对Freescale i.mx53 ADC驱动程序的透彻分析

对Freescale i.mx53 ADC驱动程序的透彻分析

应该说是freescalebsp提供了N多的东东，但是相对于三星提供的来说要复杂一些，感觉三星的简单，飞思将这些东东弄得复杂了。当然，这只是我个人见解，也有可能当初在学校接触的是s3c2410，所以现在才这样说。哈哈。见笑了。

飞思将ADC的驱动程序放在drivers/mxc/adc目录下，这个目录下有以下几个文件：

Imx_adc.c 这个实现的就是ADC的驱动程序

Imx_adc_reg.h 这个主要就是定义了跟ADC相关的一些寄存器

Kconfig 使用make menuconfig配置时必须配置的文件

Makefile 编译文件

首先，咱们来看看Kconfig文件，这个比较简单的：

Menu “i.MX ADC support”

Config IMX_ADC 此处会被定义成宏的！Makefile里就是在之前加CONFIG-

Tristate“i.MX ADC”

Dependson ARCH_MXC

Defaultn

Help

Thisselects the Freescale i.MX on-chip ADC driver.

Endmenu

这个文件应该没有好说的吧。我绍言在这里也不多说了。如果不懂的话，自己去看看我的博客里写的《如何在Linux2.6中增加自己的驱动程序》。

下面来看一下Makefile，如下：

Obj-$(CONFIG_IMX_ADC) += imx_adc.o

这些都是例行公事，最最主要的还是看驱动源码啊。看吧。为了深入进去，这里还是不限篇幅，列出源码，一条一条的分析！

#ifndef __IMX_ADC_H__

#define __IMX_ADC_H__

/* TSC General Config Register */

#define TGCR 0x000

#define TGCR_IPG_CLK_EN (1 << 0)

#define TGCR_TSC_RST (1 << 1)

#define TGCR_FUNC_RST (1 << 2)

#define TGCR_SLPC (1 << 4)

#define TGCR_STLC (1 << 5)

#define TGCR_HSYNC_EN (1 << 6)

#define TGCR_HSYNC_POL (1 << 7)

#define TGCR_POWERMODE_SHIFT 8

#define TGCR_POWER_OFF (0x0 << TGCR_POWERMODE_SHIFT)

#define TGCR_POWER_SAVE (0x1 << TGCR_POWERMODE_SHIFT)

#define TGCR_POWER_ON (0x3 << TGCR_POWERMODE_SHIFT)

#define TGCR_POWER_MASK (0x3 << TGCR_POWERMODE_SHIFT)

#define TGCR_INTREFEN (1 << 10)

#define TGCR_ADCCLKCFG_SHIFT 16

#define TGCR_PD_EN (1 << 23)

#define TGCR_PDB_EN (1 << 24)

#define TGCR_PDBTIME_SHIFT 25

#define TGCR_PDBTIME128 (0x3f << TGCR_PDBTIME_SHIFT)

#define TGCR_PDBTIME_MASK (0x7f << TGCR_PDBTIME_SHIFT)

/* TSC General Status Register */

#define TGSR 0x004

#define TCQ_INT (1 << 0)

#define GCQ_INT (1 << 1)

#define SLP_INT (1 << 2)

#define TCQ_DMA (1 << 16)

#define GCQ_DMA (1 << 17)

/* TSC IDLE Config Register */

#define TICR 0x008

/* TouchScreen Convert Queue FIFO Register */

#define TCQFIFO 0x400

/* TouchScreen Convert Queue Control Register */

#define TCQCR 0x404

#define CQCR_QSM_SHIFT 0

#define CQCR_QSM_STOP (0x0 << CQCR_QSM_SHIFT)

#define CQCR_QSM_PEN (0x1 << CQCR_QSM_SHIFT)

#define CQCR_QSM_FQS (0x2 << CQCR_QSM_SHIFT)

#define CQCR_QSM_FQS_PEN (0x3 << CQCR_QSM_SHIFT)

#define CQCR_QSM_MASK (0x3 << CQCR_QSM_SHIFT)

#define CQCR_FQS (1 << 2)

#define CQCR_RPT (1 << 3)

#define CQCR_LAST_ITEM_ID_SHIFT 4

#define CQCR_LAST_ITEM_ID_MASK (0xf << CQCR_LAST_ITEM_ID_SHIFT)

#define CQCR_FIFOWATERMARK_SHIFT 8

#define CQCR_FIFOWATERMARK_MASK (0xf << CQCR_FIFOWATERMARK_SHIFT)

#define CQCR_REPEATWAIT_SHIFT 12

#define CQCR_REPEATWAIT_MASK (0xf << CQCR_REPEATWAIT_SHIFT)

#define CQCR_QRST (1 << 16)

#define CQCR_FRST (1 << 17)

#define CQCR_PD_MSK (1 << 18)

#define CQCR_PD_CFG (1 << 19)

/* TouchScreen Convert Queue Status Register */

#define TCQSR 0x408

#define CQSR_PD (1 << 0)

#define CQSR_EOQ (1 << 1)

#define CQSR_FOR (1 << 4)

#define CQSR_FUR (1 << 5)

#define CQSR_FER (1 << 6)

#define CQSR_EMPT (1 << 13)

#define CQSR_FULL (1 << 14)

#define CQSR_FDRY (1 << 15)

/* TouchScreen Convert Queue Mask Register */

#define TCQMR 0x40c

#define TCQMR_PD_IRQ_MSK (1 << 0)

#define TCQMR_EOQ_IRQ_MSK (1 << 1)

#define TCQMR_FOR_IRQ_MSK (1 << 4)

#define TCQMR_FUR_IRQ_MSK (1 << 5)

#define TCQMR_FER_IRQ_MSK (1 << 6)

#define TCQMR_PD_DMA_MSK (1 << 16)

#define TCQMR_EOQ_DMA_MSK (1 << 17)

#define TCQMR_FOR_DMA_MSK (1 << 20)

#define TCQMR_FUR_DMA_MSK (1 << 21)

#define TCQMR_FER_DMA_MSK (1 << 22)

#define TCQMR_FDRY_DMA_MSK (1 << 31)

