I'm currently trying to detect if a machine has a specific NVME SSD installed. On my machine, the file name is: SCSI#Disk&Ven_NVMe&Prod_XPG_SPECTRIX_S40#5&1363da6c&0&000000#{53f56307-b6bf-11d0-94f2-00a0c91efb8b}
What would be a reliable way to detect this universally on any machine? I don't know if any of these fields are unique to each machine, and I'm not very familiar with Windows' API.
when disk type hardware is detected, kernel create device for it (really 2 device usually PDO and FDO attached to it) and register well known interface GUID_DEVINTERFACE_DISK (by call IoRegisterDeviceInterface ). as result Symbolic Link will be created under \GLOBAL?? directory. we can got all registered disk interfaces via CM_Get_Device_Interface_ListW.
SCSI#Disk&Ven_NVMe&Prod_XPG_SPECTRIX_S40# obvious unique and will be the same anywhere for this device.
so code can be next
CONFIGRET Is_XPG_SPECTRIX_S40_Present(PBOOL pb)
{
CONFIGRET cr;
ULONG cb = 0, rcb;
union {
PVOID buf;
PZZWSTR Buffer;
};
static volatile UCHAR guz = 0;
PVOID stack = alloca(guz);
do
{
cr = CM_Get_Device_Interface_List_SizeW(&rcb, const_cast<GUID*>(&GUID_DEVINTERFACE_DISK), 0, CM_GET_DEVICE_INTERFACE_LIST_PRESENT);
if (cr != CR_SUCCESS)
{
break;
}
if (cb < (rcb *= sizeof(WCHAR)))
{
cb = RtlPointerToOffset(buf = alloca(rcb - cb), stack);// /RTCs must be off
}
cr = CM_Get_Device_Interface_ListW(const_cast<GUID*>(&GUID_DEVINTERFACE_DISK),
0, Buffer, cb, CM_GET_DEVICE_INTERFACE_LIST_PRESENT);
} while (cr == CR_BUFFER_SMALL);
if (cr == CR_SUCCESS)
{
while (*Buffer)
{
if (wcsstr(Buffer, L"\\SCSI#Disk&Ven_NVMe&Prod_XPG_SPECTRIX_S40#"))
{
*pb = TRUE;
break;
}
Buffer += wcslen(Buffer) + 1;
}
}
return cr;
}
In my project I'm using a global variable but it's not working as expected because it is initialized everytime it's executed and honestly I don't know what could be going on.
The variable is cookingSignalReceived.
The program is structured as follows:
//File Controller.c:
while (1)
{
Controller_Run_State_Machine();
}
void Controller_Run_State_Machine(void)
{
/* start of activity code */
Inputs_ReadSensors();
Comms_CheckReceivedData();
Controller_UpdateSTM();
}
The problem is inside Comms file:
//File Comms.c
uint8_t cookingSignalReceived = 0;
void Comms_CheckReceivedData(void)
{
/* start of activity code */
uint8_t uartDataAvailable = Comms_R_UART0_checkIfDataAvailable();
if (uartDataAvailable == 1)
{
Comms_ParseReceivedCommand();
}
}
void Comms_ParseReceivedCommand(void)
{
/* start of activity code */
/* UserCode{499E2AA6-1F61-4753-9221-77F85E7B5D92}:YjMeKqu95e */
uint8_t CRC_check_OK = 0;
uint8_t* buffer;
/* UserCode{499E2AA6-1F61-4753-9221-77F85E7B5D92} */
Comms_R_UART0_resetFlag_dataAvailable();
buffer = Comms_R_UART0_getBuffer();
CRC_check_OK = Comms_crcCheck(buffer);
if (CRC_check_OK == 1)
{
Comms_processMessage(buffer); //<-- Variable is used in this function
}
}
Global variable is used inside Comms_processMessage(). The issue is that every time that the function is called, the global variable is set to the initial value. Do you find anything strange here?
EDITED:
void Comms_processMessage(uint8_t* buffer)
{
/* UserCode{BCB3B791-2DF9-492b-B53B-6FEB24BD8F77}:eyCoSfmCKb */
uint8_t message = buffer[0];
uint8_t param1 = buffer[1];
uint8_t param2 = buffer[2];
//---------------------------------------------------------------------
// START COOKING 1ST STEP REQUEST
//---------------------------------------------------------------------
if (message == MSG_COOK_1ST && param1 == START_PARAM)
{
// Wait for second frame
cookingSignalReceived = 1;
#ifdef DEBUG
R_UART0_Send("Cook 1st step!!", sizeof(char) * 15);
#endif
}
//---------------------------------------------------------------------
// START COOKING 2ND STEP REQUEST
//---------------------------------------------------------------------
else if (message == MSG_COOK_2ND && param1 == START_PARAM)
{
// Wait for second frame
if (cookingSignalReceived == 1)
{
Controller_signalsBufferEnqueue(cookingSignal);
}
#ifdef DEBUG
R_UART0_Send("Cook 2nd step!!", sizeof(char) * 15);
#endif
}
}
Note that my original idea was to use a local static variable but I was having the same issue so I tried with a global variable.
