Драйвер ADC

http://www.at91.com/index.php?option=com_jfusion&Itemid=57&jfile=viewtopic.php&f=12&t=4992

Вольный перевод авторского комментария:

Этот драйвер ADC настраивает модуль TCO для генерации прерываний каждые X мс и собирает данные в небольшой ring-буфер. Это подразумевает, что клиент читает данные от ADC с периодом 1 секунда. Поддерживаются два канала, для этого создаются файлы устройств /dev/at91adc0 и /dev/at91adc1.

Прилагаются 4 файла:

1. сам драйвер

2. makefile

3. скрипт установки

4. тестовый код написанный на ... TCL. Да, странный выбор, но так как Atmel использует TCL для различных целей, мы используем его для тестирования. Скрипт просто открывает /dev/at91adc0 и читает байты данных.

Удачи,

Gertjan

Драйвер at91adc.c

/******************************************************************************

| File name : at91adc.c |

| Description : Source code for the EDAQ ADC driver. This driver supports two |

| : adc channesl with minor numbers 0 and 1. When the module is |

| : is inserted to kernel, TC0 module is setup to generate interr- |

| : upt every 1 msec. Both ADC channels are sampled in the ISR |

| : and the samples are copied into a ring buffer. Sampling rate |

| : can be changed by changing SAMPLE_INTERVAL_MS. In response to |

| : the read from user space, latest requested number of samples |

| : are returned as an unsigned short array. Channel 0/1 data is |

| : returned depending on the minor number of the device opened. |

| History : |

| ### Date Author Comments |

| 001 30-Jul-08 S. Thalore Initial creation |

| This program is free software: you can redistribute it and/or modify |

| it under the terms of the GNU General Public License as published by |

| the Free Software Foundation, either version 3 of the License, or |

| (at your option) any later version. |

| |

| This program is distributed in the hope that it will be useful, |

| but WITHOUT ANY WARRANTY; without even the implied warranty of |

| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |

| GNU General Public License for more details. |

| |

| You should have received a copy of the GNU General Public License |

| along with this program. If not, see <http://www.gnu.org/licenses/>. |

******************************************************************************/

#include <linux/module.h>

#include <linux/fs.h>

#include <linux/cdev.h>

#include <linux/clk.h>

#include <linux/irq.h>

#include <linux/interrupt.h>

#include <asm/arch/gpio.h>

#include <asm/arch/at91_tc.h>

#include <asm/arch/at91_adc.h>

#include <asm/uaccess.h>

// Set the period between reads (max allowed value 1000)

#define SAMPLE_INTERVAL_MS 5

// Assume client always reads data at 1 second intervals; so the client will read:

#define READ_SAMPLES 1000/SAMPLE_INTERVAL_MS

// Allocate to be at least 5 x bigger so that ISR will never catch up with reading.

#define MAX_ADCSAMPLES 5* READ_SAMPLES

int at91adc_devno;

struct cdev at91adc_cdev;

struct file_operations at91adc_fops;

unsigned short *at91adc_pbuf0, *at91adc_pbuf1, at91adc_appidx;

void __iomem *at91tc0_base;

void __iomem *at91adc_base;

struct clk *at91adc_clk;

struct clk *at91tc0_clk;

/*****************************************************************************************

| Timer counter 0 ISR: Sample both ADC channels and copy the data to module ring buffer. |

*****************************************************************************************/

static irqreturn_t at91tc0_isr (int irq, void *dev_id)

{

int status;

static int timecount = 0;

// Read TC0 status register to reset RC compare status.

status = ioread32(at91tc0_base + AT91_TC_SR);

timecount++;

if (timecount >= SAMPLE_INTERVAL_MS)

{

timecount = 0;

// Trigger the ADC (this will be done using TIOA automatically eventually).

iowrite32(AT91_ADC_START, (at91adc_base + AT91_ADC_CR));

// Wait for conversion to be complete.

while ((ioread32(at91adc_base + AT91_ADC_SR) & AT91_ADC_DRDY) == 0) cpu_relax();

// Copy converted data to module ring buffer.

at91adc_pbuf0[at91adc_appidx] = ioread32(at91adc_base + AT91_ADC_CHR(0));

at91adc_pbuf1[at91adc_appidx] = ioread32(at91adc_base + AT91_ADC_CHR(1));

// Increment the ring buffer index and check for wrap around.

