linux触摸屏驱动分析，touchscreen, struct input_dev,基于TSC2007

代码从2.6.32拷贝：

/* * drivers/input/touchscreen/tsc2007.c * * Copyright (c) 2008 MtekVision Co., Ltd. * Kwangwoo Lee <kwlee@mtekvision.com> * * Using code from: * - ads7846.c * Copyright (c) 2005 David Brownell * Copyright (c) 2006 Nokia Corporation * - corgi_ts.c * Copyright (C) 2004-2005 Richard Purdie * - omap_ts.[hc], ads7846.h, ts_osk.c * Copyright (C) 2002 MontaVista Software * Copyright (C) 2004 Texas Instruments * Copyright (C) 2005 Dirk Behme * * 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/slab.h> #include <linux/input.h> #include <linux/interrupt.h> #include <linux/i2c.h> #include <linux/i2c/tsc2007.h> #define TS_POLL_DELAY 1 /* ms delay between samples */ #define TS_POLL_PERIOD 1 /* ms delay between samples */ #define TSC2007_MEASURE_TEMP0 (0x0 << 4) #define TSC2007_MEASURE_AUX (0x2 << 4) #define TSC2007_MEASURE_TEMP1 (0x4 << 4) #define TSC2007_ACTIVATE_XN (0x8 << 4) #define TSC2007_ACTIVATE_YN (0x9 << 4) #define TSC2007_ACTIVATE_YP_XN (0xa << 4) #define TSC2007_SETUP (0xb << 4) #define TSC2007_MEASURE_X (0xc << 4) #define TSC2007_MEASURE_Y (0xd << 4) #define TSC2007_MEASURE_Z1 (0xe << 4) #define TSC2007_MEASURE_Z2 (0xf << 4) #define TSC2007_POWER_OFF_IRQ_EN (0x0 << 2) #define TSC2007_ADC_ON_IRQ_DIS0 (0x1 << 2) #define TSC2007_ADC_OFF_IRQ_EN (0x2 << 2) #define TSC2007_ADC_ON_IRQ_DIS1 (0x3 << 2) #define TSC2007_12BIT (0x0 << 1) #define TSC2007_8BIT (0x1 << 1) #define MAX_12BIT ((1 << 12) - 1) #define ADC_ON_12BIT (TSC2007_12BIT | TSC2007_ADC_ON_IRQ_DIS0) #define READ_Y (ADC_ON_12BIT | TSC2007_MEASURE_Y) #define READ_Z1 (ADC_ON_12BIT | TSC2007_MEASURE_Z1) #define READ_Z2 (ADC_ON_12BIT | TSC2007_MEASURE_Z2) #define READ_X (ADC_ON_12BIT | TSC2007_MEASURE_X) #define PWRDOWN (TSC2007_12BIT | TSC2007_POWER_OFF_IRQ_EN) struct ts_event { u16 x; u16 y; u16 z1, z2; }; struct tsc2007 { struct input_dev *input; char phys[32]; struct delayed_work work; struct i2c_client *client; u16 model; u16 x_plate_ohms; bool pendown; int irq; int (*get_pendown_state)(void); void (*clear_penirq)(void); }; static inline int tsc2007_xfer(struct tsc2007 *tsc, u8 cmd) { s32 data; u16 val; data = i2c_smbus_read_word_data(tsc->client, cmd); if (data < 0) { dev_err(&tsc->client->dev, "i2c io error: %d/n", data); return data; } /* The protocol and raw data format from i2c interface: * S Addr Wr [A] Comm [A] S Addr Rd [A] [DataLow] A [DataHigh] NA P * Where DataLow has [D11-D4], DataHigh has [D3-D0 << 4 | Dummy 4bit]. */ val = swab16(data) >> 4; dev_dbg(&tsc->client->dev, "data: 0x%x, val: 0x%x/n", data, val); return val; } static void tsc2007_read_values(struct tsc2007 *tsc, struct ts_event *tc) { /* y- still on; turn on only y+ (and ADC) */ tc->y = tsc2007_xfer(tsc, READ_Y); /* turn y- off, x+ on, then leave in lowpower */ tc->x = tsc2007_xfer(tsc, READ_X); /* turn y+ off, x- on; we'll use formula #1 */ tc->z1 = tsc2007_xfer(tsc, READ_Z1); tc->z2 = tsc2007_xfer(tsc, READ_Z2); /* Prepare for next touch reading - power down ADC, enable PENIRQ */ tsc2007_xfer(tsc, PWRDOWN); } static