In certain cases the MCUs restart because unrecoverable errors or bad hardware settings. This should be the problem! A cause of this MCUs behaviour may be also bad pointers management.
I've written this code by looking at various examples: Python pulseaudio monitor, Pavumeter source, async playback example, and Pacat source.
I have successfully connected to a sink and am able to record it, but my problem is, I'm stuck at getting the volume value out. If I try printing value from the read function, I just get a bunch of random numbers at a second's interval.
Now I'm not asking for someone to finish writing the code for me, I'd just like some tips, help so that I could head towards the right direction. How do I retrieve the volume value?
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <pulse/pulseaudio.h>
static int latency = 20000; // start latency in micro seconds
static int sampleoffs = 0;
static short sampledata[300000];
static pa_buffer_attr bufattr;
static int underflows = 0;
static pa_sample_spec ss;
// This callback gets called when our context changes state. We really only
// care about when it's ready or if it has failed
void pa_state_cb(pa_context *c, void *userdata) {
pa_context_state_t state;
int *pa_ready = userdata;
state = pa_context_get_state(c);
switch (state) {
// These are just here for reference
case PA_CONTEXT_UNCONNECTED:
case PA_CONTEXT_CONNECTING:
case PA_CONTEXT_AUTHORIZING:
case PA_CONTEXT_SETTING_NAME:
default:
break;
case PA_CONTEXT_FAILED:
case PA_CONTEXT_TERMINATED:
*pa_ready = 2;
break;
case PA_CONTEXT_READY:
*pa_ready = 1;
break;
}
}
static void stream_read_cb(pa_stream *s, size_t length, void *userdata) {
const void *data;
pa_stream_peek(s, &data, &length);
data = (const unsigned char*) data;
printf("%u", data);
pa_stream_drop(s);
}
int main(int argc, char *argv[]) {
pa_mainloop *pa_ml;
pa_mainloop_api *pa_mlapi;
pa_context *pa_ctx;
pa_stream *recordstream;
int r;
int pa_ready = 0;
int retval = 0;
unsigned int a;
double amp;
int test = 0;
// Create a mainloop API and connection to the default server
pa_ml = pa_mainloop_new();
pa_mlapi = pa_mainloop_get_api(pa_ml);
pa_ctx = pa_context_new(pa_mlapi, "Simple PA test application");
pa_context_connect(pa_ctx, NULL, 0, NULL);
// This function defines a callback so the server will tell us it's state.
// Our callback will wait for the state to be ready. The callback will
// modify the variable to 1 so we know when we have a connection and it's
// ready.
// If there's an error, the callback will set pa_ready to 2
pa_context_set_state_callback(pa_ctx, pa_state_cb, &pa_ready);
// We can't do anything until PA is ready, so just iterate the mainloop
// and continue
while (pa_ready == 0) {
pa_mainloop_iterate(pa_ml, 1, NULL);
}
if (pa_ready == 2) {
retval = -1;
goto exit;
}
ss.rate = 44100;
ss.channels = 2;
ss.format = PA_SAMPLE_U8;
recordstream = pa_stream_new(pa_ctx, "Record", &ss, NULL);
if (!recordstream) {
printf("pa_stream_new failed\n");
}
pa_stream_set_read_callback(recordstream, stream_read_cb, NULL);
r = pa_stream_connect_record(recordstream, NULL, NULL, PA_STREAM_PEAK_DETECT);
if (r < 0) {
printf("pa_stream_connect_playback failed\n");
retval = -1;
goto exit;
}
// Run the mainloop until pa_mainloop_quit() is called
// (this example never calls it, so the mainloop runs forever).
// printf("%s", "Running Loop");
pa_mainloop_run(pa_ml, NULL);
exit:
// clean up and disconnect
pa_context_disconnect(pa_ctx);
pa_context_unref(pa_ctx);
pa_mainloop_free(pa_ml);
return retval;
}
Looking at the original question from UNIX.StackExchange, it looks like you're trying to create a VU meter. It can be done using an envelope detector. You have to read the input values and then average their rectified value. A simple envelope detector can be done as an exponential moving average filter.
float level = 0; // Init time
const float alpha = COEFFICIENT; // See below
...