at91adc_appidx += 1;

if (at91adc_appidx >= MAX_ADCSAMPLES) at91adc_appidx = 0;

}

return IRQ_HANDLED;

}

/*****************************************************************************************

| Module initialization: Allocate device numbers, register device, setup ADC and timer |

| counter registers for 100 msec periodic sampling. |

*****************************************************************************************/

static int __init at91adc_init (void)

{

int ret;

// Dynamically allocate major number and minor number

ret = alloc_chrdev_region(&at91adc_devno, // pointer to where the device number to be stored

0, // first minor number requested

2, // number of devices

"at91adc"); // device name

if (ret < 0)

{

printk(KERN_INFO "at91adc: Device number allocation failed\n");

ret = -ENODEV;

goto exit_1;

}

// Initialize cdev structure.

cdev_init(&at91adc_cdev, // pointer to the cdev structure

&at91adc_fops); // pointer to the file operations structure.

at91adc_cdev.owner = THIS_MODULE;

at91adc_cdev.ops = &at91adc_fops;

// Register the device with kernel

ret = cdev_add(&at91adc_cdev, // pointer to the initialized cdev structure

at91adc_devno, // device number allocated

2); // number of devices

if (ret != 0)

{

printk(KERN_INFO "at91adc: Device registration failed\n");

ret = -ECANCELED;

goto exit_2;

}

// Character device driver initialization complete. Do device specific initialization now.

// Allocate ring buffer memory for storing ADC values for both channels.

at91adc_pbuf0 = (unsigned short *)kmalloc((MAX_ADCSAMPLES * sizeof(unsigned short)), // Number of bytes

GFP_KERNEL); // Flags

at91adc_pbuf1 = (unsigned short *)kmalloc((MAX_ADCSAMPLES * sizeof(unsigned short)), // Number of bytes

GFP_KERNEL); // Flags

if ((at91adc_pbuf0 == NULL) || (at91adc_pbuf1 == NULL))

{

printk(KERN_INFO "at91adc: Memory allocation failed\n");

ret = -ECANCELED;

goto exit_3;

}

// Initialize the ring buffer and append index.

at91adc_appidx = 0;

for (ret = 0; ret < MAX_ADCSAMPLES; ret++)

{

at91adc_pbuf0[ret] = 0;

at91adc_pbuf1[ret] = 0;

}

// Initialize ADC. The following two lines set the appropriate PMC bit

// for the ADC. Easier than mapping PMC registers and then setting the bit.

at91adc_clk = clk_get(NULL, // Device pointer - not required.

"adc_clk"); // Clock name.

clk_enable(at91adc_clk);

// Map ADC registers to the current address space.

at91adc_base = ioremap_nocache(AT91SAM9260_BASE_ADC, // Physical address

64); // Number of bytes to be mapped.

if (at91adc_base == NULL)

{

printk(KERN_INFO "at91adc: ADC memory mapping failed\n");

ret = -EACCES;

goto exit_4;

}

// MUX GPIO pins for ADC (peripheral A) operation

at91_set_A_periph(AT91_PIN_PC0, 0);

at91_set_A_periph(AT91_PIN_PC1, 0);

// Reset the ADC

iowrite32(AT91_ADC_SWRST, (at91adc_base + AT91_ADC_CR));

// Enable both ADC channels

iowrite32((AT91_ADC_CH(1) | AT91_ADC_CH(0)), (at91adc_base + AT91_ADC_CHER));

// Configure ADC mode register.

// From table 43-31 in page #775 and page#741 of AT91SAM9260 user manual:

// Maximum ADC clock frequency = 5MHz = MCK / ((PRESCAL+1) * 2)

// PRESCAL = ((MCK / 5MHz) / 2) -1 = ((100MHz / 5MHz)/2)-1) = 9

// Maximum startup time = 15uS = (STARTUP+1)*8/ADC_CLOCK

// STARTUP = ((15uS*ADC_CLOK)/8)-1 = ((15uS*5MHz)/8)-1 = 9

// Minimum hold time = 1.2uS = (SHTIM+1)/ADC_CLOCK

// SHTIM = (1.2uS*ADC_CLOCK)-1 = (1.2uS*5MHz)-1 = 5, Use 9 to ensure 2uS hold time.

