- add example FreeBSD 5.X driver submitted by S<F8>ren (Xride) Straarup
(driver tested on i386 and sparc64 platforms) - minor formatting fixes (add <example></example>) - minor spelling/grammar fixes Approved: blackend (mentor)
This commit is contained in:
Ken Smith
parent
0a49fed78d
commit
c6674adc3d
Notes:
svn2git
2020-12-08 03:00:23 +00:00
svn path=/head/; revision=18238
1 changed files with 167 additions and 4 deletions
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@ -174,7 +174,12 @@ KMOD=skeleton
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<para>This simple example pseudo-device remembers whatever values
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you write to it and can then supply them back to you when you
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read from it.</para>
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read from it. Two versions are shown, one for &os; 4.X and
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one for &os; 5.X.</para>
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<example>
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<title>Example of a Sample Echo Pseudo-Device Driver for
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&os; 4.X</title>
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<programlisting>/*
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* Simple `echo' pseudo-device KLD
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@ -334,9 +339,167 @@ echo_write(dev_t dev, struct uio *uio, int ioflag)
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}
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DEV_MODULE(echo,echo_loader,NULL);</programlisting>
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</example>
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<para>To install this driver you will first need to make a node on
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your filesystem with a command such as:</para>
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<example>
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<title>Example of a Sample Echo Pseudo-Device Driver for
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&os; 5.X</title>
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<programlisting>/*
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* Simple `echo' pseudo-device KLD
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*
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* Murray Stokely
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*
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* Converted to 5.X by Søren (Xride) Straarup
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*/
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#include <sys/types.h>
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#include <sys/module.h>
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#include <sys/systm.h> /* uprintf */
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#include <sys/errno.h>
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#include <sys/param.h> /* defines used in kernel.h */
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#include <sys/kernel.h> /* types used in module initialization */
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#include <sys/conf.h> /* cdevsw struct */
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#include <sys/uio.h> /* uio struct */
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#include <sys/malloc.h>
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#define BUFFERSIZE 256
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#define CDEV_MAJOR 33
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/* Function prototypes */
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static d_open_t echo_open;
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static d_close_t echo_close;
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static d_read_t echo_read;
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static d_write_t echo_write;
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/* Character device entry points */
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static struct cdevsw echo_cdevsw = {
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.d_open = echo_open,
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.d_close = echo_close,
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.d_maj = CDEV_MAJOR,
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.d_name = "echo",
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.d_read = echo_read,
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.d_write = echo_write
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};
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typedef struct s_echo {
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char msg[BUFFERSIZE];
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int len;
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} t_echo;
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/* vars */
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static dev_t echo_dev;
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static int count;
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static t_echo *echomsg;
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MALLOC_DECLARE(M_ECHOBUF);
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MALLOC_DEFINE(M_ECHOBUF, "echobuffer", "buffer for echo module");
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/*
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* This function is called by the kld[un]load(2) system calls to
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* determine what actions to take when a module is loaded or unloaded.
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*/
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static int
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echo_loader(struct module *m, int what, void *arg)
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{
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int err = 0;
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switch (what) {
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case MOD_LOAD: /* kldload */
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echo_dev = make_dev(<literal>&</literal>echo_cdevsw,
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0,
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UID_ROOT,
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GID_WHEEL,
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0600,
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"echo");
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/* kmalloc memory for use by this driver */
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MALLOC(echomsg, t_echo *, sizeof(t_echo), M_ECHOBUF, M_WAITOK);
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printf("Echo device loaded.\n");
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break;
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case MOD_UNLOAD:
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destroy_dev(echo_dev);
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FREE(echomsg,M_ECHOBUF);
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printf("Echo device unloaded.\n");
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break;
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default:
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err = EINVAL;
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break;
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}
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return(err);
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}
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static int
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echo_open(dev_t dev, int oflags, int devtype, struct thread *p)
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{
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int err = 0;
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uprintf("Opened device \"echo\" successfully.\n");
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return(err);
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}
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static int
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echo_close(dev_t dev, int fflag, int devtype, struct thread *p)
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{
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uprintf("Closing device \"echo.\"\n");
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return(0);
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}
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/*
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* The read function just takes the buf that was saved via
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* echo_write() and returns it to userland for accessing.
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* uio(9)
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*/
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static int
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echo_read(dev_t dev, struct uio *uio, int ioflag)
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{
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int err = 0;
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int amt;
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/*
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* How big is this read operation? Either as big as the user wants,
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* or as big as the remaining data
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*/
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amt = MIN(uio->uio_resid, (echomsg->len - uio->uio_offset > 0) ?
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echomsg->len - uio->uio_offset : 0);
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if ((err = uiomove(echomsg->msg + uio->uio_offset,amt,uio)) != 0) {
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uprintf("uiomove failed!\n");
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}
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return(err);
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}
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/*
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* echo_write takes in a character string and saves it
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* to buf for later accessing.
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*/
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static int
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echo_write(dev_t dev, struct uio *uio, int ioflag)
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{
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int err = 0;
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/* Copy the string in from user memory to kernel memory */
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err = copyin(uio->uio_iov->iov_base, echomsg->msg,
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MIN(uio->uio_iov->iov_len,BUFFERSIZE));
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/* Now we need to null terminate, then record the length */
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*(echomsg->msg + MIN(uio->uio_iov->iov_len,BUFFERSIZE)) = 0;
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echomsg->len = MIN(uio->uio_iov->iov_len,BUFFERSIZE);
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if (err != 0) {
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uprintf("Write failed: bad address!\n");
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}
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count++;
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return(err);
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}
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DEV_MODULE(echo,echo_loader,NULL);</programlisting>
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</example>
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<para>To install this driver on &os; 4.X you will first need to
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make a node on your filesystem with a command such as:</para>
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<screen>&prompt.root; <userinput>mknod /dev/echo c 33 0</userinput></screen>
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@ -347,7 +510,7 @@ DEV_MODULE(echo,echo_loader,NULL);</programlisting>
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&prompt.root; <userinput>cat /dev/echo</userinput>
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Test Data</screen>
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<para>Real hardware devices in the next chapter..</para>
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<para>Real hardware devices are described in the next chapter.</para>
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<para>Additional Resources
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<itemizedlist>
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