// Inside sample loop
float input_signal = fabsf(get_current_sample());
level = level + alpha * (input_signal - level);
Here, alpha is the filter coefficient, which can be calculated as:
const float alpha = 1.0 - expf( (-2.0 * M_PI) / (TC * SAMPLE_RATE) );
Where TC is known as the "time constant" parameter, measured in seconds, which defines how fast you want to "follow" the signal. Setting it too short makes the VU meter very "bumpy" and setting it too long will miss transients in the signal. 10 mS is a good value to start from.
I am not an expert c programmers and in the c code I m getting these kinds of errors. I got many and tried to sort them out but can not solve these. The code is as follows:
/*
* EEPROM.c
* interfacing microchip 24aa64f IC with atmel sam4e
*/
#include <asf.h>
#include "EEPROM_I2C.h"
#define DEVICE_ADDRESS 0x50 // 7-bit device identifier 0101000, (refer datasheet)
//#define EEPROM_NAME 24AA6F
#define I2C_FAST_MODE_SPEED 400000//TWI_BUS_CLOCK 400KHz
#define TWI_CLK_DIVIDER 2
#define TWI_CLK_DIV_MIN 7
#define TWI_CLK_CALC_ARGU 4
#define TWI_CLK_DIV_MAX 0xFF
/*************************** Main function ******************************/
int eeprom_main( void )
{
struct micro24 ptMicro24 ;
typedef struct twi_options twi_options_t;
typedef struct Twi_registers Twi;
char TxBuffer[128] ;
char RxBuffer[128] ;
int BufferIndex;
unsigned int PageCount;
unsigned int error = 0 ;
unsigned int i;
ptMicro24.PageSize = 32;
ptMicro24.NumOfPage = 128;
ptMicro24.EepromSize = 128*32;
ptMicro24.SlaveAddress = DEVICE_ADDRESS;
ptMicro24.EepromName = 64;
/***************************** CLOCK SETTINGS TO GET 400KHz **********************
* Set the I2C bus speed in conjunction with the clock frequency.
* param p_twi Pointer to a TWI instance.
* return value PASS\Fail New speed setting is accepted\rejected
**********************************************************************************/
uint32_t twi_set_speed(struct Twi_registers *Twi, uint32_t ul_speed, uint32_t ul_mck)
//uint32_t twi_set_speed(Twi *p_twi, uint32_t ul_speed, uint32_t ul_mck)
{
uint32_t ckdiv = 0; //clock divider is used to increase both TWCK high and low periods (16-18)
uint32_t c_lh_div; //CHDIV (0-7) and CLDIV (8-15)
if (ul_speed > I2C_FAST_MODE_SPEED) { //ul_speed is the desired I2C bus speed
return FAIL;
}
c_lh_div = ul_mck / (ul_speed * TWI_CLK_DIVIDER) - TWI_CLK_CALC_ARGU; //ul_mck main clock of the device
/* cldiv must fit in 8 bits, ckdiv must fit in 3 bits */
while ((c_lh_div > TWI_CLK_DIV_MAX) && (ckdiv < TWI_CLK_DIV_MIN))
{
ckdiv++; // Increase clock divider
c_lh_div /= TWI_CLK_DIVIDER; //Divide cldiv value
}
/* set clock waveform generator register */
Twi->TWI_CWGR =
TWI_CWGR_CLDIV(c_lh_div) | TWI_CWGR_CHDIV(c_lh_div) |
TWI_CWGR_CKDIV(ckdiv);
return PASS;
}
/************************************ Initialize TWI master mode ************************
* Set the control register TWI_CR by MSEN and SVDIS
* param p_opt Options for initializing the TWI module
* return TWI_SUCCESS if initialization is complete
* twi_options... structure contains clock speed, master clock, chip and smbus
*****************************************************************************************/
uint32_t twi_master_start(struct Twi_registers *Twi, struct twi_options_t *twi_options_t)
//uint32_t twi_master_start(Twi *p_twi, const twi_options_t *p_opt)
{
uint32_t status = TWI_SUCCESS; // status success return code is 0
// Enable master mode and disable slave mode in TWI_CR
Twi -> TWI_CR_START = TWI_CR_START;
Twi->TWI_CR_MSEN = TWI_CR_MSEN; // Set Master Enable bit
Twi->TWI_CR_SVDIS = TWI_CR_SVDIS; // Set Slave Disable bit
/* Select the speed */
//new//if (twi_set_speed(Twi->TWI_SR, twi_options_t->speed, twi_options_t->master_clk) == FAIL)
//if (twi_set_speed(Twi, twi_options_t->speed, twi_options_t->master_clk) == FAIL)
//{
//status = TWI_INVALID_ARGUMENT; /* The desired speed setting is rejected */
//}
if (twi_options_t->smbus == 0)
{
Twi->TWI_CR_QUICK == 0;
status = TWI_INVALID_ARGUMENT;
}
else
if (twi_options_t->smbus == 1)
{
Twi->TWI_CR_QUICK == 1;
status = TWI_SUCCESS;
}
return status;
}
/***************************** WriteByte Function ********************************
This function uses a two bytes internal address (IADR) along with
Internal word address of eeprom.