/* TouchScreen Convert Queue ITEM 7~0 */

#define TCQ_ITEM_7_0 0x420

/* TouchScreen Convert Queue ITEM 15~8 */

#define TCQ_ITEM_15_8 0x424

#define TCQ_ITEM7_SHIFT 28

#define TCQ_ITEM6_SHIFT 24

#define TCQ_ITEM5_SHIFT 20

#define TCQ_ITEM4_SHIFT 16

#define TCQ_ITEM3_SHIFT 12

#define TCQ_ITEM2_SHIFT 8

#define TCQ_ITEM1_SHIFT 4

#define TCQ_ITEM0_SHIFT 0

#define TCQ_ITEM_TCC0 0x0

#define TCQ_ITEM_TCC1 0x1

#define TCQ_ITEM_TCC2 0x2

#define TCQ_ITEM_TCC3 0x3

#define TCQ_ITEM_TCC4 0x4

#define TCQ_ITEM_TCC5 0x5

#define TCQ_ITEM_TCC6 0x6

#define TCQ_ITEM_TCC7 0x7

#define TCQ_ITEM_GCC7 0x8

#define TCQ_ITEM_GCC6 0x9

#define TCQ_ITEM_GCC5 0xa

#define TCQ_ITEM_GCC4 0xb

#define TCQ_ITEM_GCC3 0xc

#define TCQ_ITEM_GCC2 0xd

#define TCQ_ITEM_GCC1 0xe

#define TCQ_ITEM_GCC0 0xf

/* TouchScreen Convert Config 0-7 */

#define TCC0 0x440

#define TCC1 0x444

#define TCC2 0x448

#define TCC3 0x44c

#define TCC4 0x450

#define TCC5 0x454

#define TCC6 0x458

#define TCC7 0x45c

#define CC_PEN_IACK (1 << 1)

#define CC_SEL_REFN_SHIFT 2

#define CC_SEL_REFN_YNLR (0x1 << CC_SEL_REFN_SHIFT)

#define CC_SEL_REFN_AGND (0x2 << CC_SEL_REFN_SHIFT)

#define CC_SEL_REFN_MASK (0x3 << CC_SEL_REFN_SHIFT)

#define CC_SELIN_SHIFT 4

#define CC_SELIN_XPUL (0x0 << CC_SELIN_SHIFT)

#define CC_SELIN_YPLL (0x1 << CC_SELIN_SHIFT)

#define CC_SELIN_XNUR (0x2 << CC_SELIN_SHIFT)

#define CC_SELIN_YNLR (0x3 << CC_SELIN_SHIFT)

#define CC_SELIN_WIPER (0x4 << CC_SELIN_SHIFT)

#define CC_SELIN_INAUX0 (0x5 << CC_SELIN_SHIFT)

#define CC_SELIN_INAUX1 (0x6 << CC_SELIN_SHIFT)

#define CC_SELIN_INAUX2 (0x7 << CC_SELIN_SHIFT)

#define CC_SELIN_MASK (0x7 << CC_SELIN_SHIFT)

#define CC_SELREFP_SHIFT 7

#define CC_SELREFP_YPLL (0x0 << CC_SELREFP_SHIFT)

#define CC_SELREFP_XPUL (0x1 << CC_SELREFP_SHIFT)

#define CC_SELREFP_EXT (0x2 << CC_SELREFP_SHIFT)

#define CC_SELREFP_INT (0x3 << CC_SELREFP_SHIFT)

#define CC_SELREFP_MASK (0x3 << CC_SELREFP_SHIFT)

#define CC_XPULSW (1 << 9)

#define CC_XNURSW_SHIFT 10

#define CC_XNURSW_HIGH (0x0 << CC_XNURSW_SHIFT)

#define CC_XNURSW_OFF (0x1 << CC_XNURSW_SHIFT)

#define CC_XNURSW_LOW (0x3 << CC_XNURSW_SHIFT)

#define CC_XNURSW_MASK (0x3 << CC_XNURSW_SHIFT)

#define CC_YPLLSW_SHIFT 12

#define CC_YPLLSW_MASK (0x3 << CC_YPLLSW_SHIFT)

#define CC_YNLRSW (1 << 14)

#define CC_WIPERSW (1 << 15)

#define CC_NOS_SHIFT 16

#define CC_YPLLSW_HIGH (0x0 << CC_NOS_SHIFT)

#define CC_YPLLSW_OFF (0x1 << CC_NOS_SHIFT)

#define CC_YPLLSW_LOW (0x3 << CC_NOS_SHIFT)

#define CC_NOS_MASK (0xf << CC_NOS_SHIFT)

#define CC_IGS (1 << 20)

#define CC_SETTLING_TIME_SHIFT 24

#define CC_SETTLING_TIME_MASK (0xff <<CC_SETTLING_TIME_SHIFT)

#define TSC_4WIRE_PRECHARGE 0x158c

#define TSC_4WIRE_TOUCH_DETECT 0x578e

#define TSC_4WIRE_X_MEASUMENT 0x1c90

#define TSC_4WIRE_Y_MEASUMENT 0x4604

#define TSC_GENERAL_ADC_GCC0 0x17dc

#define TSC_GENERAL_ADC_GCC1 0x17ec

#define TSC_GENERAL_ADC_GCC2 0x17fc

/* GeneralADC Convert Queue FIFO Register */

#define GCQFIFO 0x800

#define GCQFIFO_ADCOUT_SHIFT 4

#define GCQFIFO_ADCOUT_MASK (0xfff << GCQFIFO_ADCOUT_SHIFT)

/* GeneralADC Convert Queue Control Register */

#define GCQCR 0x804

/* GeneralADC Convert Queue Status Register */

#define GCQSR 0x808

/* GeneralADC Convert Queue Mask Register */

#define GCQMR 0x80c

/* GeneralADC Convert Queue ITEM 7~0 */

#define GCQ_ITEM_7_0 0x820

/* GeneralADC Convert Queue ITEM 15~8 */

#define GCQ_ITEM_15_8 0x824

#define GCQ_ITEM7_SHIFT 28

#define GCQ_ITEM6_SHIFT 24

#define GCQ_ITEM5_SHIFT 20

#define GCQ_ITEM4_SHIFT 16

#define GCQ_ITEM3_SHIFT 12

#define GCQ_ITEM2_SHIFT 8

#define GCQ_ITEM1_SHIFT 4

#define GCQ_ITEM0_SHIFT 0

#define GCQ_ITEM_GCC0 0x0

#define GCQ_ITEM_GCC1 0x1

#define GCQ_ITEM_GCC2 0x2

#define GCQ_ITEM_GCC3 0x3

/* GeneralADC Convert Config 0-7 */

#define GCC0 0x840

#define GCC1 0x844

#define GCC2 0x848

#define GCC3 0x84c

#define GCC4 0x850

#define GCC5 0x854

#define GCC6 0x858

#define GCC7 0x85c

/* TSC Test Register R/W */

#define TTR 0xc00

/* TSC Monitor Register 1, 2 */

#define MNT1 0xc04

#define MNT2 0xc04

#define DETECT_ITEM_ID_1 1

#define DETECT_ITEM_ID_2 5

#define TS_X_ITEM_ID 2

#define TS_Y_ITEM_ID 3

#define TSI_DATA 1

#define FQS_DATA 0

#endif /* __IMX_ADC_H__*/

上面的常数及寄存器offset定义都没什么，如果不明白的话，好好看看芯片手册里的寄存器说明就可以了。

下面就是真正的驱动实现文件，精华都在这里面呢！

/*!

* @fileadc/imx_adc.c

* @briefThis is the main file of i.MX ADC driver.

