT.5.5.c8/adsp\_proc/core/settings/buses/qup\_fw/config/<chipset>/fw\_devcfg.xml.
The following configuration is a sample of SSC QUP SE1, SE2, and SE3 settings loaded
with the I2C
firmware.
se_cfg se1_cfg = { 0x84000, SE_PROTOCOL_I2C, GSI, TRUE, TRUE };
se_cfg se2_cfg = { 0x88000, SE_PROTOCOL_I2C, GSI, TRUE, TRUE };
se_cfg se3_cfg = { 0x8C000, SE_PROTOCOL_I2C, GSI, FALSE, TRUE };Copy to clipboard
**GPIO configuration**: Each serial engine in the QUP v3 common driver is
configured with the default GPIO configuration. The GPIO configuration is picked up
by the QUP v3 common driver according to the protocol loaded in the serial engine.
File
path: /firmware/qualcomm-linux-spf-1-0\_ap\_standard\_oem\_nomodem/ADSP.HT.5.5.c8/adsp\_proc/core/settings/buses/qup\_common/config/<chipset>/adsp/ssc/qup\_instance\_mapping.c.
The default GPIO configuration can be overwritten as follows.
{ .instance_id = 5 , //Instance ID
.qup = QUP_SSC, //QUP Type
.se_index = 4, //SE ID
.se_data = NULL, //devcfg_map
.protocol_io_cfg = {
TLMM_MAP(TLMM_GPIO_KEEPER ,TLMM_GPIO_2MA,TLMM_GPIO_KEEPER ), //SLEEP CFG
TLMM_MAP(TLMM_GPIO_NO_PULL,TLMM_GPIO_6MA,TLMM_GPIO_KEEPER ), //SPI CFG
TLMM_MAP(TLMM_GPIO_NO_PULL,TLMM_GPIO_2MA,TLMM_GPIO_NO_PULL), //UART CFG
TLMM_MAP(TLMM_GPIO_PULL_UP,TLMM_GPIO_2MA,TLMM_GPIO_NO_PULL), //I2C CFG
TLMM_MAP(TLMM_GPIO_PULL_UP,TLMM_GPIO_2MA,TLMM_GPIO_KEEPER ) //I3C CFG
},
.se_exclusive = TRUE,
}
Copy to clipboard
TLMM\_MAP is a macro to initialize the active and sleep state GPIO configurations. For
example, sample usage of the TLMM\_MAP macro.
TLMM_MAP (active state pull type, drive strength, sleep state pull type)Copy to clipboard
### Qualcomm TEE
The QUP v3 serial engine for I2C can be configured as follows. File path: settings/buses/i2c/qupv3/config/<chipset>/tz/i2c\_devcfg\_user.h.
#define ENABLE_I2C_08Copy to clipboard
The `ENABLE_I2C_` number is based on the serial number of the
serial engine (starting from 0). For example, if there are two QUPs: QUPV3\_0 with
seven serial engines and QUPV3\_1 with eight serial engines, then the user must
enable QUPV3\_2\_SE2. The macro should be `ENABLE_I2C_08`.
GPIO configuration: drive strength and pull are configured per PIN for SDA at zero
index and SCL at one index. File path: settings/buses/i2c/qupv3/config/<chipset>/tz/i2c\_devcfg\_user.c
i2c_plat_device_config_user i2c_device_user_config_0 =
{
{0,0}, //.drive_strength index: 0 - SDA, 1 - SCL
value: 0 - 2MA, 1 - 4MA, 2 - 6MA
{3,3}, //.pull index: 0 - SDA, 1 - SCL
value: 0 - NO_PULL, 1 = PULL_DOWN, 2 = KEEPER, 3 = PULL_UP
0xFF, //.gpii_idx
0, //.mode_select not supported for TZ
0, //.flags not supported for TZ
};
Copy to clipboard
QUPAC access control: controls the firmware loading and access control permission
from the Qualcomm TEE subsystem are configured in the QUPAC access file
at /firmware/qualcomm-linux-spf-1-0\_ap\_standard\_oem\_nomodem/TZ.XF.5.0/trustzone\_images/core/settings/buses/qup\_accesscontrol/qupv3/config/<chipset>/QUPAC\_Access.c.
## Configure I2C interface
Source: [https://docs.qualcomm.com/doc/80-70030-8/topic/i2c.html](https://docs.qualcomm.com/doc/80-70030-8/topic/i2c.html)
This section provides information about the I2C software driver kernel configuration and
device tree node changes.
### Linux
The following driver kernel configurations are required to support the I2C
interface.