Return Value: None
***********************************************************************************/
void WriteByte (struct micro24 *ptMicro24, char Data2Write,
unsigned int Address)
//Data2Write is the data to be written n the eeprom
//struct <micro24 *ptMicro24> : Structure of Microchip 24AA Two-wire Eeprom
//unsigned int Address>: Address where to write
{
unsigned int WordAddress;
unsigned int SlaveAddress;
unsigned char p0=0;
TWI_CR_START ==1;
if (ptMicro24->EepromName == 64 )
{
if ( Address > 0xFFFF)
{
p0 = 1;
/* Mask the 17th bit to get the 16th LSB */
WordAddress = Address & 0xFFFF ;
SlaveAddress = ptMicro24->SlaveAddress + (p0<<16) ;
}
else {
SlaveAddress = ptMicro24->SlaveAddress ;
WordAddress = Address ;
}
}
TWI_CR_STOP ==1;
//TWI_WriteSingleIadr(TWI_IADR_IADR,SlaveAddress, WordAddress,
// TWI_MMR_IADRSZ_2_BYTE, &Data2Write); // declared as extern
// to write to internal address, utilizing internal address and master mode register
//}
/******************** Increase Speed Function *****************************
* TWI is accessed without calling TWI functions
/***************************************************************************/
int NumOfBytes, Count;
int status;
uint32_t Buffer;
/* Enable Master Mode of the TWI */
TWI_CR_MSEN == 1;
// Twi.TWI_CR_MSEN ==1;
//TWI_CR->TWI_CR_MSEN = TWI_CR_MSEN ;
/* Set the TWI Master Mode Register */
Twi->TWI_MMR = (SlaveAddress & (~TWI_MMR_MREAD) | (TWI_MMR_IADRSZ_2_BYTE));
/* Set the internal address to access the wanted page */
Twi -> TWI_IADR = WordAddress ;
/* Wait until TXRDY is high to transmit the next data */
status = TWI_SR_TXRDY;
while (!(status & TWI_SR_TXRDY))
status = TWI_SR_TXRDY;
/* Send the buffer to the page */
for (Count=0; Count < NumOfBytes ;Count++ )
{
Twi ->TWI_THR_TXDATA = Buffer++;
/* Wait until TXRDY is high to transmit the next data */
status = TWI_SR_TXRDY;
while (!(status & TWI_SR_TXRDY))
status = TWI_SR_TXRDY;
}
/* Wait for the Transmit complete is set */
status = TWI_SR_TXCOMP;
while (!(status & TWI_SR_TXCOMP))
status = TWI_SR_TXCOMP;
// add some wait function according to datasheet before sending the next data
// e.g: 10ms
// e.g: WaitMiliSecond (10);
}
/****************************** ReadByte Function **************************
This function uses a two bytes internal address (IADR) along with
Internal word address of eeprom.
