78 lines
2.2 KiB
Plaintext
78 lines
2.2 KiB
Plaintext
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uio_usbdebug - Run coreboot's usbdebug driver in userspace
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==========================================================
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## Purpose
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uio_usbdebug enables you to debug coreboot's usbdebug driver inside a
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running operating system (only Linux at this time). This comes very
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handy if you're hacking the usbdebug driver and don't have any other
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debug output from coreboot itself.
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## State
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Currently only Intel chipsets are supported. Support for other chipsets
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should be straightforward (normally just some port-enable code has to
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be implemented).
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The Linux kernel driver (see linux/uio_ehci_pci.c) has only one PCI ID
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hardcoded (for ICH7). The whole setup has been developed and tested on
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a ThinkPad T60.
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### Files
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uio_usbdebug.c - The userspace part of the uio interface.
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uio_usbdebug_intel.c - Port enable code for Intel chipsets.
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linux/uio_ehci_pci.c - Kernel part of the uio interface.
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console/printk.c - A do_printk() implementation so you can see debug
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output with CONFIG_DEBUG_USBDEBUG enabled.
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device/*.c lib/*.c - Some stubs for (hopefully) unneeded functions for
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proper linking.
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## Usage
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### Preparations
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The MMIO space has to be a whole 4K page in size and alignment to be
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mapped into userspace. This is very uncommon, so you'll most probably
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have to remap the MMIO space. The Linux kernel does that for you with
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the `pci=resource_alignment=<pci address>` kernel parameter (e.g.
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`pci=resource_alignment=0:1d.7` for ICH7).
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If your PCI device isn't listed in the kernel driver yet, you might want
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to add it to the `ehci_pci_ids` table in `linux/uio_ehci_pci.c` (or do
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some module alias magic if you know how to).
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### Build / Install
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Somehow like this:
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$ # Configure coreboot for your board and enable CONFIG_USBDEBUG
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$ make menuconfig
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$ cd util/uio_usbdebug/
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$ make -Clinux/
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$ sudo make -Clinux/ install
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$ make
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### Run
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$ # Unload Linux' EHCI driver (high-speed devices will stop working)
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$ sudo modprobe -r ehci-pci
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$ # Load the uio driver
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$ sudo modprobe uio-ehci-pci
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$ # Find your uio device
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$ ls /sys/module/uio_ehci_pci/drivers/*/*/uio/
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uio0
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$ # Run uio_usbdebug on this device
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$ sudo ./uio_usbdebug /dev/uio0
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Sadly, uio_usbdebug has to be run with root privileges since there are
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port-80 writes in the usbdebug driver.
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