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minix/lib/libchardriver/chardriver.c
Lionel Sambuc b41d3ab74e Message type for CDEV_{READ,WRITE,IOCTL} 
Change-Id: Ia89c98410d3775fe3b6621576eadd186d60ec894
2014-07-28 17:05:52 +02:00

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/* This file contains the device independent character driver interface.
*
* Character drivers support the following requests. Message format m10 is
* used. Field names are prefixed with CDEV_. Separate field names are used for
* the "access", "ops", "user", and "request" fields.
*
* m_type MINOR GRANT COUNT FLAGS ID POS_LO POS_HI
* +-------------+-------+--------+-------+-------+------+---------+--------+
* | CDEV_OPEN | minor | access | user | | id | | |
* |-------------+-------+--------+-------+-------+------+---------+--------|
* | CDEV_CLOSE | minor | | | | id | | |
* |-------------+-------+--------+-------+-------+------+---------+--------|
* | CDEV_READ | minor | grant | bytes | flags | id | position |
* |-------------+-------+--------+-------+-------+------+---------+--------|
* | CDEV_WRITE | minor | grant | bytes | flags | id | position |
* |-------------+-------+--------+-------+-------+------+---------+--------|
* | CDEV_IOCTL | minor | grant | user | flags | id | request | |
* |-------------+-------+--------+-------+-------+------+---------+--------|
* | CDEV_CANCEL | minor | | | | id | | |
* |-------------+-------+--------+-------+-------+------+---------+--------|
* | CDEV_SELECT | minor | ops | | | | | |
* --------------------------------------------------------------------------
*
* The following reply messages are used.
*
* m_type MINOR STATUS ID
* +-----------------+-------+--------+-----+-----+------+---------+--------+
* | CDEV_REPLY | | status | | | id | | |
* |-----------------+-------+--------+-----+-----+------+---------+--------|
* | CDEV_SEL1_REPLY | minor | status | | | | | |
* |-----------------+-------+--------+-----+-----+------+---------+--------|
* | CDEV_SEL2_REPLY | minor | status | | | | | |
* --------------------------------------------------------------------------
*
* Changes:
* Sep 01, 2013 complete rewrite of the API (D.C. van Moolenboek)
* Aug 20, 2013 retire synchronous protocol (D.C. van Moolenbroek)
* Oct 16, 2011 split character and block protocol (D.C. van Moolenbroek)
* Aug 27, 2011 move common functions into driver.c (A. Welzel)
* Jul 25, 2005 added SYS_SIG type for signals (Jorrit N. Herder)
* Sep 15, 2004 added SYN_ALARM type for timeouts (Jorrit N. Herder)
* Jul 23, 2004 removed kernel dependencies (Jorrit N. Herder)
* Apr 02, 1992 constructed from AT wini and floppy driver (Kees J. Bot)
*/
#include <assert.h>
#include <minix/drivers.h>
#include <minix/chardriver.h>
#include <minix/ds.h>
static int running;
/* Management data for opened devices. */
static devminor_t open_devs[MAX_NR_OPEN_DEVICES];
static int next_open_devs_slot = 0;
/*===========================================================================*
* clear_open_devs *
*===========================================================================*/
static void clear_open_devs(void)
{
/* Reset the set of previously opened minor devices. */
next_open_devs_slot = 0;
}
/*===========================================================================*
* is_open_dev *
*===========================================================================*/
static int is_open_dev(devminor_t minor)
{
/* Check whether the given minor device has previously been opened. */
int i;
for (i = 0; i < next_open_devs_slot; i++)
if (open_devs[i] == minor)
return TRUE;
return FALSE;
}
/*===========================================================================*
* set_open_dev *
*===========================================================================*/
static void set_open_dev(devminor_t minor)
{
/* Mark the given minor device as having been opened. */
if (next_open_devs_slot >= MAX_NR_OPEN_DEVICES)
panic("out of slots for open devices");
open_devs[next_open_devs_slot] = minor;
next_open_devs_slot++;
}
/*===========================================================================*
* chardriver_announce *
*===========================================================================*/
void chardriver_announce(void)
{
/* Announce we are up after a fresh start or restart. */
int r;
char key[DS_MAX_KEYLEN];
char label[DS_MAX_KEYLEN];
char *driver_prefix = "drv.chr.";
/* Callers are allowed to use ipc_sendrec to communicate with drivers.