Return Value: None
****************************************************************************/
char ReadByte (struct micro24 *ptMicro24,
unsigned int Address) //int Address to read
{
unsigned int WordAddress;
unsigned int SlaveAddress;
char Data2Read ;
unsigned char p0=0;
TWI_CR_START == 1;
//p_twi -> TWI_CR_START = TWI_CR_START;
if (ptMicro24->EepromName == 64)
{
if ( Address > 0xFFFF) {
p0 = 1;
// Mask the 17th bit to get the 16th LSB
WordAddress = Address & 0xFFFF ;
SlaveAddress = ptMicro24->SlaveAddress + (p0<<16) ;
}
else {
SlaveAddress = ptMicro24->SlaveAddress ;
WordAddress = Address ;
}
}
//TWI_ReadSingleIadr(TWI_IADR_IADR,SlaveAddress,WordAddress,
// TWI_MMR_IADRSZ_2_BYTE,&Data2Read);
// declared as extern
// to write to internal address, utilizing internal address and master mode register
return (Data2Read);
}
}
errors are:
(24,19): error: storage size of 'ptMicro24' isn't known
67,5): error: dereferencing pointer to incomplete type
Twi->TWI_CWGR =
error: expected identifier before '(' token
#define TWI_CR_START (0x1u << 0) /**< \brief (TWI_CR) Send a START Condition */
error: expected identifier before '(' token
#define TWI_CR_MSEN (0x1u << 2) /**< \brief (TWI_CR) TWI Master Mode Enabled */
error: expected identifier before '(' token
#define TWI_CR_SVDIS (0x1u << 5) /**< \brief (TWI_CR) TWI Slave Mode Disabled */
error: dereferencing pointer to incomplete type
if (twi_options_t->smbus == 0)
It seems missing the declaration of struct micro24, this may be the cause of first error: error: storage size of 'ptMicro24' isn't known.
The same for declaration of Twi_registers, that is causing other errors.
Either you forgot to declare these structs or to include an header file declaring them.
I try to use the DMAengine API from a custom kernel driver to perform a scatter-gather operation. I have a contiguous memory region as source and I want to copy its data in several distributed buffers through a scatterlist structure. The DMA controller is the PL330 one that supports the DMAengine API (see PL330 DMA controller).
My test code is the following:
In my driver header file (test_driver.h):
#ifndef __TEST_DRIVER_H__
#define __TEST_DRIVER_H__
#include <linux/platform_device.h>
#include <linux/device.h>
#include <linux/scatterlist.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/of_dma.h>
#define SG_ENTRIES 3
#define BUF_SIZE 16
#define DEV_BUF 0x10000000
struct dma_block {
void * data;
int size;
};
struct dma_private_info {
struct sg_table sgt;
struct dma_block * blocks;
int nblocks;
int dma_started;
struct dma_chan * dma_chan;
struct dma_slave_config dma_config;
struct dma_async_tx_descriptor * dma_desc;
dma_cookie_t cookie;
};
struct test_platform_device {
struct platform_device * pdev;
struct dma_private_info dma_priv;
};
#define _get_devp(tdev) (&((tdev)->pdev->dev))
#define _get_dmapip(tdev) (&((tdev)->dma_priv))
int dma_stop(struct test_platform_device * tdev);
int dma_start(struct test_platform_device * tdev);
int dma_start_block(struct test_platform_device * tdev);
int dma_init(struct test_platform_device * tdev);
int dma_exit(struct test_platform_device * tdev);
#endif
In my source that contains the dma functions (dma_functions.c):
#include <linux/slab.h>
#include "test_driver.h"
#define BARE_RAM_BASE 0x10000000
#define BARE_RAM_SIZE 0x10000000
struct ram_bare {
uint32_t * __iomem map;
uint32_t base;
uint32_t size;
};
static void dma_sg_check(struct test_platform_device * tdev)
{
struct dma_private_info * dma_priv = _get_dmapip(tdev);
struct device * dev = _get_devp(tdev);
uint32_t * buf;
unsigned int bufsize;
int nwords;
int nbytes_word = sizeof(uint32_t);
int nblocks;
struct ram_bare ramb;
uint32_t * p;
int i;
int j;
ramb.map = ioremap(BARE_RAM_BASE,BARE_RAM_SIZE);
ramb.base = BARE_RAM_BASE;
ramb.size = BARE_RAM_SIZE;
dev_info(dev,"nblocks: %d \n",dma_priv->nblocks);
p = ramb.map;
nblocks = dma_priv->nblocks;
