diff options
| -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 |
