AM3359: dm timer

#include <linux/module.h>		
#include <linux/kernel.h>		
#include <linux/init.h>			
#include <linux/clk.h>		
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <asm/io.h>
#include <linux/types.h>			
#include <linux/platform_device.h>
#include <linux/platform_data/dmtimer-omap.h>
#include <linux/sched_clock.h>
#include </opt/work/trunk/BSP/AM335X/Linux/linux-3.14.26-g2489c02/arch/arm/plat-omap/include/plat/counter-32k.h>
#include </opt/work/trunk/BSP/AM335X/Linux/linux-3.14.26-g2489c02/arch/arm/plat-omap/include/plat/dmtimer.h>
#include <linux/gpio.h>

#define DRIVER_NAME "test_dev"
#define TIMER_MAX 0xFFFFFFFF
static struct omap_dm_timer *timer_ptr = NULL;
static struct omap_dm_timer *timer_ptr1 = NULL;
static int32_t timer_irq;
static int32_t timer_irq1;
static uint32_t timer_rate;
u32 irq_count =0;


static irqreturn_t timer_irq_handler( int irq, void * dev_id)
{
	unsigned int retval;

	retval = omap_dm_timer_read_status(timer_ptr);
	if (!retval)
		return IRQ_NONE;

	if (retval & ~OMAP_TIMER_INT_MATCH)
		printk("Unexpected interrupt source: %x\n", retval);

	omap_dm_timer_write_status(timer_ptr,
				OMAP_TIMER_INT_MATCH	|
				OMAP_TIMER_INT_OVERFLOW	|
				OMAP_TIMER_INT_CAPTURE);

	omap_dm_timer_read_status(timer_ptr);
	
	irq_count++;
	omap_dm_timer_start(timer_ptr1);
	if(irq_count > 100)
	{
	
		omap_dm_timer_stop(timer_ptr);		
		omap_dm_timer_stop(timer_ptr1);
		printk("________________DM Timer Count  %d\n", irq_count );
		irq_count =0;
	}

	return IRQ_HANDLED;
}

static irqreturn_t timer_irq_handler1( int irq, void * dev_id)
{
	unsigned int retval;


	retval = omap_dm_timer_read_status(timer_ptr1);
	if (!retval)
		return IRQ_NONE;

	if (retval & ~OMAP_TIMER_INT_MATCH)
		printk("Unexpected interrupt source: %x\n", retval);

	omap_dm_timer_write_status(timer_ptr1,
				OMAP_TIMER_INT_MATCH	|
				OMAP_TIMER_INT_OVERFLOW	|
				OMAP_TIMER_INT_CAPTURE);

	omap_dm_timer_read_status(timer_ptr1);

	omap_dm_timer_stop(timer_ptr1);

	return IRQ_HANDLED;
}

static int init_timing(struct omap_dm_timer *timer,unsigned int on_time,unsigned int off_time)
{
		
	u32 load, match;
	load = timer_rate * (on_time + off_time) / 1000;
	match = timer_rate * on_time / 1000;
	
	omap_dm_timer_set_load(timer, 1, -load);
	omap_dm_timer_set_match(timer, 1, -match); 
	omap_dm_timer_write_counter(timer, - 2);
	omap_dm_timer_set_pwm(timer, 1, 1, OMAP_TIMER_TRIGGER_OVERFLOW_AND_COMPARE);
	omap_dm_timer_set_int_enable(timer, OMAP_TIMER_INT_MATCH);
	return 0;
}

static int test_module_init(struct platform_device *pdev)
{
	int ret = 1,i;
	struct clk *timer_clk;  

	struct device_node *timer_device_node; 
	struct device_node *timer_device_node1; 
	printk(KERN_INFO " INIT  DM Timer\n");   
	
	timer_device_node = of_parse_phandle(pdev->dev.of_node, "DMtimer", 0); 

	timer_ptr = omap_dm_timer_request_by_node(timer_device_node);
	if(timer_ptr == NULL)
	{
		/* no timers available */
		printk(KERN_INFO "Can't request specified DM Timer 4\n");
		return -1;
	}   

	timer_device_node1 = of_parse_phandle(pdev->dev.of_node, "DMtimer1", 0); 

	timer_ptr1 = omap_dm_timer_request_by_node(timer_device_node1);
	if(timer_ptr1 == NULL)
	{
		/* no timers available */
		printk(KERN_INFO "Can't request specified DM Timer 7\n");
		return -1;
	}   


