First of all, try to get 2 free GPIO's. I'm using a custom board and had to change the MMC3 pins to allow them as GPIOs. The changed u-boot can be found here: https://github.com/erazor83/u-boot

Next step would be the integration of fbtft into the kernel, so just fallow install instructions, given here: https://github.com/notro/fbtft .

I had modify the arch/arm/mach-omap2/board-overo.c. Check that spidev and no other modules take claim the spi-bus fbtft uses.

...

#if defined(CONFIG_FB_TFT_ST7735R)
	{

		.modalias = "fb_st7735r",
		.max_speed_hz = 32000000,
		.bus_num = 1,
		.chip_select = 0,
		.mode = SPI_MODE_0,
		.platform_data = &(struct fbtft_platform_data) {
			.display = {
					.buswidth = 8,
			},
			.gpios = (const struct fbtft_gpio []) {
					{ "reset", 17 },
					{ "dc", 19 },
			 },
		}
	},
#else
	{
		.modalias		= "spidev",
		.bus_num		= 1,
		.chip_select		= 0,
		.max_speed_hz		= 48000000,
		.mode			= SPI_MODE_0,
	},
#endif
...

Integrate into kernel:

• Drivers -> SPI -> McSPI
• Drivers -> SPI -> User mode SPI
• Graphics -> Lowlevel video
• Graphics -> Support for framebuffer
• Graphics -> Support for small TFT
• Graphics -> Support for small TFT -> FB driver for the ST7735R LCD Controller
• Graphics -> Console display driver support -> Map the console to the primary display device
• Graphics -> Console display driver support -> Framebuffer Console Rotation
• Graphics -> Console display driver support -> VGA 8x8 font
• Graphics -> Console display driver support -> Mini 4x6 font

These have to go into your u-boot config:

console=tty1 fbcon=rotate:1,font:MINI4x6