Add a #template device
This is for quickly crafting simple devices that use a devdir table and
devgen().
Signed-off-by: Barret Rhoden <brho@cs.berkeley.edu>
diff --git a/kern/drivers/dev/template.c b/kern/drivers/dev/template.c
new file mode 100644
index 0000000..5d92116
--- /dev/null
+++ b/kern/drivers/dev/template.c
@@ -0,0 +1,141 @@
+/* Copyright (c) 2020 Google Inc
+ * Barret Rhoden <brho@cs.berkeley.edu>
+ * See LICENSE for details.
+ *
+ * #template. Dummy device with a devdir table.
+ */
+
+#include <ns.h>
+#include <kmalloc.h>
+#include <string.h>
+#include <stdio.h>
+#include <assert.h>
+#include <error.h>
+
+struct dev template_devtab;
+
+static char *devname(void)
+{
+ return template_devtab.name;
+}
+
+enum {
+ Qdir,
+ Qctl,
+};
+
+static struct dirtab XXX_dir[] = {
+ {".", {Qdir, 0, QTDIR}, 0, DMDIR | 0555},
+ {"ctl", {Qctl, 0, QTFILE}, 0, 0666},
+};
+
+static struct chan *XXX_attach(char *spec)
+{
+ return devattach(devname(), spec);
+}
+
+static struct walkqid *XXX_walk(struct chan *c, struct chan *nc, char **name,
+ unsigned int nname)
+{
+ return devwalk(c, nc, name, nname, XXX_dir, ARRAY_SIZE(XXX_dir),
+ devgen);
+}
+
+static size_t XXX_stat(struct chan *c, uint8_t *db, size_t n)
+{
+ return devstat(c, db, n, XXX_dir, ARRAY_SIZE(XXX_dir), devgen);
+}
+
+static struct chan *XXX_open(struct chan *c, int omode)
+{
+ return devopen(c, omode, XXX_dir, ARRAY_SIZE(XXX_dir), devgen);
+}
+
+static void XXX_close(struct chan *c)
+{
+ /* If you do anything after open, only undo it for COPEN chans */
+ if (!(c->flag & COPEN))
+ return;
+}
+
+static size_t XXX_read(struct chan *c, void *ubuf, size_t n, off64_t offset)
+{
+ switch (c->qid.path) {
+ case Qdir:
+ return devdirread(c, ubuf, n, XXX_dir, ARRAY_SIZE(XXX_dir),
+ devgen);
+ case Qctl:
+ return readstr(offset, ubuf, n, "XXX");
+ default:
+ panic("Bad Qid %p!", c->qid.path);
+ }
+ return -1;
+}
+
+#define XXX_CTL_USAGE "start|stop|print|reset"
+
+static void XXX_ctl_cmd(struct chan *c, struct cmdbuf *cb)
+{
+ ERRSTACK(1);
+
+ if (cb->nf < 1)
+ error(EFAIL, XXX_CTL_USAGE);
+
+ if (waserror()) {
+ nexterror();
+ }
+ if (!strcmp(cb->f[0], "start")) {
+ ;
+ } else if (!strcmp(cb->f[0], "stop")) {
+ ;
+ } else if (!strcmp(cb->f[0], "print")) {
+ ;
+ } else if (!strcmp(cb->f[0], "reset")) {
+ ;
+ } else {
+ error(EFAIL, XXX_CTL_USAGE);
+ }
+ poperror();
+}
+
+static size_t XXX_write(struct chan *c, void *ubuf, size_t n, off64_t unused)
+{
+ ERRSTACK(1);
+ struct cmdbuf *cb = parsecmd(ubuf, n);
+
+ if (waserror()) {
+ kfree(cb);
+ nexterror();
+ }
+ switch (c->qid.path) {
+ case Qctl:
+ XXX_ctl_cmd(c, cb);
+ break;
+ default:
+ error(EFAIL, "Unable to write to %s", devname());
+ }
+ kfree(cb);
+ poperror();
+ return n;
+}
+
+struct dev template_devtab __devtab = {
+ .name = "template",
+ .reset = devreset,
+ .init = devinit,
+ .shutdown = devshutdown,
+ .attach = XXX_attach,
+ .walk = XXX_walk,
+ .stat = XXX_stat,
+ .open = XXX_open,
+ .create = devcreate,
+ .close = XXX_close,
+ .read = XXX_read,
+ .bread = devbread,
+ .write = XXX_write,
+ .bwrite = devbwrite,
+ .remove = devremove,
+ .wstat = devwstat,
+ .power = devpower,
+ .chaninfo = devchaninfo,
+};