* @ingroupIMX_ADC

* Includes

#include <linux/slab.h>

#include <linux/clk.h>

#include <linux/delay.h>

#include <linux/device.h>

#include <linux/interrupt.h>

#include <linux/io.h>

#include <linux/platform_device.h>

#include <linux/poll.h>

#include <linux/sched.h>

#include <linux/time.h>

#include <linux/wait.h>

#include <linux/imx_adc.h>

#include "imx_adc_reg.h"

static int imx_adc_major;

/*!

* Number ofusers waiting in suspendq

static int swait;

/*!

* Toindicate whether any of the adc devices are suspending

static int suspend_flag;

/*!

* Thesuspendq is used by blocking application calls

static wait_queue_head_t suspendq;

static wait_queue_head_t tsq;

static bool imx_adc_ready;

static bool ts_data_ready;

static int tsi_data = TSI_DATA;

static unsigned short ts_data_buf[16];

static struct class *imx_adc_class;

static struct imx_adc_data *adc_data;

static DECLARE_MUTEX(general_convert_mutex); 声明2个互斥锁

static DECLARE_MUTEX(ts_convert_mutex);

unsigned long tsc_base;

int is_imx_adc_ready(void)

{

returnimx_adc_ready;

}

EXPORT_SYMBOL(is_imx_adc_ready);

void tsc_clk_enable(void) 使能时钟，说白了就是读写寄存器

{

unsignedlong reg;

clk_enable(adc_data->adc_clk);

reg =__raw_readl(tsc_base + TGCR);

reg |=TGCR_IPG_CLK_EN;

__raw_writel(reg,tsc_base + TGCR);

}

void tsc_clk_disable(void) 禁止时钟，说白了就是读写寄存器

{

unsignedlong reg;

clk_disable(adc_data->adc_clk);

reg =__raw_readl(tsc_base + TGCR);

reg&= ~TGCR_IPG_CLK_EN;

__raw_writel(reg,tsc_base + TGCR);

}

void tsc_self_reset(void)

{

unsignedlong reg;

reg =__raw_readl(tsc_base + TGCR);

reg |=TGCR_TSC_RST;

__raw_writel(reg,tsc_base + TGCR);

while(__raw_readl(tsc_base + TGCR) & TGCR_TSC_RST)

continue;

}

/* Internal reference */

void tsc_intref_enable(void)

{

unsignedlong reg;

reg =__raw_readl(tsc_base + TGCR);

reg |=TGCR_INTREFEN;

__raw_writel(reg,tsc_base + TGCR);

}

/* initialize touchscreen */

void imx_tsc_init(void)

{

unsignedlong reg;

intlastitemid;

/* Levelsense */

reg =__raw_readl(tsc_base + TCQCR);

reg&= ~CQCR_PD_CFG; /* edge sensitive*/

reg |=(0xf << CQCR_FIFOWATERMARK_SHIFT); /* watermark */

__raw_writel(reg,tsc_base + TCQCR);

/*Configure 4-wire */

reg = TSC_4WIRE_PRECHARGE;

reg |=CC_IGS;

__raw_writel(reg,tsc_base + TCC0);

reg =TSC_4WIRE_TOUCH_DETECT;

reg |= 3<< CC_NOS_SHIFT; /* 4 samples */

reg |= 32<< CC_SETTLING_TIME_SHIFT; /* it'simportant! */

__raw_writel(reg,tsc_base + TCC1);

reg = TSC_4WIRE_X_MEASUMENT;

reg |= 3<< CC_NOS_SHIFT; /* 4 samples */

reg |= 16<< CC_SETTLING_TIME_SHIFT; /*settling time */

__raw_writel(reg,tsc_base + TCC2);

reg =TSC_4WIRE_Y_MEASUMENT;

reg |= 3<< CC_NOS_SHIFT; /* 4 samples */

reg |= 16<< CC_SETTLING_TIME_SHIFT; /*settling time */

__raw_writel(reg,tsc_base + TCC3);

reg =(TCQ_ITEM_TCC0 << TCQ_ITEM7_SHIFT) |

(TCQ_ITEM_TCC0 << TCQ_ITEM6_SHIFT)|

(TCQ_ITEM_TCC1 << TCQ_ITEM5_SHIFT)|

(TCQ_ITEM_TCC0 << TCQ_ITEM4_SHIFT)|

(TCQ_ITEM_TCC3 << TCQ_ITEM3_SHIFT)|

(TCQ_ITEM_TCC2 << TCQ_ITEM2_SHIFT)|

(TCQ_ITEM_TCC1 << TCQ_ITEM1_SHIFT)|

(TCQ_ITEM_TCC0 << TCQ_ITEM0_SHIFT);

__raw_writel(reg,tsc_base + TCQ_ITEM_7_0);

lastitemid= 5;

reg =__raw_readl(tsc_base + TCQCR);

reg =(reg & ~CQCR_LAST_ITEM_ID_MASK) |

(lastitemid <<CQCR_LAST_ITEM_ID_SHIFT);

__raw_writel(reg,tsc_base + TCQCR);

/* Configidle for 4-wire */

reg =TSC_4WIRE_PRECHARGE;

__raw_writel(reg,tsc_base + TICR);

reg =TSC_4WIRE_TOUCH_DETECT;

__raw_writel(reg,tsc_base + TICR);

/* pendown mask */

reg =__raw_readl(tsc_base + TCQCR);

reg&= ~CQCR_PD_MSK;

__raw_writel(reg,tsc_base + TCQCR);

reg =__raw_readl(tsc_base + TCQMR);

reg&= ~TCQMR_PD_IRQ_MSK;

__raw_writel(reg,tsc_base + TCQMR);

/*Debounce time = dbtime*8 adc clock cycles */

reg =__raw_readl(tsc_base + TGCR);

reg&= ~TGCR_PDBTIME_MASK;

reg |=TGCR_PDBTIME128 | TGCR_HSYNC_EN;

__raw_writel(reg,tsc_base + TGCR);

/* pendown enable */

reg =__raw_readl(tsc_base + TGCR);

reg |=TGCR_PDB_EN;

__raw_writel(reg,tsc_base + TGCR);

reg |=TGCR_PD_EN;

__raw_writel(reg,tsc_base + TGCR);

}

static irqreturn_t imx_adc_interrupt(int irq, void*dev_id)

{

unsignedlong reg;

if(__raw_readl(tsc_base + TGSR) & 0x4) {

/*deep sleep wakeup interrupt */

/*clear tgsr */

__raw_writel(0, tsc_base + TGSR);

/*clear deep sleep wakeup irq */

reg =__raw_readl(tsc_base + TGCR);

reg&= ~TGCR_SLPC;

__raw_writel(reg,tsc_base + TGCR);

/*un-mask pen down and pen down irq */

reg =__raw_readl(tsc_base + TCQCR);

reg&= ~CQCR_PD_MSK;

__raw_writel(reg,tsc_base + TCQCR);

reg =__raw_readl(tsc_base + TCQMR);

reg&= ~TCQMR_PD_IRQ_MSK;

