AM335x: i2c_read returns wrong values in U-boot

Moving to Sitara forum

Regards,
Gigi Joseph.

Hi Yordan,
my code is base on the code from board.c file that locate in:
ti-processor-sdk-linux-am335x-evm-02.00.00.00/board-support/u-boot-2015.07+gitAUTOINC+d49aa5effa/board/ti/am335x
So I operate i2c_read() after i2c_probe(), as you can see for example in:
static int read_eeprom(struct am335x_baseboard_id *header).
and the value is 0.
What do you mean by operate i2c md command from u-boot prompt? How to do it?
Thanks Oded.

Hi,

You can execute i2c md from u-boot prompt, by following the steps bellow:

Oded Almog said:

What do you mean by operate i2c md command from u-boot prompt? How to do it?

1. Stop your board at u-boot (when the countdown appears, hit any key from your keyboard).

2. type i2c md 0x21 0 0x10   => you'll read 16 bytes from the slave at address 0x21 starting from register 0.

Could you also attach the modified board.c file? 

Best Regards, 
Yordan

Hi Yordan,

This is the output when I operate i2c md 0x21 0 0x10:

U-Boot SPL 2015.07 (Jan 06 2016 - 10:46:28)
reading args
spl_load_image_fat_os: error reading image args, err - -1
reading u-boot.img
reading u-boot.img


U-Boot 2015.07 (Jan 06 2016 - 10:46:28 +0200)

Watchdog enabled
I2C: ready
DRAM: 256 MiB
NAND: 0 MiB
MMC: OMAP SD/MMC: 0, OMAP SD/MMC: 1
reading uboot.env
Net: Phy 0 not found
cpsw, usb_ether
Hit any key to stop autoboot: 0
U-Boot#
U-Boot#
U-Boot#
U-Boot#
U-Boot#
U-Boot# i2c md 0x21 0 0x10
0000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
U-Boot#


And this is the output when I operate i2cget -f -y 0 0x21 when application is up:

root@am335x-evm:~# i2cget -f -y 0 0x21
0xe2
root@am335x-evm:~#


What is the problem?

Thanks Oded.

Hi Biser,
How and where can I configure CONF_<module>_<pin>_RXACTIVE bit ?
Thanks Oded.

Hi,

Those registers CONF_<module>_<pin> are located in the Control module: Table 9-10. CONTROL_MODULE REGISTERS

Have a look at mux.c to see which macros are used to mux module pins in u-boot.

Best Regards,
Yordan

Hi Yordan,
We try to read extgpio1: pcf8574@21 device in i2c device . This is how it declare in DTS file:

&i2c0 {
pinctrl-names = "default";
pinctrl-0 = <&i2c0_pins>;

status = "okay";
clock-frequency = <100000>;

tps: tps@2d {
reg = <0x2d>;
};

lis331dlh: lis331dlh@18 {
compatible = "st,lis331dlh", "st,lis3lv02d";
reg = <0x18>;
Vdd-supply = <&lis3_reg>;
Vdd_IO-supply = <&lis3_reg>;

st,click-single-x;
st,click-single-y;
st,click-single-z;
st,click-thresh-x = <10>;
st,click-thresh-y = <10>;
st,click-thresh-z = <10>;
st,irq1-click;
st,irq2-click;
st,wakeup-x-lo;
st,wakeup-x-hi;
st,wakeup-y-lo;
st,wakeup-y-hi;
st,wakeup-z-lo;
st,wakeup-z-hi;
st,min-limit-x = <120>;
st,min-limit-y = <120>;
st,min-limit-z = <140>;
st,max-limit-x = <550>;
st,max-limit-y = <550>;
st,max-limit-z = <750>;
};

tlv320aic3106: tlv320aic3106@1b {
compatible = "ti,tlv320aic3106";
reg = <0x1b>;
status = "okay";

/* Regulators */
AVDD-supply = <&vaux2_reg>;
IOVDD-supply = <&vaux2_reg>;
DRVDD-supply = <&vaux2_reg>;
DVDD-supply = <&vbat>;
};

extgpio0: pcf8574@20 {
compatible = "nxp,pcf8574";
reg = <0x20>;
gpio-controller;
#gpio-cells = <2>;

reset_fg_i2c_mux{
gpio-hog;
gpios = <0 0>;
output-high;
};

/*battery_1_enable{
gpio-hog;
gpios = <6 0>;
output-high;
};*/
};

extgpio1: pcf8574@21 {
compatible = "nxp,pcf8574";
reg = <0x21>;
gpio-controller;
#gpio-cells = <2>;
};

extgpio2: pcf8574@22 {
compatible = "nxp,pcf8574";
reg = <0x22>;
gpio-controller;
#gpio-cells = <2>;
};

extgpio3: tca9554@70 {
compatible = "ti,tca9554";
reg = <0x70>;
gpio-controller;
#gpio-cells = <2>;

};

s35390a: s35390a@30 {
compatible = "s35390a";
reg = <0x30>;
status = "okay";
};
};


In mux.c file in ti-processor-sdk-linux-am335x-evm-02.00.00.00/board-support/u-boot-2015.07+gitAUTOINC+d49aa5effa/board/ti/am335x,
i2c0_pin_mux declare like this:

static struct module_pin_mux i2c0_pin_mux[] = {
{OFFSET(i2c0_sda), (MODE(0) | RXACTIVE |
PULLUDEN | SLEWCTRL)}, /* I2C_DATA */
{OFFSET(i2c0_scl), (MODE(0) | RXACTIVE |
PULLUDEN | SLEWCTRL)}, /* I2C_SCLK */
{-1},
};

static struct module_pin_mux i2c1_pin_mux[] = {
{OFFSET(spi0_d1), (MODE(2) | RXACTIVE |
PULLUDEN | SLEWCTRL)}, /* I2C_DATA */
{OFFSET(spi0_cs0), (MODE(2) | RXACTIVE |
PULLUDEN | SLEWCTRL)}, /* I2C_SCLK */
{-1},
};


Is it OK?

