[beagleboard] SPI with DMA
Hi Folks, I have recently decided to learn embedded linux development and I am currently working on a project to use the SPI on Beagle Bone to transfer 64+bytes of data as one block in one write cycle to an Atmel SAM 32 bit uC. I would like to use DMA with the SPI and I have read online that this is not possible from user space with spidev. I came across omap2_mcspi.c driver and I noticed that this has dma functions in it. I would like to enable two DMA channels(tx and rx) to provide and receive data from the respective registers on the SPI. Could someone guide as to how I am to go about using omap2_mcspi? Would i need to make a module? Thanks! -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[beagleboard] Re: SPI with DMA
I'm using BeagleBone with AM3517 and Linux kernel version: 2.6.37 On Tuesday, August 19, 2014 5:00:24 PM UTC+1, Siddarth Sharma wrote: > > Hi Folks, > > I have recently decided to learn embedded linux development and I am > currently working on a project to use the SPI on Beagle Bone to transfer > 64+bytes of data as one block in one write cycle to an Atmel SAM 32 bit uC. > I would like to use DMA with the SPI and I have read online that this is > not possible from user space with spidev. I came across omap2_mcspi.c > driver and I noticed that this has dma functions in it. I would like to > enable two DMA channels(tx and rx) to provide and receive data from the > respective registers on the SPI. Could someone guide as to how I am to go > about using omap2_mcspi? Would i need to make a module? > > Thanks! > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [beagleboard] Re: SPI with DMA
Sorry, its the AM335x On Tue, Aug 19, 2014 at 5:04 PM, Robert Nelson wrote: > On Tue, Aug 19, 2014 at 11:02 AM, Siddarth Sharma > wrote: > > I'm using BeagleBone with AM3517 and Linux kernel version: 2.6.37 > > are you sure? > > Regards, > > -- > Robert Nelson > http://www.rcn-ee.com/ > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to a topic in the > Google Groups "BeagleBoard" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/beagleboard/ZtfEPoACcXE/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > beagleboard+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [beagleboard] Re: SPI with DMA
Hi John,
Attached is my user space code to transmit 1 byte of data stored in buffer
- data using spidev. Would this then call dma controller automatically if i
increase the size of my buffer data to 64 bytes? Also, I want to setup a
interrupt handler that gets called when data is received or transmitted by
the dma. How do i do this?
Thanks!
On Tue, Aug 19, 2014 at 5:19 PM, John Syn wrote:
>
> From: Siddarth Sharma
> Reply-To: "beagleboard@googlegroups.com"
> Date: Tuesday, August 19, 2014 at 9:02 AM
> To: "beagleboard@googlegroups.com"
> Subject: [beagleboard] Re: SPI with DMA
>
> I'm using BeagleBone with AM3517 and Linux kernel version: 2.6.37
>
> BeagleBone use AM3359 or AM3358 processors. When using the mcspi driver,
> DMA is automatically invoked when the size of your transfer exceeds a
> defined threshold which you will find in the mcspi driver. If you want to
> see how this is done, look at examples of SPI drivers in the /drivers/iio
> or /drivers/staging/iio folder. BTW, you don’t invoke the mcspi driver
> functions directly. Instead you use the generic linux SPI functions which
> in turn call the mcspi functions. Read the /Documentation/spi docs.
>
> Regards,
> John
>
>
>
> On Tuesday, August 19, 2014 5:00:24 PM UTC+1, Siddarth Sharma wrote:
>>
>> Hi Folks,
>>
>> I have recently decided to learn embedded linux development and I am
>> currently working on a project to use the SPI on Beagle Bone to transfer
>> 64+bytes of data as one block in one write cycle to an Atmel SAM 32 bit uC.
>> I would like to use DMA with the SPI and I have read online that this is
>> not possible from user space with spidev. I came across omap2_mcspi.c
>> driver and I noticed that this has dma functions in it. I would like to
>> enable two DMA channels(tx and rx) to provide and receive data from the
>> respective registers on the SPI. Could someone guide as to how I am to go
>> about using omap2_mcspi? Would i need to make a module?
>>
>> Thanks!
>>
> --
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/*
* main.cpp
*
* Created on: 4 Aug 2014
* Author: siddharth
*/
#include "Spi.h"
using namespace std;
int main(void)
{
Spi spi("/dev/spidev1.0", SPI_MODE_0, 500, 8);
//Spi spi;
int i = 6;
unsigned char data[1];
int rx_data=0;
while(i > 0)
{
data[0] = 1;
//data[1] = 'A';
//data[2] = 0;
spi.spiWriteRead(data, sizeof(data) );
rx_data = (int)data[0];
cout<<"the received data is:"</*
* Spi.cpp
*
* Created on: 4 Aug 2014
* Author: siddharth
*/
#include "Spi.h"
#include
using namespace std;
int Spi::spiOpen(std::string devspi){
int statusVal = -1;
this->spifd = open(devspi.c_str(), O_RDWR);
if(this->spifd < 0){
perror("could not open SPI device");
exit(1);
}
statusVal = ioctl (this->spifd, SPI_IOC_WR_MODE, &(this->mode));
if(statusVal < 0){
perror("Could not set SPIMode (WR)...ioctl fail");
exit(1);
}
statusVal = ioctl (this->spifd, SPI_IOC_RD_MODE, &(this->mode));
if(statusVal < 0) {
perror("Could not set SPIMode (RD)...ioctl fail");
exit(1);
}
statusVal = ioctl (this->spifd, SPI_IOC_WR_BITS_PER_WORD, &(this->bitsPerWord));
if(statusVal < 0) {
perror("Could not set SPI bitsPerWord (WR)...ioctl fail");
exit(1);
}
statusVal = ioctl (this->spifd, SPI_IOC_RD_BITS_PER_WORD, &(t
[beagleboard] detecting interrupt on GPIO in kernel module
I am toggling the input into a GPIO line on my BeagleBone from high to low
every 500 ms using an Atmel uC. I have registered a handler for this in my
Linux Kernel Module, but the handler is not being called for some reason.