// Enable sleep mode and hardware trigger from TIOA output from TC0.

iowrite32((AT91_ADC_SHTIM_(9) | AT91_ADC_STARTUP_(9) | AT91_ADC_PRESCAL_(9) |

AT91_ADC_SLEEP | AT91_ADC_TRGEN), (at91adc_base + AT91_ADC_MR));

// Initialize Timer Counter module 0. The following two lines set the appropriate

// PMC bit for TC0. Easier than mapping PMC registers and then setting the bit.

at91tc0_clk = clk_get(NULL, // Device pointer - not required.

"tc0_clk"); // Clock name.

clk_enable(at91tc0_clk);

// Map TC0 registers to the current address space.

at91tc0_base = ioremap_nocache(AT91SAM9260_BASE_TC0, // Physical address

64); // Number of bytes to be mapped.

if (at91tc0_base == NULL)

{

printk(KERN_INFO "at91adc: TC0 memory mapping failed\n");

ret = -EACCES;

goto exit_5;

}

// Configure TC0 in waveform mode, TIMER_CLK1 and to generate interrupt on RC compare.

// Load 50000 to RC so that with TIMER_CLK1 = MCK/2 = 50MHz, the interrupt will be

// generated every 1/50MHz * 50000 = 20nS * 50000 = 1 milli second.

// NOTE: Even though AT91_TC_RC is a 32-bit register, only 16-bits are programmble.

iowrite32(50000, (at91tc0_base + AT91_TC_RC));

iowrite32((AT91_TC_WAVE | AT91_TC_WAVESEL_UP_AUTO), (at91tc0_base + AT91_TC_CMR));

iowrite32(AT91_TC_CPCS, (at91tc0_base + AT91_TC_IER));

iowrite32((AT91_TC_SWTRG | AT91_TC_CLKEN), (at91tc0_base + AT91_TC_CCR));

// Install interrupt for TC0.

ret = request_irq(AT91SAM9260_ID_TC0, // Interrupt number

at91tc0_isr, // Pointer to the interrupt sub-routine

0, // Flags - fast, shared or contributing to entropy pool

"at91adc", // Device name to show as owner in /proc/interrupts

NULL); // Private data for shared interrupts

if (ret != 0)

{

printk(KERN_INFO "at91adc: Timer interrupt request failed\n");

ret = -EBUSY;

goto exit_6;

}

printk(KERN_INFO "at91adc: Loaded module\n");

return 0;

exit_6:

iounmap(at91tc0_base);

exit_5:

clk_disable(at91tc0_clk);

iounmap(at91adc_base);

exit_4:

clk_disable(at91adc_clk);

exit_3:

kfree(at91adc_pbuf0);

kfree(at91adc_pbuf1);

exit_2:

// Free device number allocated.

unregister_chrdev_region(at91adc_devno, // allocated device number

2); // number of devices

exit_1:

return ret;

}

static void __exit at91adc_exit (void)

{

// Reset PMC bit for ADC and TC0

clk_disable(at91adc_clk);

clk_disable(at91tc0_clk);

// Free TC0 IRQ.

free_irq(AT91SAM9260_ID_TC0, // Interrupt number

NULL); // Private data for shared interrupts

// Unmap ADC and TC0 register map.

iounmap(at91adc_base);

iounmap(at91tc0_base);

// Free kernel memory allocated

kfree(at91adc_pbuf0);

kfree(at91adc_pbuf1);

// Free device number allocated.

unregister_chrdev_region(at91adc_devno, // allocated device number

2); // number of devices

printk(KERN_INFO "at91adc: Unloaded module\n");

}

/*****************************************************************************************

| Module open: |

*****************************************************************************************/

static int at91adc_open (struct inode *inode, struct file *filp)

{

return 0;

}

/*****************************************************************************************

| Module close: |

*****************************************************************************************/

static int at91adc_release (struct inode *inode, struct file *filp)

{

return 0;

}

/*****************************************************************************************

| Module read: Return last READ_SAMPLES samples from ADC chan 0 or 1 depending on the |

| minor number. |

*****************************************************************************************/

static ssize_t at91adc_read (struct file *filp, char __iomem *buf, size_t bufsize, loff_t *f_pos)

{

unsigned int minor;

unsigned short idx, readidx, *psrc;

// Latch the index of the latest data

readidx = at91adc_appidx;

readidx = (readidx >= READ_SAMPLES) ? readidx - READ_SAMPLES

: MAX_ADCSAMPLES - (READ_SAMPLES - readidx);

// Read from ADC channel 0 or 1 depending on minor number.

minor = iminor(filp->f_dentry->d_inode);