- Driver source: [https://github.com/torvalds/linux/blob/master/drivers/i2c/busses/i2c-qcom-geni.c](https://github.com/torvalds/linux/blob/master/drivers/i2c/busses/i2c-qcom-geni.c)
- Kernel defconfig file path:
<workspace\_path\_of\_LINUX\_kernel\_image>/sources/kernel/kernel\_platform/kernel/arch/arm64/configs/qcom\_defconfig
The following kernel configurations are to be enabled.
- `CONFIG_QCOM_GENI_SE=y`
- `CONFIG_I2C_CHARDEV=m`
- `CONFIG_I2C_QCOM_GENI=m` to configure user space
applications
- `CONFIG_QCOM_GPI_DMA=m` to enable GSI support
To enable the I2C DT node for validations, apply the following patch to the /arch/arm64/boot/dts/qcom/<chipset>.dtsi
file.
diff --git a/arch/arm64/boot/dts/qcom/.dtsi b/arch/arm64/boot/dts/qcom/.dtsi
index 8575f0b..cced7c0 100644
--- a/arch/arm64/boot/dts/qcom/.dtsi
+++ b/arch/arm64/boot/dts/qcom/.dtsi
@@ -6865,3 +6865,7 @@
;
};
};
+
+ &i2c1 {
+ status = "ok";
+};
Copy to clipboard
Note: You should compile the kernel configuration and device tree
changes. After compilation, you can load the images to the device to verify the
interface. For information about interface verification, see the [Verify I2C interface](https://docs.qualcomm.com/doc/80-70030-8/topic/i2c.html#i2c-verification) section.
## Verify I2C interface
Source: [https://docs.qualcomm.com/doc/80-70030-8/topic/i2c.html](https://docs.qualcomm.com/doc/80-70030-8/topic/i2c.html)
This section describes the validation procedure and test results for the I2C drivers and
the Qualcomm drivers.
### Linux
For upstream I2C kernel test applications, see [https://cdn.kernel.org/pub/software/utils/i2c-tools/i2c-tools-4.3.tar.gz](https://cdn.kernel.org/pub/software/utils/i2c-tools/i2c-tools-4.3.tar.gz).
To cross-compile tools, do the following.
1. Download `i2c-tool` from [https://cdn.kernel.org/pub/software/utils/i2c-tools/i2c-tools-4.3.tar.gz](https://cdn.kernel.org/pub/software/utils/i2c-tools/i2c-tools-4.3.tar.gz).
2. Extract the tool from the downloaded
`tar` file.
tar -xzvf Copy to clipboard
3. Change the current directory to the
`i2c-tool`
path.
cd Copy to clipboard
4. Install the
tool.
sudo apt-get install gcc-aarch64-linux-gnuCopy to clipboard
5. Set up the environment for
cross-compilation.
export CC=aarch64-linux-gnu-gccCopy to clipboard
6. Compile the
tool.
make USE_STATIC_LIB=1Copy to clipboard
The
binary is generated at
`/tools/`.
Validate the driver by checking for `dev` node
(`/dev/i2c-0` and `/dev/i2c-1`) in the SSH shell
or use the ADB shell. For more information about how to run SSH, see the [Use SSH](https://docs.qualcomm.com/bundle/publicresource/topics/80-70030-254/how_to.html) section.
**Verify I2C driver**
1. To verify the I2C driver, do the following:
1. Open the SSH shell in permissive mode or use
the ADB shell.
2. Mount the file
system.
mount -o remount,rw /usrCopy to clipboard
3. Transfer files using SCP or similar
tools.
For example, `scp i2cdetect
root@10.92.162.185:/bin`
4. Assign permission to
execute.
chmod 777 i2cdetectCopy to clipboard
2. Verify an I2C device with the
`i2cdetect` tool. For example, `./i2cdetect -y -r
`.
/lib # ./i2cdetect -y -r 0
Copy to clipboard
The following output is
displayed.
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- 2b -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- 44 -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
/lib # exit
Copy to clipboard
**View I2C detect help**
For more information about I2C detection, and
how to use it, run the following commands.
/lib # ./i2cdetect --helpCopy to clipboard
The
following output is displayed.
Error: Unsupported option "--help"!
Usage: i2cdetect [-y] [-a] [-q|-r] I2CBUS [FIRST LAST]
i2cdetect -F I2CBUS
i2cdetect -l
I2CBUS is an integer or an I2C bus name
If provided, FIRST and LAST limit of the probing range.
Copy to clipboard
**Identify probed device in DUT**
To identify the device probed from
the DUT, run the following
command.
