ADS1191: error while reading adc value

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/spi/spi.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <asm/uaccess.h>
#include <linux/clk.h>
#include <linux/errno.h>
#include <linux/irq.h>
#include <linux/list.h>
//#include <mach/hardware.h>
#include <asm/delay.h>
#include <asm/pmu.h>
#include <asm/gpio.h>
//#include <mach/gpio.h>
#include <linux/gpio.h>
#include <asm/io.h>
#include "ads1191.h"
#include "Am335x_gpio.h"
#define DEBUG_ENABLE 1
#define CS GPIO_TO_PIN(3, 26) 
#define Set(X,V) gpio_set_value(X,V)

static unsigned char TransBuf[8];
static unsigned char RecvBuf[18];
long AdsResult;
struct ads1191_bus {
	struct spi_message Pmsg;
	struct spi_transfer Pxfer[2];
};
struct spi_device *ads1191spi;
int ads1191init(void);
void ads1191ConvertRaw(void);
unsigned char ads1191ReadReg(unsigned char );
unsigned char ads1191ReadRegID(unsigned char );
void ads1191WriteReg(unsigned char ,unsigned char );
unsigned char Msb2Lsb(unsigned char Data);
static int ads1191_user_read(struct file *file, unsigned int *buf, size_t count, loff_t *ppos)
{
	int p=0;
	Set(CS,0);	// CHIP_SELECT LOW
	while(p <= count)
	{
		ads1191ConvertRaw();
		if(AdsResult>0) 
			buf[p++] = AdsResult;
	}
	Set(CS,1);	// CHIP_SELECT HIGH
	return 0;
}
static long ads1191_user_ioctl(struct file *file, int arg)
{
	int p;
	long adcval=0;
	char chnum;
	chnum = arg;
	Set(CS,0);	// CHIP_SELECT LOW
	chnum=0;
	for(p=0; p<10; p++)
	{
		ads1191ConvertRaw();
		if(AdsResult>0)
			adcval = adcval+AdsResult;
		else chnum++;
	}
	adcval = adcval/(10 - chnum);
	printk("adcval value in ioctl=%d\n",adcval);
	Set(CS,1);	// CHIP_SELECT HIGH
	return adcval;
}
int ads1191init(void)
{
	unsigned char  ID=0,LOFF=0;    
	Set(CS,0);	// CHIP_SELECT LOW
	TransBuf[0] = RESET;
	spi_write_then_read(ads1191spi,TransBuf, 1,NULL,0);
	mdelay(50);
	TransBuf[0] = SDATAC;
	spi_write_then_read(ads1191spi,TransBuf, 1,NULL,0);
	mdelay(5);
	ID=0;	// 0 previous
	ID=ads1191ReadRegID(ADS1191_ID_REG);
#ifdef DEBUG_ENABLE
	printk("\n.......Ads1191 ID in INIT= %d",ID);
#endif
	if(ID != ADS1191_ID)
	{
		printk("\n.......Ads1191 ID = %d",ID);
		mdelay(10);
		ID=0;
		ID=ads1191ReadRegID(ADS1191_ID_REG);
		if(ID != ADS1191_ID)
		{
			printk("\n.......Ads1191 ID = %d",ID);
#ifdef DEBUG_ENABLE
			printk("\nAds1191 ID Not Matched/Device not Detected");
#endif
			//return -1;
		}
	}
	ads1191WriteReg(ADS1191_CONFIG1, 0x02);		//Single-Short with 125 SPS=0x80 old, continous=0x00
	ads1191WriteReg(ADS1191_CONFIG2, 0xB0);		//0x80	//old 0xB0
	ads1191WriteReg(ADS1191_CH1SET, 0x10);		//0x00	//old 0x10
	ads1191WriteReg(ADS1191_CH2SET, 0x80);		//0x00	//old 0x80
	ads1191WriteReg(ADS1191_MISC1, 0x02);		
	ads1191WriteReg(ADS1191_GPIO, 0x0C);
	ads1191WriteReg(ADS1191_LOFF_STAT, 0x00);	//	fclk=512 fmod=fclk/4 
	TransBuf[0] = SDATAC;
	spi_write_then_read(ads1191spi,TransBuf, 1,NULL,0);
	mdelay(5);	
	LOFF=ads1191ReadReg(ADS1191_LOFF);
#ifdef DEBUG_ENABLE
	printk("\nAds1191 LOFF = %d\n",LOFF);
#endif
	printk("\n- Reg Read... ");
	for(ID=0;ID<12;ID++)
	{
		memset(RecvBuf, 0x00, sizeof(RecvBuf));	
		TransBuf[0] = ADS1191_REG_READ | ID;
		TransBuf[1] = 0x00;
		spi_write_then_read(ads1191spi,TransBuf, 2,RecvBuf,1);
		//printk("[%02x %02x %02x %02x]",RecvBuf[0],RecvBuf[1],RecvBuf[2],RecvBuf[3]); 
		printk("[%02x] ",RecvBuf[0]); 
	}
	ads1191ConvertRaw();
	Set(CS,1);	// CHIP_SELECT HIGH
	return 1;
}
void ads1191ConvertRaw(void)
{
	unsigned char p,val=0x00;
	AdsResult = 0x00;
	TransBuf[0] = START;
	spi_write_then_read(ads1191spi,TransBuf, 1,NULL,0);
	mdelay(4); /*5*/
	for(p=0;p<2;p++) /*10*/
	{
		memset(RecvBuf, 0x00, sizeof(RecvBuf));	
		TransBuf[0] = ADS1191_REG_READ | ADS1191_GPIO;
		TransBuf[1] = 0x00;
		spi_write_then_read(ads1191spi,TransBuf, 2,RecvBuf,1);
		//printk("\n-GPIO Read... %02x \n",RecvBuf[0]);
		val=RecvBuf[0];
		if(!(val&0x02))
		{
			//printk("\n DREADY LOW...\n");
			memset(RecvBuf, 0x00, sizeof(RecvBuf));
			TransBuf[0] = RDATA;
			spi_write_then_read(ads1191spi,TransBuf, 1,RecvBuf,6);
			//printk("ADC Value [0x%02x 0x%02x]",RecvBuf[2],RecvBuf[3]); 
			break;
		}
	}
	AdsResult = RecvBuf[2];
	AdsResult <<= 8;//bits a2d11 to a2d4
	AdsResult |= RecvBuf[3]; //bits a2d3 to a2d0 + 4 dummy bits
#ifdef DEBUG_ENABLE
	//	printk("\nAdsResult = 0x%x %ld\n",AdsResult,AdsResult);
	//printk("\nAdsResult = 0x%x %f\n",AdsResult,(AdsResult*12.099)/(2*32768));
#endif
}
unsigned char Msb2Lsb(unsigned char Data)
{
	unsigned char k,tmp1,tmp=0x00;
	tmp1 = Data;
	for(k=0;k<8;k++)
	{
		tmp = tmp << 1;
		tmp |= tmp1&0x01;
		tmp1 = tmp1 >> 1;
	}
	return tmp;
}
unsigned char ads1191ReadRegID(unsigned char reg)
{
	unsigned char data = 0x00;