// Select the source buffer pointer based on the minor number.

if (minor == 0) psrc = at91adc_pbuf0;

else if (minor == 1) psrc = at91adc_pbuf1;

else return 0;

// Return up to READ_SAMPLES samples depending on the size of the buffer.

for (idx = 0; idx < READ_SAMPLES; idx++)

{

if (bufsize < sizeof(unsigned short)) break;

if (copy_to_user(buf, &psrc[readidx], sizeof(unsigned short)) != 0) return -EFAULT;

buf = buf + sizeof(unsigned short);

bufsize = bufsize - sizeof(unsigned short);

readidx += 1;

if (readidx >= MAX_ADCSAMPLES) readidx = 0;

}

// Return number of characters copied.

return (idx * sizeof(unsigned short));

}

struct file_operations at91adc_fops = {

.owner = THIS_MODULE,

.open = at91adc_open,

.read = at91adc_read,

.release = at91adc_release,

};

module_init(at91adc_init);

module_exit(at91adc_exit);

MODULE_AUTHOR("Sudhir Thalore");

MODULE_DESCRIPTION("Initialize and read AT91SAM9260 ADC channels");

MODULE_LICENSE("GPL");

Коррекция драйвера от repairmen (http://www.starterkit.ru/new/index.php?name=Forums&op=showtopic&id=152&pagenum=4).

Замена cpurelax().

static irqreturn_t at91tc0_isr (int irq, void *dev_id)

{

int status;

//struct timeval time;

static int timecount = 0;

// Read TC0 status register to reset RC compare status.

status = ioread32(at91tc0_base + AT91_TC_SR);

timecount++;

if (timecount >= SAMPLE_INTERVAL_MS)

{

timecount = 0;

if (ioread32(at91adc_base + AT91_ADC_SR) & AT91_ADC_DRDY)

{

// Copy converted data to module ring buffer.

at91adc_pbuf0[at91adc_appidx] = ioread32(at91adc_base + AT91_ADC_CHR(0));

at91adc_pbuf1[at91adc_appidx] = ioread32(at91adc_base + AT91_ADC_CHR(1));

// Increment the ring buffer index and check for wrap around.

at91adc_appidx += 1;

if (at91adc_appidx >= MAX_ADCSAMPLES)

at91adc_appidx = 0;

}

// Trigger the ADC (this will be done using TIOA automatically eventually).

iowrite32(AT91_ADC_START, (at91adc_base + AT91_ADC_CR));

}

return IRQ_HANDLED;

}

Makefile

#******************************************************************************

# File name : Makefile |

# Description : GNU makefile to build the AT91 ADC driver module at91adc.ko. |

# : This makefile must be invoked using the command line |

# : "make ARCH=arm CROSS_COMPILE=path_to_compiler KERN_DIR= |

# : path_to_kernel_source" |

# History : |

# ### Date Author Comments |

# 001 31-Jul-08 S. Thalore Initial creation |

#*****************************************************************************/

EXTRA_CFLAGS = -Wall -O2

ifneq ($(KERNELRELEASE),)

# Call from kernel build system

obj-m := at91adc.o

else

# Call from module source directory

PWD := $(shell pwd)

# Verify command line arguments if this is not make clean

ifneq ($(MAKECMDGOALS),clean)

ifeq ($(ARCH),)

$(error Run using make ARCH=arm CROSS_COMPILE=path_to_compiler KERN_DIR=path_to_kernel_source. Missing ARCH)

endif

ifeq ($(CROSS_COMPILE),)

$(error Run using make ARCH=arm CROSS_COMPILE=path_to_compiler KERN_DIR=path_to_kernel_source. Missing CROSS_COMPILE)

endif

ifeq ($(KERN_DIR),)

$(error Run using make ARCH=arm CROSS_COMPILE=path_to_compiler KERN_DIR=path_to_kernel_source. Missing KERN_DIR)

endif

default:

$(MAKE) -C $(KERN_DIR) M=$(PWD) modules

clean:

rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c *.symvers .tmp_versions

endif

Скрипт загрузки драйвера

#!/bin/sh

major=-1

module="at91adc"

device="at91adc"

/sbin/rmmod $module

if [ "$?" != "0" ] then

echo ...error ignored

/sbin/insmod ./$module.ko

if [ "$?" = "0" ] then

rm -rf /dev/${device}[0-1]

major=`cat /proc/devices | awk "\\$2==\"$device\" {print \\$1}"`

if [ "$?" = "0" ] then

mknod /dev/${device}0 c $major 0

mknod /dev/${device}1 c $major 1

echo "Created nodes /dev/${device}0 and /dev/${device}1"