/lib # ./i2cdump -r 0-0xff 0 0x2b bCopy to clipboard
Output:
WARNING! This program can confuse your I2C bus, cause data loss and worse!
will probe file /dev/i2c-0, address 0x2b, mode byte
Probe range limited to 0x00-0xff.
Continue? [Y/n] Y
0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
Copy to clipboard
**Read I2C data from device**
To read I2C data from the device, run the
following
commands.
/lib # ./i2cget 0 0x2b 4 bCopy to clipboard
Output:
WARNING! This program can confuse your I2C bus, cause data loss and worse!
Will read from device file /dev/i2c-0, chip address 0x2b, data address
0x04, using read byte data.
Continue? [Y/n] Y
0x00Copy to clipboard
## Debug I2C issues
Source: [https://docs.qualcomm.com/doc/80-70030-8/topic/i2c.html](https://docs.qualcomm.com/doc/80-70030-8/topic/i2c.html)
The section describes the default logging method of the I2C software driver to enable
logging the I2C transfer failures.
### Linux
The I2C driver logs are enabled through the kernel dynamic debugging method. Enable
`CONFIG_DYNAMIC_DEBUG`
in <workspace\_path\_of\_LINUX\_kernel\_image>/sources/kernel/kernel\_platform/kernel/arch/arm64/configs/qcom\_defconfig
to support the dynamic debugging of the kernel drivers.
To enable and view the I2C driver logs in the kernel logs (`dmesg`),
run the following
commands.
mount -t debugfs none /sys/kernel/debug
echo -n "file i2c-qcom-geni.c +p" > /sys/kernel/debug/dynamic_debug/control
echo -n "file i2c-core-base.c +p" > /sys/kernel/debug/dynamic_debug/control
echo -n "file i2c-dev.c +p" > /sys/kernel/debug/dynamic_debug/control
echo -n "file i2c-mux.c +p" > /sys/kernel/debug/dynamic_debug/control
echo -n "file gpi.c +p" > /sys/kernel/debug/dynamic_debug/control
Copy to clipboard
To debug the error message: `[ 8.583248] geni_i2c a94000.i2c: Invalid proto
1` for driver protocol load failures, do the following.
1. Identify the board type.
Example: QUPV3\_1\_SE5 board type
details
B - 461251 - CDT Version:3,Platform ID:34,Major ID:1,Minor ID:0,Subtype:2Copy to clipboard
2. From the kernel log, locate the platform ID and subtype related details at /firmware/qualcomm-linux-spf-1-0\_ap\_standard\_oem\_nomodem/TZ.XF.5.0/trustzone\_images/core/settings/buses/qup\_accesscontrol/qupv3/config/<chipset>/QUPAC\_Access.xml
3. Obtain the Qualcomm TEE QUPAC\_Access.c file configurations.
4. Identify the configuration specific to the serial engine.
5. Locate the platform ID type within the `QUPAC_Access.xml`
file.
6. Map this platform ID type to the corresponding `qupv3_perms`
structure within the `QUPAC_Access.c` file.
7. Verify the protocol and mode configurations in the
`QUPAC_Access.c` file.
## I2C examples
Source: [https://docs.qualcomm.com/doc/80-70030-8/topic/i2c.html](https://docs.qualcomm.com/doc/80-70030-8/topic/i2c.html)
For information about the upstream device tree reference, see the following DTSI
files.
- QCS6490 and QCS5430: [https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/qcom/kodiak.dtsi](https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/qcom/kodiak.dtsi)
- Dragonwing IQ-9075: [https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/qcom/lemans.dtsi](https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/qcom/lemans.dtsi)
- Dragonwing IQ-615: [https://git.kernel.org/pub/scm/linux/kernel/git/qcom/linux.git/tree/arch/arm64/boot/dts/qcom/qcs615.dtsi?h=arm64-for-6.16](https://git.kernel.org/pub/scm/linux/kernel/git/qcom/linux.git/tree/arch/arm64/boot/dts/qcom/qcs615.dtsi?h=arm64-for-6.16)
For information about device-tree node for the Qualcomm Linux hardware SoCs, see the
following DTSI files.
- QCS6490 and QCS5430: [https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts](https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts)
- Dragonwing IQ-9075: [https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/qcom/lemans.dtsi](https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/qcom/lemans.dtsi)
- Dragonwing IQ-615: [https://git.kernel.org/pub/scm/linux/kernel/git/qcom/linux.git/tree/arch/arm64/boot/dts/qcom/qcs615.dtsi?h=arm64-for-6.16](https://git.kernel.org/pub/scm/linux/kernel/git/qcom/linux.git/tree/arch/arm64/boot/dts/qcom/qcs615.dtsi?h=arm64-for-6.16)
Last Published: Jul 03, 2026
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