[S390] cio: Update documentation.
- read_dev_chars()/read_conf_data() are deprecated. Don't document them, but advise to issue the channel program from the driver itself. - Remove some really obsolete and incorrect stuff. Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Cornelia Huck
Martin Schwidefsky
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@ -51,13 +51,8 @@ The major changes are:
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* The interrupt handlers must be adapted to use a ccw_device as argument.
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Moreover, they don't return a devstat, but an irb.
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* Before initiating an io, the options must be set via ccw_device_set_options().
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read_dev_chars()
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read device characteristics
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read_conf_data()
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read_conf_data_lpm()
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read configuration data.
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* Instead of calling read_dev_chars()/read_conf_data(), the driver issues
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the channel program and handles the interrupt itself.
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ccw_device_get_ciw()
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get commands from extended sense data.
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@ -130,11 +125,6 @@ present their hardware status by the same (shared) IRQ, the operating system
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has to call every single device driver registered on this IRQ in order to
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determine the device driver owning the device that raised the interrupt.
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In order not to introduce a new I/O concept to the common Linux code,
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Linux/390 preserves the IRQ concept and semantically maps the ESA/390
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subchannels to Linux as IRQs. This allows Linux/390 to support up to 64k
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different IRQs, uniquely representing a single device each.
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Up to kernel 2.4, Linux/390 used to provide interfaces via the IRQ (subchannel).
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For internal use of the common I/O layer, these are still there. However,
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device drivers should use the new calling interface via the ccw_device only.
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@ -151,9 +141,8 @@ information during their initialization step to recognize the devices they
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support using the information saved in the struct ccw_device given to them.
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This methods implies that Linux/390 doesn't require to probe for free (not
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armed) interrupt request lines (IRQs) to drive its devices with. Where
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applicable, the device drivers can use the read_dev_chars() to retrieve device
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characteristics. This can be done without having to request device ownership
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previously.
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applicable, the device drivers can use issue the READ DEVICE CHARACTERISTICS
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ccw to retrieve device characteristics in its online routine.
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In order to allow for easy I/O initiation the CDS layer provides a
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ccw_device_start() interface that takes a device specific channel program (one
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@ -170,69 +159,6 @@ SUBCHANNEL (HSCH) command without having pending I/O requests. This function is
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also covered by ccw_device_halt().
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read_dev_chars() - Read Device Characteristics
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This routine returns the characteristics for the device specified.
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The function is meant to be called with the device already enabled; that is,
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at earliest during set_online() processing.
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The ccw_device must not be locked prior to calling read_dev_chars().
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The function may be called enabled or disabled.
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int read_dev_chars(struct ccw_device *cdev, void **buffer, int length );
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cdev - the ccw_device the information is requested for.
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buffer - pointer to a buffer pointer. The buffer pointer itself
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must contain a valid buffer area.
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length - length of the buffer provided.
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The read_dev_chars() function returns :
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0 - successful completion
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-ENODEV - cdev invalid
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-EINVAL - an invalid parameter was detected, or the function was called early.
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-EBUSY - an irrecoverable I/O error occurred or the device is not
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operational.
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read_conf_data(), read_conf_data_lpm() - Read Configuration Data
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Retrieve the device dependent configuration data. Please have a look at your
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device dependent I/O commands for the device specific layout of the node
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descriptor elements. read_conf_data_lpm() will retrieve the configuration data
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for a specific path.
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The function is meant to be called with the device already enabled; that is,
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at earliest during set_online() processing.
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The function may be called enabled or disabled, but the device must not be
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locked
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int read_conf_data(struct ccw_device, void **buffer, int *length);
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int read_conf_data_lpm(struct ccw_device, void **buffer, int *length, __u8 lpm);
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cdev - the ccw_device the data is requested for.
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buffer - Pointer to a buffer pointer. The read_conf_data() routine
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will allocate a buffer and initialize the buffer pointer
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accordingly. It's the device driver's responsibility to
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release the kernel memory if no longer needed.
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length - Length of the buffer allocated and retrieved.
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lpm - Logical path mask to be used for retrieving the data. If
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zero the data is retrieved on the next path available.
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The read_conf_data() function returns :
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0 - Successful completion
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-ENODEV - cdev invalid.
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-EINVAL - An invalid parameter was detected, or the function was called early.
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-EIO - An irrecoverable I/O error occurred or the device is
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not operational.
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-ENOMEM - The read_conf_data() routine couldn't obtain storage.
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-EOPNOTSUPP - The device doesn't support the read configuration
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data command.
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get_ciw() - get command information word
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This call enables a device driver to get information about supported commands
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