Thanks Oded.

Hi Biser,
Base on Note 1 below Table 21-5 in the AM335x TRM Rev. M, when I changed :

static struct module_pin_mux i2c0_pin_mux[] = {
{OFFSET(i2c0_sda), (MODE(0) | RXACTIVE |
PULLUDEN | SLEWCTRL)}, /* I2C_DATA */
{OFFSET(i2c0_scl), (MODE(0) | RXACTIVE |
PULLUDEN | SLEWCTRL)}, /* I2C_SCLK */
{-1},
};

to:

static struct module_pin_mux i2c0_pin_mux[] = {
{OFFSET(i2c0_sda), (MODE(0) | RXACTIVE |
PULLUDEN | SLEWCTRL)}, /* I2C_DATA */
{OFFSET(i2c0_scl), (MODE(1) | RXACTIVE |
PULLUDEN | SLEWCTRL)}, /* I2C_SCLK */
{-1},
};

the result are the same:

U-Boot 2015.07 (Jan 06 2016 - 10:46:28 +0200)

Watchdog enabled
I2C: ready
DRAM: 256 MiB
NAND: 0 MiB
MMC: OMAP SD/MMC: 0, OMAP SD/MMC: 1
reading uboot.env
Net: Phy 0 not found
cpsw, usb_ether
Hit any key to stop autoboot: 0
U-Boot#
U-Boot#
U-Boot#
U-Boot#
U-Boot#
U-Boot# i2c md 0x21 0 0x10
0000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
U-Boot#

What the problem?

Thanks Oded.

Hi Yordan,
Base on Note 1 below Table 21-5 in the AM335x TRM Rev. M, when I changed :

static struct module_pin_mux i2c0_pin_mux[] = {
{OFFSET(i2c0_sda), (MODE(0) | RXACTIVE |
PULLUDEN | SLEWCTRL)}, /* I2C_DATA */
{OFFSET(i2c0_scl), (MODE(0) | RXACTIVE |
PULLUDEN | SLEWCTRL)}, /* I2C_SCLK */
{-1},
};

to:

static struct module_pin_mux i2c0_pin_mux[] = {
{OFFSET(i2c0_sda), (MODE(0) | RXACTIVE |
PULLUDEN | SLEWCTRL)}, /* I2C_DATA */
{OFFSET(i2c0_scl), (MODE(1) | RXACTIVE |
PULLUDEN | SLEWCTRL)}, /* I2C_SCLK */
{-1},
};

the result are the same:

U-Boot 2015.07 (Jan 06 2016 - 10:46:28 +0200)

Watchdog enabled
I2C: ready
DRAM: 256 MiB
NAND: 0 MiB
MMC: OMAP SD/MMC: 0, OMAP SD/MMC: 1
reading uboot.env
Net: Phy 0 not found
cpsw, usb_ether
Hit any key to stop autoboot: 0
U-Boot#
U-Boot#
U-Boot#
U-Boot#
U-Boot#
U-Boot# i2c md 0x21 0 0x10
0000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
U-Boot#

What the problem?

Thanks Oded.

Hi Yordan,
Does the problem relate to read extgpio1: pcf8574@21 device from i2c?
Thanks Oded.

Hi,

"I work on Sitara am335x-evmsk with ti-processor-sdk-linux-am335x-evm-02.00.00.00"

You've modified the board, by connecting an I/O expander to I2C0, right?

So can you verify that the expander is initialized: can you probe:

1. I2C0_SDA & I2C0_SCL

2. then if i2c0_sda/scl toggle, can you verify that you get a something on the Px, x = 0..7,  pins, to which your EEPROM is connected?

If you check the kernel, you'll see that the dts node for PCF8574 binds the expander with the gpio-pcf857x.c driver. So can you perform the above experiment (on both the i2c0 pins & pcf8574_Px pins)?  My guess is that i2c_read() works, but you need some additional initialization of the expander.  

Best Regards,

Yordan

Hi Yordan,

I don't know how to verify that the expander is initialized by I2C0_SDA & I2C0_SCL but we saw via scope that there are toggle
and when kernel is up, I operate i2cget and receive:

root@am335x-evm:~# i2cget -f -y 0 0x21
0xe2
root@am335x-evm:~#

My problem is that I need to read pcf8574 expander during boot phase and I expect 0xe2 value, but I receive 0 value:

U-Boot 2015.07 (Jan 06 2016 - 10:46:28 +0200)

Watchdog enabled
I2C: ready
DRAM: 256 MiB
NAND: 0 MiB
MMC: OMAP SD/MMC: 0, OMAP SD/MMC: 1
reading uboot.env
Net: Phy 0 not found
cpsw, usb_ether
Hit any key to stop autoboot: 0
U-Boot#
U-Boot#
U-Boot#
U-Boot#
U-Boot#
U-Boot# i2c md 0x21 0 0x10
0000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
U-Boot#


So what else can I do to solve this problem?

Thanks Oded.

Hi Yordan,

I still have this problem so can you help me to solve it?

Thanks Oded

Hi Yordan,
This problem not resolved. Can you help me to solve it?
Thanks Oded.