	TransBuf[0] = ADS1191_REG_READ | reg;
	TransBuf[1] = 0x01;    //0x00 old
	//printk("\n Reg to be Read... %02x ",TransBuf[0]);
	spi_write_then_read(ads1191spi,TransBuf, 2,RecvBuf,1);
	data = RecvBuf[0];
	//data = 0X50;
	printk("\n Value Read... %02x %02x %02x %02x",RecvBuf[0],RecvBuf[1],RecvBuf[2],RecvBuf[3]);
	printk("\n Msb2Lsb ...   %02x %02x %02x %02x",Msb2Lsb(RecvBuf[0]),Msb2Lsb(RecvBuf[1]),Msb2Lsb(RecvBuf[2]),Msb2Lsb(RecvBuf[3]));
	return data;
}
unsigned char ads1191ReadReg(unsigned char reg)
{
	unsigned char data = 0xff;

	TransBuf[0] = ADS1191_REG_READ | reg;
	TransBuf[1] = 0x00;
	//printk("\n Reg to be Read... %02x ",TransBuf[0]);
	spi_write_then_read(ads1191spi,TransBuf, 1,RecvBuf,1);
	data = RecvBuf[0];
	//printk("\n Value Read... %02x ",RecvBuf[0]);
	return data;
}
void ads1191WriteReg(unsigned char reg,unsigned char value)
{
	TransBuf[0] = ADS1191_REG_WRITE | reg;
	TransBuf[1] = 0x00;
	TransBuf[2] = value;
	spi_write_then_read(ads1191spi,TransBuf, 3,NULL,0);
}

static int ads1191_probe(struct spi_device *spi)
{
	int err;
	spi->bits_per_word = 8;
	spi->mode = SPI_MODE_1;//RAISE/FALL is COnnected to GND so MODE_2
	err = spi_setup(spi);
	if (err < 0)
		return err;
	Gpio_set_value(CS,"adc_cs",1,1);
	ads1191spi = spi;
	if(ads1191init() < 0)
	{
#ifdef DEBUG_ENABLE
		printk("\n>>>>>> Failed to detect ads1191");
#endif
		return -1; 
	}
#ifdef DEBUG_ENABLE
	printk("\n>>>>>>ads1191 detect success<<<<<<<");
#endif
	return 0;
}
static const struct of_device_id ads_match_table[] = {
	{.compatible = "ads1191_ADC",},
	{ },
};
static struct spi_driver ads1191Driver = {
	.driver = {
		.name = "ads1191",
		.bus = &spi_bus_type,
		.owner = THIS_MODULE,
		.of_match_table = of_match_ptr(ads_match_table),
	},
	.probe = ads1191_probe,
};

static  struct file_operations ads1191_user_file_ops = {
	.owner 	 = THIS_MODULE,
	.read    = ads1191_user_read,
	.unlocked_ioctl   = ads1191_user_ioctl,
};

static struct miscdevice ads1191_device = {
	55,
	"ads1191dev",
	&ads1191_user_file_ops,	
};

static int ads1191_init(void)
{
	int ret;
	ret = spi_register_driver(&ads1191Driver);
	if(ret < 0)
	{
		mdelay(10);
		ret = spi_register_driver(&ads1191Driver);	
	}
	ret = misc_register(&ads1191_device);
	return ret;
}
module_init(ads1191_init);
static void ads1191_exit(void)
{
	spi_unregister_driver(&ads1191Driver);
	misc_deregister(&ads1191_device);
}
module_exit(ads1191_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("RAVINDRANATH");
MODULE_DESCRIPTION("ADS 1191 INTERFACE");