* Atmel AT91 Pinmux Controller The AT91 Pinmux Controller, enables the IC to share one PAD to several functional blocks. The sharing is done by multiplexing the PAD input/output signals. For each PAD there are up to 8 muxing options (called periph modes). Since different modules require different PAD settings (like pull up, keeper, etc) the contoller controls also the PAD settings parameters. Please refer to pinctrl-bindings.txt in this directory for details of the common pinctrl bindings used by client devices, including the meaning of the phrase "pin configuration node". Atmel AT91 pin configuration node is a node of a group of pins which can be used for a specific device or function. This node represents both mux and config of the pins in that group. The 'pins' selects the function mode(also named pin mode) this pin can work on and the 'config' configures various pad settings such as pull-up, multi drive, etc. Required properties for iomux controller: - compatible: "atmel,at91rm9200-pinctrl" or "atmel,at91sam9x5-pinctrl" or "atmel,sama5d3-pinctrl" - atmel,mux-mask: array of mask (periph per bank) to describe if a pin can be configured in this periph mode. All the periph and bank need to be describe. How to create such array: Each column will represent the possible peripheral of the pinctrl Each line will represent a pio bank Take an example on the 9260 Peripheral: 2 ( A and B) Bank: 3 (A, B and C) => /* A B */ 0xffffffff 0xffc00c3b /* pioA */ 0xffffffff 0x7fff3ccf /* pioB */ 0xffffffff 0x007fffff /* pioC */ For each peripheral/bank we will descibe in a u32 if a pin can be configured in it by putting 1 to the pin bit (1 << pin) Let's take the pioA on peripheral B From the datasheet Table 10-2. Peripheral B PA0 MCDB0 PA1 MCCDB PA2 PA3 MCDB3 PA4 MCDB2 PA5 MCDB1 PA6 PA7 PA8 PA9 PA10 ETX2 PA11 ETX3 PA12 PA13 PA14 PA15 PA16 PA17 PA18 PA19 PA20 PA21 PA22 ETXER PA23 ETX2 PA24 ETX3 PA25 ERX2 PA26 ERX3 PA27 ERXCK PA28 ECRS PA29 ECOL PA30 RXD4 PA31 TXD4 => 0xffc00c3b Required properties for pin configuration node: - atmel,pins: 4 integers array, represents a group of pins mux and config setting. The format is atmel,pins = . The PERIPH 0 means gpio, PERIPH 1 is periph A, PERIPH 2 is periph B... PIN_BANK 0 is pioA, PIN_BANK 1 is pioB... Bits used for CONFIG: PULL_UP (1 << 0): indicate this pin needs a pull up. MULTIDRIVE (1 << 1): indicate this pin needs to be configured as multi-drive. Multi-drive is equivalent to open-drain type output. DEGLITCH (1 << 2): indicate this pin needs deglitch. PULL_DOWN (1 << 3): indicate this pin needs a pull down. DIS_SCHMIT (1 << 4): indicate this pin needs to the disable schmitt trigger. DRIVE_STRENGTH (3 << 5): indicate the drive strength of the pin using the following values: 00 - No change (reset state value kept) 01 - Low 10 - Medium 11 - High DEBOUNCE (1 << 16): indicate this pin needs debounce. DEBOUNCE_VAL (0x3fff << 17): debounce value. NOTE: Some requirements for using atmel,at91rm9200-pinctrl binding: 1. We have pin function node defined under at91 controller node to represent what pinmux functions this SoC supports. 2. The driver can use the function node's name and pin configuration node's name describe the pin function and group hierarchy. For example, Linux at91 pinctrl driver takes the function node's name as the function name and pin configuration node's name as group name to create the map table. 3. Each pin configuration node should have a phandle, devices can set pins configurations by referring to the phandle of that pin configuration node. 4. The gpio controller must be describe in the pinctrl simple-bus. Examples: pinctrl@fffff400 { #address-cells = <1>; #size-cells = <1>; ranges; compatible = "atmel,at91rm9200-pinctrl", "simple-bus"; reg = <0xfffff400 0x600>; atmel,mux-mask = < /* A B */ 0xffffffff 0xffc00c3b /* pioA */ 0xffffffff 0x7fff3ccf /* pioB */ 0xffffffff 0x007fffff /* pioC */ >; /* shared pinctrl settings */ dbgu { pinctrl_dbgu: dbgu-0 { atmel,pins = <1 14 0x1 0x0 /* PB14 periph A */ 1 15 0x1 0x1>; /* PB15 periph A with pullup */ }; }; }; dbgu: serial@fffff200 { compatible = "atmel,at91sam9260-usart"; reg = <0xfffff200 0x200>; interrupts = <1 4 7>; pinctrl-names = "default"; pinctrl-0 = <&pinctrl_dbgu>; status = "disabled"; };