linux-2.6.32在mini2440开发板上移植（9）之添加触摸屏驱动程序

在内核中添加触摸屏驱动程序

编者：linux2.6.32并没有带S3C2440触摸屏驱动程序，需要自己实现。而在此的触摸屏驱动程序时作为一个输入设备来实现的。在linux中，对于输入设备而言，内核专为其设计了输入子系统，由核心层处理公共的工作。因为对于输入设备而言，只是中断、读键值/坐标值是与设备相关的，其余的如输入事件的缓冲区的管理以及字符设备驱动的file_operations接口则是输入设备通用的。所以在此是在输入子系统的框架下进行编写触摸屏驱动程序。对于这个驱动的移植以及讲解，参考了网上的一些文章，一部分摒弃了手册。

1 在内核中添加触摸屏驱动程序
Linux-2.6.32.2 内核也没有包含支持S3C2440 的触摸屏驱动，因此我们自行设计了一个s3c2410_ts.c，它位于linux-src/drivers/input/touchscreen 目录下，你可以自己增加一个s3c2410_ts.c 文件，并复制如下内容：

#include <linux/errno.h>#include <linux/kernel.h>#include <linux/module.h>#include <linux/slab.h>#include <linux/input.h>#include <linux/init.h>#include <linux/serio.h>#include <linux/delay.h>#include <linux/platform_device.h>#include <linux/clk.h>#include <linux/gpio.h>#include <asm/io.h>#include <asm/irq.h>#include <plat/regs-adc.h>#include <mach/regs-gpio.h>/* For ts.dev.id.version */#define S3C2410TSVERSION 0x0101#define WAIT4INT(x) (((x)<<8) | \S3C2410_ADCTSC_YM_SEN | S3C2410_ADCTSC_YP_SEN | S3C2410_ADCTSC_XP_SEN | \S3C2410_ADCTSC_XY_PST(3))#define AUTOPST (S3C2410_ADCTSC_YM_SEN | S3C2410_ADCTSC_YP_SEN |S3C2410_ADCTSC_XP_SEN | \S3C2410_ADCTSC_AUTO_PST | S3C2410_ADCTSC_XY_PST(0))static char *s3c2410ts_name = "s3c2410 TouchScreen";static struct input_dev *dev;static long xp;static long yp;static int count;extern struct semaphore ADC_LOCK;static int OwnADC = 0;static void __iomem *base_addr;static inline void s3c2410_ts_connect(void){s3c2410_gpio_cfgpin(S3C2410_GPG(12), S3C2410_GPG12_XMON);s3c2410_gpio_cfgpin(S3C2410_GPG(13), S3C2410_GPG13_nXPON);s3c2410_gpio_cfgpin(S3C2410_GPG(14), S3C2410_GPG14_YMON);s3c2410_gpio_cfgpin(S3C2410_GPG(15), S3C2410_GPG15_nYPON);}static void touch_timer_fire(unsigned long data){unsigned long data0;unsigned long data1;int updown;data0 = ioread32(base_addr+S3C2410_ADCDAT0);data1 = ioread32(base_addr+S3C2410_ADCDAT1);updown = (!(data0 & S3C2410_ADCDAT0_UPDOWN)) && (!(data1 & S3C2410_ADCDAT0_UPDOWN));if (updown) {if (count != 0) {long tmp;tmp = xp;xp = yp;yp = tmp;xp >>= 2;yp >>= 2;input_report_abs(dev, ABS_X, xp);input_report_abs(dev, ABS_Y, yp);input_report_key(dev, BTN_TOUCH, 1);input_report_abs(dev, ABS_PRESSURE, 1);input_sync(dev);}xp = 0;yp = 0;count = 0;iowrite32(S3C2410_ADCTSC_PULL_UP_DISABLE | AUTOPST, base_addr+S3C2410_ADCTSC);iowrite32(ioread32(base_addr+S3C2410_ADCCON) | S3C2410_ADCCON_ENABLE_START,base_addr+S3C2410_ADCCON);} else {count = 0;input_report_key(dev, BTN_TOUCH, 0);input_report_abs(dev, ABS_PRESSURE, 0);input_sync(dev);iowrite32(WAIT4INT(0), base_addr+S3C2410_ADCTSC);if (OwnADC) {OwnADC = 0;up(&ADC_LOCK);}}}static struct timer_list touch_timer =TIMER_INITIALIZER(touch_timer_fire, 0, 0);static irqreturn_t stylus_updown(int irq, void *dev_id){unsigned long data0;unsigned long data1;int updown;if (down_trylock(&ADC_LOCK) == 0) {OwnADC = 1;data0 = ioread32(base_addr+S3C2410_ADCDAT0);data1 = ioread32(base_addr+S3C2410_ADCDAT1);updown = (!(data0 & S3C2410_ADCDAT0_UPDOWN)) && (!(data1 &S3C2410_ADCDAT0_UPDOWN));if (updown) {touch_timer_fire(0);} else {OwnADC = 0;up(&ADC_LOCK);}}return IRQ_HANDLED;}static irqreturn_t stylus_action(int irq, void *dev_id){unsigned long data0;unsigned long data1;if (OwnADC) {data0 = ioread32(base_addr+S3C2410_ADCDAT0);data1 = ioread32(base_addr+S3C2410_ADCDAT1);xp += data0 & S3C2410_ADCDAT0_XPDATA_MASK;yp += data1 & S3C2410_ADCDAT1_YPDATA_MASK;count++;if (count < (1<<2)) {iowrite32(S3C2410_ADCTSC_PULL_UP_DISABLE | AUTOPST,base_addr+S3C2410_ADCTSC);iowrite32(ioread32(base_addr+S3C2410_ADCCON) | S3C2410_ADCCON_ENABLE_START,base_addr+S3C2410_ADCCON);} else {mod_timer(&touch_timer, jiffies+1);iowrite32(WAIT4INT(1), base_addr+S3C2410_ADCTSC);}}return IRQ_HANDLED;}static struct clk *adc_clock;static int __init s3c2410ts_init(void){struct input_dev *input_dev;adc_clock = clk_get(NULL, "adc");if (!adc_clock) {printk(KERN_ERR "failed to get adc clock source\n");return -ENOENT;}clk_enable(adc_clock);base_addr=ioremap(S3C2410_PA_ADC,0x20);if (base_addr == NULL) {printk(KERN_ERR "Failed to remap register block\n");return -ENOMEM;}/* Configure GPIOs */s3c2410_ts_connect();iowrite32(S3C2410_ADCCON_PRSCEN | S3C2410_ADCCON_PRSCVL(0xFF),\base_addr+S3C2410_ADCCON);iowrite32(0xffff, base_addr+S3C2410_ADCDLY);iowrite32(WAIT4INT(0), base_addr+S3C2410_ADCTSC);/* Initialise input stuff */input_dev = input_allocate_device();if (!input_dev) {printk(KERN_ERR "Unable to allocate the input device !!\n");return -ENOMEM;}dev = input_dev;dev->evbit[0] = BIT(EV_SYN) | BIT(EV_KEY) | BIT(EV_ABS);dev->keybit[BITS_TO_LONGS(BTN_TOUCH)] = BIT(BTN_TOUCH);input_set_abs_params(dev, ABS_X, 0, 0x3FF, 0, 0);input_set_abs_params(dev, ABS_Y, 0, 0x3FF, 0, 0);input_set_abs_params(dev, ABS_PRESSURE, 0, 1, 0, 0);dev->name = s3c2410ts_name;dev->id.bustype = BUS_RS232;dev->id.vendor = 0xDEAD;dev->id.product = 0xBEEF;dev->id.version = S3C2410TSVERSION;/* Get irqs */if (request_irq(IRQ_ADC, stylus_action, IRQF_SHARED|IRQF_SAMPLE_RANDOM,"s3c2410_action", dev)) {printk(KERN_ERR "s3c2410_ts.c: Could not allocate ts IRQ_ADC !\n");iounmap(base_addr);return -EIO;}if (request_irq(IRQ_TC, stylus_updown, IRQF_SAMPLE_RANDOM,"s3c2410_action", dev)) {printk(KERN_ERR "s3c2410_ts.c: Could not allocate ts IRQ_TC !\n");iounmap(base_addr);return -EIO;}printk(KERN_INFO "%s successfully loaded\n", s3c2410ts_name);/* All went ok, so register to the input system */input_register_device(dev);return 0;}static void __exit s3c2410ts_exit(void){disable_irq(IRQ_ADC);disable_irq(IRQ_TC);free_irq(IRQ_TC,dev);free_irq(IRQ_ADC,dev);if (adc_clock) {clk_disable(adc_clock);clk_put(adc_clock);adc_clock = NULL;}input_unregister_device(dev);iounmap(base_addr);}module_init(s3c2410ts_init);module_exit(s3c2410ts_exit);

