Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754005AbbGQXmv (ORCPT ); Fri, 17 Jul 2015 19:42:51 -0400 Received: from mail-pa0-f42.google.com ([209.85.220.42]:34080 "EHLO mail-pa0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752300AbbGQXms (ORCPT ); Fri, 17 Jul 2015 19:42:48 -0400 Date: Fri, 17 Jul 2015 16:42:42 -0700 From: Dmitry Torokhov To: Sanchayan Maity Cc: linux-input@vger.kernel.org, devicetree@vger.kernel.org, mark.rutland@arm.com, pawel.moll@arm.com, ijc+devicetree@hellion.org.uk, linux-kernel@vger.kernel.org, stefan@agner.ch, robh+dt@kernel.org, kernel@pengutronix.de, galak@codeaurora.org, shawn.guo@linaro.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v2 3/4] touchscreen: colibri-vf50-ts: Add touchscreen support for Colibri VF50 Message-ID: <20150717234242.GJ39282@dtor-ws> References: <26748bd9a7bde7c2304b6b971f1150bb575e4938.1437058481.git.maitysanchayan@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <26748bd9a7bde7c2304b6b971f1150bb575e4938.1437058481.git.maitysanchayan@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 15992 Lines: 558 Hi Sanchayan, On Thu, Jul 16, 2015 at 08:43:21PM +0530, Sanchayan Maity wrote: > The Colibri Vybrid VF50 module supports 4-wire touchscreens using > FETs and ADC inputs. This driver uses the IIO consumer interface > and relies on the vf610_adc driver based on the IIO framework. This looks pretty good, thank you. Just a few comments below. > > Signed-off-by: Sanchayan Maity > --- > drivers/input/touchscreen/Kconfig | 12 + > drivers/input/touchscreen/Makefile | 1 + > drivers/input/touchscreen/colibri-vf50-ts.c | 451 ++++++++++++++++++++++++++++ > 3 files changed, 464 insertions(+) > create mode 100644 drivers/input/touchscreen/colibri-vf50-ts.c > > diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig > index 80f6386..28948ca 100644 > --- a/drivers/input/touchscreen/Kconfig > +++ b/drivers/input/touchscreen/Kconfig > @@ -1027,4 +1027,16 @@ config TOUCHSCREEN_ZFORCE > To compile this driver as a module, choose M here: the > module will be called zforce_ts. > > +config TOUCHSCREEN_COLIBRI_VF50 > + tristate "Toradex Colibri on board touchscreen driver" > + depends on GPIOLIB && IIO && VF610_ADC > + help > + Say Y here if you have a Colibri VF50 and plan to use > + the on-board provided 4-wire touchscreen driver. > + > + If unsure, say N. > + > + To compile this driver as a module, choose M here: the > + module will be called colibri_vf50_ts. > + > endif > diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile > index 44deea7..93746a0 100644 > --- a/drivers/input/touchscreen/Makefile > +++ b/drivers/input/touchscreen/Makefile > @@ -84,3 +84,4 @@ obj-$(CONFIG_TOUCHSCREEN_W90X900) += w90p910_ts.o > obj-$(CONFIG_TOUCHSCREEN_SX8654) += sx8654.o > obj-$(CONFIG_TOUCHSCREEN_TPS6507X) += tps6507x-ts.o > obj-$(CONFIG_TOUCHSCREEN_ZFORCE) += zforce_ts.o > +obj-$(CONFIG_TOUCHSCREEN_COLIBRI_VF50) += colibri-vf50-ts.o > diff --git a/drivers/input/touchscreen/colibri-vf50-ts.c b/drivers/input/touchscreen/colibri-vf50-ts.c > new file mode 100644 > index 0000000..eb16bdc > --- /dev/null > +++ b/drivers/input/touchscreen/colibri-vf50-ts.c > @@ -0,0 +1,451 @@ > +/* Copyright 2015 Toradex AG > + * > + * Toradex Colibri VF50 Touchscreen driver > + * > + * Originally authored by Stefan Agner for 3.0 kernel > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation; either version 2 of the License, or > + * (at your option) any later version. > + */ > + > +#include Why? > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include Is not used as far as