__raw_writel(reg,tsc_base + TCQMR);

} else if((__raw_readl(tsc_base + TGSR) & 0x1) &&

(__raw_readl(tsc_base + TCQSR) & 0x1)) {

/*mask pen down detect irq */

reg =__raw_readl(tsc_base + TCQMR);

reg |=TCQMR_PD_IRQ_MSK;

__raw_writel(reg,tsc_base + TCQMR);

ts_data_ready= 1;

wake_up_interruptible(&tsq);

}

returnIRQ_HANDLED;

}

enum IMX_ADC_STATUS imx_adc_read_general(unsignedshort *result)

{

unsignedlong reg;

unsignedint data_num = 0;

reg =__raw_readl(tsc_base + GCQCR);

reg |=CQCR_FQS;

__raw_writel(reg,tsc_base + GCQCR);

while(!(__raw_readl(tsc_base + GCQSR) & CQSR_EOQ))

continue;

reg =__raw_readl(tsc_base + GCQCR);

reg&= ~CQCR_FQS;

__raw_writel(reg,tsc_base + GCQCR);

reg =__raw_readl(tsc_base + GCQSR);

reg |=CQSR_EOQ;

__raw_writel(reg,tsc_base + GCQSR);

while(!(__raw_readl(tsc_base + GCQSR) & CQSR_EMPT)) {

result[data_num]= __raw_readl(tsc_base + GCQFIFO) >>

GCQFIFO_ADCOUT_SHIFT;

data_num++;

}

returnIMX_ADC_SUCCESS;

}

/*!

* Thisfunction will get raw (X,Y) value by converting the voltage

*@param touch_sample Pointer totouch sample

*return This funciton returns 0 ifsuccessful.

enum IMX_ADC_STATUS imx_adc_read_ts(structt_touch_screen *touch_sample,

int wait_tsi)

{

unsignedlong reg;

intdata_num = 0;

intdetect_sample1, detect_sample2;

memset(ts_data_buf,0, sizeof ts_data_buf);

touch_sample->valid_flag= 1;

if(wait_tsi) {

/*Config idle for 4-wire */

reg =TSC_4WIRE_TOUCH_DETECT;

__raw_writel(reg,tsc_base + TICR);

/* Peninterrupt starts new conversion queue */

reg =__raw_readl(tsc_base + TCQCR);

reg&= ~CQCR_QSM_MASK;

reg |=CQCR_QSM_PEN;

__raw_writel(reg,tsc_base + TCQCR);

/*unmask pen down detect irq */

reg =__raw_readl(tsc_base + TCQMR);

reg&= ~TCQMR_PD_IRQ_MSK;

__raw_writel(reg,tsc_base + TCQMR);

wait_event_interruptible(tsq,ts_data_ready);

while(!(__raw_readl(tsc_base + TCQSR) & CQSR_EOQ))

continue;

/*stop the conversion */

reg =__raw_readl(tsc_base + TCQCR);

reg&= ~CQCR_QSM_MASK;

__raw_writel(reg,tsc_base + TCQCR);

reg =CQSR_PD | CQSR_EOQ;

__raw_writel(reg,tsc_base + TCQSR);

/*change configuration for FQS mode */

tsi_data= TSI_DATA;

reg =(0x1 << CC_YPLLSW_SHIFT) | (0x1 << CC_XNURSW_SHIFT) |

CC_XPULSW;

__raw_writel(reg,tsc_base + TICR);

} else {

/* FQSsemaphore */

down(&ts_convert_mutex);

reg =(0x1 << CC_YPLLSW_SHIFT) | (0x1 << CC_XNURSW_SHIFT) |

CC_XPULSW;

__raw_writel(reg,tsc_base + TICR);

/* FQS*/

reg =__raw_readl(tsc_base + TCQCR);

reg&= ~CQCR_QSM_MASK;

reg |=CQCR_QSM_FQS;

__raw_writel(reg,tsc_base + TCQCR);

reg =__raw_readl(tsc_base + TCQCR);

reg |=CQCR_FQS;

__raw_writel(reg,tsc_base + TCQCR);

while(!(__raw_readl(tsc_base + TCQSR) & CQSR_EOQ))

continue;

/*stop FQS */

reg =__raw_readl(tsc_base + TCQCR);

reg&= ~CQCR_QSM_MASK;

__raw_writel(reg,tsc_base + TCQCR);

reg =__raw_readl(tsc_base + TCQCR);

reg&= ~CQCR_FQS;

__raw_writel(reg,tsc_base + TCQCR);

/*clear status bit */

reg =__raw_readl(tsc_base + TCQSR);

reg |=CQSR_EOQ;

__raw_writel(reg,tsc_base + TCQSR);

tsi_data= FQS_DATA;

/*Config idle for 4-wire */

reg =TSC_4WIRE_PRECHARGE;

__raw_writel(reg,tsc_base + TICR);

reg =TSC_4WIRE_TOUCH_DETECT;

__raw_writel(reg,tsc_base + TICR);

}

while(!(__raw_readl(tsc_base + TCQSR) & CQSR_EMPT)) {

reg =__raw_readl(tsc_base + TCQFIFO);

ts_data_buf[data_num]= reg;

data_num++;

}

touch_sample->x_position1= ts_data_buf[4] >> 4;

touch_sample->x_position2= ts_data_buf[5] >> 4;

touch_sample->x_position3= ts_data_buf[6] >> 4;

touch_sample->y_position1= ts_data_buf[9] >> 4;

touch_sample->y_position2= ts_data_buf[10] >> 4;

touch_sample->y_position3= ts_data_buf[11] >> 4;

detect_sample1= ts_data_buf[0];

detect_sample2= ts_data_buf[12];

if((detect_sample1 > 0x6000) || (detect_sample2 > 0x6000))

touch_sample->valid_flag= 0;

ts_data_ready= 0;

if(!(touch_sample->x_position1 ||

touch_sample->x_position2 ||touch_sample->x_position3))

touch_sample->contact_resistance= 0;

else

touch_sample->contact_resistance= 1;

if(tsi_data == FQS_DATA)

up(&ts_convert_mutex);

returnIMX_ADC_SUCCESS;

}

/*!

* Thisfunction performs filtering and rejection of excessive noise prone

* sampl.

