Hello,
thank you very much for your answer.
Am 25. Januar 2010 20:31 schrieb Uwe Kleine-König
<u.kleine-koenig@xxxxxxxxxxxxxx>:
> On Mon, Jan 25, 2010 at 06:16:08PM +0100, Julian Fuchs wrote:
(...)
> Did you try with IRQF_NODELAY on vanilla and without it in rt?
I tried it with IRQF_NODELAY in rt and without IRQF_NODELAY on vanilla
(vanilla won't compile with IRQF_NODELAY AFAIR).
> Are you sure the irq fires in rt?
It fires in the normal kernel (i.e. the hardware is working). How can
I determine whether the interrupt fires in rt?
> Does your interrupt appear in /proc/interrupts?
Yes, it appears there (and the name of the module is listed correctly
in the same line).
On vanilla, the counter in /proc/interrupts increases, on rt, it
doesn't. It seems that the interrupt just doesn't fire... is there any
kind of "magic" I can do on rt to "enable" the interrupt? It seems
disabled :-(
> What platform are you working on?
I'm working on a Intel Celeron 1,8 GHz board (x86) with Ubuntu Linux
9.10 as a distro.
> Do you can send the code of a minimal example?
Sure. Below you find the code of a minimal example for a rs232
interface. If you have any suggestions for a smaller example, please
tell me and will create it (I just don't know how to create the
interrupt otherwise).
Thanks a lot for your help,
Julian
-----
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <asm/uaccess.h>
#include <linux/sched.h>
#include <linux/ioport.h>
#include <asm/io.h>
#include <linux/proc_fs.h>
#include <linux/inet.h>
#include <linux/net.h>
#include <net/tcp.h>
#include <net/ip.h>
#include <net/protocol.h>
/* --- DEFITIONS AND SETTINGS --- */
// Module information
MODULE_AUTHOR("Somebody");
MODULE_DESCRIPTION("some serial interface driver");
MODULE_LICENSE("GPL");
#define MODULE_IDENT "foobar"
#define VERSION_STRING "foobar v0.1\n"
// Configurable parameters
int base_port = 0xcf00;
const int port_range = 8;
int irq = 16;
int irq_counter = 0;
module_param(base_port, int, 0644);
MODULE_PARM_DESC(base_port, "The base port address of the serial interface");
module_param(irq, int, 0644);
MODULE_PARM_DESC(irq, "IRQ of the serial interface");
// Serial port communication
// registers
#define IER 1 // interrupt enable register
#define FCR 2 // FIFO control register (write) / Interrupt
Identification Register (read)
#define LCR 3 // line control register
// serial port settings
#define PARITY_NO 0x0
#define STOPBIT_1 0
#define CS_8 0x3
#define MAX_BAUDRATE 921600
#define DIVISOR_ACCESS 0x80
// interrupt identification and enabling
#define IER_DATA_AVAILABLE 0x1
#define IER_LS_CHANGE 0x4
// Global control variables
int stage = 0;
/* --- SERIAL PORT CONFIGURATION INTERFACE --- */
void set_serial_options(void);
void set_serial_options(void) {
unsigned int divisor;
unsigned char parity, stopbit, cs, status;
stopbit = STOPBIT_1;
parity = PARITY_NO;
cs = CS_8;
status = parity | stopbit | cs | DIVISOR_ACCESS;
outb(status, base_port+LCR);
divisor = 24;
outb(divisor & 0x00ff, base_port);
outb(divisor & 0xff00, base_port+1);
// reset divisor access bit
outb(status &~ DIVISOR_ACCESS, base_port+LCR);
}
irqreturn_t interrupt_handler(int myirq, void *dev_id) {
unsigned char iir_byte, bitmask;
iir_byte = inb(base_port + FCR);
bitmask = 1;
if ( (iir_byte & bitmask) == 1) {
// interrupt is not for this module
return IRQ_NONE;
}
// interrupt is for this module
unsigned char data_byte;
data_byte = inb(base_port);
irq_counter++;
return IRQ_HANDLED;
}
void cleanup_module(void) {
// I/O ports reserved
if (stage >= 2) {
release_region(base_port, port_range);
printk(KERN_INFO "%s: releasing I/O ports\n", MODULE_IDENT);
}
// IRQ reserved
if (stage >= 1) {
// because of shared irq, &stage is given, otherwise NULL will do, too
free_irq(irq, &stage);
// disable interrupts from the card
outb(0, base_port + IER);
printk(KERN_INFO "%s: freeing irq %i\n", MODULE_IDENT, irq);
}
printk(KERN_INFO "%s: module unloaded\n", MODULE_IDENT);
printk(KERN_ERR "%d irq_counter\n", irq_counter);
}
/* Setup all operations - called by kernel when module is loaded */
int init_module(void) {
int err = 0;
printk(KERN_INFO VERSION_STRING);
// Stage 1. Request IRQ using shared interrupts
// dev_id can't be NULL since the kernel needs to label the different ISRs
// stage is just as a pointer to our address space, any other address
will do, too.
if ((err = request_irq(irq, interrupt_handler, IRQF_SHARED |
IRQF_DISABLED | IRQF_NODELAY, MODULE_IDENT, &stage)) < 0) return err;
stage++;
// Stage 2. Request access to I/O ports
if ((err = check_region(base_port, port_range)) < 0) {
cleanup_module();
return err;
}
request_region(base_port, port_range, MODULE_IDENT);
stage++;
printk(KERN_INFO "Using serial port at %x, IRQ %i\n", base_port, irq);
// Configure serial port
set_serial_options();
// disable FIFO
outb(0, base_port+FCR);
// enable interrupts if data available or break signal received
outb(IER_DATA_AVAILABLE | IER_LS_CHANGE, base_port+IER);
printk(KERN_ERR "INIT MODULE DONE!\n");
return 0;
}
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