首先了解一下tslib的运行原理，tslib的运行分成两部分(1)校验在LCD固定坐标位置依次显示出5个坐标让用户触摸，把LCD坐标和用户触摸时驱动屏驱动底层的坐标总共5组值保存起来运行tslib库的算法对其进行运算，得出校准用7个值(2)校准每次触摸屏驱动读取到硬件坐标时应用校准用的7个值对该坐标进行一次运算，然后将运算后的坐标作为正常坐标即可。按照上面的原理，(1)我们先修改内核部分，我的平台用的触摸屏幕驱动是tsc2007，驱动文件为内核/drivers/input/touchscreen目录下的tsc2007.c和ts_linear.c其中，ts_linear.c中定义的是校准模块，该模块在proc文件系统中建立了7个文件，用来存放校准用的7个点，7的点的默认值为1,0,0,0,1,0,1，对应的目标平台文件系统的位置为/proc/sys/dev/ts_device目录下a0,a1,a2,a3,a4,a5,a6等7个文件此模块中还定义了一个校准函数ts_linear_scale，此函数的主要内容是读取a0,a1,a2,a3,a4,a5,a6等7个文件中的值作为7个校准值与传入的触摸平坐标值进行运算，返回运算结果。ts_linear_scale函数定义如下：int ts_linear_scale(int *x, int *y, int swap_xy){ int xtemp, ytemp; xtemp = *x; ytemp = *y; if (cal.a[6] == 0) return -EINVAL; *x = (cal.a[2] + cal.a[0] * xtemp + cal.a[1] * ytemp) / cal.a[6]; *y = (cal.a[5] + cal.a[3] * xtemp + cal.a[4] * ytemp) / cal.a[6]; if (swap_xy) { int tmp = *x; *x = *y; *y = tmp; } return 0;}
ts2007.c为触摸屏驱，与其他驱动不同的地方是在取得硬件坐标值发送之前先调用了ts_linear_scale函数对坐标值进行了校准 if (x > 0 && y > 0) { ts_linear_scale(&x, &y, invert); input_report_abs(input, ABS_X, x); input_report_abs(input, ABS_Y, y); input_report_abs(input, ABS_PRESSURE, 255); input_report_abs(input, ABS_TOOL_WIDTH, 1); input_report_key(input, BTN_TOUCH, 1); input_sync(input); }(2)在android源代码/system/core/rootdir/init.rc文件中添加tslib相关的宏定义如下：# touchscreen parameters export TSLIB_FBDEVICE /dev/graphics/fb0 export TSLIB_CALIBFILE /data/etc/pointercal export TSLIB_CONFFILE /system/etc/ts.conf export TSLIB_TRIGGERDEV /dev/input/event0 export TSLIB_TSDEVICE /dev/input/event1(2)移植tslib库到android系统，比较麻烦，看下一节的内容。(3)校验程序完成后会将生成的7个校准值写入到环境变量TSLIB_CALIBFILE对应的路径/data/etc/pointercal文件中(4)校验完后将pointercal文件中的7个值分别写入到/proc/sys/dev/ts_device目录下a0,a1,a2,a3,a4,a5,a6文件即可。(5)开机启动的时候我们编写一个应用程序，首先判断环境变量TSLIB_CALIBFILE对应的路径/data/etc/pointercal文件是否存在，如果文件存在而且非空，则将该文件中的7个值取出来分别写入到/proc/sys/dev/ts_device目录下a0,a1,a2,a3,a4,a5,a6文件(6)为了确保未校验前触摸屏可用，我们将一次校验后得出的7个坐标值作为初始值，修改到内核ts_linear.c文件中。
下面是源代码：ts_linear.c文件/* * Touchscreen Linear Scale Adaptor * * Copyright (C) 2009 Marvell Corporation * * Author: Mark F. Brown <markb@marvell.com> * Based on tslib 1.0 plugin linear.c by Russel King * * This library is licensed under GPL. * */#include <linux/module.h>#include <linux/init.h>#include <linux/kernel.h>#include <linux/input.h>#include <linux/interrupt.h>#include <linux/wait.h>#include <linux/delay.h>#include <linux/platform_device.h>#include <linux/proc_fs.h>#include <linux/sysctl.h>#include <asm/system.h>/* * sysctl-tuning infrastructure. */static struct ts_calibration {/* Linear scaling and offset parameters for x,y (can include rotation) */ int a[7];} cal;static ctl_table ts_proc_calibration_table[] = { { .ctl_name = CTL_UNNUMBERED, .procname = "a0", .data = &cal.a[0], .maxlen = sizeof(int), .mode = 0666, .proc_handler = &proc_dointvec, }, { .ctl_name = CTL_UNNUMBERED, .procname = "a1", .data = &cal.a[1], .maxlen = sizeof(int), .mode = 0666, .proc_handler = &proc_dointvec, }, { .ctl_name = CTL_UNNUMBERED, .procname = "a2", .data = &cal.a[2], .maxlen = sizeof(int), .mode = 0666, .proc_handler = &proc_dointvec, }, { .ctl_name = CTL_UNNUMBERED, .procname = "a3", .data = &cal.a[3], .maxlen = sizeof(int), .mode = 0666, .proc_handler = &proc_dointvec, }, { .ctl_name = CTL_UNNUMBERED, .procname = "a4", .data = &cal.a[4], .maxlen = sizeof(int), .mode = 0666, .proc_handler = &proc_dointvec, }, { .ctl_name = CTL_UNNUMBERED, .procname = "a5", .data = &cal.a[5], .maxlen = sizeof(int), .mode = 0666, .proc_handler = &proc_dointvec, }, { .ctl_name = CTL_UNNUMBERED, .procname = "a6", .data = &cal.a[6], .maxlen = sizeof(int), .mode = 0666, .proc_handler = &proc_dointvec, }, {.ctl_name = 0}};static ctl_table ts_proc_root[] = { { .ctl_name = CTL_UNNUMBERED, .procname = "ts_device", .mode = 0555, .child = ts_proc_calibration_table, }, {.ctl_name = 0}};static ctl_table ts_dev_root[] = { { .ctl_name = CTL_DEV, .procname = "dev", .mode = 0555, .child = ts_proc_root, }, {.ctl_name = 0}};static struct ctl_table_header *ts_sysctl_header;int ts_linear_scale(int *x, int *y, int swap_xy){ int xtemp, ytemp; xtemp = *x; ytemp = *y; if (cal.a[6] == 0) return -EINVAL; *x = (cal.a[2] + cal.a[0] * xtemp + cal.a[1] * ytemp) / cal.a[6]; *y = (cal.a[5] + cal.a[3] * xtemp + cal.a[4] * ytemp) / cal.a[6]; if (swap_xy) { int tmp = *x; *x = *y; *y = tmp; } return 0;}EXPORT_SYMBOL(ts_linear_scale);static int __init ts_linear_init(void){ ts_sysctl_header = register_sysctl_table(ts_dev_root); /* Use default values that leave ts numbers unchanged after transform */ cal.a[0] = 1; cal.a[1] = 0; cal.a[2] = 0; cal.a[3] = 0; cal.a[4] = 1; cal.a[5] = 0; cal.a[6] = 1; return 0;}static void __exit ts_linear_cleanup(void){ unregister_sysctl_table(ts_sysctl_header);}module_init(ts_linear_init);module_exit(ts_linear_cleanup);MODULE_DESCRIPTION("touch screen linear scaling driver");MODULE_LICENSE("GPL");ts2007.c文件/* * linux/drivers/input/touchscreen/tsc2007.c * * touch screen driver for tsc2007 * * Copyright (C) 2006, Marvell Corporation * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */#include <linux/module.h>#include <linux/init.h>#include <linux/kernel.h>#include <linux/input.h>#include <linux/interrupt.h>#include <linux/wait.h>#include <linux/delay.h>#include <linux/platform_device.h>#include <linux/freezer.h>#include <linux/proc_fs.h>#include <linux/clk.h>#include <linux/i2c.h>#include <mach/gpio.h>#include <linux/sysctl.h>#include <asm/system.h>extern int ts_linear_scale(int *x, int *y, int swap_xy);/* Use MAV filter */#define TSC_CMD_SETUP 0xb0/* Use 12-bit */#define TSC_CMD_X 0xc0#define TSC_CMD_PLATEX 0x80#define TSC_CMD_Y 0xd0#define TSC_CMD_PLATEY 0x90#define TSC_X_MAX 4096#define TSC_Y_MAX 4096#define TSC_X_MIN 0#define TSC_Y_MIN 0/* delay time for compute x, y, computed as us */#define DEBUG#ifdef DEBUG#define TS_DEBUG(fmt,args...) printk(KERN_DEBUG fmt, ##args )#else#define TS_DEBUG(fmt,args...)#endifstatic int x_min=TSC_X_MIN;static int y_min=TSC_Y_MIN;static int x_max=TSC_X_MAX;static int y_max=TSC_Y_MAX;static int invert = 0;static int debounce_time = 150;static int init_debounce = true;static int delay_time = 1;enum tsc2007_status { PEN_UP, PEN_DOWN,};struct _tsc2007 { struct input_dev *dev; int x; /* X sample values */ int y; /* Y sample values */ int status; struct work_struct irq_work; struct i2c_client *client; unsigned long last_touch;};struct _tsc2007 *g_tsc2007;/* update abs params when min and max coordinate values are set */int tsc2007_proc_minmax(struct ctl_table *table, int write, struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos){ struct _tsc2007 *tsc2007= g_tsc2007; struct input_dev *input = tsc2007->dev; /* update value */ int ret = proc_dointvec(table, write, filp, buffer, lenp, ppos); /* updated abs