I can see. > +#include > +#include > +#include > +#include > + > +#define DRIVER_NAME "colibri-vf50-ts" > +#define DRV_VERSION "1.0" > + > +#define VF_ADC_MAX ((1 << 12) - 1) > + > +#define COLI_TOUCH_MIN_DELAY_US 1000 > +#define COLI_TOUCH_MAX_DELAY_US 2000 > + > +static int min_pressure = 200; > + > +struct vf50_touch_device { > + struct platform_device *pdev; > + struct input_dev *ts_input; > + struct workqueue_struct *ts_workqueue; > + struct work_struct ts_work; > + struct iio_channel *channels; > + struct gpio_desc *gpio_xp; > + struct gpio_desc *gpio_xm; > + struct gpio_desc *gpio_yp; > + struct gpio_desc *gpio_ym; > + struct gpio_desc *gpio_pen_detect; > + struct gpio_desc *gpio_pen_detect_pullup; > + int pen_irq; > + bool stop_touchscreen; > +}; > + > +/* > + * Enables given plates and measures touch parameters using ADC > + */ > +static int adc_ts_measure(struct iio_channel *channel, > + struct gpio_desc *plate_p, struct gpio_desc *plate_m) > +{ > + int i, value = 0, val = 0; > + int ret; > + > + gpiod_set_value(plate_p, 1); > + gpiod_set_value(plate_m, 1); > + > + usleep_range(COLI_TOUCH_MIN_DELAY_US, COLI_TOUCH_MAX_DELAY_US); > + > + for (i = 0; i < 5; i++) { > + ret = iio_read_channel_raw(channel, &val); > + if (ret < 0) > + return -EINVAL; > + > + value += val; > + } > + > + value /= 5; > + > + gpiod_set_value(plate_p, 0); > + gpiod_set_value(plate_m, 0); > + > + return value; > +} > + > +/* > + * Enable touch detection using falling edge detection on XM > + */ > +static void vf50_ts_enable_touch_detection(struct vf50_touch_device *vf50_ts) > +{ > + /* Enable plate YM (needs to be strong GND, high active) */ > + gpiod_set_value(vf50_ts->gpio_ym, 1); > + > + /* > + * Let the platform mux to idle state in order to enable > + * Pull-Up on GPIO > + */ > + pinctrl_pm_select_idle_state(&vf50_ts->pdev->dev); > +} > + > +/* > + * ADC touch screen sampling worker function > + */ > +static void vf50_ts_work(struct work_struct *ts_work) > +{ > + struct vf50_touch_device *vf50_ts = container_of(ts_work, > + struct vf50_touch_device, ts_work); > + struct device *dev = &vf50_ts->pdev->dev; > + int val_x, val_y, val_z1, val_z2, val_p = 0; > + bool discard_val_on_start = true; > + > + while (!vf50_ts->stop_touchscreen) { > + /* X-Direction */ > + val_x = adc_ts_measure(&vf50_ts->channels[0], > + vf50_ts->gpio_xp, vf50_ts->gpio_xm); > + if (val_x < 0) > + continue; > + > + /* Y-Direction */ > + val_y = adc_ts_measure(&vf50_ts->channels[1], > + vf50_ts->gpio_yp, vf50_ts->gpio_ym); > + if (val_y < 0) > + continue; > + > + /* > + * Touch pressure > + * Measure on XP/YM > + */ > + val_z1 = adc_ts_measure(&vf50_ts->channels[2], > + vf50_ts->gpio_yp, vf50_ts->gpio_xm); > + if (val_z1 < 0) > + continue; > + val_z2 = adc_ts_measure(&vf50_ts->channels[3], > + vf50_ts->gpio_yp, vf50_ts->gpio_xm); > + if (val_z2 < 0) > + continue; > + > + /* Validate signal (avoid calculation using noise) */ > + if (val_z1 > 64 && val_x > 64) { > + /* > + * Calculate resistance between the plates > + * lower resistance means higher pressure > + */ > + int r_x = (1000 * val_x) / VF_ADC_MAX; > + > + val_p = (r_x * val_z2) / val_z1 - r_x; > + > + } else { > + val_p = 2000; > + } > + > + val_p = 2000 - val_p; > + dev_dbg(dev, "Measured values: x: %d, y: %d, z1: %d, z2: %d, " > + "p: %d\n", val_x, val_y, val_z1, val_z2, val_p); > + > + /* > + * If touch pressure is too low, stop measuring and reenable > + * touch detection > + */ > + if (val_p < min_pressure || val_p > 2000) > + break; > + > + /* > + * The pressure may not be enough for the