* For this reason, there may blocked callers when a driver restarts.
* Ask the kernel to unblock them (if any).
*/
if ((r = sys_statectl(SYS_STATE_CLEAR_IPC_REFS)) != OK)
panic("chardriver_announce: sys_statectl failed: %d", r);
/* Publish a driver up event. */
if ((r = ds_retrieve_label_name(label, sef_self())) != OK)
panic("chardriver_announce: unable to get own label: %d", r);
snprintf(key, DS_MAX_KEYLEN, "%s%s", driver_prefix, label);
if ((r = ds_publish_u32(key, DS_DRIVER_UP, DSF_OVERWRITE)) != OK)
panic("chardriver_announce: unable to publish driver up event: %d", r);
/* Expect an open for any device before serving regular driver requests. */
clear_open_devs();
}
/*===========================================================================*
* chardriver_reply_task *
*===========================================================================*/
void chardriver_reply_task(endpoint_t endpt, cdev_id_t id, int r)
{
/* Reply to a (read, write, ioctl) task request that was suspended earlier.
* Not-so-well-written drivers may use this function to send a reply to a
* request that is being processed right now, and then return EDONTREPLY later.
*/
message m_reply;
if (r == EDONTREPLY || r == SUSPEND)
panic("chardriver: bad task reply: %d", r);
memset(&m_reply, 0, sizeof(m_reply));
m_reply.m_type = CDEV_REPLY;
m_reply.m_lchardriver_vfs_reply.status = r;
m_reply.m_lchardriver_vfs_reply.id = id;
if ((r = asynsend3(endpt, &m_reply, AMF_NOREPLY)) != OK)
printf("chardriver_reply_task: send to %d failed: %d\n", endpt, r);
}
/*===========================================================================*
* chardriver_reply_select *
*===========================================================================*/
void chardriver_reply_select(endpoint_t endpt, devminor_t minor, int r)
{
/* Reply to a select request with a status update. This must not be used to
* reply to a select request that is being processed right now.
*/
message m_reply;
/* Replying with an error is allowed (if unusual). */
if (r == EDONTREPLY || r == SUSPEND)
panic("chardriver: bad select reply: %d", r);
memset(&m_reply, 0, sizeof(m_reply));
m_reply.m_type = CDEV_SEL2_REPLY;
m_reply.m_lchardriver_vfs_sel2.minor = minor;
m_reply.m_lchardriver_vfs_sel2.status = r;
if ((r = asynsend3(endpt, &m_reply, AMF_NOREPLY)) != OK)
printf("chardriver_reply_select: send to %d failed: %d\n", endpt, r);
}
/*===========================================================================*
* send_reply *
*===========================================================================*/
static void send_reply(endpoint_t endpt, message *m_ptr, int ipc_status)
{
/* Send a reply message to a request. */
int r;
/* If we would block sending the message, send it asynchronously. */
if (IPC_STATUS_CALL(ipc_status) == SENDREC)
r = ipc_sendnb(endpt, m_ptr);
else
r = asynsend3(endpt, m_ptr, AMF_NOREPLY);
if (r != OK)
printf("chardriver: unable to send reply to %d: %d\n", endpt, r);
}
/*===========================================================================*
* chardriver_reply *
*===========================================================================*/
static void chardriver_reply(message *mess, int ipc_status, int r)
{
/* Prepare and send a reply message. */
message reply_mess;
/* If the EDONTREPLY pseudo-reply is given, we do not reply. This is however
* allowed only for blocking task calls. Perform a sanity check.
