Hi,
I am writing a driver that implements read_rt and read_nrt handlers for
Xenomai 3-rc4 Cobalt.
But I am having problems when trying to read from user space in comand line:
$> cat /dev/rtdm/device0
cat: /dev/rtdm/device0: Invalid argument
and also from a user space real time thread:
f = open("/dev/rtdm/device0");
for(;;){
rt_task_wait_period(NULL);
read (f, &count, 1);
//...
This read gives me garbage.
The handler is registered with:
static struct rtdm_driver device_driver = {
.profile_info = RTDM_PROFILE_INFO(DEVICENAME,
RTDM_CLASS_MISC,
RTDM_SUBCLASS_IOPORTS,
DRIVERVER),
.device_flags = RTDM_NAMED_DEVICE|RTDM_EXCLUSIVE,
.device_count = 1,
.context_size = 0,
.ops = {
.open = device_open,
.close = device_close,
//.write_rt = device_write_rt,
.read_rt = device_read_rt,
.read_nrt = device_read_rt,
},
};
static struct rtdm_device device_devices[2] = {
[ 0 ... 1 ] = {
.driver = &device_driver,
.label = DEVICENAMEN,
}
};
And the rt and nrt read handlers are the same function:
//Read from the device
static ssize_t device_read_rt(struct rtdm_fd *fd, void __user *buf, size_t
size) {
int err;
unsigned char rawdata[2];
rawdata[0] = 'A';
rawdata[1] = '\0';
rtdm_printk("rtdm_read called\n");
if ((err=rtdm_safe_copy_to_user(fd, buf, rawdata, RAWDATALEN))) {
rtdm_printk("radaradcdriverRTDM: rtdm_safe_copy_to_user, error %d\n", err);
return -EFAULT;
}
rtdm_printk("rtdm_safe_copy_to_user, send %d bytes\n", err);
return err;
}
Open and close have just printks to show if they were called:
//Open the device
static int device_open(struct rtdm_fd *fd, int oflags){
rtdm_printk("rtdm_open called\n");
return 0;
}
//Close the device
static void device_close(struct rtdm_fd *fd) {
rtdm_printk("rtdm_close called\n");
}
Looking at kernel log, after accessing the driver from user spcae both:
in cmd line with:
$> cat /dev/rtdm/device0
and from a real time task
it seems that the open, close and read are never called, since there is no
entry in kernel log.
I am doing something wrong?
Should I use rtdm_read in user space to access the driver?
I tried to use it including <rtdm/rtdm.h> on user space app, but when
linking it gave me the error:
radarserver.c:(.text+0x138): undefined reference to `rtdm_read'
I thought that if I set read_nrt I can use just read.
rtdm_read will only be necessary for read_rt.
But I never implemented this kernel/user space transfer before with Xenomai
(only Linux), I just took a look at the implementation of some RTDM drivers
from xenomai sources: <xenomai-3.0-rc4>/kernel/drivers/testing/
But I might have missed something and doing something wrong.
Thanks for any suggestion
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