My module code is -
#define GPIO 54
#define GPIO_INT_NAME "gpio_int"
#define GPIO_HIGH gpio_get_value(GPIO)
#define GPIO_LOW (gpio_get_value(GPIO) == 0)
short int irq_any_gpio= 0;
int count =0;
enum { falling, rising } type;
static irqreturn_t r_irq_handler(int irq, void *dev_id)
{
count++;
printk(KERN_DEBUG "interrupt received (irq: %d)\n", irq);
if (irq == gpio_to_irq(GPIO))
{
type = GPIO_LOW ? falling : rising;
if(type == falling)
{
printk("gpio pin is low\n");
}
else
printk("gpio pin is high\n");
}
return IRQ_HANDLED;
}
void r_int_config(void) {
if (gpio_request(GPIO, GPIO_INT_NAME ))
{
printk("GPIO request failure: %s\n", GPIO_INT_NAME );
return;
}
if ( (irq_any_gpio = gpio_to_irq(GPIO)) < 0 ) {
printk("GPIO to IRQ mapping failure %s\n",GPIO_INT_NAME );
return;
}
printk(KERN_NOTICE "Mapped int %d\n", irq_any_gpio);
if (request_irq(irq_any_gpio,(irq_handler_t ) r_irq_handler,
IRQF_TRIGGER_HIGH, GPIO_INT_NAME, NULL))
{
printk("Irq Request failure\n");
return;
}
return;
}
void r_int_release(void) {
free_irq(gpio_to_irq(GPIO), NULL);
gpio_free(GPIO);;
return;
}
int init_module(void)
{
printk("<1>Hello World\n");
r_int_config();
return 0;
}
On calling insmod interrupt_test.ko, i get the following message
[ 76.594543] Hello World
[ 76.597137] Mapped int 214
But now when I start toggling the input into this gpio pin, the interrupt
handler doesn't get called and the message - "interrupt received" is not
being displayed.
How do I solve this ? What's causing the problem?
--
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[beagleboard] Re: detecting interrupt on GPIO in kernel module
Does the problem have something to do with dev id paramter in the interrupt
handler?
On Tuesday, August 26, 2014 3:08:01 PM UTC+1, Siddarth Sharma wrote:
>
> I am toggling the input into a GPIO line on my BeagleBone from high to low
> every 500 ms using an Atmel uC. I have registered a handler for this in my
> Linux Kernel Module, but the handler is not being called for some reason.
>
> My module code is -
>
> #define GPIO 54
> #define GPIO_INT_NAME "gpio_int"
>
> #define GPIO_HIGH gpio_get_value(GPIO)
> #define GPIO_LOW (gpio_get_value(GPIO) == 0)
> short int irq_any_gpio= 0;
> int count =0;
>
> enum { falling, rising } type;
> static irqreturn_t r_irq_handler(int irq, void *dev_id)
> {
> count++;
> printk(KERN_DEBUG "interrupt received (irq: %d)\n", irq);
> if (irq == gpio_to_irq(GPIO))
> {
>
> type = GPIO_LOW ? falling : rising;
>
> if(type == falling)
> {
> printk("gpio pin is low\n");
> }
> else
> printk("gpio pin is high\n");
>
> }
>
> return IRQ_HANDLED;
> }
>
>
> void r_int_config(void) {
>
>if (gpio_request(GPIO, GPIO_INT_NAME ))
>{
> printk("GPIO request failure: %s\n", GPIO_INT_NAME );
> return;
>}
>
>if ( (irq_any_gpio = gpio_to_irq(GPIO)) < 0 ) {
> printk("GPIO to IRQ mapping failure %s\n",GPIO_INT_NAME );
> return;
>}
>
>printk(KERN_NOTICE "Mapped int %d\n", irq_any_gpio);
>
>if (request_irq(irq_any_gpio,(irq_handler_t ) r_irq_handler,
> IRQF_TRIGGER_HIGH, GPIO_INT_NAME, NULL))
>{
> printk("Irq Request failure\n");
> return;
>}
>
>return;
> }
>
> void r_int_release(void) {
>
>free_irq(gpio_to_irq(GPIO), NULL);
> gpio_free(GPIO);;
>return;
> }
>
> int init_module(void)
> {
> printk("<1>Hello World\n");
> r_int_config();
> return 0;
> }
>
> On calling insmod interrupt_test.ko, i get the following message
>
> [ 76.594543] Hello World
>
> [ 76.597137] Mapped int 214
>
> But now when I start toggling the input into this gpio pin, the interrupt
> handler doesn't get called and the message - "interrupt received" is not
> being displayed.
>
> How do I solve this ? What's causing the problem?
>
--
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