params */ if (input) { TS_DEBUG(KERN_DEBUG "update x_min %d x_max %d" " y_min %d y_max %d/n", x_min, x_max, y_min, y_max); input_set_abs_params(input, ABS_X, x_min, x_max, 0, 0); input_set_abs_params(input, ABS_Y, y_min, y_max, 0, 0); } return ret;}static ctl_table tsc2007_proc_table[] = { { .ctl_name = CTL_UNNUMBERED, .procname = "x-max", .data = &x_max, .maxlen = sizeof(int), .mode = 0666, .proc_handler = &tsc2007_proc_minmax, }, { .ctl_name = CTL_UNNUMBERED, .procname = "y-max", .data = &y_max, .maxlen = sizeof(int), .mode = 0666, .proc_handler = &tsc2007_proc_minmax, }, { .ctl_name = CTL_UNNUMBERED, .procname = "x-min", .data = &x_min, .maxlen = sizeof(int), .mode = 0666, .proc_handler = &tsc2007_proc_minmax, }, { .ctl_name = CTL_UNNUMBERED, .procname = "y-min", .data = &y_min, .maxlen = sizeof(int), .mode = 0666, .proc_handler = &tsc2007_proc_minmax, }, { .ctl_name = CTL_UNNUMBERED, .procname = "invert_xy", .data = &invert, .maxlen = sizeof(int), .mode = 0666, .proc_handler = &proc_dointvec, }, { .ctl_name = CTL_UNNUMBERED, .procname = "debounce_time", .data = &debounce_time, .maxlen = sizeof(int), .mode = 0666, .proc_handler = &proc_dointvec, }, { .ctl_name = CTL_UNNUMBERED, .procname = "delay_time", .data = &delay_time, .maxlen = sizeof(int), .mode = 0666, .proc_handler = &proc_dointvec, }, { .ctl_name = 0 }};static ctl_table tsc2007_proc_root[] = { { .ctl_name = CTL_UNNUMBERED, .procname = "ts_device", .mode = 0555, .child = tsc2007_proc_table, }, { .ctl_name = 0 }};static ctl_table tsc2007_proc_dev_root[] = { { .ctl_name = CTL_DEV, .procname = "dev", .mode = 0555, .child = tsc2007_proc_root, }, { .ctl_name = 0 }};static struct ctl_table_header *sysctl_header;static int __init init_sysctl(void){ sysctl_header = register_sysctl_table(tsc2007_proc_dev_root); return 0;}static void __exit cleanup_sysctl(void){ unregister_sysctl_table(sysctl_header);}static int tsc2007_measure(struct i2c_client *client, int *x, int * y){ u8 x_buf[2] = {0, 0}; u8 y_buf[2] = {0, 0}; i2c_smbus_write_byte(client, TSC_CMD_PLATEX); msleep_interruptible(delay_time); i2c_smbus_write_byte(client, TSC_CMD_X); i2c_master_recv(client, x_buf, 2); *x = (x_buf[0]<<4) | (x_buf[1] >>4); i2c_smbus_write_byte(client, TSC_CMD_PLATEY); msleep_interruptible(delay_time); i2c_smbus_write_byte(client, TSC_CMD_Y); i2c_master_recv(client, y_buf, 2); *y = (y_buf[0]<<4) | (y_buf[1] >>4); *y = 4096 - *y; //added by allen printk("/ntouchscreen x = 0x%x, y = 0x%x/n",*x,*y); return 0;}static void tsc2007_irq_work(struct work_struct *work){ struct _tsc2007 *tsc2007= g_tsc2007; struct i2c_client *client = tsc2007-> client; struct input_dev *input = tsc2007->dev; int x = -1, y = -1, is_valid = 0; int tmp_x = 0, tmp_y = 0; int gpio = irq_to_gpio(client->irq); /* Ignore if PEN_DOWN */ if(PEN_UP == tsc2007->status){ if (gpio_request(gpio, "tsc2007 touch detect")) { printk(KERN_ERR "Request GPIO failed, gpio: %X/n", gpio); return; } gpio_direction_input(gpio); while(0 == gpio_get_value(gpio)){ if ((jiffies_to_msecs( ((long)jiffies - (long)tsc2007->last_touch)) < debounce_time && tsc2007->status == PEN_DOWN) || init_debounce) { init_debounce = false; tsc2007_measure(client, &tmp_x, &tmp_y); TS_DEBUG(KERN_DEBUG "dropping pen touch %lu %lu (%u)/n", jiffies, tsc2007->last_touch, jiffies_to_msecs( (long)jiffies - (long)tsc2007->last_touch)); schedule(); continue; } /* continue report x, y */ if (x > 0 && y > 0) { ts_linear_scale(&x, &y, invert); input_report_abs(input, ABS_X, x); input_report_abs(input, ABS_Y, y); input_report_abs(input, ABS_PRESSURE, 255); input_report_abs(input, ABS_TOOL_WIDTH, 1); input_report_key(input, BTN_TOUCH, 1); input_sync(input); } tsc2007->status = PEN_DOWN; tsc2007_measure(client, &x, &y); TS_DEBUG(KERN_DEBUG "pen down x=%d y=%d!