AM5718: PMIC Register access over I2C

Hi Anjali,

You can read/write PMIC registers from user space. You can use omapconf tool, refer to below wiki for details:

You can also use I2C linux user space commands to read/write PMIC registers, these commamnds are i2cget and i2cset. Refer to below links for details:

Regards,
Pavel

Hi Pavel,

Thanks for your quick reply

I tried linux user space commads to read PMIC .I can only read registers  in PMIC page 0x0(slave address 0x12) .but while trying to read the registers in page0x1 (slave address 0x58) I got 'Device or resource busy 'from the Linux  and it is OK from u-boot.

From kernel:

root@am57xx-evm:~/apps# i2cget 0 0x12 0x2B

[ 3448.994470] i2c /dev open

WARNING! This program can confuse your I2C bus, cause data loss and worse!

I will read from device file /dev/i2c-0, chip address 0x12, data address

0x2b, using read byte data.

Continue? [Y/n] Y

0x3e

root@am57xx-evm:~/apps# i2cget 0 0x58 0x27

[ 3454.354488] i2c /dev open

Error: Could not set address to 0x58: Device or resource busy

From u boot:

=>i2c md 0x12 2b.1 1

002b: 3e

=>i2c md 0x58 27.1 1

0027: 5b

What would be the reason for this issue?

regards,

anjali

Anjali,

I2C chip at addr0x58 is used and busy by the linux kernel:

linux-kernel/arch/arm/boot/am57xx-idk-common.dtsi

&i2c1 {
    status = "okay";
    clock-frequency = <400000>;

    tps659038: tps659038@58 {
        compatible = "ti,tps659038";
        reg = <0x58>;

While for addr 0x12 we do not have allocation in linux kernel.

"Device or resource busy" literally means that your i2c driver is loaded and being used by some other module. Either you disable that module in kernel or use "force" option to see if the slave responds (use -f at your risk). Please refer to below e2e threads for details:

Regards,
Pavel

Hi ,

   I  want to set and reset   "DEV_ON" bit in the PMIC for implementing PMIC shutdown from linux.I reffered below link for this.

  http://e2e.ti.com/support/processors/f/791/t/807604?Linux-AM5718-Kernel-and-PMIC-shutdown

but, while  trying to accessing slave 0x58(register address 0xA0 for DEV_ON ) I got  "Device or resource busy" ,then How  it can  be possible from userspace?

regards

Anjali