Tristating i2c0 bus in am335x BBB

Hi Srini,

Why do you want to tristate the i2c bus ?

http://processors.wiki.ti.com/index.php/I2C_Tips

http://elinux.org/Interfacing_with_I2C_Devices#i2c-tools

Thanks a lot Titus for your quick replies,

1) In my custom board PMIC TPS65217C is connected to i2c-1 bus, so now in beaglebone black it is connected to i2c-0 bus & now provision is made to connect the same i2c-1 bus in beaglebone black but since both buses are connected to same PMIC so verification can't be done inorder to verify i2c-1 bus to PMIC, so I need to tristate this i2c-0 bus could you please let me know how this can be done

as am searching fro this from yesterday no clues yet in uboot source code or kernel source code can be this be modified in dts hope it should be easier , if this is the case could you please let me know how this can be done in dts

2) I downloaded i2c-tools & cross compiled (http://www.lm-sensors.org/wiki/I2CTools) & modified the makefile  also to CC ?= arm-linux-gnueabihf- of  i2c-tools-3.1.1.tar.bz2,

srinivasan@tata-HP-Elite-7100-Microtower-PC:~/TUNSTALL/board-support/i2c-tools-3.1.1$ sudo make CROSS_COMPILE=arm-linux-gnueabihf- ARCH=arm

I copied the exes in the rootfs/usr/bin/, but when I am using the i2c utiliites am facing the below errors

root@beaglebone:~# i2cdetect 0
-sh: /usr/bin/i2cdetect: cannot execute binary file: Exec format error
root@beaglebone:~#

Kindly do the needful as early as possible

Many Thanks once gaian for your quick responses

I think, you have to change the below code for i2c1.

board/ti/am335x/mux.c

board/ti/am335x/board.c

enable_i2c1_pin_mux();

void enable_i2c1_pin_mux(void)
{
    configure_module_pin_mux(i2c1_pin_mux);
}

1780.board.c

3806.mux.c

Hi TiTus,

Thanks for your timley support, as you suggested

1) I have commented i2c0 pin configuration & have enabled i2c1 configuration,
since this u-boot source for this platform, before booting it is trying to read the board id & other am335x header information from eeprom via i2c0 & then proceeds for further booting
In my custom board eeprom is configured to I2C1 bus, could you please let me know some where else also we need to change the bus num from 0 to 1 towards eeprom side ie., in core driver file, could you please let me know the path of i2c driver related files in uboot for am335x platform(beaglebone black) where the bus num needs to be changed

U-Boot SPL 2013.10-00189-g78d8ebd-dirty (Nov 28 2014 - 18:02:09)
i2c_probe: pads on bus 0 probably not configured (status=0x10)
Could not probe the EEPROM; something fundamentally wrong on the I2C bus.
Could not get board ID.
i2c_probe: pads on bus 0 probably not configured (status=0x10)
Could not probe the EEPROM; something fundamentally wrong on the I2C bus.
Could not get board ID.
Unknown board, cannot configure pinmux.### ERROR ### Please RESET the board ###

2) As since my custom board is under fabrication, Hardware changes for I2C1 (ie., i2c1 scl& sda lines are shorted to i2c0 sda & scl)is done in beaglebone black only as of now, And as per my understanding even after commenting out i2c0 configuration, I Hope by default the i2c0 mode would be changed to gpio by default(since am not sure how this is in am335x processor, could you please confirm whether this is true or not in case of Am335x, if this is the case then could you please let me know whether by default this gpio pin is in high impedance state or not, if not could you please let me know how & where to configure this gpio pin to high impedance state) in uboot source code 

3)Could you please let me know as before booting it is trying to read the board id & other am335x header information from eeprom, where this board id & other am335x header information are being written to eeprom before trying to read the source code path, if it is being written to eeprom via i2c0 then this also needs to be changed to i2c1 (please also let me know which i2c driver code path needs to be changed for this as well)

Kindly do the needful as early as possible, if I get this i2c1 bus up then I feel I would get uboot up & running in my custom board as well

Many Many Thanks a lot in advance for all your support so far & henceforth

Hi Srini,

Have you modified the BBB hardware for I2C1 ?

Then, how did you this ?

Confirm that EEPROM & PMIC IC are connected to the I2C bus 1.

http://processors.wiki.ti.com/index.php/AM335x_General_Purpose_EVM_HW_User_Guide#Configuration.2FSetup

U-Boot SPL 2013.10-00189-g78d8ebd-dirty (Nov 28 2014 - 18:02:09)
i2c_probe: pads on bus 0 probably not configured (status=0x10)
Could not probe the EEPROM; something fundamentally wrong on the I2C bus.
Could not get board ID.
i2c_probe: pads on bus 0 probably not configured (status=0x10)
Could not probe the EEPROM; something fundamentally wrong on the I2C bus.
Could not get board ID.
Unknown board, cannot configure pinmux.### ERROR ### Please RESET the board ###

I think, the above error is due to the following lines of code snippet.