*@param ts_curr Touch screen value

*@return This function returns 0 onsuccess, -1 otherwise.

static int imx_adc_filter(struct t_touch_screen*ts_curr)

{

unsignedint ydiff1, ydiff2, ydiff3, xdiff1, xdiff2, xdiff3;

unsignedint sample_sumx, sample_sumy;

staticunsigned int prev_x[FILTLEN], prev_y[FILTLEN];

int index= 0;

unsignedint y_curr, x_curr;

staticint filt_count;

/* Addeda variable filt_type to decide filtering at run-time */

unsignedint filt_type = 0;

/* ignorethe data converted when pen down and up */

if((ts_curr->contact_resistance == 0) || tsi_data == TSI_DATA) {

ts_curr->x_position= 0;

ts_curr->y_position= 0;

filt_count= 0;

return0;

}

/* ignorethe data valid */

if(ts_curr->valid_flag == 0)

return-1;

ydiff1 =abs(ts_curr->y_position1 - ts_curr->y_position2);

ydiff2 =abs(ts_curr->y_position2 - ts_curr->y_position3);

ydiff3 =abs(ts_curr->y_position1 - ts_curr->y_position3);

if((ydiff1 > DELTA_Y_MAX) ||

(ydiff2 > DELTA_Y_MAX) || (ydiff3 >DELTA_Y_MAX)) {

pr_debug("imx_adc_filter:Ret pos 1\n");

return-1;

}

xdiff1 =abs(ts_curr->x_position1 - ts_curr->x_position2);

xdiff2 =abs(ts_curr->x_position2 - ts_curr->x_position3);

xdiff3 =abs(ts_curr->x_position1 - ts_curr->x_position3);

if ((xdiff1> DELTA_X_MAX) ||

(xdiff2 > DELTA_X_MAX) || (xdiff3 >DELTA_X_MAX)) {

pr_debug("imx_adc_filter:Ret pos 2\n");

return-1;

}

/*Compute two closer values among the three available Y readouts */

if(ydiff1 < ydiff2) {

if(ydiff1 < ydiff3) {

/*Sample 0 & 1 closest together */

sample_sumy= ts_curr->y_position1 +

ts_curr->y_position2;

} else{

/*Sample 0 & 2 closest together */

sample_sumy= ts_curr->y_position1 +

ts_curr->y_position3;

}

} else {

if(ydiff2 < ydiff3) {

/*Sample 1 & 2 closest together */

sample_sumy= ts_curr->y_position2 +

ts_curr->y_position3;

} else{

/*Sample 0 & 2 closest together */

sample_sumy= ts_curr->y_position1 +

ts_curr->y_position3;

}

* Compute two closer values among the threeavailable X

* readouts

if(xdiff1 < xdiff2) {

if(xdiff1 < xdiff3) {

/*Sample 0 & 1 closest together */

sample_sumx= ts_curr->x_position1 +

ts_curr->x_position2;

} else{

/*Sample 0 & 2 closest together */

sample_sumx= ts_curr->x_position1 +

ts_curr->x_position3;

}

} else {

if(xdiff2 < xdiff3) {

/*Sample 1 & 2 closest together */

sample_sumx= ts_curr->x_position2 +

ts_curr->x_position3;

} else{

/*Sample 0 & 2 closest together */

sample_sumx= ts_curr->x_position1 +

ts_curr->x_position3;

}

* Wait FILTER_MIN_DELAY number of samples torestart

* filtering

if(filt_count < FILTER_MIN_DELAY) {

* Current output is the average of the twocloser

* values and no filtering is used

y_curr= (sample_sumy / 2);

x_curr= (sample_sumx / 2);

ts_curr->y_position= y_curr;

ts_curr->x_position= x_curr;

filt_count++;

} else {

if(abs(sample_sumx - (prev_x[0] + prev_x[1])) >

(DELTA_X_MAX * 16)) {

pr_debug("imx_adc_filter:: Ret pos 3\n");

return-1;

}

if(abs(sample_sumy - (prev_y[0] + prev_y[1])) >

(DELTA_Y_MAX * 16)) {

pr_debug("imx_adc_filter:: Ret pos 4\n");

return-1;

}

sample_sumy/= 2;

sample_sumx/= 2;

/* Usehard filtering if the sample difference < 10 */

if((abs(sample_sumy - prev_y[0]) > 10) ||

(abs(sample_sumx - prev_x[0]) > 10))

filt_type= 1;

* Current outputs are the average of three previous

* values and the present readout

y_curr= sample_sumy;

for(index = 0; index < FILTLEN; index++) {

if(filt_type == 0)

y_curr= y_curr + (prev_y[index]);

else

y_curr= y_curr + (prev_y[index] / 3);

}

if(filt_type == 0)

y_curr= y_curr >> 2;

else

y_curr= y_curr >> 1;

ts_curr->y_position= y_curr;

x_curr= sample_sumx;

for(index = 0; index < FILTLEN; index++) {

if(filt_type == 0)

x_curr= x_curr + (prev_x[index]);

else

x_curr= x_curr + (prev_x[index] / 3);

}

if(filt_type == 0)

x_curr= x_curr >> 2;

else

x_curr= x_curr >> 1;

ts_curr->x_position= x_curr;

}

/* Updateprevious X and Y values */

for(index = (FILTLEN - 1); index > 0; index--) {

prev_x[index]= prev_x[index - 1];

prev_y[index]= prev_y[index - 1];

}

* Current output will be the most recent pastfor the

* next sample

prev_y[0]= y_curr;

prev_x[0]= x_curr;

return 0;

}

/*!

* Thisfunction retrieves the current touch screen (X,Y) coordinates.

*@param touch_sample Pointer totouch sample.

*@return This function returnsIMX_ADC_SUCCESS if successful.

enum IMX_ADC_STATUSimx_adc_get_touch_sample(struct t_touch_screen

*touch_sample, int wait_tsi)

{

if (imx_adc_read_ts(touch_sample,wait_tsi))

returnIMX_ADC_ERROR;

if(!imx_adc_filter(touch_sample))

returnIMX_ADC_SUCCESS;

else

returnIMX_ADC_ERROR;

}

EXPORT_SYMBOL(imx_adc_get_touch_sample);

void imx_adc_set_hsync(int on)

{

unsignedlong reg;

if(imx_adc_ready) {

reg =__raw_readl(tsc_base + TGCR);

if(on)

reg|= TGCR_HSYNC_EN;

else

reg&= ~TGCR_HSYNC_EN;

__raw_writel(reg,tsc_base + TGCR);

}

EXPORT_SYMBOL(imx_adc_set_hsync);

/*!

* This isthe suspend of power management for the i.MX ADC API.

* Itsupports SAVE and POWER_DOWN state.

*@param pdev the device

*@param state the state

*@return This function returns 0 ifsuccessful.

static int imx_adc_suspend(struct platform_device*pdev, pm_message_t state)

{

unsignedlong reg;

/* Configidle for 4-wire */

reg =TSC_4WIRE_PRECHARGE;

__raw_writel(reg,tsc_base + TICR);

reg =TSC_4WIRE_TOUCH_DETECT;

__raw_writel(reg,tsc_base + TICR);

/* enabledeep sleep wake up */

reg =__raw_readl(tsc_base + TGCR);

reg |=TGCR_SLPC;

__raw_writel(reg,tsc_base + TGCR);

/* maskpen down and pen down irq */

reg =__raw_readl(tsc_base + TCQCR);

reg |=CQCR_PD_MSK;

__raw_writel(reg,tsc_base + TCQCR);

reg =__raw_readl(tsc_base + TCQMR);

reg |=TCQMR_PD_IRQ_MSK;

__raw_writel(reg,tsc_base + TCQMR);

/* Setpower mode to off */

reg =__raw_readl(tsc_base + TGCR) & ~TGCR_POWER_MASK;

reg |=TGCR_POWER_OFF;

__raw_writel(reg,tsc_base + TGCR);

if(device_may_wakeup(&pdev->dev)) {

enable_irq_wake(adc_data->irq);

} else {

suspend_flag= 1;

tsc_clk_disable();

}

return 0;

};

/*!