/n", x, y); is_valid = 1; schedule(); } if (is_valid) { /*consider PEN_UP */ tsc2007->status = PEN_UP; input_report_abs(input, ABS_PRESSURE, 0); input_report_abs(input, ABS_TOOL_WIDTH, 1); input_report_key(input, BTN_TOUCH, 0); input_sync(input); tsc2007->last_touch = jiffies; TS_DEBUG(KERN_DEBUG "pen up!/n"); } gpio_free(gpio); }}static irqreturn_t tsc2007_interrupt(int irq, void *dev_id){ schedule_work(&g_tsc2007->irq_work); return IRQ_HANDLED;}static int __devinit tsc2007_probe(struct i2c_client *client, const struct i2c_device_id *id){ struct _tsc2007 *tsc2007; struct input_dev *input_dev; int ret; tsc2007 = kzalloc(sizeof(struct _tsc2007), GFP_KERNEL); input_dev = input_allocate_device(); g_tsc2007 = tsc2007; if (!tsc2007 || !input_dev) { ret = -ENOMEM; goto fail1; } i2c_set_clientdata(client, tsc2007); tsc2007->dev = input_dev; input_dev->name = "tsc2007"; input_dev->phys = "tsc2007/input0"; //input_dev->id.bustype = BUS_HOST; input_dev->dev.parent = &client->dev; __set_bit(EV_KEY, input_dev->evbit); __set_bit(BTN_TOUCH, input_dev->keybit); __set_bit(EV_ABS, input_dev->evbit); __set_bit(ABS_PRESSURE, input_dev->evbit); __set_bit(ABS_X, input_dev->evbit); __set_bit(ABS_Y, input_dev->evbit); input_set_abs_params(input_dev, ABS_X, x_min, x_max, 0, 0); input_set_abs_params(input_dev, ABS_Y, y_min, y_max, 0, 0); input_set_abs_params(input_dev, ABS_PRESSURE, 0, 255, 0, 0); ret = request_irq(client->irq, tsc2007_interrupt, IRQF_DISABLED | IRQF_TRIGGER_FALLING, "tsc2007 irq", NULL); if (ret){ printk(KERN_ERR "tsc2007 request irq failed/n"); goto fail2; } ret = input_register_device(tsc2007->dev); if (ret){ printk(KERN_ERR "tsc2007 register device fail/n"); goto fail2; } /*init */ tsc2007->status = PEN_UP; tsc2007->client = client; tsc2007->last_touch = jiffies; INIT_WORK(&tsc2007->irq_work, tsc2007_irq_work); /* init tsc2007 */ i2c_smbus_write_byte(client, TSC_CMD_SETUP); return 0; fail2: free_irq(client->irq, client); fail1: i2c_set_clientdata(client, NULL); input_free_device(input_dev); kfree(tsc2007); return ret;}static int __devexit tsc2007_remove(struct i2c_client *client){ struct _tsc2007 *tsc2007 = i2c_get_clientdata(client); if(client->irq) free_irq(client->irq, client); i2c_set_clientdata(client, NULL); input_unregister_device(tsc2007->dev); kfree(tsc2007); return 0;}static struct i2c_device_id tsc2007_idtable[] = { { "tsc2007", 0 }, { } }; MODULE_DEVICE_TABLE(i2c, tsc2007_idtable);static struct i2c_driver tsc2007_driver = { .driver = { .name = "tsc2007", }, .id_table = tsc2007_idtable, .probe = tsc2007_probe, .remove = __devexit_p(tsc2007_remove),};static int __init tsc2007_ts_init(void){ init_sysctl(); return i2c_add_driver(&tsc2007_driver); }static void __exit tsc2007_ts_exit(void){ cleanup_sysctl(); i2c_del_driver(&tsc2007_driver);}module_init(tsc2007_ts_init);module_exit(tsc2007_ts_exit);MODULE_DESCRIPTION("tsc2007 touch screen driver");MODULE_LICENSE("GPL");