	/* Set the Clock source to the System Clock */
	ret = omap_dm_timer_set_source(timer_ptr, OMAP_TIMER_SRC_SYS_CLK);
	ret = omap_dm_timer_set_source(timer_ptr1, OMAP_TIMER_SRC_SYS_CLK);
	// set prescalar to 1:1
	//omap_dm_timer_set_prescaler(timer_ptr, 0); 

	omap_dm_timer_enable(timer_ptr);
	omap_dm_timer_enable(timer_ptr1);

	/* Determine what IRQ the timer triggers */
	timer_irq = omap_dm_timer_get_irq(timer_ptr);
	timer_irq1 = omap_dm_timer_get_irq(timer_ptr1);
	/* Setup the IRQ handler */
	ret = request_irq(timer_irq, timer_irq_handler, IRQF_TIMER, "DMTimer 4", NULL);
	/* Setup the IRQ handler */
	ret = request_irq(timer_irq1, timer_irq_handler1, IRQF_TIMER, "DMTimer 7", NULL);

	/* Get the Clock rate in Hz */
	timer_clk = omap_dm_timer_get_fclk(timer_ptr);
	timer_rate = clk_get_rate(timer_clk)/1000;

	init_timing(timer_ptr,180,5);  //180 microsec
	init_timing(timer_ptr1,100,5);   // 100 microsec


	/* Start the timer */
	omap_dm_timer_start(timer_ptr);
	//omap_dm_timer_start(timer_ptr1);
	
	return 0;
}


static int test_module_exit(struct platform_device *pdev)
{
	int ret = 1;

	/* stop the timer */
	ret = omap_dm_timer_stop(timer_ptr);
	printk(KERN_INFO "Timer Stop ret = %d\n", ret); 
	ret = omap_dm_timer_stop(timer_ptr1);
	printk(KERN_INFO "Timer Stop ret = %d\n", ret); 
	/* Release the IRQ handler */
	free_irq(timer_irq, NULL);
	free_irq(timer_irq1, NULL);
	printk(KERN_INFO "Free IRQ Done\n");    

	/* Release the timer */
	ret = omap_dm_timer_free(timer_ptr);
	printk(KERN_INFO "Timer Free ret = %d\n", ret); 
	ret = omap_dm_timer_free(timer_ptr1);
	printk(KERN_INFO "Timer Free ret = %d\n", ret); 

	return 0;
}

static const struct of_device_id test_module_timer_of_match[] = {
    { .compatible   ="ti,am335x-timer" },
    {},
};

static struct platform_driver test_module_timer_driver = {
    .driver = {
        .name   = DRIVER_NAME,
        .of_match_table = test_module_timer_of_match,
    },
    .probe  = test_module_init,
    .remove = test_module_exit,
};

module_platform_driver(test_module_timer_driver);

MODULE_LICENSE("GPL");            
MODULE_AUTHOR("Sahaya Darcius");    
MODULE_DESCRIPTION("Sample DMTimer Test Driver");  
MODULE_VERSION("0.1"); 

I use this example, but it's not work. I have this error : 

Can't request specified DM Timer 4

Hello Neguimeya,

You posted a custom kernel driver. Note that the .probe function is set to test_module_init. That means that during bootup, when Linux is reading through the device tree and finds a node with compatible = ti,am335x-timer, then it will go to this driver and run function test_module_init. Note that in Linux Processor SDK 6.3, driver timer-ti-dm.c also lists compatible = "ti,am335x-timer'. I am not sure what happens when two different drivers list the same compatible string.

1) Are you trying to create a custom kernel driver, or just access a timer from user space?

2) What are you trying to do with the timer?

Regards,

Nick

Hello Nick,

I have to programm a custom kernel driver. I will be use it to generated 400 nicrosecond PWM and I want to use timer dmtimer nummer 4. I have also change the name of timer for to compatible = "ti,am335x-timer-hadware" , but this does'nt work.