for( i = 0 ; i < nblocks ; i++ ) {
buf = (uint32_t *) dma_priv->blocks[i].data;
bufsize = dma_priv->blocks[i].size;
nwords = dma_priv->blocks[i].size/nbytes_word;
dev_info(dev,"block[%d],size %d: ",i,bufsize);
for ( j = 0 ; j < nwords; j++, p++) {
dev_info(dev,"DMA: 0x%x, RAM: 0x%x",buf[j],ioread32(p));
}
}
iounmap(ramb.map);
}
static int dma_sg_exit(struct test_platform_device * tdev)
{
struct dma_private_info * dma_priv = _get_dmapip(tdev);
int ret = 0;
int i;
for( i = 0 ; i < dma_priv->nblocks ; i++ ) {
kfree(dma_priv->blocks[i].data);
}
kfree(dma_priv->blocks);
sg_free_table(&(dma_priv->sgt));
return ret;
}
int dma_stop(struct test_platform_device * tdev)
{
struct dma_private_info * dma_priv = _get_dmapip(tdev);
struct device * dev = _get_devp(tdev);
int ret = 0;
dma_unmap_sg(dev,dma_priv->sgt.sgl,\
dma_priv->sgt.nents, DMA_FROM_DEVICE);
dma_sg_exit(tdev);
dma_priv->dma_started = 0;
return ret;
}
static void dma_callback(void * param)
{
enum dma_status dma_stat;
struct test_platform_device * tdev = (struct test_platform_device *) param;
struct dma_private_info * dma_priv = _get_dmapip(tdev);
struct device * dev = _get_devp(tdev);
dev_info(dev,"Checking the DMA state....\n");
dma_stat = dma_async_is_tx_complete(dma_priv->dma_chan,\
dma_priv->cookie, NULL, NULL);
if(dma_stat == DMA_COMPLETE) {
dev_info(dev,"DMA complete! \n");
dma_sg_check(tdev);
dma_stop(tdev);
} else if (unlikely(dma_stat == DMA_ERROR)) {
dev_info(dev,"DMA error! \n");
dma_stop(tdev);
}
}
static void dma_busy_loop(struct test_platform_device * tdev)
{
struct dma_private_info * dma_priv = _get_dmapip(tdev);
struct device * dev = _get_devp(tdev);
enum dma_status status;
int status_change = -1;
do {
status = dma_async_is_tx_complete(dma_priv->dma_chan, dma_priv->cookie, NULL, NULL);
switch(status) {
case DMA_COMPLETE:
if(status_change != 0)
dev_info(dev,"DMA status: COMPLETE\n");
status_change = 0;
break;
case DMA_PAUSED:
if (status_change != 1)
dev_info(dev,"DMA status: PAUSED\n");
status_change = 1;
break;
case DMA_IN_PROGRESS:
if(status_change != 2)
dev_info(dev,"DMA status: IN PROGRESS\n");
status_change = 2;
break;
case DMA_ERROR:
if (status_change != 3)
dev_info(dev,"DMA status: ERROR\n");
status_change = 3;
break;
default:
dev_info(dev,"DMA status: UNKNOWN\n");
status_change = -1;
break;
}
} while(status != DMA_COMPLETE);
dev_info(dev,"DMA transaction completed! \n");
}
static int dma_sg_init(struct test_platform_device * tdev)
{
struct dma_private_info * dma_priv = _get_dmapip(tdev);
struct scatterlist *sg;
int ret = 0;
int i;
ret = sg_alloc_table(&(dma_priv->sgt), SG_ENTRIES, GFP_ATOMIC);
if(ret)
goto out_mem2;
dma_priv->nblocks = SG_ENTRIES;
dma_priv->blocks = (struct dma_block *) kmalloc(dma_priv->nblocks\
*sizeof(struct dma_block), GFP_ATOMIC);
if(dma_priv->blocks == NULL)
goto out_mem1;
for( i = 0 ; i < dma_priv->nblocks ; i++ ) {
dma_priv->blocks[i].size = BUF_SIZE;
dma_priv->blocks[i].data = kmalloc(dma_priv->blocks[i].size, GFP_ATOMIC);
if(dma_priv->blocks[i].data == NULL)
goto out_mem3;
}
for_each_sg(dma_priv->sgt.sgl, sg, dma_priv->sgt.nents, i)
sg_set_buf(sg,dma_priv->blocks[i].data,dma_priv->blocks[i].size);
return ret;
out_mem3:
i--;
while(i >= 0)
kfree(dma_priv->blocks[i].data);
kfree(dma_priv->blocks);
out_mem2:
sg_free_table(&(dma_priv->sgt));
out_mem1:
ret = -ENOMEM;
return ret;
}
static int _dma_start(struct test_platform_device * tdev,int block)
{
struct dma_private_info * dma_priv = _get_dmapip(tdev);
struct device * dev = _get_devp(tdev);
int ret = 0;
int sglen;
/* Step 1: Allocate and initialize the SG list */
dma_sg_init(tdev);
/* Step 2: Map the SG list */
sglen = dma_map_sg(dev,dma_priv->sgt.sgl,\
dma_priv->sgt.nents, DMA_FROM_DEVICE);
if(! sglen)
goto out2;
/* Step 3: Configure the DMA */
(dma_priv->dma_config).direction = DMA_DEV_TO_MEM;
(dma_priv->dma_config).src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