u32 tsc2007_calculate_pressure(struct tsc2007 *tsc, struct ts_event *tc) { u32 rt = 0; /* range filtering */ if (tc->x == MAX_12BIT) tc->x = 0; if (likely(tc->x && tc->z1)) { /* compute touch pressure resistance using equation #1 */ rt = tc->z2 - tc->z1; rt *= tc->x; rt *= tsc->x_plate_ohms; rt /= tc->z1; rt = (rt + 2047) >> 12; } return rt; } static void tsc2007_send_up_event(struct tsc2007 *tsc) { struct input_dev *input = tsc->input; dev_dbg(&tsc->client->dev, "UP/n"); input_report_key(input, BTN_TOUCH, 0); input_report_abs(input, ABS_PRESSURE, 0); input_sync(input); } //中断后跑到这里来 static void tsc2007_work(struct work_struct *work) { struct tsc2007 *ts = container_of(to_delayed_work(work), struct tsc2007, work); struct ts_event tc; u32 rt; /* * NOTE: We can't rely on the pressure to determine the pen down * state, even though this controller has a pressure sensor. * The pressure value can fluctuate for quite a while after * lifting the pen and in some cases may not even settle at the * expected value. * * The only safe way to check for the pen up condition is in the * work function by reading the pen signal state (it's a GPIO * and IRQ). Unfortunately such callback is not always available, * in that case we have rely on the pressure anyway. */ if (ts->get_pendown_state) { if (unlikely(!ts->get_pendown_state())) { tsc2007_send_up_event(ts); ts->pendown = false; goto out; } dev_dbg(&ts->client->dev, "pen is still down/n"); } tsc2007_read_values(ts, &tc); rt = tsc2007_calculate_pressure(ts, &tc); //计算压力 if (rt > MAX_12BIT) { /* * Sample found inconsistent by debouncing or pressure is * beyond the maximum. Don't report it to user space, * repeat at least once more the measurement. */ dev_dbg(&ts->client->dev, "ignored pressure %d/n", rt); goto out; } if (rt) { struct input_dev *input = ts->input; if (!ts->pendown) { dev_dbg(&ts->client->dev, "DOWN/n"); input_report_key(input, BTN_TOUCH, 1); ts->pendown = true; } input_report_abs(input, ABS_X, tc.x); input_report_abs(input, ABS_Y, tc.y); input_report_abs(input, ABS_PRESSURE, rt); input_sync(input); dev_dbg(&ts->client->dev, "point(%4d,%4d), pressure (%4u)/n", tc.x, tc.y, rt); } else if (!ts->get_pendown_state && ts->pendown) { /* * We don't have callback to check pendown state, so we * have to assume that since pressure reported is 0 the * pen was lifted up. */ tsc2007_send_up_event(ts); ts->pendown = false; } out: if (ts->pendown) schedule_delayed_work(&ts->work, msecs_to_jiffies(TS_POLL_PERIOD)); else enable_irq(ts->irq); } static irqreturn_t tsc2007_irq(int irq, void *handle) { struct tsc2007 *ts = handle; if (!ts->get_pendown_state || likely(ts->get_pendown_state())) { disable_irq_nosync(ts->irq); schedule_delayed_work(&ts->work, msecs_to_jiffies(TS_POLL_DELAY)); } if (ts->clear_penirq) ts->clear_penirq(); return IRQ_HANDLED; } static void tsc2007_free_irq(struct tsc2007 *ts) { free_irq(ts->irq, ts); if (cancel_delayed_work_sync(&ts->work)) { /* * Work was pending, therefore we need to enable * IRQ here to balance the disable_irq() done in the * interrupt handler. */ enable_irq(ts->irq); } } static int __devinit tsc2007_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct tsc2007 *ts; struct tsc2007_platform_data *pdata = pdata = client->dev.platform_data; struct input_dev *input_dev; int err; if (!pdata) { dev_err(&client->dev, "platform data is required!