Attachment #16711 for bug #30540

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 * I/O access to the controller/keyboard/mouse. The convention requires
 * close cooperation of the calling device driver.
 *
 * The device drivers which utilize the `kbdio' module are assumed to
 * have the following set of routines.
 *    a. An interrupt handler (the bottom half of the driver).
 *    b. Timeout routines which may briefly poll the keyboard controller.
 *    c. Routines outside interrupt context (the top half of the driver).
 * They should follow the rules below:
 *    1. The interrupt handler may assume that it always has full access 

 *       Therefore, `spltty()' must be strategically placed in the device
 *       driver code. Also note that the timeout routine may interrupt
 *       `kbdc_lock()' called by the top half of the driver, but this
 *       interruption is OK so long as the timeout routine observes
 *       rule 4 below.
 *    4. The interrupt and timeout routines should not extend I/O operation
 *       across more than one interrupt or timeout; they must complete any
 *       necessary I/O operation within one invocation of the routine.
 *       This means that if the timeout routine acquires the lock flag,
 *       it must reset the flag to FALSE before it returns.
 */

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Lines 217-226 Link Here

(-)sys/dev/kbd//atkbdc.c (-7 / +7 lines)
217	* I/O access to the controller/keyboard/mouse. The convention requires	217	* I/O access to the controller/keyboard/mouse. The convention requires
218	* close cooperation of the calling device driver.	218	* close cooperation of the calling device driver.
219	*	219	*
220	* The device driver which utilizes the `kbdio' module are assumed to	220	* The device drivers which utilize the `kbdio' module are assumed to
221	* have the following set of routines.	221	* have the following set of routines.
222	* a. An interrupt handler (the bottom half of the driver).	222	* a. An interrupt handler (the bottom half of the driver).
223	* b. Timeout routines which may briefly polls the keyboard controller.	223	* b. Timeout routines which may briefly poll the keyboard controller.
224	* c. Routines outside interrupt context (the top half of the driver).	224	* c. Routines outside interrupt context (the top half of the driver).
225	* They should follow the rules below:	225	* They should follow the rules below:
226	* 1. The interrupt handler may assume that it always has full access	226	* 1. The interrupt handler may assume that it always has full access
Lines 239-250 Link Here
239	* Therefore, `spltty()' must be strategically placed in the device	239	* Therefore, `spltty()' must be strategically placed in the device
240	* driver code. Also note that the timeout routine may interrupt	240	* driver code. Also note that the timeout routine may interrupt
241	* `kbdc_lock()' called by the top half of the driver, but this	241	* `kbdc_lock()' called by the top half of the driver, but this
242	* interruption is OK so long as the timeout routine observes the	242	* interruption is OK so long as the timeout routine observes
243	* the rule 4 below.	243	* rule 4 below.
244	* 4. The interrupt and timeout routines should not extend I/O operation	244	* 4. The interrupt and timeout routines should not extend I/O operation
245	* across more than one interrupt or timeout; they must complete	245	* across more than one interrupt or timeout; they must complete any
246	* necessary I/O operation within one invokation of the routine.	246	* necessary I/O operation within one invocation of the routine.
247	* This measns that if the timeout routine acquires the lock flag,	247	* This means that if the timeout routine acquires the lock flag,
248	* it must reset the flag to FALSE before it returns.	248	* it must reset the flag to FALSE before it returns.
249	*/	249	*/