On 19/11/2019 11:58, Russell King - ARM Linux admin wrote: > On Tue, Nov 19, 2019 at 11:46:21AM +0100, Marc Gonzalez wrote: > >> On 19/11/2019 10:57, Russell King - ARM Linux admin wrote: >> >>> On Tue, Nov 19, 2019 at 10:28:15AM +0100, Marc Gonzalez wrote: >>> >>>> The board I'm working on provides a TCA9539 I/O expander. >>>> Or, as the datasheet(*) calls it, a "Low Voltage 16-Bit I2C and >>>> SMBus Low-Power I/O Expander with Interrupt Output, Reset Pin, >>>> and Configuration Registers" >>>> >>>> (*) http://www.ti.com/lit/ds/symlink/tca9539.pdf >>>> >>>> The binding is documented in Documentation/devicetree/bindings/gpio/gpio-pca953x.txt >>>> >>>> I have some doubts about the interrupt output, described as: >>>> >>>> Optional properties: >>>> - interrupts: interrupt specifier for the device's interrupt output. >>>> >>>> In my board's DT, the I/O expander is described as: >>>> >>>> exp1: gpio@74 { >>>> compatible = "ti,tca9539"; >>>> reg = <0x74>; >>>> gpio-controller; >>>> #gpio-cells = <2>; >>>> reset-gpios = <&tlmm 96 GPIO_ACTIVE_LOW>; >>>> pinctrl-names = "default"; >>>> pinctrl-0 = <&top_exp_rst>; >>>> interrupt-parent = <&tlmm>; >>>> interrupts = <42 IRQ_TYPE_LEVEL_HIGH>; >> >> As pointed out by ukleinek on IRC, I might have (??) specified the wrong >> trigger type. The data-sheet states: >> "The TCA9539 open-drain interrupt (INTn) output is activated when any input state >> differs from its corresponding Input Port register state, and is used to indicate >> to the system master that an input state has changed." >> (The data sheet speaks of "INT with a line on top"; what is the typical way to >> write that in ASCII? I was told that adding a trailing 'n' or 'b' was common.) > > /INT or nINT are commonly used - I've never heard or seen 'b' (which is > commonly used as a suffix on binary numbers) or a trailing 'n'. Perhaps the 'b' suffix is only used in French... 'b' might stand for "barre" (i.e. the line above the symbol). > Is pin 42 something that can be muxed? If so, it seems sane to specify > configuration for it. Whether it needs to be a GPIO or whether it has > a specific "interrupt" function mux state depends on the SoC. According to drivers/pinctrl/qcom/pinctrl-msm8998.c PINGROUP(42, EAST, blsp_spi6, blsp_uart3_b, blsp_uim3_b, _, qdss, _, _, _, _) I don't think there is an explicit "interrupt" function in this pinctrl driver... except FUNCTION(ssc_irq). static const char * const ssc_irq_groups[] = { "gpio58", "gpio59", "gpio60", "gpio61", "gpio62", "gpio63", "gpio78", "gpio79", "gpio80", "gpio117", "gpio118", "gpio119", "gpio120", "gpio121", "gpio122", "gpio123", "gpio124", "gpio125", }; @Bjorn, do you know what these are used for? Regards.
