The aim of this document is to explain how to setup pins of SP7350 in device-tree source. SP7350 has 106 general purpose IO (GPIO) pins which are multiplexed with other special functions, like eMMC device, SPI-NOR flash, SPI-NAND flash, Ethernet PHY (RGMII or RMII interface), UART, I2C pins, and etc.
The following sections will explain how to setup GPIOs and special function pins in device-tree source file. Note that the same device-tree source file is used by U-Boot and Linux in SP7350. Both Pinctrl drivers support generic helper bindings.
Contents
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IO Pins
In the Linux, name of IO pin is in form of GPIO(id), like GPIO0, GPIO1, GPIO2, …, GPIO105, and etc. These IO pins of SP7350 are categorized, based on their operating voltage, into two groups:
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GPIO # | Power domain | Type | Pin name | Power-supply |
0 - 19 | Main | 1.8V GPIO | G_MX0 - G_MX19 | VDDPST18_GPIO |
20 | 1.8V/3.0V DVIO | G_MX20 | VDDPST3018_DVIO_2 | |
21 - 27 | G_MX21 - G_MX27 | VDDPST3018_DVIO_1 | ||
28 - 37 | G_MX28 - G_MX37 | VDDPST3018_DVIO_2 | ||
38 - 43 | G_MX38 - G_MX43 | AVDDIO_3018_SD | ||
44 - 49 | G_MX44 - G_MX49 | AVDDIO_3018_SDIO | ||
50 - 59 | CM4 (AO) | AO_MX0 - AO_MX9 | VDDPST3018_DVIO_AO_1 | |
60 - 69 | AO_MX10 - AO_MX19 | VDDPST3018_DVIO_AO_2 | ||
70 - 79 | AO_MX20 - AO_MX29 | VDDPST3018_DVIO_AO_3 | ||
80 - 98 | 1.8V GPIO | AO_MX30 - AO_MX48 | VDDPST18_GPIO_AO | |
99 - 105 | IV_MX0 - IV_MX6 |
Voltage Mode Select
Beyond configuring the 1.8V or 3.0V power to supply pins of a DVIO group in circuit boards (hardware), setting up the voltage mode select (ms control) control-bits is crucial for the normal operation of IO pins. The following properties configure voltage mode select control-bits in the Device Tree Source (DTS) file:
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