Hello all,
I modified a kernel module ( in a ARM board from Digi - www.digi.com )
to use procfs, when I pass data to this device using proc file using
shell commands works fine ( cat filebuff > /proc/ns9360_fb/screen_1
filebuff about 600KB size ), but when I use an write() call from
user-space program this doesn't works (after open() OK), when debugging
I found that the function copy_from_user() cannot transfer 0 byte to
buffer returning the same size of passed to it.
Why this occurs ?
Theres some way to write in procfs files using write() call ?
Thanks for any help
Flavio Alberto Lopes Soares
PS: Follow the procfs write function in driver
int ns9xxxfb_write_func_procfs(struct file* file, const char* buffer,
unsigned long count, void* data)
{
struct proc_fb_data *ptr_proc_fb_data;
struct auxiliar_fb *ptr_aux_fb;
int res;
unsigned char n;
ptr_proc_fb_data = (struct proc_fb_data *)data;
ptr_aux_fb = (struct auxiliar_fb *)ptr_proc_fb_data->data;
printk("%d BYTES\n", count);
switch(ptr_proc_fb_data->id){
case PROC_MAIN_DIR:
res = count;
break;
case PROC_SCR_1:
printk(KERN_WARNING DRIVER_NAME "NA TELA 1\n");
if(count <= info.fb.fix.smem_len){
//res = count;
n = 0;
}
else{
printk("ERRO TELA 1\n");
res = -ENOMEM;
}
break;
case PROC_SCR_2:
printk(KERN_WARNING DRIVER_NAME "NA TELA 2\n");
if(count <= info.fb.fix.smem_len){
//res = count;
n = 1;
}
else{
printk("ERRO TELA 2\n");
res = -ENOMEM;
}
break;
case PROC_CTRL:
{
struct fb_fix_screeninfo *fixptr;
copy_from_user((void *)&proc_cmd, (const void *)buffer,
1);
res = 1;
switch(proc_cmd){
case PROC_CMD_SWITCH_SCR_ORIG:
/*Switch one framebuffer with other*/
fixptr = &fix_orig;
info.fb.screen_base = screen_base_orig;
ns9xxxfb_switch_fb(*fixptr);
break;
case PROC_CMD_SWITCH_SCR_1:
/*Switch one framebuffer with other*/
fixptr =
&info_fb_dbbuff[0].info_fb.fb.fix;
info.fb.screen_base =
info_fb_dbbuff[0].info_fb.fb.screen_base;
ns9xxxfb_switch_fb(*fixptr);
break;
case PROC_CMD_SWITCH_SCR_2:
/*Switch one framebuffer with other*/
fixptr =
&info_fb_dbbuff[1].info_fb.fb.fix;
info.fb.screen_base =
info_fb_dbbuff[1].info_fb.fb.screen_base;
ns9xxxfb_switch_fb(*fixptr);
break;
case PROC_CMD_SWITCH_LCD_ON:
LCD_CONTROL = (lcd_active->control |=
LCD_CONTROL_EN );
break;
case PROC_CMD_SWITCH_LCD_OFF:
LCD_CONTROL = (lcd_active->control &=
~LCD_CONTROL_EN);
break;
default:
printk(KERN_WARNING DRIVER_NAME ": Unknown control command :
%c\n", proc_cmd);
res = -ENOSYS;
}
}
break;
}
if(ptr_proc_fb_data->id != PROC_CTRL && res != -ENOMEM){
unsigned long remain = 0;
long pos = 0;
pos = ptr_aux_fb->datasize - ptr_aux_fb->datacopyremain;
pos = (pos < 0) ? 0 : pos;
remain = copy_from_user((void *)ptr_aux_fb->info_fb.fb.screen_base +
pos, (const void *)buffer, count);
printk("SOBROU : %ld\n", remain);
res = count;
ptr_aux_fb->datacopyremain -= (count + remain);
if(ptr_aux_fb->datacopyremain <= 0){
ptr_aux_fb->datacopyremain = ptr_aux_fb->datasize;
}
//printk(DRIVER_NAME ": Copiando %d bytes\n", count);
//printk(DRIVER_NAME ": Faltaram %d bytes\n", remain);
}
return res;
}
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