 

然后在linux-2.6.32.2/drivers/input/touchscreen/Makefile 文件中添加该源代码的目标模块，如图红色部分：
obj-$(CONFIG_TOUCHSCREEN_WM97XX_ZYLONITE) += zylonite-wm97xx.o
obj-$(CONFIG_TOUCHSCREEN_W90X900) += w90p910_ts.o
obj-$(CONFIG_TOUCHSCREEN_PCAP) += pcap_ts.o
obj-$(CONFIG_TOUCHSCREEN_S3C2410) += s3c2410_ts.o

再打开linux-2.6.32.2/drivers/input/touchscreen/Kconfig 文件，加入如下红色部分，这样就在内核配置中添加了mini2440 的触摸屏驱动选项：

menuconfig INPUT_TOUCHSCREEN
      bool "Touchscreens"
      help
      Say Y here, and a list of supported touchscreens will be displayed.
      This option doesn't affect the kernel.
      If unsure, say Y.
      if INPUT_TOUCHSCREEN
config TOUCHSCREEN_S3C2410
      tristate "Samsung S3C2410 touchscreen input driver"
      depends on MACH_MINI2440 && INPUT && INPUT_TOUCHSCREEN && MINI2440_ADC
      help
      Say Y here if you have the s3c2410 touchscreen.
      If unsure, say N.
     To compile this driver as a module, choose M here: the
      module will be called s3c2410_ts.
config TOUCHSCREEN_ADS7846
     tristate "ADS7846/TSC2046 and ADS7843 based touchscreens"
     depends on SPI_MASTER
     depends on HWMON = n || HWMON
     help

至此，我们就已经在内核中添加完了触摸屏驱动。

2 配置编译内核并测试触摸屏驱动
在命令行执行：make menuconfig，然后依次选择如下子菜单，找到刚刚添加的触摸屏驱动选项：
Device Drivers --->
      Input device support --->
                [*] Touchscreens --->
按空格键选中触摸屏驱动配置选项：退出并保存以上内核配置，在命令行输入：make zImage，将生成arch/arm/boot/zImage文件，使用supervivi 的“k”命令把它烧写到开发板。在此我们还是使用缺省的文件系统root_qtopia，可以看到屏幕上出现校正界面：依照屏幕提示，使用触摸笔逐步点击“十”型交叉点，即可进入qtopia 系统。

3、触摸屏驱动程序的详细分析。

      这个内容由于较多，放在下一个文章里，见下链接。

       linux-2.6.32在mini2440开发板上移植（10）之触摸屏工作原理以及驱动程序详细分析。