/*
* Design
+ * Issues :
*
+ * The other Linux SCSI drivers were written when Linux was Intel PC-only,
+ * and specifically for each board rather than each chip. This makes their
+ * adaptation to platforms like the Mac (Some of which use NCR5380's)
+ * more difficult than it has to be.
+ *
+ * Also, many of the SCSI drivers were written before the command queuing
+ * routines were implemented, meaning their implementations of queued
+ * commands were hacked on rather than designed in from the start.
+ *
+ * When I designed the Linux SCSI drivers I figured that
+ * while having two different SCSI boards in a system might be useful
+ * for debugging things, two of the same type wouldn't be used.
+ * Well, I was wrong and a number of users have mailed me about running
+ * multiple high-performance SCSI boards in a server.
+ *
+ * Finally, when I get questions from users, I have no idea what
+ * revision of my driver they are running.
+ *
+ * This driver attempts to address these problems :
* This is a generic 5380 driver. To use it on a different platform,
* one simply writes appropriate system specific macros (ie, data
* transfer - some PC's will use the I/O bus, 68K's must use
* memory mapped) and drops this file in their 'C' wrapper.
*
- * (Note from hch: unfortunately it was not enough for the different
- * m68k folks and instead of improving this driver they copied it
- * and hacked it up for their needs. As a consequence they lost
- * most updates to this driver. Maybe someone will fix all these
- * drivers to use a common core one day..)
- *
* As far as command queueing, two queues are maintained for
* each 5380 in the system - commands that haven't been issued yet,
* and commands that are currently executing. This means that an
* allowing multiple commands to propagate all the way to a SCSI-II device
* while a command is already executing.
*
+ * To solve the multiple-boards-in-the-same-system problem,
+ * there is a separate instance structure for each instance
+ * of a 5380 in the system. So, multiple NCR5380 drivers will
+ * be able to coexist with appropriate changes to the high level
+ * SCSI code.
+ *
+ * A NCR5380_PUBLIC_REVISION macro is provided, with the release
+ * number (updated for each public release) printed by the
+ * NCR5380_print_options command, which should be called from the
+ * wrapper detect function, so that I know what release of the driver
+ * users are using.
*
* Issues specific to the NCR5380 :
*
* Architecture :
*
* At the heart of the design is a coroutine, NCR5380_main,
- * which is started from a workqueue for each NCR5380 host in the
- * system. It attempts to establish I_T_L or I_T_L_Q nexuses by
- * removing the commands from the issue queue and calling
- * NCR5380_select() if a nexus is not established.
+ * which is started when not running by the interrupt handler,
+ * timer, and queue command function. It attempts to establish
+ * I_T_L or I_T_L_Q nexuses by removing the commands from the
+ * issue queue and calling NCR5380_select() if a nexus
+ * is not established.
*
* Once a nexus is established, the NCR5380_information_transfer()
* phase goes through the various phases as instructed by the target.
* NCR5380_pwrite(instance, src, count)
* NCR5380_pread(instance, dst, count);
*
+ * If nothing specific to this implementation needs doing (ie, with external
+ * hardware), you must also define
+ *
+ * NCR5380_queue_command
+ * NCR5380_reset
+ * NCR5380_abort
+ * NCR5380_proc_info
+ *
+ * to be the global entry points into the specific driver, ie
+ * #define NCR5380_queue_command t128_queue_command.
+ *
+ * If this is not done, the routines will be defined as static functions
+ * with the NCR5380* names and the user must provide a globally
+ * accessible wrapper function.
+ *
* The generic driver is initialized by calling NCR5380_init(instance),
* after setting the appropriate host specific fields and ID. If the
* driver wishes to autoprobe for an IRQ line, the NCR5380_probe_irq(instance,
- * possible) function may be used.
+ * possible) function may be used. Before the specific driver initialization
+ * code finishes, NCR5380_print_options should be called.
*/
-
static int do_abort(struct Scsi_Host *host);
static void do_reset(struct Scsi_Host *host);
git://git.onelab.eu / linux-2.6.git / blobdiff