minix/drivers/hello/hello.c
David van Moolenbroek b4d909d415 Split block/character protocols and libdriver
This patch separates the character and block driver communication
protocols. The old character protocol remains the same, but a new
block protocol is introduced. The libdriver library is replaced by
two new libraries: libchardriver and libblockdriver. Their exposed
API, and drivers that use them, have been updated accordingly.
Together, libbdev and libblockdriver now completely abstract away
the message format used by the block protocol. As the memory driver
is both a character and a block device driver, it now implements its
own message loop.

The most important semantic change made to the block protocol is that
it is no longer possible to return both partial results and an error
for a single transfer. This simplifies the interaction between the
caller and the driver, as the I/O vector no longer needs to be copied
back. Also, drivers are now no longer supposed to decide based on the
layout of the I/O vector when a transfer should be cut short. Put
simply, transfers are now supposed to either succeed completely, or
result in an error.

After this patch, the state of the various pieces is as follows:
- block protocol: stable
- libbdev API: stable for synchronous communication
- libblockdriver API: needs slight revision (the drvlib/partition API
  in particular; the threading API will also change shortly)
- character protocol: needs cleanup
- libchardriver API: needs cleanup accordingly
- driver restarts: largely unsupported until endpoint changes are
  reintroduced

As a side effect, this patch eliminates several bugs, hacks, and gcc
-Wall and -W warnings all over the place. It probably introduces a
few new ones, too.

Update warning: this patch changes the protocol between MFS and disk
drivers, so in order to use old/new images, the MFS from the ramdisk
must be used to mount all file systems.
2011-11-23 14:06:37 +01:00

187 lines
4.7 KiB
C

#include <minix/drivers.h>
#include <minix/chardriver.h>
#include <stdio.h>
#include <stdlib.h>
#include <minix/ds.h>
#include "hello.h"
/*
* Function prototypes for the hello driver.
*/
FORWARD _PROTOTYPE( int hello_open, (message *m) );
FORWARD _PROTOTYPE( int hello_close, (message *m) );
FORWARD _PROTOTYPE( struct device * hello_prepare, (dev_t device) );
FORWARD _PROTOTYPE( int hello_transfer, (endpoint_t endpt, int opcode,
u64_t position, iovec_t *iov,
unsigned int nr_req,
endpoint_t user_endpt) );
/* SEF functions and variables. */
FORWARD _PROTOTYPE( void sef_local_startup, (void) );
FORWARD _PROTOTYPE( int sef_cb_init, (int type, sef_init_info_t *info) );
FORWARD _PROTOTYPE( int sef_cb_lu_state_save, (int) );
FORWARD _PROTOTYPE( int lu_state_restore, (void) );
/* Entry points to the hello driver. */
PRIVATE struct chardriver hello_tab =
{
hello_open,
hello_close,
nop_ioctl,
hello_prepare,
hello_transfer,
nop_cleanup,
nop_alarm,
nop_cancel,
nop_select,
NULL
};
/** Represents the /dev/hello device. */
PRIVATE struct device hello_device;
/** State variable to count the number of times the device has been opened. */
PRIVATE int open_counter;
PRIVATE int hello_open(message *UNUSED(m))
{
printf("hello_open(). Called %d time(s).\n", ++open_counter);
return OK;
}
PRIVATE int hello_close(message *UNUSED(m))
{
printf("hello_close()\n");
return OK;
}
PRIVATE struct device * hello_prepare(dev_t UNUSED(dev))
{
hello_device.dv_base = make64(0, 0);
hello_device.dv_size = make64(strlen(HELLO_MESSAGE), 0);
return &hello_device;
}
PRIVATE int hello_transfer(endpoint_t endpt, int opcode, u64_t position,
iovec_t *iov, unsigned nr_req, endpoint_t UNUSED(user_endpt))
{
int bytes, ret;
printf("hello_transfer()\n");
if (nr_req != 1)
{
/* This should never trigger for character drivers at the moment. */
printf("HELLO: vectored transfer request, using first element only\n");
}
bytes = strlen(HELLO_MESSAGE) - ex64lo(position) < iov->iov_size ?
strlen(HELLO_MESSAGE) - ex64lo(position) : iov->iov_size;
if (bytes <= 0)
{
return OK;
}
switch (opcode)
{
case DEV_GATHER_S:
ret = sys_safecopyto(endpt, (cp_grant_id_t) iov->iov_addr, 0,
(vir_bytes) (HELLO_MESSAGE + ex64lo(position)),
bytes, D);
iov->iov_size -= bytes;
break;
default:
return EINVAL;
}
return ret;
}
PRIVATE int sef_cb_lu_state_save(int UNUSED(state)) {
/* Save the state. */
ds_publish_u32("open_counter", open_counter, DSF_OVERWRITE);
return OK;
}
PRIVATE int lu_state_restore() {
/* Restore the state. */
u32_t value;
ds_retrieve_u32("open_counter", &value);
ds_delete_u32("open_counter");
open_counter = (int) value;
return OK;
}
PRIVATE void sef_local_startup()
{
/*
* Register init callbacks. Use the same function for all event types
*/
sef_setcb_init_fresh(sef_cb_init);
sef_setcb_init_lu(sef_cb_init);
sef_setcb_init_restart(sef_cb_init);
/*
* Register live update callbacks.
*/
/* - Agree to update immediately when LU is requested in a valid state. */
sef_setcb_lu_prepare(sef_cb_lu_prepare_always_ready);
/* - Support live update starting from any standard state. */
sef_setcb_lu_state_isvalid(sef_cb_lu_state_isvalid_standard);
/* - Register a custom routine to save the state. */
sef_setcb_lu_state_save(sef_cb_lu_state_save);
/* Let SEF perform startup. */
sef_startup();
}
PRIVATE int sef_cb_init(int type, sef_init_info_t *UNUSED(info))
{
/* Initialize the hello driver. */
int do_announce_driver = TRUE;
open_counter = 0;
switch(type) {
case SEF_INIT_FRESH:
printf("%s", HELLO_MESSAGE);
break;
case SEF_INIT_LU:
/* Restore the state. */
lu_state_restore();
do_announce_driver = FALSE;
printf("%sHey, I'm a new version!\n", HELLO_MESSAGE);
break;
case SEF_INIT_RESTART:
printf("%sHey, I've just been restarted!\n", HELLO_MESSAGE);
break;
}
/* Announce we are up when necessary. */
if (do_announce_driver) {
chardriver_announce();
}
/* Initialization completed successfully. */
return OK;
}
PUBLIC int main(void)
{
/*
* Perform initialization.
*/
sef_local_startup();
/*
* Run the main loop.
*/
chardriver_task(&hello_tab, CHARDRIVER_SYNC);
return OK;
}