1* Spreadtrum Pin Controller 2 3The Spreadtrum pin controller are organized in 3 blocks (types). 4 5The first block comprises some global control registers, and each 6register contains several bit fields with one bit or several bits 7to configure for some global common configuration, such as domain 8pad driving level, system control select and so on ("domain pad 9driving level": One pin can output 3.0v or 1.8v, depending on the 10related domain pad driving selection, if the related domain pad 11slect 3.0v, then the pin can output 3.0v. "system control" is used 12to choose one function (like: UART0) for which system, since we 13have several systems (AP/CP/CM4) on one SoC.). 14 15There are too much various configuration that we can not list all 16of them, so we can not make every Spreadtrum-special configuration 17as one generic configuration, and maybe it will add more strange 18global configuration in future. Then we add one "sprd,control" to 19set these various global control configuration, and we need use 20magic number for this property. 21 22Moreover we recognise every fields comprising one bit or several 23bits in one global control register as one pin, thus we should 24record every pin's bit offset, bit width and register offset to 25configure this field (pin). 26 27The second block comprises some common registers which have unified 28register definition, and each register described one pin is used 29to configure the pin sleep mode, function select and sleep related 30configuration. 31 32Now we have 4 systems for sleep mode on SC9860 SoC: AP system, 33PUBCP system, TGLDSP system and AGDSP system. And the pin sleep 34related configuration are: 35- input-enable 36- input-disable 37- output-high 38- output-low 39- bias-pull-up 40- bias-pull-down 41 42In some situation we need set the pin sleep mode and pin sleep related 43configuration, to set the pin sleep related configuration automatically 44by hardware when the system specified by sleep mode goes into deep 45sleep mode. For example, if we set the pin sleep mode as PUBCP_SLEEP 46and set the pin sleep related configuration as "input-enable", which 47means when PUBCP system goes into deep sleep mode, this pin will be set 48input enable automatically. 49 50Moreover we can not use the "sleep" state, since some systems (like: 51PUBCP system) do not run linux kernel OS (only AP system run linux 52kernel on SC9860 platform), then we can not select "sleep" state 53when the PUBCP system goes into deep sleep mode. Thus we introduce 54"sprd,sleep-mode" property to set pin sleep mode. 55 56The last block comprises some misc registers which also have unified 57register definition, and each register described one pin is used to 58configure drive strength, pull up/down and so on. Especially for pull 59up, we have two kind pull up resistor: 20K and 4.7K. 60 61Required properties for Spreadtrum pin controller: 62- compatible: "sprd,<soc>-pinctrl" 63 Please refer to each sprd,<soc>-pinctrl.txt binding doc for supported SoCs. 64- reg: The register address of pin controller device. 65- pins : An array of pin names. 66 67Optional properties: 68- function: Specified the function name. 69- drive-strength: Drive strength in mA. 70- input-schmitt-disable: Enable schmitt-trigger mode. 71- input-schmitt-enable: Disable schmitt-trigger mode. 72- bias-disable: Disable pin bias. 73- bias-pull-down: Pull down on pin. 74- bias-pull-up: Pull up on pin. 75- input-enable: Enable pin input. 76- input-disable: Enable pin output. 77- output-high: Set the pin as an output level high. 78- output-low: Set the pin as an output level low. 79- sleep-hardware-state: Indicate these configs in this state are sleep related. 80- sprd,control: Control values referring to databook for global control pins. 81- sprd,sleep-mode: Sleep mode selection. 82 83Please refer to each sprd,<soc>-pinctrl.txt binding doc for supported values. 84