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Diffstat (limited to 'Documentation/driver-api/uio-howto.rst')
| -rw-r--r-- | Documentation/driver-api/uio-howto.rst | 49 |
1 files changed, 37 insertions, 12 deletions
diff --git a/Documentation/driver-api/uio-howto.rst b/Documentation/driver-api/uio-howto.rst index f73d660b2956..907ffa3b38f5 100644 --- a/Documentation/driver-api/uio-howto.rst +++ b/Documentation/driver-api/uio-howto.rst @@ -274,10 +274,10 @@ fields of ``struct uio_mem``: region, it will show up in the corresponding sysfs node. - ``int memtype``: Required if the mapping is used. Set this to - ``UIO_MEM_PHYS`` if you you have physical memory on your card to be + ``UIO_MEM_PHYS`` if you have physical memory on your card to be mapped. Use ``UIO_MEM_LOGICAL`` for logical memory (e.g. allocated - with :c:func:`kmalloc()`). There's also ``UIO_MEM_VIRTUAL`` for - virtual memory. + with :c:func:`__get_free_pages()` but not kmalloc()). There's also + ``UIO_MEM_VIRTUAL`` for virtual memory. - ``phys_addr_t addr``: Required if the mapping is used. Fill in the address of your memory block. This address is the one that appears in @@ -408,6 +408,13 @@ handler code. You also do not need to know anything about the chip's internal registers to create the kernel part of the driver. All you need to know is the irq number of the pin the chip is connected to. +When used in a device-tree enabled system, the driver needs to be +probed with the ``"of_id"`` module parameter set to the ``"compatible"`` +string of the node the driver is supposed to handle. By default, the +node's name (without the unit address) is exposed as name for the +UIO device in userspace. To set a custom name, a property named +``"linux,uio-name"`` may be specified in the DT node. + Using uio_dmem_genirq for platform devices ------------------------------------------ @@ -463,8 +470,8 @@ Getting information about your UIO device Information about all UIO devices is available in sysfs. The first thing you should do in your driver is check ``name`` and ``version`` to make -sure your talking to the right device and that its kernel driver has the -version you expect. +sure you're talking to the right device and that its kernel driver has +the version you expect. You should also make sure that the memory mapping you need exists and has the size you expect. @@ -667,27 +674,28 @@ Making the driver recognize the device Since the driver does not declare any device GUID's, it will not get loaded automatically and will not automatically bind to any devices, you must load it and allocate id to the driver yourself. For example, to use -the network device GUID:: +the network device class GUID:: modprobe uio_hv_generic echo "f8615163-df3e-46c5-913f-f2d2f965ed0e" > /sys/bus/vmbus/drivers/uio_hv_generic/new_id If there already is a hardware specific kernel driver for the device, the generic driver still won't bind to it, in this case if you want to -use the generic driver (why would you?) you'll have to manually unbind -the hardware specific driver and bind the generic driver, like this:: +use the generic driver for a userspace library you'll have to manually unbind +the hardware specific driver and bind the generic driver, using the device specific GUID +like this:: - echo -n vmbus-ed963694-e847-4b2a-85af-bc9cfc11d6f3 > /sys/bus/vmbus/drivers/hv_netvsc/unbind - echo -n vmbus-ed963694-e847-4b2a-85af-bc9cfc11d6f3 > /sys/bus/vmbus/drivers/uio_hv_generic/bind + echo -n ed963694-e847-4b2a-85af-bc9cfc11d6f3 > /sys/bus/vmbus/drivers/hv_netvsc/unbind + echo -n ed963694-e847-4b2a-85af-bc9cfc11d6f3 > /sys/bus/vmbus/drivers/uio_hv_generic/bind You can verify that the device has been bound to the driver by looking for it in sysfs, for example like the following:: - ls -l /sys/bus/vmbus/devices/vmbus-ed963694-e847-4b2a-85af-bc9cfc11d6f3/driver + ls -l /sys/bus/vmbus/devices/ed963694-e847-4b2a-85af-bc9cfc11d6f3/driver Which if successful should print:: - .../vmbus-ed963694-e847-4b2a-85af-bc9cfc11d6f3/driver -> ../../../bus/vmbus/drivers/uio_hv_generic + .../ed963694-e847-4b2a-85af-bc9cfc11d6f3/driver -> ../../../bus/vmbus/drivers/uio_hv_generic Things to know about uio_hv_generic ----------------------------------- @@ -697,6 +705,23 @@ prevents the device from generating further interrupts until the bit is cleared. The userspace driver should clear this bit before blocking and waiting for more interrupts. +When host rescinds a device, the interrupt file descriptor is marked down +and any reads of the interrupt file descriptor will return -EIO. Similar +to a closed socket or disconnected serial device. + +The vmbus device regions are mapped into uio device resources: + 0) Channel ring buffers: guest to host and host to guest + 1) Guest to host interrupt signalling pages + 2) Guest to host monitor page + 3) Network receive buffer region + 4) Network send buffer region + +If a subchannel is created by a request to host, then the uio_hv_generic +device driver will create a sysfs binary file for the per-channel ring buffer. +For example:: + + /sys/bus/vmbus/devices/3811fe4d-0fa0-4b62-981a-74fc1084c757/channels/21/ring + Further information =================== |