| Message ID | 20201004162908.3216898-1-martin.blumenstingl@googlemail.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | GPIO support on the Etron EJ168/EJ188/EJ198 xHCI controllers | expand |
On Sun, Oct 4, 2020 at 8:00 PM Martin Blumenstingl <martin.blumenstingl@googlemail.com> wrote: > The goal of this series to add support for the GPIO controller on the > Etron EJ168/EJ188/EJ198 controllers. This overall is a fine driver, but have you considered the option of just implementing the GPIO chip in drivers/usb/host/xhci-pci.c? There are several USB serial adapters that have a GPIO chip embedded and we just add the GPIO chip into the serial driver. I have done the same with some networking switches. It is perfectly fine for drivers outside of drivers/gpio to occasionally define a minor GPIO chip if GPIO is not their primary function. Please consider simply activating the XHCI driver and make it instantiate a GPIO chip if it happens to be an EJ168/EJ188/EJ198 controller. Yours, Linus Walleij
Hello, I have a "Belkin F9K115v2" (wifi router) [0]. It comes with an Etron EJ168 xHCI controllers soldered to the board. One of the LEDs on this device is connected to one of the four GPIO lines provided by the Etron xHCI controller. The goal of this series to add support for the GPIO controller on the Etron EJ168/EJ188/EJ198 controllers. Unfortunately there's no (public) datasheet available. I have Cc'ed Etron and I'm hoping that they can either provide a datasheet or at least some code-review feedback. Instead I used the GPL tarball [0] for this device. Inside this tarball the relevant "reference" code is in: linux/kernels/mips-linux-2.6.31/drivers/usb/host/etxhci-pci.c Unfortunately it uses magic numbers for the registers instead of human-readable names. The register names are what I came up with. For reference, I have tested this on a patched OpenWrt build with the following .dts changes (I am showing these here so it will be easier to review the whole series): &pcie1 { status = "okay"; xhci: usb-controller@0,0,0 { compatible = "pci1b6f,7023"; reg = <0x0 0x0 0x0 0x0 0x1000>; #address-cells = <1>; #size-cells = <0>; gpio-controller; #gpio-cells = <2>; xhci_port0: port@1 { reg = <1>; #trigger-source-cells = <0>; }; }; }; leds { compatible = "gpio-leds"; usb3 { label = "green:usb3"; gpios = <&xhci 2 GPIO_ACTIVE_LOW>; trigger-sources = <&xhci_port0>; linux,default-trigger = "usbport"; }; }; In general I followed [2] because it says: PCI drivers should have a really good reason for not using the pci_register_driver() [...] The main reason [...] is because one PCI device implements several different HW services. My understanding that my driver fits into this category. I am sending this as RFC because this is my first self-written GPIO driver as well as my first PCI device driver. Any feedback is welcome! Best regards, Martin [0] https://openwrt.org/toh/belkin/f9k1115v2 [1] https://www.belkin.com/support/dl/F9K1115v2.03.97-GPL-10.2.85.tar.gz [2] https://www.kernel.org/doc/html/latest/PCI/pci.html#how-to-find-pci-devices-manually Martin Blumenstingl (3): PCI: Add the IDs for Etron EJ168 and EJ188 dt-bindings: gpio: Add binding documentation for Etron EJ168/EJ188/EJ198 gpio: ej1x8: Add GPIO driver for Etron Tech Inc. EJ168/EJ188/EJ198 .../devicetree/bindings/gpio/etron,ej1x8.yaml | 48 +++ drivers/gpio/Kconfig | 9 + drivers/gpio/Makefile | 1 + drivers/gpio/gpio-ej1x8.c | 311 ++++++++++++++++++ include/linux/pci_ids.h | 4 + 5 files changed, 373 insertions(+) create mode 100644 Documentation/devicetree/bindings/gpio/etron,ej1x8.yaml create mode 100644 drivers/gpio/gpio-ej1x8.c