OLPC XO-4

OLPC XO-4 is a MMP3-based laptop. It’s reasonably well supported by the mainline kernel.

Most of what applies to OLPC XO-1.75 applies to XO-4 as well. This page deals with the differencies.

Pin Assignment

Certain signals are assigned diferently on XO-4, mostly due to extra peripherals on XO-4 laptop (such as touch screen and HDMI port) as well as MMP3 SoC (extra pins for MMC5 controller used for internal SD card slot).

Here’s the summary:

Signal	Function		Note
	XO-1.75	XO-4
BOOT_DEV_SEL	GPIO_56	GPIO_2	eMMC or Internal SD selector
CAM_SCL	GPIO_108	GPIO_165	OV7670 I2C
CAM_SDA	GPIO_109	GPIO_166	OV7670 I2C
DCON_IRQ#	GPIO_124	GPIO_126	HX8837
DCON_SCL	GPIO_161	GPIO_168	HX8837 I2C
DCON_SDA	GPIO_110	GPIO_167	HX8837 I2C
EB_MODE#	GPIO_128	GPIO_130	Display rotated in e-book mode
EC_SPI_ACK	GPIO_125	GPIO_113	To Embedded Controller
HP_PLUG	GPIO_97	GPIO_13	Headphone
HUB_RESET#	GPIO_146	GPIO_148	USB Hub Reset
VID2	GPIO_11	GPIO_123	Vcore voltage control
WLAN_PD#	GPIO_57	GPIO_35	Wi-Fi Power Down
WLAN_RESET#	GPIO_58	GPIO_36	Wi-Fi Reset
eMMC_RST#	GPIO_149	GPIO_144	eMMC Reset
I2S_SYSCLK	I2S_SYSCLK	APPMU_SYSCLK	Different I2S sysclk. Why?
SD1_CLK	MMC3_CLK	MMC5_CLK	eMMC and Internal SD share MMC3 on XO-1.75. MMC5 only on MMP3
SD1_CMD	MMC3_CMD	MMC5_CMD	〃
SD1_DATA0	MMC3_DATA0	MMC5_DATA_0	〃
SD1_DATA1	MMC3_DATA1	MMC5_DATA_1	〃
SD1_DATA2	MMC3_DATA2	MMC5_DATA_2	〃
SD1_DATA3	MMC3_DATA3	MMC5_DATA_3	〃
EN_eMMC_PWR#		GPIO_97	eMMC power off on XO-4 can work around MMP3 leakage issue
SOC_SEL		GPIO_3	MMP3 CPU Speed: 1 - 1GHz, 0 - 1.2GHz
MEM_SZ0		GPIO_0	Memory size: 0 - 1GB, 1 - 2GB
MEM_SZ1		GPIO_1	Memory size: always 0
HDMI_HP_DET		GPIO_14	HDMI port only on XO-4
HDMI_SCL		GPIO_4	〃
HDMI_DAT		GPIO_5	〃
TOUCH_BSL_RXD		UART4_TXD	Touch only on XO-4
TOUCH_BSL_TXD		UART4_RXD	〃
TOUCH_HD		GPIO_12	〃
TOUCH_RST#		GPIO_98	〃
TOUCH_TCK		GPIO_139	〃
CONSOLE_RXD	UART3_RXD	UART2_RXD	OFW/Linux Console (XO-1.75: CN8, XO-4: CN18)
CONSOLE_TXD	UART3_RXD	UART2_TXD	OFW/Linux Console (XO-1.75: CN8, XO-4: CN18)