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Allow multiple console devices per driver without insane code duplication.

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Say, a driver wants to have multiple console devices to pick from, you
would normally write down something like this:

	CONSOLE_DRIVER(dev1);
	CONSOLE_DRIVER(dev2);

Unfortunately, this means that you have to declare 10 cn routines,
instead of 5. It also isn't possible to initialize cn_arg on beforehand.

I noticed this restriction when I was implementing some of the console
bits for my vt(4) driver in my newcons branch. I have a single set of cn
routines (termcn_*) which are shared by all vt(4) console devices.

In order to solve this, I'm adding a separate consdev_ops structure,
which contains all the function pointers. This structure is referenced
through consdev's cn_ops field.

While there, I'm removing CONS_DRIVER() and cn_checkc, which have been
deprecated for years. They weren't used throughout the source, until the
Xen console driver showed up. CONSOLE_DRIVER() has been changed to do
the right thing. It now declares both the consdev and consdev_ops
structure and ties them together. In other words: this change doesn't
change the KPI for drivers that used the regular way of declaring
console devices.

If drivers want to use multiple console devices, they can do this as
follows:

	static const struct consdev_ops mydriver_cnops = {
		.cn_probe	= mydriver_cnprobe,
		...
	};
	static struct mydriver_softc cons0_softc = {
		...
	};
	CONSOLE_DEVICE(cons0, mydriver_cnops, &cons0_softc);
	static struct mydriver_softc cons1_softc = {
		...
	};
	CONSOLE_DEVICE(cons1, mydriver_cnops, &cons1_softc);

Obtained from:	//depot/user/ed/newcons/...
This commit is contained in:
Ed Schouten 2009-08-24 10:53:30 +00:00
parent 0cb8b6a9b7
commit 2992abe047
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=196506
2 changed files with 24 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
sys/kern/kern_cons.c
View File

@ -124,9 +124,10 @@ cninit(void)
SET_FOREACH(list, cons_set) {
cn = *list;
cnremove(cn);
if (cn->cn_probe == NULL)
/* Skip cons_consdev. */
if (cn->cn_ops == NULL)
continue;
cn->cn_probe(cn);
cn->cn_ops->cn_probe(cn);
if (cn->cn_pri == CN_DEAD)
continue;
if (best_cn == NULL || cn->cn_pri > best_cn->cn_pri)
@ -135,14 +136,14 @@ cninit(void)
/*
* Initialize console, and attach to it.
*/
cn->cn_init(cn);
cn->cn_ops->cn_init(cn);
cnadd(cn);
}
}
if (best_cn == NULL)
return;
if ((boothowto & RB_MULTIPLE) == 0) {
best_cn->cn_init(best_cn);
best_cn->cn_ops->cn_init(best_cn);
cnadd(best_cn);
}
if (boothowto & RB_PAUSE)
@ -218,7 +219,7 @@ cnremove(struct consdev *cn)
* freed after the system has initialized.
*/
if (cn->cn_term != NULL)
cn->cn_term(cn);
cn->cn_ops->cn_term(cn);
#endif
return;
}
@ -371,13 +372,9 @@ cncheckc(void)
STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
cn = cnd->cnd_cn;
if (!kdb_active || !(cn->cn_flags & CN_FLAG_NODEBUG)) {
if (cn->cn_checkc != NULL)
c = cn->cn_checkc(cn);
else
c = cn->cn_getc(cn);
if (c != -1) {
c = cn->cn_ops->cn_getc(cn);
if (c != -1)
return (c);
}
}
}
return (-1);
@ -396,8 +393,8 @@ cnputc(int c)
cn = cnd->cnd_cn;
if (!kdb_active || !(cn->cn_flags & CN_FLAG_NODEBUG)) {
if (c == '\n')
cn->cn_putc(cn, '\r');
cn->cn_putc(cn, c);
cn->cn_ops->cn_putc(cn, '\r');
cn->cn_ops->cn_putc(cn, c);
}
}
if (console_pausing && c == '\n' && !kdb_active) {

25
sys/sys/cons.h
View File

@ -45,10 +45,9 @@ typedef void cn_probe_t(struct consdev *);
typedef void cn_init_t(struct consdev *);
typedef void cn_term_t(struct consdev *);
typedef int cn_getc_t(struct consdev *);
typedef int cn_checkc_t(struct consdev *);
typedef void cn_putc_t(struct consdev *, int);
struct consdev {
struct consdev_ops {
cn_probe_t *cn_probe;
/* probe hardware and fill in consdev info */
cn_init_t *cn_init;
@ -57,10 +56,13 @@ struct consdev {
/* turn off as console */
cn_getc_t *cn_getc;
/* kernel getchar interface */
cn_checkc_t *cn_checkc;
/* kernel "return char if available" interface */
cn_putc_t *cn_putc;
/* kernel putchar interface */
};
struct consdev {
const struct consdev_ops *cn_ops;
/* console device operations. */
short cn_pri; /* pecking order; the higher the better */
void *cn_arg; /* drivers method argument */
int cn_flags; /* capabilities of this console */
@ -83,21 +85,22 @@ struct consdev {
extern struct msgbuf consmsgbuf; /* Message buffer for constty. */
extern struct tty *constty; /* Temporary virtual console. */
#define CONS_DRIVER(name, probe, init, term, getc, checkc, putc, dbctl) \
static struct consdev name##_consdev = { \
probe, init, term, getc, checkc, putc \
#define CONSOLE_DEVICE(name, ops, arg) \
static struct consdev name = { \
.cn_ops = &ops, \
.cn_arg = (arg), \
}; \
DATA_SET(cons_set, name##_consdev)
DATA_SET(cons_set, name)
#define CONSOLE_DRIVER(name) \
static struct consdev name##_consdev = { \
#define CONSOLE_DRIVER(name) \
static const struct consdev_ops name##_consdev_ops = { \
.cn_probe = name##_cnprobe, \
.cn_init = name##_cninit, \
.cn_term = name##_cnterm, \
.cn_getc = name##_cngetc, \
.cn_putc = name##_cnputc, \
}; \
DATA_SET(cons_set, name##_consdev)
CONSOLE_DEVICE(name##_consdev, name##_consdev_ops, NULL)
/* Other kernel entry points. */
void cninit(void);