Скрипт для теста

#!/usr/bin/tclsh

#******************************************************************************

# File name : adctst |

# Description : TCL script to run stability test on on-chip ADC channels. |

# : The script reads ten 100 msec samples from both ADC channels |

# : every second and assigns average of these readings as 1-sec |

# : value. Max and Min of 60 1-sec values is computed and 1-minute |

# : error is calculated using (1-secMax - 1-secMin)*100/1-secMean. |

# : The test is run for the specified number of minutes and the |

# : results are written into the file ./adctst.dat. |

# History : |

# ### Date Author Comments |

# 001 30-Jul-08 S. Thalore Initial creation |

#*****************************************************************************/

lappend auto_path /usr/lib/tcllib1.8

package require math::statistics

if {$argc < 1} {

puts "Specify length of test in minutes"

exit

}

set numsamples_per_s 200 ; # from ADC driver - see: SAMPLE_INTERVAL_MS

set num_bytes [expr 2 *$numsamples_per_s]

set tlen [lindex $argv 0]

set fptr [open "adctst.dat" "w"]

puts $fptr "ADC0AVE, ADC0MIN, ADC0MAX, ADC0ERR, ADC1AVE, ADC1MIN, ADC1MAX, ADC1ERR"

close $fptr

set fptr0 [open "/dev/at91adc0" "r"]

fconfigure $fptr0 -translation binary

set fptr1 [open "/dev/at91adc1" "r"]

fconfigure $fptr1 -translation binary

while {$tlen > 0} {

#puts "$tlen minutes left..."

incr tlen -1

set adc0onesecval ""

set adc1onesecval ""

set secsinmin 60

while {$secsinmin > 0} {

incr secsinmin -1

set adcdata ""

set data [read $fptr0 $num_bytes ]

if {[string length $data] == $num_bytes } {

while {[string length $data] >= 2} {

binary scan $data "s" sample

puts $sample

lappend adcdata $sample

set data [string range $data 2 end]

}

lappend adc0onesecval [::math::statistics::mean $adcdata]

} else {

puts "Invalid length [string length $data]; ignoring the read data"

}

set adcdata ""

set data [read $fptr1 $num_bytes]

if {[string length $data] == $num_bytes} {

while {[string length $data] >= 2} {

binary scan [string range $data 0 1] "s" sample

lappend adcdata $sample

set data [string range $data 2 end]

}

lappend adc1onesecval [::math::statistics::mean $adcdata]

} else {

puts "Invalid length [string length $data]; ignoring the read data"

}

after 1010 ; # waiting 1 sec should be long enough not to see repeated samples from the buffer

}

set adc0oneminmin [::math::statistics::min $adc0onesecval]

set adc0oneminmax [::math::statistics::max $adc0onesecval]

set adc0oneminval [::math::statistics::mean $adc0onesecval]

set adc0oneminerr [expr {(($adc0oneminmax-$adc0oneminmin)*100)/$adc0oneminval}]

set adc1oneminmin [::math::statistics::min $adc1onesecval]

set adc1oneminmax [::math::statistics::max $adc1onesecval]

set adc1oneminval [::math::statistics::mean $adc1onesecval]

set adc1oneminerr [expr {(($adc1oneminmax-$adc1oneminmin)*100)/$adc1oneminval}]

set fptr [open "adctst.dat" "a"]

puts $fptr "$adc0oneminval, $adc0oneminmin, $adc0oneminmax, $adc0oneminerr \

$adc1oneminval, $adc1oneminmin, $adc1oneminmax, $adc1oneminerr"

close $fptr

close $fptr0

close $fptr1

puts "Output saved in ./adctst.dat"

Тестовый код на Си

#include <stdio.h>

#include <stdlib.h>

int main(void)

{

FILE* f;

int chr;

f = fopen("/dev/adc0","r");

while( 1 )

{

chr = fgetc( f );

printf( "%02x%02x\r", fgetc(f), chr );

}

Смотри также

ADC Driver for AT91SAM9260

http://prod-at91.fullsix.com.cn/forum/viewtopic.php/f,12/t,5607/view,next/

Using ADC on AT91SAM9G20 based products

http://www.armbedded.eu/node/339

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