*/
if (r == EDONTREPLY) {
switch (mess->m_type) {
case CDEV_READ:
case CDEV_WRITE:
case CDEV_IOCTL:
/* FIXME: we should be able to check FLAGS against
* CDEV_NONBLOCK here, but in practice, several drivers do not
* send a reply through this path (eg TTY) or simply do not
* implement nonblocking calls properly (eg audio, LWIP).
*/
#if 0
if (mess->m_vfs_lchardriver_readwrite.flags & CDEV_NONBLOCK)
panic("chardriver: cannot suspend nonblocking I/O");
#endif
/*fall-through*/
case CDEV_CANCEL:
return; /* alright */
default:
panic("chardriver: cannot suspend request %d", mess->m_type);
}
}
if (r == SUSPEND)
panic("chardriver: SUSPEND should not be used anymore");
/* Do not reply with ERESTART. The only possible caller, VFS, will find out
* through other means when we have restarted, and is not (fully) ready to
* deal with ERESTART errors.
*/
if (r == ERESTART)
return;
memset(&reply_mess, 0, sizeof(reply_mess));
switch (mess->m_type) {
case CDEV_OPEN:
case CDEV_CLOSE:
reply_mess.m_type = CDEV_REPLY;
reply_mess.m_lchardriver_vfs_reply.status = r;
reply_mess.m_lchardriver_vfs_reply.id =
mess->m_vfs_lchardriver_openclose.id;
break;
case CDEV_READ:
case CDEV_WRITE:
case CDEV_IOCTL:
reply_mess.m_type = CDEV_REPLY;
reply_mess.m_lchardriver_vfs_reply.status = r;
reply_mess.m_lchardriver_vfs_reply.id =
mess->m_vfs_lchardriver_readwrite.id;
break;
case CDEV_CANCEL: /* For cancel, this is a reply to the original request! */
reply_mess.m_type = CDEV_REPLY;
reply_mess.m_lchardriver_vfs_reply.status = r;
reply_mess.m_lchardriver_vfs_reply.id =
mess->m_vfs_lchardriver_cancel.id;
break;
case CDEV_SELECT:
reply_mess.m_type = CDEV_SEL1_REPLY;
reply_mess.m_lchardriver_vfs_sel1.status = r;
reply_mess.m_lchardriver_vfs_sel1.minor =
mess->m_vfs_lchardriver_select.minor;
break;
default:
panic("chardriver: unknown request %d", mess->m_type);
}
send_reply(mess->m_source, &reply_mess, ipc_status);
}
/*===========================================================================*
* do_open *
*===========================================================================*/
static int do_open(struct chardriver *cdp, message *m_ptr)
{
/* Open a minor device. */
endpoint_t user_endpt;
devminor_t minor;
int r, access;
/* Default action if no open hook is in place. */
if (cdp->cdr_open == NULL)
return OK;
/* Call the open hook. */
minor = m_ptr->m_vfs_lchardriver_openclose.minor;
access = m_ptr->m_vfs_lchardriver_openclose.access;
user_endpt = m_ptr->m_vfs_lchardriver_openclose.user;
r = cdp->cdr_open(minor, access, user_endpt);
/* If the device has been cloned, mark the new minor as open too. */
if (r >= 0 && (r & CDEV_CLONED)) {
minor = r & ~(CDEV_CLONED | CDEV_CTTY);
if (!is_open_dev(minor))
set_open_dev(minor);
}
return r;
}
/*===========================================================================*
* do_close *
*===========================================================================*/
static int do_close(struct chardriver *cdp, message *m_ptr)
{
/* Close a minor device. */
devminor_t minor;
/* Default action if no close hook is in place. */
if (cdp->cdr_close == NULL)
return OK;
/* Call the close hook. */
minor = m_ptr->m_vfs_lchardriver_openclose.minor;
return cdp->cdr_close(minor);
}
/*===========================================================================*
* do_trasnfer *
*===========================================================================*/
static int do_transfer(struct chardriver *cdp, message *m_ptr, int do_write)
{
/* Carry out a read or write task request. */
devminor_t minor;
off_t position;
endpoint_t endpt;
cp_grant_id_t grant;
size_t size;
int flags;
cdev_id_t id;
ssize_t r;
minor = m_ptr->m_vfs_lchardriver_readwrite.minor;
position = m_ptr->m_vfs_lchardriver_readwrite.pos;