Please ensure that CPLD had connected with I2C bus 1.

/* CPLD registers */
#define I2C_CPLD_ADDR	0x35
#define CFG_REG		0x10

static unsigned short detect_daughter_board_profile(void)
{
	unsigned short val;

	if (i2c_probe(I2C_CPLD_ADDR))
		return PROFILE_NONE;

	if (i2c_read(I2C_CPLD_ADDR, CFG_REG, 1, (unsigned char *)(&val), 2))
		return PROFILE_NONE;

	return (1 << (val & PROFILE_MASK));
}

Hi Srini,

I think, the I2C bus no is configured to '1' by default.

We can change this i2c bus through "i2c_set_bus_num"

If you interchanged the i2c 0 to i2c 1 in hardware then it should work.

Try to use the following lines.

board/ti/am335x/board.c

	/* Initalize the board header */
//	enable_i2c0_pin_mux();
	enable_i2c1_pin_mux();
	i2c_set_bus_num(1);
	i2c_init(CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);
#ifndef CONFIG_NOR_BOOT
	if (read_eeprom() < 0)
		puts("Could not get board ID.\n");
#endif

	/* Check if baseboard eeprom is available */
	if (i2c_probe(CONFIG_SYS_I2C_EEPROM_ADDR)) {
		puts("Could not probe the EEPROM; something fundamentally "
			"wrong on the I2C bus.\n");
	}

	/* read the eeprom using i2c */
	if (i2c_read(CONFIG_SYS_I2C_EEPROM_ADDR, 0, 2, (uchar *)&header,
							sizeof(header))) {
		puts("Could not read the EEPROM; something fundamentally"
			" wrong on the I2C bus.\n");
	}

Thanks a lot for your quick replies & updates Titus,

1) The hardware changes is we have just shorted i2c0 scl & sda lines to i2c1 scl & sda lines in begalebone black

2) As you suggested I did the following changes, in ti/am335x/board.c

const struct dpll_params *get_dpll_ddr_params(void)
{
struct am335x_baseboard_id header;

//enable_i2c0_pin_mux();

enable_i2c1_pin_mux();

i2c_set_bus_num(1);

// i2c_init(CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);
if (read_eeprom(&header) < 0)
puts("Could not get board ID.\n");

if (board_is_evm_sk(&header))
return &dpll_ddr_evm_sk;
else if (board_is_bone_lt(&header))
return &dpll_ddr_bone_black;
else if (board_is_evm_15_or_later(&header))
return &dpll_ddr_evm_sk;
else
return &dpll_ddr;
}

U-Boot SPL 2013.10-00189-g78d8ebd-dirty (Dec 01 2014 - 15:53:53)
INSIDEEEEEEEEEEE i2c_inttttttttttttttttt function, the slaveadd is 1
INSIDEEEEEEEEEEE i2c_inttttttttttttttttt function, the CURRENT BUS is 1
EOFFFFFFFFFFFFFFFFFFFF i2c_inttttttttttttttttt function, the slaveadd is 1
INSIDE read_eeprom functionnnnnnnnnnnnnnnnnn
INSIDEEEEEEEEEEEEEEEEE I2C_PROBEEEEEEEEEEEEEE FUNCTION
Timed out in wait_for_bb: status=1000
Could not probe the EEPROM; something fundamentally wrong on the I2C bus.
Could not get board ID.
INSIDE read_eeprom functionnnnnnnnnnnnnnnnnn
INSIDEEEEEEEEEEEEEEEEE I2C_PROBEEEEEEEEEEEEEE FUNCTION
Timed out in wait_for_bb: status=1000
Could not probe the EEPROM; something fundamentally wrong on the I2C bus.
Could not get board ID.
Unknown board, cannot configure pinmux.### ERROR ### Please RESET the board ###

I donnu why I'm getting this timeout error, could you please do the needful in resolving this issue as early as possible

Could you please correct me if am progressing in any wrong direction

Many Thanks in advance

Hi Srini,

The problem could be from hw side, so you can try to use AM335x starterware i2c example code through CCS with JTAG.

http://software-dl.ti.com/dsps/dsps_public_sw/am_bu/starterware/latest/index_FDS.html

Is there any ways to bypass eeprom reading & get the u-boot prompt

If so, could you please let me know the appropriate code changes that needs to be done??

awaiting for your replies,

Kindly do the needful as early as possible

Sounds good.

Thanks for your update.