/n"); return -EINVAL; } if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)) return -EIO; ts = kzalloc(sizeof(struct tsc2007), GFP_KERNEL); input_dev = input_allocate_device(); if (!ts || !input_dev) { err = -ENOMEM; goto err_free_mem; } ts->client = client; ts->irq = client->irq; ts->input = input_dev; INIT_DELAYED_WORK(&ts->work, tsc2007_work); ts->model = pdata->model; ts->x_plate_ohms = pdata->x_plate_ohms; ts->get_pendown_state = pdata->get_pendown_state; ts->clear_penirq = pdata->clear_penirq; snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(&client->dev)); input_dev->name = "TSC2007 Touchscreen"; input_dev->phys = ts->phys; input_dev->id.bustype = BUS_I2C; input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS); input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH); input_set_abs_params(input_dev, ABS_X, 0, MAX_12BIT, 0, 0); input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, 0, 0); input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_12BIT, 0, 0); if (pdata->init_platform_hw) pdata->init_platform_hw(); err = request_irq(ts->irq, tsc2007_irq, 0, client->dev.driver->name, ts); if (err < 0) { dev_err(&client->dev, "irq %d busy?/n", ts->irq); goto err_free_mem; } /* Prepare for touch readings - power down ADC and enable PENIRQ */ err = tsc2007_xfer(ts, PWRDOWN); if (err < 0) goto err_free_irq; err = input_register_device(input_dev); if (err) goto err_free_irq; i2c_set_clientdata(client, ts); return 0; err_free_irq: tsc2007_free_irq(ts); if (pdata->exit_platform_hw) pdata->exit_platform_hw(); err_free_mem: input_free_device(input_dev); kfree(ts); return err; } static int __devexit tsc2007_remove(struct i2c_client *client) { struct tsc2007 *ts = i2c_get_clientdata(client); struct tsc2007_platform_data *pdata = client->dev.platform_data; tsc2007_free_irq(ts); if (pdata->exit_platform_hw) pdata->exit_platform_hw(); input_unregister_device(ts->input); kfree(ts); return 0; } static struct i2c_device_id tsc2007_idtable[] = { { "tsc2007", 0 }, { } }; MODULE_DEVICE_TABLE(i2c, tsc2007_idtable); static struct i2c_driver tsc2007_driver = { .driver = { .owner = THIS_MODULE, .name = "tsc2007" }, .id_table = tsc2007_idtable, .probe = tsc2007_probe, .remove = __devexit_p(tsc2007_remove), }; static int __init tsc2007_init(void) { return i2c_add_driver(&tsc2007_driver); } static void __exit tsc2007_exit(void) { i2c_del_driver(&tsc2007_driver); } module_init(tsc2007_init); module_exit(tsc2007_exit); MODULE_AUTHOR("Kwangwoo Lee <kwlee@mtekvision.com>"); MODULE_DESCRIPTION("TSC2007 TouchScreen Driver"); MODULE_LICENSE("GPL");  

看一遍后就大概知道流程了。

当按下触摸板后产生中断，中断里面调用延时函数进入底半部程序。

在调度函数里面，先读取坐标，计算压力，然后根据压力大小上报坐标。

若触摸板一直按下，那么就重新调用，并通过压力值来看触摸板是否释放。

 

简单吧？