* This isthe resume of power management for the i.MX adc API.

* Itsupports RESTORE state.

*@param pdev the device

* @return This function returns 0 if successful.

static int imx_adc_resume(struct platform_device*pdev) 从休眠状态唤醒

{

unsignedlong reg;

if(device_may_wakeup(&pdev->dev)) {

disable_irq_wake(adc_data->irq);

} else {

suspend_flag= 0;

tsc_clk_enable();

while(swait > 0) {

swait--;

wake_up_interruptible(&suspendq);

}

/*recover power mode */

reg =__raw_readl(tsc_base + TGCR) & ~TGCR_POWER_MASK;

reg |=TGCR_POWER_SAVE;

__raw_writel(reg,tsc_base + TGCR);

return 0;

}

/*!

* Thisfunction implements the open method on an i.MX ADC device.

*@param inode pointer on the node

*@param file pointer on the file

*@return This function returns 0.

static int imx_adc_open(struct inode *inode, structfile *file)

{

while(suspend_flag) {

swait++;

/*Block if the device is suspended */

if(wait_event_interruptible(suspendq, !suspend_flag))

return-ERESTARTSYS;

}

pr_debug("imx_adc: imx_adc_open()\n");

return 0;

}

/*!

* Thisfunction implements the release method on an i.MX ADC device.

*@param inode pointer on the node

*@param file pointer on the file

*@return This function returns 0.

static int imx_adc_free(struct inode *inode,struct file *file)

{

pr_debug("imx_adc: imx_adc_free()\n");

return 0;

}

/*!

* Thisfunction initializes all ADC registers with default values. This

* functionalso registers the interrupt events.

*@return This function returnsIMX_ADC_SUCCESS if successful.

int imx_adc_init(void)

{

unsignedlong reg;

pr_debug("imx_adc_init()\n");

if(suspend_flag)

return-EBUSY;

tsc_clk_enable();

/* Reset*/

tsc_self_reset();

/*Internal reference */

tsc_intref_enable();

/* Setpower mode */

reg = __raw_readl(tsc_base+ TGCR) & ~TGCR_POWER_MASK;这里又是操作寄存器，读取->修改->写回

reg |=TGCR_POWER_SAVE;

__raw_writel(reg,tsc_base + TGCR);

imx_tsc_init();

returnIMX_ADC_SUCCESS;

}

EXPORT_SYMBOL(imx_adc_init);

/*!

* Thisfunction disables the ADC, de-registers the interrupt events.

*@return This function returnsIMX_ADC_SUCCESS if successful.

enum IMX_ADC_STATUS imx_adc_deinit(void)

{

pr_debug("imx_adc_deinit()\n");

returnIMX_ADC_SUCCESS;

}

EXPORT_SYMBOL(imx_adc_deinit);

/*!

* Thisfunction triggers a conversion and returns one sampling result of one

* channel.

*@param channel The channel to be sampled

*@param result The pointer to the conversion result. Thememory

* should be allocated bythe caller of this function.

*@return This function returnsIMX_ADC_SUCCESS if successful.

这个函数就是AD采样函数，说白了就是操作ADC的寄存器。

enum IMX_ADC_STATUS imx_adc_convert(enum t_channelchannel,

unsigned short *result)

{

unsignedlong reg;

int lastitemid;

structt_touch_screen touch_sample;

switch(channel) {

case TS_X_POS:

imx_adc_get_touch_sample(&touch_sample,0);

result[0]= touch_sample.x_position;

/* ifno pen down ,recover the register configuration */

if(touch_sample.contact_resistance == 0) {

reg= __raw_readl(tsc_base + TCQCR);

reg&= ~CQCR_QSM_MASK;

reg|= CQCR_QSM_PEN;

__raw_writel(reg,tsc_base + TCQCR);

reg= __raw_readl(tsc_base + TCQMR); 这里对寄存器的操作：读取->修改->写回

reg&= ~TCQMR_PD_IRQ_MSK;

__raw_writel(reg,tsc_base + TCQMR);

}

break;

case TS_Y_POS:

imx_adc_get_touch_sample(&touch_sample,0);

result[1]= touch_sample.y_position;

/* ifno pen down ,recover the register configuration */

if(touch_sample.contact_resistance == 0) {

reg= __raw_readl(tsc_base + TCQCR);

reg&= ~CQCR_QSM_MASK;

reg|= CQCR_QSM_PEN;

__raw_writel(reg,tsc_base + TCQCR);

reg= __raw_readl(tsc_base + TCQMR);

reg&= ~TCQMR_PD_IRQ_MSK;

__raw_writel(reg, tsc_base + TCQMR);

}

break;

case GER_PURPOSE_ADC0:

down(&general_convert_mutex);加锁

lastitemid= 0;

reg =(0xf << CQCR_FIFOWATERMARK_SHIFT) |

(lastitemid <<CQCR_LAST_ITEM_ID_SHIFT) | CQCR_QSM_FQS;

__raw_writel(reg,tsc_base + GCQCR);

reg =TSC_GENERAL_ADC_GCC0;

reg |=(3 << CC_NOS_SHIFT) | (16 << CC_SETTLING_TIME_SHIFT);

__raw_writel(reg,tsc_base + GCC0);写寄存器

imx_adc_read_general(result);读取结果

up(&general_convert_mutex);解锁

break;

case GER_PURPOSE_ADC1:

down(&general_convert_mutex);

lastitemid= 0;

reg =(0xf << CQCR_FIFOWATERMARK_SHIFT) |

(lastitemid <<CQCR_LAST_ITEM_ID_SHIFT) | CQCR_QSM_FQS;

__raw_writel(reg,tsc_base + GCQCR);

reg =TSC_GENERAL_ADC_GCC1;

reg |=(3 << CC_NOS_SHIFT) | (16 << CC_SETTLING_TIME_SHIFT);

__raw_writel(reg,tsc_base + GCC0);

imx_adc_read_general(result);

up(&general_convert_mutex);

break;

case GER_PURPOSE_ADC2:

down(&general_convert_mutex);

lastitemid= 0;

reg =(0xf << CQCR_FIFOWATERMARK_SHIFT) |

(lastitemid <<CQCR_LAST_ITEM_ID_SHIFT) | CQCR_QSM_FQS;

__raw_writel(reg,tsc_base + GCQCR);

reg =TSC_GENERAL_ADC_GCC2;

reg |=(3 << CC_NOS_SHIFT) | (16 << CC_SETTLING_TIME_SHIFT);

__raw_writel(reg,tsc_base + GCC0);

imx_adc_read_general(result);

up(&general_convert_mutex);

break;

caseGER_PURPOSE_MULTICHNNEL:

down(&general_convert_mutex);

reg =TSC_GENERAL_ADC_GCC0;

reg |=(3 << CC_NOS_SHIFT) | (16 << CC_SETTLING_TIME_SHIFT);

