/**************************************************************************** * drivers/input/stmpe811_tsc.c * * Copyright (C) 2012 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * References: * "STMPE811 S-Touch® advanced resistive touchscreen controller with 8-bit * GPIO expander," Doc ID 14489 Rev 6, CD00186725, STMicroelectronics" * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * 3. Neither the name NuttX nor the names of its contributors may be * used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "stmpe811.h" #if defined(CONFIG_INPUT) && defined(CONFIG_INPUT_STMPE811) && !defined(CONFIG_STMPE811_TSC_DISABLE) /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ #define Direction_IN 0x00 #define Direction_OUT 0x01 #define Polarity_Low 0x00 #define Polarity_High 0x04 #define Type_Level 0x00 #define Type_Edge 0x02 #define IO_IT_0 0x01 #define IO_IT_1 0x02 #define IO_IT_2 0x04 #define IO_IT_3 0x08 #define IO_IT_4 0x10 #define IO_IT_5 0x20 #define IO_IT_6 0x40 #define IO_IT_7 0x80 #define ALL_IT 0xFF #define IOE_JOY_IT (uint8_t)(IO_IT_3 | IO_IT_4 | IO_IT_5 | IO_IT_6 | IO_IT_7) #define IOE_TS_IT (uint8_t)(IO_IT_0 | IO_IT_1 | IO_IT_2) #define IOE_INMEMS_IT (uint8_t)(IO_IT_2 | IO_IT_3) #define EDGE_FALLING 0x01 #define EDGE_RISING 0x02 #define TIMEOUT_MAX 0x3000 /*nwaiters > 0) { /* After posting this semaphore, we need to exit because the STMPE811 * is no longer available. */ sem_post(&priv->waitsem); } /* If there are threads waiting on poll() for STMPE811 data to become available, * then wake them up now. NOTE: we wake up all waiting threads because we * do not know that they are going to do. If they all try to read the data, * then some make end up blocking after all. */ #ifndef CONFIG_DISABLE_POLL for (i = 0; i < CONFIG_STMPE811_NPOLLWAITERS; i++) { struct pollfd *fds = priv->fds[i]; if (fds) { fds->revents |= POLLIN; ivdbg("Report events: %02x\n", fds->revents); sem_post(fds->sem); } } #endif } /**************************************************************************** * Name: stmpe811_sample * * Description: * Check if touchscreen sample data is available now and, if so, return * the sample data. This is part of the stmpe811_read logic. * * Assumption: * Pre-emption is disable to prevent the worker thread from running. * Otherwise, sampled data may continue to change. * ****************************************************************************/ static int stmpe811_sample(FAR struct stmpe811_dev_s *priv, FAR struct stmpe811_sample_s *sample) { int ret = -EAGAIN; /* Is there new STMPE811 sample data available? */ if (priv->penchange) { /* Yes.. the state has changed in some way. Return a copy of the * sampled data. */ memcpy(sample, &priv->sample, sizeof(struct stmpe811_sample_s)); /* Now manage state transitions */ if (sample->contact == CONTACT_UP) { /* The sampling logic has detected pen-up in some condition other * than CONTACT_NONE. Set the next state to CONTACT_NONE: Further * pen-down reports will be ignored. Increment the ID so that * next contact ID will be unique */ priv->sample.contact = CONTACT_NONE; priv->sample.valid = false; priv->id++; } else if (sample->contact == CONTACT_DOWN) { /* The sampling logic has detected pen-up in some condition other * than CONTACT_MOVE. Set the next state to CONTACT_MOVE: Further * samples collected while the pen is down will reported as movement * events. */ priv->sample.contact = CONTACT_MOVE; } priv->penchange = false; ret = OK; } return ret; } /**************************************************************************** * Name: stmpe811_waitsample * * Description: * Wait for a sample to become available (this is really part of the * stmpe811_read logic). * ****************************************************************************/ static inline int stmpe811_waitsample(FAR struct stmpe811_dev_s *priv, FAR struct stmpe811_sample_s *sample) { int ret; /* Disable pre-emption to prevent the worker thread from running * asynchronously. */ sched_lock(); /* Now release the semaphore that manages mutually exclusive access to * the