endpt = m_ptr->m_source;
grant = m_ptr->m_vfs_lchardriver_readwrite.grant;
size = m_ptr->m_vfs_lchardriver_readwrite.count;
flags = m_ptr->m_vfs_lchardriver_readwrite.flags;
id = m_ptr->m_vfs_lchardriver_readwrite.id;
/* Call the read/write hook, if the appropriate one is in place. */
if (!do_write && cdp->cdr_read != NULL)
r = cdp->cdr_read(minor, position, endpt, grant, size, flags, id);
else if (do_write && cdp->cdr_write != NULL)
r = cdp->cdr_write(minor, position, endpt, grant, size, flags, id);
else
r = EIO; /* Default action if no read/write hook is in place. */
return r;
}
/*===========================================================================*
* do_ioctl *
*===========================================================================*/
static int do_ioctl(struct chardriver *cdp, message *m_ptr)
{
/* Carry out an I/O control task request. */
devminor_t minor;
unsigned long request;
cp_grant_id_t grant;
endpoint_t endpt, user_endpt;
int flags;
cdev_id_t id;
/* Default action if no ioctl hook is in place. */
if (cdp->cdr_ioctl == NULL)
return ENOTTY;
/* Call the ioctl hook. */
minor = m_ptr->m_vfs_lchardriver_readwrite.minor;
request = m_ptr->m_vfs_lchardriver_readwrite.request;
endpt = m_ptr->m_source;
grant = m_ptr->m_vfs_lchardriver_readwrite.grant;
flags = m_ptr->m_vfs_lchardriver_readwrite.flags;
user_endpt = m_ptr->m_vfs_lchardriver_readwrite.user;
id = m_ptr->m_vfs_lchardriver_readwrite.id;
return cdp->cdr_ioctl(minor, request, endpt, grant, flags, user_endpt, id);
}
/*===========================================================================*
* do_cancel *
*===========================================================================*/
static int do_cancel(struct chardriver *cdp, message *m_ptr)
{
/* Cancel a suspended (read, write, ioctl) task request. The original request
* may already have finished, in which case no reply should be sent.
*/
devminor_t minor;
endpoint_t endpt;
cdev_id_t id;
/* Default action if no cancel hook is in place: let the request finish. */
if (cdp->cdr_cancel == NULL)
return EDONTREPLY;
/* Call the cancel hook. */
minor = m_ptr->m_vfs_lchardriver_cancel.minor;
endpt = m_ptr->m_source;
id = m_ptr->m_vfs_lchardriver_cancel.id;
return cdp->cdr_cancel(minor, endpt, id);
}
/*===========================================================================*
* do_select *
*===========================================================================*/
static int do_select(struct chardriver *cdp, message *m_ptr)
{
/* Perform a select query on a minor device. */
devminor_t minor;
unsigned int ops;
endpoint_t endpt;
/* Default action if no select hook is in place. */
if (cdp->cdr_select == NULL)
return EBADF;
/* Call the select hook. */
minor = m_ptr->m_vfs_lchardriver_select.minor;
ops = m_ptr->m_vfs_lchardriver_select.ops;
endpt = m_ptr->m_source;
return cdp->cdr_select(minor, ops, endpt);
}
/*===========================================================================*
* do_block_open *
*===========================================================================*/
static void do_block_open(message *m_ptr, int ipc_status)
{
/* Reply to a block driver open request stating there is no such device. */
message m_reply;
memset(&m_reply, 0, sizeof(m_reply));
m_reply.m_type = BDEV_REPLY;
m_reply.BDEV_STATUS = ENXIO;
m_reply.BDEV_ID = m_ptr->BDEV_ID;
send_reply(m_ptr->m_source, &m_reply, ipc_status);
}
/*===========================================================================*
* chardriver_process *
*===========================================================================*/
void chardriver_process(struct chardriver *cdp, message *m_ptr, int ipc_status)
{
/* Call the appropiate driver function, based on the type of request. Send a
* reply to the caller if necessary.