__raw_writel(reg,tsc_base + GCC0);

reg =TSC_GENERAL_ADC_GCC1;

reg |=(3 << CC_NOS_SHIFT) | (16 << CC_SETTLING_TIME_SHIFT);

__raw_writel(reg,tsc_base + GCC1);

reg =TSC_GENERAL_ADC_GCC2;

reg |=(3 << CC_NOS_SHIFT) | (16 << CC_SETTLING_TIME_SHIFT);

__raw_writel(reg,tsc_base + GCC2);

reg =(GCQ_ITEM_GCC2 << GCQ_ITEM2_SHIFT) |

(GCQ_ITEM_GCC1 << GCQ_ITEM1_SHIFT)|

(GCQ_ITEM_GCC0 << GCQ_ITEM0_SHIFT);

__raw_writel(reg,tsc_base + GCQ_ITEM_7_0);

lastitemid= 2;

reg =(0xf << CQCR_FIFOWATERMARK_SHIFT) |

(lastitemid <<CQCR_LAST_ITEM_ID_SHIFT) | CQCR_QSM_FQS;

__raw_writel(reg,tsc_base + GCQCR);

imx_adc_read_general(result);

up(&general_convert_mutex);

break;

default:

pr_debug("%s:bad channel number\n", __func__);

returnIMX_ADC_ERROR;

}

returnIMX_ADC_SUCCESS;

}

EXPORT_SYMBOL(imx_adc_convert);

/*!

* Thisfunction triggers a conversion and returns sampling results of each

* specifiedchannel.

*@param channels This input parameter is bitmap to specifychannels

* to be sampled.

*@param result The pointer to array to store samplingresults.

* The memory should beallocated by the caller of this

* function.

*@return This function returnsIMX_ADC_SUCCESS if successful.

这可是枚举类型啊！C也支持？

enumIMX_ADC_STATUS imx_adc_convert_multichnnel(enum t_channel channels,

unsignedshort *result)

{

imx_adc_convert(GER_PURPOSE_MULTICHNNEL,result);

returnIMX_ADC_SUCCESS;

}

EXPORT_SYMBOL(imx_adc_convert_multichnnel);

/*!

* Thisfunction implements IOCTL controls on an i.MX ADC device.

*@param inode pointer on the node

*@param file pointer on the file

*@param cmd the command 这里是命令，记得好像得用幻数或魔数来定义，这样防止与其他设备的命令冲突，发出错误的命令。

*@param arg the parameter 这里是命令的参数

*@return This function returns 0 ifsuccessful.

static int imx_adc_ioctl(struct inode *inode,struct file *file,

unsigned int cmd,unsigned long arg)

{

structt_adc_convert_param *convert_param;

if((_IOC_TYPE(cmd) != 'p') && (_IOC_TYPE(cmd) != 'D'))

return-ENOTTY;

while(suspend_flag) {

swait++;

/*Block if the device is suspended */

if(wait_event_interruptible(suspendq, !suspend_flag))

return-ERESTARTSYS;

}

switch(cmd) {

case IMX_ADC_INIT:

pr_debug("initadc\n");

CHECK_ERROR(imx_adc_init());

break;

case IMX_ADC_DEINIT:

pr_debug("deinitadc\n");

CHECK_ERROR(imx_adc_deinit());

break;

case IMX_ADC_CONVERT:

在内核空间中申请一块内存

convert_param= kmalloc(sizeof(*convert_param), GFP_KERNEL);

if(convert_param == NULL)

return-ENOMEM;

将用户空间请求结构体拷贝到内核空间的结构体中

if(copy_from_user(convert_param,

(struct t_adc_convert_param *)arg,

sizeof(*convert_param))) {

kfree(convert_param);

return-EFAULT;

}

按照用户空间传来的结构体中指定的通道进行AD转换并将结果保存在内核空间的结构体中

CHECK_ERROR_KFREE(imx_adc_convert(convert_param->channel,

convert_param->result),

(kfree(convert_param)));

再将内核空间的结构体数据拷贝到用户空间

if(copy_to_user((struct t_adc_convert_param *)arg,

convert_param, sizeof(*convert_param))) {

kfree(convert_param);

return-EFAULT;

}

kfree(convert_param);

break;

case IMX_ADC_CONVERT_MULTICHANNEL:多通道转换跟单通道采样差不多，唯一不同的是底层调用了多通路采样函数

convert_param= kmalloc(sizeof(*convert_param), GFP_KERNEL);

if(convert_param == NULL)

return-ENOMEM;

if(copy_from_user(convert_param,

(struct t_adc_convert_param *)arg,

sizeof(*convert_param))) {

kfree(convert_param);

return-EFAULT;

}

CHECK_ERROR_KFREE(imx_adc_convert_multichnnel

(convert_param->channel,

convert_param->result),

(kfree(convert_param)));

if(copy_to_user((struct t_adc_convert_param *)arg,

convert_param, sizeof(*convert_param))) {

kfree(convert_param);

return-EFAULT;

}

kfree(convert_param);

break;

default:

pr_debug("imx_adc_ioctl:unsupported ioctl command 0x%x\n",

cmd);

return-EINVAL;

}

return 0;

}

为了配合register_chrdev（）所以这里定义了文件操作结构

static struct file_operations imx_adc_fops = {

.owner =THIS_MODULE,

.ioctl =imx_adc_ioctl,

.open =imx_adc_open,

.release= imx_adc_free,

};

static int imx_adc_module_probe(structplatform_device *pdev)

{

int ret =0;

intretval;

structdevice *temp_class;

structresource *res;

void __iomem*base;

/*ioremap the base address */

res =platform_get_resource(pdev, IORESOURCE_MEM, 0);

if (res== NULL) {

dev_err(&pdev->dev,"No TSC base address provided\n");

gotoerr_out0;

}

物理地址到虚拟地址的映射，驱动程序不能直接访问物理地址，必须映射到驱动程序空间中的虚拟地址才能进行操作。

base =ioremap(res->start, res->end - res->start);

if (base== NULL) {

dev_err(&pdev->dev,"failed to rebase TSC base address\n");

gotoerr_out0;

}

tsc_base= (unsigned long)base;

注册字符型设备，设备号是内态动态分配的

/* createthe chrdev */

imx_adc_major= register_chrdev(0, "imx_adc", &imx_adc_fops);

if(imx_adc_major < 0) {

dev_err(&pdev->dev,"Unable to get a major for imx_adc\n");

returnimx_adc_major;

}

init_waitqueue_head(&suspendq);

init_waitqueue_head(&tsq);

动态创建设备文件，这里会自动创建/dev/imx_adc，udev机制的好处是不需要手工mknod

imx_adc_class = class_create(THIS_MODULE,"imx_adc");

if(IS_ERR(imx_adc_class)) {

dev_err(&pdev->dev,"Error creating imx_adc class.\n");

ret =PTR_ERR(imx_adc_class);

gotoerr_out1;

