diff options
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/s390/cds.txt | 82 |
1 files changed, 4 insertions, 78 deletions
diff --git a/Documentation/s390/cds.txt b/Documentation/s390/cds.txt index 05a2b4f7e38f..58919d6a593a 100644 --- a/Documentation/s390/cds.txt +++ b/Documentation/s390/cds.txt | |||
@@ -51,13 +51,8 @@ The major changes are: | |||
51 | * The interrupt handlers must be adapted to use a ccw_device as argument. | 51 | * The interrupt handlers must be adapted to use a ccw_device as argument. |
52 | Moreover, they don't return a devstat, but an irb. | 52 | Moreover, they don't return a devstat, but an irb. |
53 | * Before initiating an io, the options must be set via ccw_device_set_options(). | 53 | * Before initiating an io, the options must be set via ccw_device_set_options(). |
54 | 54 | * Instead of calling read_dev_chars()/read_conf_data(), the driver issues | |
55 | read_dev_chars() | 55 | the channel program and handles the interrupt itself. |
56 | read device characteristics | ||
57 | |||
58 | read_conf_data() | ||
59 | read_conf_data_lpm() | ||
60 | read configuration data. | ||
61 | 56 | ||
62 | ccw_device_get_ciw() | 57 | ccw_device_get_ciw() |
63 | get commands from extended sense data. | 58 | get commands from extended sense data. |
@@ -130,11 +125,6 @@ present their hardware status by the same (shared) IRQ, the operating system | |||
130 | has to call every single device driver registered on this IRQ in order to | 125 | has to call every single device driver registered on this IRQ in order to |
131 | determine the device driver owning the device that raised the interrupt. | 126 | determine the device driver owning the device that raised the interrupt. |
132 | 127 | ||
133 | In order not to introduce a new I/O concept to the common Linux code, | ||
134 | Linux/390 preserves the IRQ concept and semantically maps the ESA/390 | ||
135 | subchannels to Linux as IRQs. This allows Linux/390 to support up to 64k | ||
136 | different IRQs, uniquely representing a single device each. | ||
137 | |||
138 | Up to kernel 2.4, Linux/390 used to provide interfaces via the IRQ (subchannel). | 128 | Up to kernel 2.4, Linux/390 used to provide interfaces via the IRQ (subchannel). |
139 | For internal use of the common I/O layer, these are still there. However, | 129 | For internal use of the common I/O layer, these are still there. However, |
140 | device drivers should use the new calling interface via the ccw_device only. | 130 | device drivers should use the new calling interface via the ccw_device only. |
@@ -151,9 +141,8 @@ information during their initialization step to recognize the devices they | |||
151 | support using the information saved in the struct ccw_device given to them. | 141 | support using the information saved in the struct ccw_device given to them. |
152 | This methods implies that Linux/390 doesn't require to probe for free (not | 142 | This methods implies that Linux/390 doesn't require to probe for free (not |
153 | armed) interrupt request lines (IRQs) to drive its devices with. Where | 143 | armed) interrupt request lines (IRQs) to drive its devices with. Where |
154 | applicable, the device drivers can use the read_dev_chars() to retrieve device | 144 | applicable, the device drivers can use issue the READ DEVICE CHARACTERISTICS |
155 | characteristics. This can be done without having to request device ownership | 145 | ccw to retrieve device characteristics in its online routine. |
156 | previously. | ||
157 | 146 | ||
158 | In order to allow for easy I/O initiation the CDS layer provides a | 147 | In order to allow for easy I/O initiation the CDS layer provides a |
159 | ccw_device_start() interface that takes a device specific channel program (one | 148 | ccw_device_start() interface that takes a device specific channel program (one |
@@ -170,69 +159,6 @@ SUBCHANNEL (HSCH) command without having pending I/O requests. This function is | |||
170 | also covered by ccw_device_halt(). | 159 | also covered by ccw_device_halt(). |
171 | 160 | ||
172 | 161 | ||
173 | read_dev_chars() - Read Device Characteristics | ||
174 | |||
175 | This routine returns the characteristics for the device specified. | ||
176 | |||
177 | The function is meant to be called with the device already enabled; that is, | ||
178 | at earliest during set_online() processing. | ||
179 | |||
180 | The ccw_device must not be locked prior to calling read_dev_chars(). | ||
181 | |||
182 | The function may be called enabled or disabled. | ||
183 | |||
184 | int read_dev_chars(struct ccw_device *cdev, void **buffer, int length ); | ||
185 | |||
186 | cdev - the ccw_device the information is requested for. | ||
187 | buffer - pointer to a buffer pointer. The buffer pointer itself | ||
188 | must contain a valid buffer area. | ||
189 | length - length of the buffer provided. | ||
190 | |||
191 | The read_dev_chars() function returns : | ||
192 | |||
193 | 0 - successful completion | ||
194 | -ENODEV - cdev invalid | ||
195 | -EINVAL - an invalid parameter was detected, or the function was called early. | ||
196 | -EBUSY - an irrecoverable I/O error occurred or the device is not | ||
197 | operational. | ||
198 | |||
199 | |||
200 | read_conf_data(), read_conf_data_lpm() - Read Configuration Data | ||
201 | |||
202 | Retrieve the device dependent configuration data. Please have a look at your | ||
203 | device dependent I/O commands for the device specific layout of the node | ||
204 | descriptor elements. read_conf_data_lpm() will retrieve the configuration data | ||
205 | for a specific path. | ||
206 | |||
207 | The function is meant to be called with the device already enabled; that is, | ||
208 | at earliest during set_online() processing. | ||
209 | |||
210 | The function may be called enabled or disabled, but the device must not be | ||
211 | locked | ||
212 | |||
213 | int read_conf_data(struct ccw_device, void **buffer, int *length); | ||
214 | int read_conf_data_lpm(struct ccw_device, void **buffer, int *length, __u8 lpm); | ||
215 | |||
216 | cdev - the ccw_device the data is requested for. | ||
217 | buffer - Pointer to a buffer pointer. The read_conf_data() routine | ||
218 | will allocate a buffer and initialize the buffer pointer | ||
219 | accordingly. It's the device driver's responsibility to | ||
220 | release the kernel memory if no longer needed. | ||
221 | length - Length of the buffer allocated and retrieved. | ||
222 | lpm - Logical path mask to be used for retrieving the data. If | ||
223 | zero the data is retrieved on the next path available. | ||
224 | |||
225 | The read_conf_data() function returns : | ||
226 | 0 - Successful completion | ||
227 | -ENODEV - cdev invalid. | ||
228 | -EINVAL - An invalid parameter was detected, or the function was called early. | ||
229 | -EIO - An irrecoverable I/O error occurred or the device is | ||
230 | not operational. | ||
231 | -ENOMEM - The read_conf_data() routine couldn't obtain storage. | ||
232 | -EOPNOTSUPP - The device doesn't support the read configuration | ||
233 | data command. | ||
234 | |||
235 | |||
236 | get_ciw() - get command information word | 162 | get_ciw() - get command information word |
237 | 163 | ||
238 | This call enables a device driver to get information about supported commands | 164 | This call enables a device driver to get information about supported commands |