*/
int r, reply;
/* Check for notifications first. We never reply to notifications. */
if (is_ipc_notify(ipc_status)) {
switch (_ENDPOINT_P(m_ptr->m_source)) {
case HARDWARE:
if (cdp->cdr_intr)
cdp->cdr_intr(m_ptr->m_notify.interrupts);
break;
case CLOCK:
if (cdp->cdr_alarm)
cdp->cdr_alarm(m_ptr->m_notify.timestamp);
break;
default:
if (cdp->cdr_other)
cdp->cdr_other(m_ptr, ipc_status);
}
return; /* do not send a reply */
}
/* Reply to block driver open requests with an error code. Otherwise, if
* someone creates a block device node for a character driver, opening that
* device node will cause the corresponding VFS thread to block forever.
*/
if (m_ptr->m_type == BDEV_OPEN) {
do_block_open(m_ptr, ipc_status);
return;
}
if (IS_CDEV_RQ(m_ptr->m_type)) {
int minor;
/* Try to retrieve minor device number */
r = chardriver_get_minor(m_ptr, &minor);
if (OK != r)
return;
/* We might get spurious requests if the driver has been restarted.
* Deny any requests on devices that have not previously been opened.
*/
if (!is_open_dev(minor)) {
/* Ignore spurious requests for unopened devices. */
if (m_ptr->m_type != CDEV_OPEN)
return; /* do not send a reply */
/* Mark the device as opened otherwise. */
set_open_dev(minor);
}
}
/* Call the appropriate function(s) for this request. */
switch (m_ptr->m_type) {
case CDEV_OPEN: r = do_open(cdp, m_ptr); break;
case CDEV_CLOSE: r = do_close(cdp, m_ptr); break;
case CDEV_READ: r = do_transfer(cdp, m_ptr, FALSE); break;
case CDEV_WRITE: r = do_transfer(cdp, m_ptr, TRUE); break;
case CDEV_IOCTL: r = do_ioctl(cdp, m_ptr); break;
case CDEV_CANCEL: r = do_cancel(cdp, m_ptr); break;
case CDEV_SELECT: r = do_select(cdp, m_ptr); break;
default:
if (cdp->cdr_other)
cdp->cdr_other(m_ptr, ipc_status);
return; /* do not send a reply */
}
chardriver_reply(m_ptr, ipc_status, r);
}
/*===========================================================================*
* chardriver_terminate *
*===========================================================================*/
void chardriver_terminate(void)
{
/* Break out of the main loop after finishing the current request. */
running = FALSE;
sef_cancel();
}
/*===========================================================================*
* chardriver_task *
*===========================================================================*/
void chardriver_task(struct chardriver *cdp)
{
/* Main program of any character device driver task. */
int r, ipc_status;
message mess;
running = TRUE;
/* Here is the main loop of the character driver task. It waits for a
* message, carries it out, and sends a reply.
*/
while (running) {
if ((r = sef_receive_status(ANY, &mess, &ipc_status)) != OK) {
if (r == EINTR && !running)
break;
panic("chardriver: sef_receive_status failed: %d", r);
}
chardriver_process(cdp, &mess, ipc_status);
}
}
/*===========================================================================*
* chardriver_get_minor *
*===========================================================================*/
int chardriver_get_minor(message *m, devminor_t *minor)
{
assert(NULL != m);
assert(NULL != minor);
switch(m->m_type)
{
case CDEV_OPEN:
case CDEV_CLOSE:
*minor = m->m_vfs_lchardriver_openclose.minor;
return OK;
case CDEV_CANCEL:
*minor = m->m_vfs_lchardriver_cancel.minor;
return OK;
case CDEV_SELECT:
*minor = m->m_vfs_lchardriver_select.minor;
return OK;
case CDEV_READ:
case CDEV_WRITE:
case CDEV_IOCTL:
*minor = m->m_vfs_lchardriver_readwrite.minor;
return OK;
default:
return EINVAL;
}
}
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