Some I2C devices need "Clock Stretch" feature, that maybe occupied a dedicated I2C resource from i.MX53, so it would be better to share a pair of GPIO pins to be used for this purpose. Following is a concrete example to approach this object.
Step 1: Define the allocated GPIO pins used for this purpose.
Platform file: mx53_xxx.c (xxx stands for your board's name, like smd referring to FSL's i.MX53 tablet ref design)
#define MX53_PCBA_MHL_SW_I2C_SCL (5 * 32 + 8) /* GPIO6-8 */
#define MX53_PCBA_MHL_SW_I2C_SDA (5 * 32 + 10) /* GPIO6-10 */
Then in system-level interface declaration array:
static iomux_v3_cfg_t mx53_pcba_pads[] = {
............
MX53_PAD_NANDF_RBO_GPIO6_10,
MX53_PAD_NANDF_ALE_GPIO6_8,
............
};
Also pls check arch/arm/plat-mxc/include/mach/iomux-mx53.h to see whether these 2 PADs configurations are appropriate to I2C application scene. Here, they are defined as :
#define MX53_PAD_NANDF_RBO__GPIO6_10 (MX53_PAD_NANDF_RBO__GPIO6_10 | MUX_PAD_CTRL(MX53_I2C_PAD_CTRL_1))
#define MX53_PAD_NANDF_ALE__GPIO6_8 (MX53_PAD_NANDF_ALE__GPIO6_8 | MUX_PAD_CTRL(MX53_I2C_PAD_CTRL_1))
That is all code involving configurations we need to set up.
Figure 1. i.MX53 pin-out
Figure 2. SiI92326 pin-out
Step 2: Code the I2C emulation code
Here I attach the GPL license I2C emulator program.