device structure. This may cause other tasks to become ready to * run, but they cannot run yet because pre-emption is disabled. */ sem_post(&priv->exclsem); /* Try to get the a sample... if we cannot, then wait on the semaphore * that is posted when new sample data is availble. */ while (stmpe811_sample(priv, sample) < 0) { /* Wait for a change in the STMPE811 state */ priv->nwaiters++; ret = sem_wait(&priv->waitsem); priv->nwaiters--; /* When we are re-awakened, pre-emption will again be disabled */ if (ret < 0) { #ifdef CONFIG_DEBUG // Sample the errno (debug output could change it) int errval = errno; /* If we are awakened by a signal, then we need to return * the failure now. */ idbg("ERROR: sem_wait failed: %d\n", errval); DEBUGASSERT(errval == EINTR); #endif ret = -EINTR; goto errout; } } /* Re-acquire the the semaphore that manages mutually exclusive access to * the device structure. We may have to wait here. But we have our sample. * Interrupts and pre-emption will be re-enabled while we wait. */ ret = sem_wait(&priv->exclsem); errout: /* Restore pre-emption. We might get suspended here but that is okay * because we already have our sample. Note: this means that if there * were two threads reading from the STMPE811 for some reason, the data * might be read out of order. */ sched_unlock(); return ret; } /**************************************************************************** * Name: stmpe811_open * * Description: * Standard character driver open method. * ****************************************************************************/ static int stmpe811_open(FAR struct file *filep) { #ifdef CONFIG_STMPE811_REFCNT FAR struct inode *inode; FAR struct stmpe811_dev_s *priv; uint8_t tmp; int ret; DEBUGASSERT(filep); inode = filep->f_inode; DEBUGASSERT(inode && inode->i_private); priv = (FAR struct stmpe811_dev_s *)inode->i_private; /* Get exclusive access to the driver data structure */ ret = sem_wait(&priv->exclsem); if (ret < 0) { /* This should only happen if the wait was canceled by an signal */ DEBUGASSERT(errno == EINTR); return -EINTR; } /* Increment the reference count */ tmp = priv->crefs + 1; if (tmp == 0) { /* More than 255 opens; uint8_t overflows to zero */ ret = -EMFILE; goto errout_with_sem; } /* When the reference increments to 1, this is the first open event * on the driver.. and an opportunity to do any one-time initialization. */ /* Save the new open count on success */ priv->crefs = tmp; errout_with_sem: sem_post(&priv->exclsem); return ret; #else return OK; #endif } /**************************************************************************** * Name: stmpe811_close * * Description: * Standard character driver close method. * ****************************************************************************/ static int stmpe811_close(FAR struct file *filep) { #ifdef CONFIG_STMPE811_REFCNT FAR struct inode *inode; FAR struct stmpe811_dev_s *priv; int ret; DEBUGASSERT(filep); inode = filep->f_inode; DEBUGASSERT(inode && inode->i_private); priv = (FAR struct stmpe811_dev_s *)inode->i_private; /* Get exclusive access to the driver data structure */ ret = sem_wait(&priv->exclsem); if (ret < 0) { /* This should only happen if the wait was canceled by an signal */ DEBUGASSERT(errno == EINTR); return -EINTR; } /* Decrement the reference count unless it would decrement a negative * value. When the count decrements to zero, there are no further * open references to the driver. */ if (priv->crefs >= 1) { priv->crefs--; } sem_post(&priv->exclsem); #endif return OK; } /**************************************************************************** * Name: stmpe811_read * * Description: * Standard character driver read method. * ****************************************************************************/ static ssize_t stmpe811_read(FAR struct file *filep, FAR char *buffer, size_t len) { FAR struct inode *inode; FAR struct stmpe811_dev_s *priv; FAR struct touch_sample_s *report; struct stmpe811_sample_s sample; int ret; ivdbg("len=%d\n", len); DEBUGASSERT(filep); inode = filep->f_inode; DEBUGASSERT(inode && inode->i_private); priv = (FAR struct stmpe811_dev_s *)inode->i_private; /* Verify that the caller has provided a buffer large enough to receive * the touch data. */ if (len < SIZEOF_TOUCH_SAMPLE_S(1)) { /* We could provide logic to break up a touch report into segments and * handle smaller reads... but why? */ return -ENOSYS; } /* Get exclusive access to the driver data structure */ ret = sem_wait(&priv->exclsem); if (ret < 0) { /* This should only happen if the wait was canceled by an signal */ DEBUGASSERT(errno == EINTR); return -EINTR; } /* Try to read sample data. */ ret = stmpe811_sample(priv, &sample); if (ret < 0) { /* Sample data is not available now. We would ave to wait to get * receive sample data. If the user has specified the O_NONBLOCK * option, then just return an error. */ if (filep->f_oflags & O_NONBLOCK) { ret = -EAGAIN; goto errout; } /* Wait for sample data */ ret = stmpe811_waitsample(priv, &sample); if (ret < 0) { /* We might have been awakened by a signal */ goto errout; } } /* In any event, we now have sampled STMPE811 data that we can report * to the caller. */ report = (FAR struct touch_sample_s *)buffer; memset(report, 0, SIZEOF_TOUCH_SAMPLE_S(1)); report->npoints = 1; report->point[0].id = sample.id; report->point[0].x = sample.x; report->point[0].y = sample.y; report->point[0].pressure = sample.z; /* Report the appropriate flags */ if (sample.contact == CONTACT_UP) { /* Pen is now up. Is the positional data valid? This is important to * know because the release will be sent to the window based on its * last positional data. */ if (sample.valid) { report->point[0].flags = TOUCH_UP | TOUCH_ID_VALID | TOUCH_POS_VALID | TOUCH_PRESSURE_VALID; } else { report->point[0].flags = TOUCH_UP | TOUCH_ID_VALID; } } else if (sample.contact == CONTACT_DOWN) { /* First contact */ report->point[0].flags = TOUCH_DOWN | TOUCH_ID_VALID | TOUCH_POS_VALID | TOUCH_PRESSURE_VALID; } else /* if (sample->contact == CONTACT_MOVE) */ { /* Movement of the same contact */ report->point[0].flags = TOUCH_MOVE | TOUCH_ID_VALID | TOUCH_POS_VALID | TOUCH_PRESSURE_VALID; } ret = SIZEOF_TOUCH_SAMPLE_S(1); errout: sem_post(&priv->exclsem); return ret; } /**************************************************************************** * Name: stmpe811_ioctl * * Description: * Standard character driver ioctl method. * ****************************************************************************/ static int stmpe811_ioctl(FAR struct file *filep, int cmd, unsigned long arg) { FAR struct inode *inode; FAR struct stmpe811_dev_s *priv; int ret; ivdbg("cmd: %d arg: %ld\n", cmd, arg); DEBUGASSERT(filep); inode = filep->f_inode; DEBUGASSERT(inode && inode->i_private); priv = (FAR struct stmpe811_dev_s *)inode->i_private; /* Get exclusive access to the driver data structure */ ret = sem_wait(&priv->exclsem); if (ret < 0) { /* This should only happen if the wait was canceled by an signal */ DEBUGASSERT(errno == EINTR); return -EINTR; } /* Process the IOCTL by command */ switch (cmd) { case TSIOC_SETFREQUENCY: /* arg: Pointer to uint32_t frequency value */ { FAR uint32_t *ptr = (FAR uint32_t *)((uintptr_t)arg); DEBUGASSERT(priv->config != NULL && ptr != NULL); priv->config->frequency = I2C_SETFREQUENCY(priv->i2c, *ptr); } break; case TSIOC_GETFREQUENCY: /* arg: Pointer to uint32_t frequency value */ { FAR uint32_t *ptr = (FAR uint32_t *)((uintptr_t)arg); DEBUGASSERT(priv->config != NULL && ptr != NULL); *ptr = priv->config->frequency; } break; default: ret = -ENOTTY; break; } sem_post(&priv->exclsem); return ret; } /**************************************************************************** * Name: stmpe811_poll * * Description: * Standard character driver poll method. * ****************************************************************************/ #ifndef CONFIG_DISABLE_POLL static int stmpe811_poll(FAR struct file *filep, FAR struct pollfd *fds, bool setup) { FAR struct inode *inode; FAR struct stmpe811_dev_s *priv; int ret; int i; ivdbg("setup: %d\n", (int)setup); DEBUGASSERT(filep && fds); inode = filep->f_inode; DEBUGASSERT(inode && inode->i_private); priv = (FAR struct stmpe811_dev_s *)inode->i_private; /* Are we setting up the poll? Or tearing it down? */ ret = sem_wait(&priv->exclsem); if (ret < 0) { /* This should only happen if the wait was canceled by an signal */ DEBUGASSERT(errno == EINTR); return -EINTR; } if (setup) { /* Ignore waits that do not include POLLIN */ if ((fds->events & POLLIN) == 0) { idbg("ERROR: Missing POLLIN: revents: %08x\n", fds->revents); ret = -EDEADLK; goto errout; } /* This is a request to set up the poll. Find an available * slot for the poll structure reference */ for (i = 0; i < CONFIG_STMPE811_NPOLLWAITERS; i++) { /* Find an available slot */ if (!priv->fds[i]) { /* Bind the poll structure and this slot */ priv->fds[i] = fds; fds->priv = &priv->fds[i]; break; } } if (i >= CONFIG_STMPE811_NPOLLWAITERS) { idbg("ERROR: No availabled slot found: %d\n", i); fds->priv = NULL; ret = -EBUSY; goto errout; } /* Should we immediately notify on any of the requested events? */ if (priv->penchange) { stmpe811_notify(priv); } } else if (fds->priv) { /* This is a request to tear down the poll. */ struct pollfd **slot = (struct pollfd **)fds->priv; DEBUGASSERT(slot != NULL); /* Remove all memory of the poll setup */ *slot = NULL; fds->priv = NULL; } errout: sem_post(&priv->exclsem); return ret; } #endif /**************************************************************************** * Name: stmpe811_timeoutworker * * Description: * A timer has expired without receiving a pen up event. Check again. * ****************************************************************************/ static void stmpe811_timeoutworker(FAR void *arg) { FAR struct stmpe811_dev_s *priv = (FAR struct stmpe811_dev_s *)arg; DEBUGASSERT(priv); /* Treat the timeout just like an interrupt occurred */ stmpe811_tscworker(priv, stmpe811_getreg8(priv, STMPE811_INT_STA)); } /**************************************************************************** * Name: stmpe811_timeout * * Description: * A timer has expired without receiving a pen up event. Schedule work * to check again. * ****************************************************************************/ static void stmpe811_timeout(int argc, uint32_t arg1, ...) { FAR struct stmpe811_dev_s *priv = (FAR struct stmpe811_dev_s *)((uintptr_t)arg1); int ret; /* Are we still stuck in the pen down state? */ if (priv->sample.contact == CONTACT_MOVE || priv->sample.contact == CONTACT_MOVE) { /* Yes... is the worker thread available? If not, then apparently * we have work already pending? */ if (work_available(&priv->timeout)) { /* Yes.. Transfer processing to the worker thread. Since STMPE811 * interrupts are disabled while the work is pending, no special * action should be required to protect the work queue. */ ret = work_queue(&priv->timeout, stmpe811_timeoutworker, priv, 0); if (ret != 0) { illdbg("Failed to queue work: %d\n", ret); } } } } /**************************************************************************** * Name: stmpe811_tscinitialize * * Description: * Initialize the touchscreen controller. This is really a part of the * stmpe811_register logic, * ****************************************************************************/ static inline void stmpe811_tscinitialize(FAR struct stmpe811_dev_s *priv) { uint8_t regval; ivdbg("Initializing touchscreen controller\n"); /* Enable TSC and ADC functions */ regval = stmpe811_getreg8(priv, STMPE811_SYS_CTRL2); regval &= ~(SYS_CTRL2_TSC_OFF | SYS_CTRL2_ADC_OFF); stmpe811_putreg8(priv, STMPE811_SYS_CTRL2, regval); /* Enable the TSC global interrupts */ regval = stmpe811_getreg8(priv, STMPE811_INT_EN); regval |= (uint32_t)(INT_TOUCH_DET | INT_FIFO_TH | INT_FIFO_OFLOW); stmpe811_putreg8(priv, STMPE811_INT_EN, regval); /* Select Sample Time, bit number and ADC Reference */ stmpe811_putreg8(priv, STMPE811_ADC_CTRL1, priv->config->ctrl1); /* Wait for 20 ms */ up_mdelay(20); /* Select the ADC clock speed */ stmpe811_putreg8(priv, STMPE811_ADC_CTRL2, priv->config->ctrl2); /* Select TSC pins in non-GPIO mode (AF=0) */ regval = stmpe811_getreg8(priv, STMPE811_GPIO_AF); regval &= ~(uint8_t)TSC_PIN_SET; stmpe811_putreg8(priv, STMPE811_GPIO_AF, regval); /* Select 2 nF filter capacitor */ stmpe811_putreg8(priv, STMPE811_TSC_CFG, (TSC_CFG_AVE_CTRL_4SAMPLES | TSC_CFG_TOUCH_DELAY_500US | TSC_CFG_SETTLING_500US)); /* Select single point reading */ stmpe811_putreg8(priv, STMPE811_FIFO_TH, 1); /* Reset and clear the FIFO. */ stmpe811_putreg8(priv, STMPE811_FIFO_STA, FIFO_STA_FIFO_RESET); stmpe811_putreg8(priv, STMPE811_FIFO_STA, 0); /* set the data format for Z value: 7 fractional part and 1 whole part */ stmpe811_putreg8(priv, STMPE811_TSC_FRACTIONZ, 0x01); /* Set the driving capability of the device for TSC pins: 50mA */ stmpe811_putreg8(priv, STMPE811_TSC_IDRIVE, TSC_IDRIVE_50MA); /* Enable the TSC. Use no tracking index, touch-screen controller * operation mode (XYZ). */ stmpe811_putreg8(priv, STMPE811_TSC_CTRL, TSC_CTRL_EN); /* Clear all the status pending bits */ stmpe811_putreg8(priv, STMPE811_INT_STA, INT_ALL); } /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: stmpe811_register * * Description: * Enable TSC functionality. GPIO4-7 must be available. This function * will register the touchsceen driver as /dev/inputN where N is the minor * device number * * Input Parameters: * handle - The handle previously returned by stmpe811_register * minor - The input device minor number * * Returned Value: * Zero is returned on success. Otherwise, a negated errno value is * returned to indicate the nature of the failure. * ****************************************************************************/ int stmpe811_register(STMPE811_HANDLE handle, int minor) { FAR struct stmpe811_dev_s *priv = (FAR struct stmpe811_dev_s *)handle; char devname[DEV_NAMELEN]; int ret; ivdbg("handle=%p minor=%d\n", handle, minor); DEBUGASSERT(priv); /* Get exclusive access to the device structure */ ret = sem_wait(&priv->exclsem); if (ret < 0) { int errval = errno; idbg("ERROR: sem_wait failed: %d\n", errval); return -errval; } /* Make sure that the pins (4-7) need by the TSC are not already in use */ if ((priv->inuse & TSC_PIN_SET) != 0) { idbg("ERROR: TSC pins is already in-use: %02x\n", priv->inuse); sem_post(&priv->exclsem); return -EBUSY; } /* Initialize the TS structure fields to their default values */ priv->minor = minor; priv->penchange = false; priv->threshx = 0; priv->threshy = 0; /* Create a timer for catching missed pen up conditions */ priv->wdog = wd_create(); if (!priv->wdog) { idbg("ERROR: Failed to create a watchdog\n", errno); sem_post(&priv->exclsem); return -ENOSPC; } /* Register the character driver */ snprintf(devname, DEV_NAMELEN, DEV_FORMAT, minor); ret = register_driver(devname, &g_stmpe811fops, 0666, priv); if (ret < 0) { idbg("ERROR: Failed to register driver %s: %d\n", devname, ret); sem_post(&priv->exclsem); return ret; } /* Initialize the touchscreen controller */ stmpe811_tscinitialize(priv); /* Inidicate that the touchscreen controller was successfully initialized */ priv->inuse |= TSC_PIN_SET; /* Pins 4-7 are now in-use */ priv->flags |= STMPE811_FLAGS_TSC_INITIALIZED; /* TSC function is initialized */ sem_post(&priv->exclsem); return ret; } /**************************************************************************** * Name: stmpe811_tscworker * * Description: * This function is called to handle a TSC interrupt. It is not really * an interrupt handle because it is called from the STMPE811 "bottom half" * logic that runs on the worker thread. * ****************************************************************************/ void stmpe811_tscworker(FAR struct stmpe811_dev_s *priv, uint8_t intsta) { FAR struct stmpe811_config_s *config; /* Convenience pointer */ bool pendown; /* true: pend is down */ uint16_t xdiff; /* X difference used in thresholding */ uint16_t ydiff; /* Y difference used in thresholding */ uint16_t x; /* X position */ uint16_t y; /* Y position */ ASSERT(priv != NULL); /* Cancel the missing pen up timer */ (void)wd_cancel(priv->wdog); /* Get a pointer the callbacks for convenience (and so the code is not so * ugly). */ config = priv->config; DEBUGASSERT(config != NULL); /* Check for pen up or down from the TSC_STA ibit n the STMPE811_TSC_CTRL register. */ pendown = (stmpe811_getreg8(priv, STMPE811_TSC_CTRL) & TSC_CTRL_TSC_STA) != 0; /* Handle the change from pen down to pen up */ if (!pendown) { /* The pen is up.. reset thresholding variables. FIFOs will read zero if * there is no data available (hence the choice of (0,0)) */ priv->threshx = 0; priv->threshy = 0; /* Ignore the interrupt if the pen was already up (CONTACT_NONE == pen up and * already reported; CONTACT_UP == pen up, but not reported) */ if (priv->sample.contact == CONTACT_NONE || priv->sample.contact == CONTACT_UP) { goto ignored; } /* A pen-down to up transition has been detected. CONTACT_UP indicates the * initial loss of contzt. The state will be changed to CONTACT_NONE * after the loss of contact is sampled. */ priv->sample.contact = CONTACT_UP; } /* The pen is down... check for data in the FIFO */ else if ((intsta & (INT_FIFO_TH|INT_FIFO_OFLOW)) != 0) { /* Read the next x and y positions from the FIFO. */ #ifdef CONFIG_STMPE811_SWAPXY x = stmpe811_getreg16(priv, STMPE811_TSC_DATAX); y = stmpe811_getreg16(priv, STMPE811_TSC_DATAY); #else x = stmpe811_getreg16(priv, STMPE811_TSC_DATAY); y = stmpe811_getreg16(priv, STMPE811_TSC_DATAX); #endif /* If we have not yet processed the last pen up event, then we * cannot handle this pen down event. We will have to discard it. That * should be okay because there will be another FIFO event right behind * this one. Other kinds of data overruns are not harmful. * * Hmm.. a better design might be to disable FIFO interrupts when we * detect pen up. Then re-enable them when CONTACT_UP is reported. * That would save processing interrupts just to discard the data. */ if (priv->sample.contact == CONTACT_UP) { /* We have not closed the loop on the last touch ... don't report * anything. */ goto ignored; } /* Perform a thresholding operation so that the results will be more stable. * If the difference from the last sample is small, then ignore the event. * REVISIT: Should a large change in pressure also generate a event? */ xdiff = x > priv->threshx ? (x - priv->threshx) : (priv->threshx - x); ydiff = y > priv->threshy ? (y - priv->threshy) : (priv->threshy - y); if (xdiff < CONFIG_STMPE811_THRESHX && ydiff < CONFIG_STMPE811_THRESHY) { /* Little or no change in either direction ... don't report anything. */ goto ignored; } /* When we see a big difference, snap to the new x/y thresholds */ priv->threshx = x; priv->threshy = y; /* Update the x/y position in the sample data */ priv->sample.x = priv->threshx; priv->sample.y = priv->threshy; /* Update the Z pressure index */ priv->sample.z = stmpe811_getreg8(priv, STMPE811_TSC_DATAZ); priv->sample.valid = true; /* If this is the first (acknowledged) pen down report, then report * this as the first contact. If contact == CONTACT_DOWN, it will be * set to set to CONTACT_MOVE after the contact is first sampled. */ if (priv->sample.contact != CONTACT_MOVE) { /* First contact */ priv->sample.contact = CONTACT_DOWN; } } /* Pen down, but no data in FIFO */ else { /* Ignore the interrupt... wait until there is data in the FIFO */ goto ignored; } /* We get here if (1) we just went from a pen down to a pen up state OR (2) * We just get a measurement from the FIFO in a pen down state. Indicate * the availability of new sample data for this ID. */ priv->sample.id = priv->id; priv->penchange = true; /* Notify any waiters that new STMPE811 data is available */ stmpe811_notify(priv); /* If we think that the pend is still down, the start/re-start the pen up * timer. */ ignored: if (priv->sample.contact == CONTACT_MOVE || priv->sample.contact == CONTACT_MOVE) { (void)wd_start(priv->wdog, STMPE811_PENUP_TICKS, stmpe811_timeout, 1, (uint32_t)((uintptr_t)priv)); } /* Reset and clear all data in the FIFO */ stmpe811_putreg8(priv, STMPE811_FIFO_STA, FIFO_STA_FIFO_RESET); stmpe811_putreg8(priv, STMPE811_FIFO_STA, 0); } #endif /* CONFIG_INPUT && CONFIG_INPUT_STMPE811 && !CONFIG_STMPE811_TSC_DISABLE */