(dma_priv->dma_config).src_maxburst = 1;
(dma_priv->dma_config).src_addr = (dma_addr_t) DEV_BUF;
dmaengine_slave_config(dma_priv->dma_chan, \
&(dma_priv->dma_config));
/* Step 4: Prepare the SG descriptor */
dma_priv->dma_desc = dmaengine_prep_slave_sg(dma_priv->dma_chan, \
dma_priv->sgt.sgl, dma_priv->sgt.nents, DMA_DEV_TO_MEM, \
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (dma_priv->dma_desc == NULL) {
dev_err(dev,"DMA could not assign a descriptor! \n");
goto out1;
}
/* Step 5: Set the callback method */
(dma_priv->dma_desc)->callback = dma_callback;
(dma_priv->dma_desc)->callback_param = (void *) tdev;
/* Step 6: Put the DMA descriptor in the queue */
dma_priv->cookie = dmaengine_submit(dma_priv->dma_desc);
/* Step 7: Fires the DMA transaction */
dma_async_issue_pending(dma_priv->dma_chan);
dma_priv->dma_started = 1;
if(block)
dma_busy_loop(tdev);
return ret;
out1:
dma_stop(tdev);
out2:
ret = -1;
return ret;
}
int dma_start(struct test_platform_device * tdev) {
return _dma_start(tdev,0);
}
int dma_start_block(struct test_platform_device * tdev) {
return _dma_start(tdev,1);
}
int dma_init(struct test_platform_device * tdev)
{
int ret = 0;
struct dma_private_info * dma_priv = _get_dmapip(tdev);
struct device * dev = _get_devp(tdev);
dma_priv->dma_chan = dma_request_slave_channel(dev, \
"dma_chan0");
if (dma_priv->dma_chan == NULL) {
dev_err(dev,"DMA channel busy! \n");
ret = -1;
}
dma_priv->dma_started = 0;
return ret;
}
int dma_exit(struct test_platform_device * tdev)
{
int ret = 0;
struct dma_private_info * dma_priv = _get_dmapip(tdev);
if(dma_priv->dma_started) {
dmaengine_terminate_all(dma_priv->dma_chan);
dma_stop(tdev);
dma_priv->dma_started = 0;
}
if(dma_priv->dma_chan != NULL)
dma_release_channel(dma_priv->dma_chan);
return ret;
}
In my driver source file (test_driver.c):
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/version.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/of_device.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/interrupt.h>
#include "test_driver.h"
static int dma_block=0;
module_param_named(dma_block, dma_block, int, 0444);
static struct test_platform_device tdev;
static struct of_device_id test_of_match[] = {
{ .compatible = "custom,test-driver-1.0", },
{}
};
static int test_probe(struct platform_device *op)
{
int ret = 0;
struct device * dev = &(op->dev);
const struct of_device_id *match = of_match_device(test_of_match, &op->dev);
if (!match)
return -EINVAL;
tdev.pdev = op;
dma_init(&tdev);
if(dma_block)
ret = dma_start_block(&tdev);
else
ret = dma_start(&tdev);
if(ret) {
dev_err(dev,"Error to start DMA transaction! \n");
} else {
dev_info(dev,"DMA OK! \n");
}
return ret;
}
static int test_remove(struct platform_device *op)
{
dma_exit(&tdev);
return 0;
}
static struct platform_driver test_platform_driver = {
.probe = test_probe,
.remove = test_remove,
.driver = {
.name = "test-driver",
.owner = THIS_MODULE,
.of_match_table = test_of_match,
},
};
static int test_init(void)
{
platform_driver_register(&test_platform_driver);
return 0;
}
static void test_exit(void)
{
platform_driver_unregister(&test_platform_driver);
}
module_init(test_init);
module_exit(test_exit);
MODULE_AUTHOR("klyone");
MODULE_DESCRIPTION("DMA SG test module");
MODULE_LICENSE("GPL");
However, the DMA never calls my callback function and I do not have any idea why it happens. Maybe, I am misunderstanding something...
Could anyone help me?
Thanks in advance.
Caveat: I don't have a definitive solution for you, but merely some observations and suggestions on how to debug this [based on many years of experience writing/debugging linux device drivers].
I presume you believe the callback is not being done because you don't get any printk messages. But, the callback is the only place that has them. But, is the printk level set high enough to see the messages? I'd add a dev_info to your module init, to prove it prints as expected.