}

temp_class= device_create(imx_adc_class, NULL,

MKDEV(imx_adc_major, 0), NULL,"imx_adc");

if(IS_ERR(temp_class)) {

dev_err(&pdev->dev,"Error creating imx_adc class device.\n");

ret =PTR_ERR(temp_class);

gotoerr_out2;

}

动态分配内存

adc_data= kmalloc(sizeof(struct imx_adc_data), GFP_KERNEL);

if(adc_data == NULL)

return-ENOMEM;

adc_data->irq= platform_get_irq(pdev, 0);获取中断资源号

向内核请求中断并传给中断处理函数地址

retval =request_irq(adc_data->irq, imx_adc_interrupt,

0, MOD_NAME, MOD_NAME);

if(retval) {

returnretval;

}

adc_data->adc_clk= clk_get(&pdev->dev, "tchscrn_clk");

ret =imx_adc_init();

if (ret!= IMX_ADC_SUCCESS) {

dev_err(&pdev->dev,"Error in imx_adc_init.\n");

gotoerr_out4;

}

imx_adc_ready= 1;

/* Bydefault, devices should wakeup if they can */

/* SoTouchScreen is set as "should wakeup" as it can */

device_init_wakeup(&pdev->dev,1);

pr_info("i.MXADC at 0x%x irq %d\n", (unsigned int)res->start,

adc_data->irq);

returnret;

err_out4:

device_destroy(imx_adc_class,MKDEV(imx_adc_major, 0));

err_out2:

class_destroy(imx_adc_class);

err_out1:

unregister_chrdev(imx_adc_major,"imx_adc");

err_out0:

returnret;

}

static int imx_adc_module_remove(structplatform_device *pdev)

{

imx_adc_ready= 0;

imx_adc_deinit();

使用udev机制动态删除设备文件节点

device_destroy(imx_adc_class,MKDEV(imx_adc_major, 0));

class_destroy(imx_adc_class);

注销字符设备

unregister_chrdev(imx_adc_major,"imx_adc");

释放中断资源

free_irq(adc_data->irq,MOD_NAME);

kfree(adc_data);跟kmalloc相对应，动态释放内存

pr_debug("i.MXADC successfully removed\n");

return 0;

}

定义平台驱动platform_driver结构体，作为平台设备驱动必须要定义这个！

static struct platform_driver imx_adc_driver = {

.driver ={

.name = "imx_adc",此处的名字必须要跟平台设备的名字一样，否则匹配不上！

.suspend= imx_adc_suspend,

.resume =imx_adc_resume,

.probe =imx_adc_module_probe, 相当于初始化的时候会自动调用这个函数

.remove =imx_adc_module_remove,

};

*Initialization and Exit

static int __init imx_adc_module_init(void)

{

pr_debug("i.MXADC driver loading...\n");

returnplatform_driver_register(&imx_adc_driver);注册平台驱动

}

static void __exit imx_adc_module_exit(void)

{

platform_driver_unregister(&imx_adc_driver);注销平台驱动

pr_debug("i.MXADC driver successfully unloaded\n");

}

* Moduleentry points

这里好奇怪噢。我记得2.6内核好像已经不再这样定义了？？？

module_init(imx_adc_module_init);

module_exit(imx_adc_module_exit);

MODULE_DESCRIPTION("i.MX ADC devicedriver");

MODULE_AUTHOR("Freescale Semiconductor,Inc.");

MODULE_LICENSE("GPL");

驱动中老爱调用一些函数，其实这些函数的实现也是比较简单的，为什么要这样做呢？搞不明白。这样使人脑袋都大了。唉。下面就是我列举的一些，大伙看看吧：

#define __raw_readl(p) (*(unsigned long *)(p))

#define __raw_writel(v,p) (*(unsigned long *)(p) = (v))

我觉得加上volatile会更好一些，可以引用的不是这个文件吧。当然，别的文件也有实现，说真的，我也不知道驱动引用的是哪个文件的。

define __raw_writel(v,a) (__chk_io_ptr(a),*(volatile unsigned int __force *)(a) = (v))

为了使驱动程序加进内核，还得考虑该文件夹上一目录的Kconfig和Makefile，因为内核是一级一级的找文件的。

# drivers/video/mxc/Kconfig

if ARCH_MXC

menu "MXC support drivers"

config MXC_IPU

bool"Image Processing Unit Driver"

dependson !ARCH_MX21

dependson !ARCH_MX27

dependson !ARCH_MX25

selectMXC_IPU_V1 if !ARCH_MX37 && !ARCH_MX5

selectMXC_IPU_V3 if ARCH_MX37 || ARCH_MX5

selectMXC_IPU_V3D if ARCH_MX37

selectMXC_IPU_V3EX if ARCH_MX5

help

If you plan to use the Image Processing unit,say

Y here. IPU is needed by Framebuffer and V4L2drivers.

source "drivers/mxc/ipu/Kconfig"

source "drivers/mxc/ipu3/Kconfig"

source "drivers/mxc/ssi/Kconfig"

source "drivers/mxc/dam/Kconfig"

source "drivers/mxc/pmic/Kconfig"

source "drivers/mxc/mcu_pmic/Kconfig"

source "drivers/mxc/security/Kconfig"

source "drivers/mxc/hmp4e/Kconfig"

source "drivers/mxc/hw_event/Kconfig"

source "drivers/mxc/vpu/Kconfig"

source "drivers/mxc/asrc/Kconfig"

source "drivers/mxc/bt/Kconfig"

source "drivers/mxc/gps_ioctrl/Kconfig"

source "drivers/mxc/mlb/Kconfig"

source"drivers/mxc/adc/Kconfig" 我们的ADC驱动在此

source "drivers/mxc/amd-gpu/Kconfig"

endmenu

endif

在看一下Makefile

obj-$(CONFIG_MXC_IPU_V1) += ipu/

obj-$(CONFIG_MXC_IPU_V3) += ipu3/

obj-$(CONFIG_MXC_SSI) +=ssi/

obj-$(CONFIG_MXC_DAM) +=dam/

obj-$(CONFIG_MXC_PMIC_MC9SDZ60) += mcu_pmic/

obj-$(CONFIG_MXC_PMIC) += pmic/

obj-$(CONFIG_MXC_HMP4E) +=hmp4e/

obj-y += security/

obj-$(CONFIG_MXC_VPU) += vpu/

obj-$(CONFIG_MXC_HWEVENT) += hw_event/

obj-$(CONFIG_MXC_ASRC) += asrc/

obj-$(CONFIG_MXC_BLUETOOTH) += bt/

obj-$(CONFIG_GPS_IOCTRL) += gps_ioctrl/

obj-$(CONFIG_MXC_MLB) += mlb/

obj-$(CONFIG_IMX_ADC) += adc/ 我们的ADC驱动在此

obj-$(CONFIG_MXC_AMD_GPU) +=amd-gpu/

以后我们自己增加驱动程序到内核的时候，完全可以参考这些做法。

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