Also, you [probably] won't get a callback if dma_start doesn't work as expected, so I'd add some dev_info calls there, too (e.g. before and after the call in step 7). I also notice that not all calls in dma_start check error returns [may be fine or void return, just mentioning in case you missed one]
At this point, it should be noted that there are really two questions here: (1) Did your DMA request start successfully [and complete]? (2) Did you get a callback?
So, I'd split off some code from dma_complete into (e.g.) dma_test_done. The latter does the same checking but only prints the "complete" message. You can call this in a poll mode to verify DMA completion.
So, if you [eventually] get a completion, then the problem reduces to why you didn't get the callback. If, however, you don't [even] get a completion, that's an even more fundamental problem.
This reminds me. You didn't show any code that calls dma_start or how you wait for the completion. I presume that if your callback were working, it would issue a wakeup of some sort that the base level would wait on. Or, the callback would do the request deallocate/cleanup (i.e. more code you'd write)
At step 7, you're calling dma_async_issue_pending, which should call pl330_issue_pending. pl330_issue_pending will call pl330_tasklet.
pl330_tasklet is a tasklet function, but it can also be called directly [to kick off DMA when there are no active requests].
pl330_tasklet will loop on its "work" queue and move any completed items to its "completed" queue. It then tries to start new requests. It then loops on its completed queue and issues the callbacks.
pl330_tasklet grabs the callback pointer, but if it's null it is silently ignored. You've set a callback, but it might be good to verify that where you set the callback is the same place [or propagates to] the place where pl330_tasklet will fetch it from.
When you make the call, everything may be busy, so there are no completed requests, no room to start a new request, so nothing to complete. In that case, pl330_tasklet will be called again later.
So, when dma_async_issue_pending returns, nothing may have happened yet. This is quite probable for your case.
pl330_tasklet tries to start new DMA by calling fill_queue. It will check that a descriptor is not [already] busy by looking at status != BUSY. So, you may wish to verify that yours has the correct value. Otherwise, you'd never get a callback [or even any DMA start].
Then, fill_queue will try to start the request via pl330_submit_req. But, that can return an error (e.g. queue already full), so, again, things are deferred.
For reference, notice the following comment at the top of pl330_submit_req:
Submit a list of xfers after which the client wants notification.
Client is not notified after each xfer unit, just once after all
xfer units are done or some error occurs.
What I'd do is start hacking up pl330.c and add debug messages and cross-checking. If your system is such that pl330 is servicing many other requests, you might limit the debug messages by checking that the device's private data pointer matches yours.
In particular, you'd like to get a message when your request actually gets started, so you could add a debug message to the end of pl330_submit_req
Then, adding messages within pl330_tasklet for requests will help, too.
Those are two good starting points. But, don't be afraid to add more printk calls as needed. You may be surprised by what gets called [or doesn't get called] or in what order.
UPDATE:
If I install the kernel module with the blocking behaviour, everything is initialized well. However, the dma_busy_loop function shows that the DMA descriptor is always IN PROGESS and the DMA transaction never completes. For this reason, the callback function is not executed. What could be happening?
Did a little more research. Cookies are just sequence numbers that increment. For example, if you issue a request that gets broken up into [say] 10 separate scatter/gather operations [descriptors], each one gets a unique cookie value. The cookie return value is the latest/last of the bunch (e.g. 10).
When you're calling (1) dma_async_is_tx_complete, (2) it calls chan->device->device_tx_status, (3) which is pl330_tx_status, (4) which calls dma_cookie_status
Side note/tip: When I was tracking this down, I just kept flipping back and forth between dmaengine.h and pl330.c. It was like: Look at (1), it calls (2). Where is that set? In pl330.c, I presume. So, I grepped for the string and got the name of pl330's function (i.e. (3)). So, I go there, and see that it does (4). So ... Back to dmaengine.h ...
However, when you make the outer call, you're ignoring [setting to NULL] the last two arguments. These can be useful because they return the "last" and "used" cookies. So, even if you don't get full completion, these values could change and show partial progress.
One of them should eventually be >= to the "return" cookie value. (i.e.) The entire operation should be complete. So, this will help differentiate what may be happening.
Also, note that in dmaengine.h, right below dma_async_is_tx_complete, there is dma_async_is_complete. This function is what decides whether to return DMA_COMPLETE or DMA_IN_PROGRESS, based on the cookie value you pass and the "last" and "used" cookie values. It's passive, and not used in the code path [AFAICT], but it does show how to calculate completion yourself.