first x and the > + * second y measurement, but, the pressure is ok when the > + * driver is doing the third and fourth measurement. To > + * take care of this, we drop the first measurement always. > + */ > + if (discard_val_on_start) { > + discard_val_on_start = false; > + } else { > + /* > + * Report touch position and sleep for > + * next measurement > + */ > + input_report_abs(vf50_ts->ts_input, > + ABS_X, VF_ADC_MAX - val_x); > + input_report_abs(vf50_ts->ts_input, > + ABS_Y, VF_ADC_MAX - val_y); > + input_report_abs(vf50_ts->ts_input, > + ABS_PRESSURE, val_p); > + input_report_key(vf50_ts->ts_input, BTN_TOUCH, 1); > + input_sync(vf50_ts->ts_input); > + } > + > + msleep(10); > + } > + > + /* Report no more touch, reenable touch detection */ > + input_report_abs(vf50_ts->ts_input, ABS_PRESSURE, 0); > + input_report_key(vf50_ts->ts_input, BTN_TOUCH, 0); > + input_sync(vf50_ts->ts_input); > + > + vf50_ts_enable_touch_detection(vf50_ts); > + > + /* Wait for the pull-up to be stable on high */ > + msleep(10); > + > + /* Reenable IRQ to detect touch */ > + enable_irq(vf50_ts->pen_irq); > + > + dev_dbg(dev, "Reenabled touch detection interrupt\n"); > +} > + > +static irqreturn_t vf50_ts_touched(int irq, void *dev_id) > +{ > + struct vf50_touch_device *vf50_ts = (struct vf50_touch_device *)dev_id; > + struct device *dev = &vf50_ts->pdev->dev; > + > + dev_dbg(dev, "Touch detected, start worker thread\n"); > + > + disable_irq_nosync(irq); > + > + /* Disable the touch detection plates */ > + gpiod_set_value(vf50_ts->gpio_ym, 0); > + > + /* Let the platform mux to default state in order to mux as ADC */ > + pinctrl_pm_select_default_state(dev); > + > + queue_work(vf50_ts->ts_workqueue, &vf50_ts->ts_work); If you convert this to a threaded interrupt you won't need to disable/reenable interrupt or queue work. You should also be able to use gpiod_set_value_cansleep() extending the range of ways the controller could be connected to systems. > + > + return IRQ_HANDLED; > +} > + > +static int vf50_ts_open(struct input_dev *dev_input) > +{ > + int ret; > + struct vf50_touch_device *touchdev = input_get_drvdata(dev_input); > + struct device *dev = &touchdev->pdev->dev; > + > + dev_dbg(dev, "Input device %s opened, starting touch detection\n", > + dev_input->name); > + > + touchdev->stop_touchscreen = false; > + > + ret = gpiod_direction_output(touchdev->gpio_xp, 0); > + if (ret) { > + dev_err(dev, "Could not set gpio xp as output %d\n", ret); > + return ret; > + } > + > + ret = gpiod_direction_output(touchdev->gpio_xm, 0); > + if (ret) { > + dev_err(dev, "Could not set gpio xm as output %d\n", ret); > + return ret; > + } > + > + ret = gpiod_direction_output(touchdev->gpio_yp, 0); > + if (ret) { > + dev_err(dev, "Could not set gpio yp as output %d\n", ret); > + return ret; > + } > + > + ret = gpiod_direction_output(touchdev->gpio_ym, 0); > + if (ret) { > + dev_err(dev, "Could not set gpio ym as output %d\n", ret); > + return ret; > + } > + > + ret = gpiod_direction_input(touchdev->gpio_pen_detect); > + if (ret) { > + dev_err(dev, > + "Could not set gpio pen detect as input %d\n", ret); > + return ret; > + } > + > + ret = gpiod_direction_input(touchdev->gpio_pen_detect_pullup); > + if (ret) { > + dev_err(dev, > + "Could not set pen detect pullup as input %d\n", ret); > + return ret; > + } I do not see this GPIO being actually used... > + > + /* Mux detection before request IRQ, wait for pull-up to settle */ > + vf50_ts_enable_touch_detection(touchdev); > + msleep(10); > + > + touchdev->pen_irq = gpiod_to_irq(touchdev->gpio_pen_detect); > + if (touchdev->pen_irq < 0) { > + dev_err(dev, "Unable to get IRQ for GPIO\n"); > + return touchdev->pen_irq; > + } > + > + ret = request_irq(touchdev->pen_irq, vf50_ts_touched, > + IRQF_TRIGGER_FALLING, "touch detected", touchdev); > + if (ret < 0) { > + dev_err(dev, "Unable to request IRQ %d\n", touchdev->pen_irq); > + return ret; > + } I'd rather we did most initialization in probe() so that -EPROBE_DEFER would get handled properly. > + > + return 0; > +} > + > +static void vf50_ts_close(struct input_dev *dev_input) > +{ > + struct vf50_touch_device *touchdev = input_get_drvdata(dev_input); > + struct device *dev = &touchdev->pdev->dev; > + > + free_irq(touchdev->pen_irq, touchdev); > + > + touchdev->stop_touchscreen = true; > + > + /* Wait until touchscreen thread finishes any possible remnants. */ > + cancel_work_sync(&touchdev->ts_work); > + > + dev_dbg(dev, "Input device %s closed, disable touch detection\n", > + dev_input->name); > +} > + > +static inline int vf50_ts_get_gpiod(struct device *dev, > + struct gpio_desc **gpio_d, const char *con_id) > +{ > + int ret; > + > + *gpio_d = devm_gpiod_get(dev, con_id); > + if (IS_ERR(*gpio_d)) { > + ret = PTR_ERR(*gpio_d); > + dev_err(dev, "Could not get gpio_%s %d\n", con_id, ret); > + return ret; > + } > + > + return 0; > +} > + > +static int vf50_ts_probe(struct platform_device *pdev) > +{ > + struct device *dev = &pdev->dev; > + struct device_node *node = dev->of_node; > + struct vf50_touch_device *touchdev; > + struct input_dev *input; > + int ret = 0; Personal preference: can we call this "error"? Also no need to gratuitously initialize it to 0. > + > + if (!node) { > + dev_err(dev, "Device does not have associated DT data\n"); > + return -EINVAL; So what? I do not see you using of_node anywhere. > + } > + > + touchdev = devm_kzalloc(dev, sizeof(*touchdev), GFP_KERNEL); > + if (touchdev == NULL) > + return -ENOMEM; > + > + input = devm_input_allocate_device(dev); > + if (!input) { > + dev_err(dev, "Failed to allocate TS input device\n"); > + ret = -ENOMEM; > + return ret; > + } > + > + platform_set_drvdata(pdev, touchdev); > + > + touchdev->pdev = pdev; > + > + input->name = DRIVER_NAME; > + input->id.bustype = BUS_HOST; > + input->dev.parent = dev; > + input->open = vf50_ts_open; > + input->close = vf50_ts_close; > + > + _set_bit(EV_ABS, input->evbit); > + _set_bit(EV_KEY, input->evbit); > + _set_bit(BTN_TOUCH, input->keybit); > + input_set_abs_params(input, ABS_X, 0, VF_ADC_MAX, 0, 0); > + input_set_abs_params(input, ABS_Y, 0, VF_ADC_MAX, 0, 0); > + input_set_abs_params(input, ABS_PRESSURE, 0, VF_ADC_MAX, 0, 0); > + > + touchdev->ts_input = input; > + input_set_drvdata(input, touchdev); > + ret = input_register_device(input); > + if (ret) { > + dev_err(dev, "Failed to register input device\n"); > + return ret; > + } > + > + ret = vf50_ts_get_gpiod(dev, &touchdev->gpio_xp, "xp"); > + if (ret) > + return ret; > + > + ret = vf50_ts_get_gpiod(dev, &touchdev->gpio_xm, "xm"); > + if (ret) > + return ret; > + > + ret = vf50_ts_get_gpiod(dev, &touchdev->gpio_yp, "yp"); > + if (ret) > + return ret; > + > + ret = vf50_ts_get_gpiod(dev, &touchdev->gpio_ym, "ym"); > + if (ret) > + return ret; > + > + ret = vf50_ts_get_gpiod(dev, &touchdev->gpio_pen_detect, > + "pen-detect"); > + if (ret) > + return ret; > + > + ret = vf50_ts_get_gpiod(dev, &touchdev->gpio_pen_detect_pullup, > + "pen-pullup"); > + if (ret) > + return ret; > + > + INIT_WORK(&touchdev->ts_work, vf50_ts_work); > + touchdev->ts_workqueue = create_singlethread_workqueue("vf50-ts-touch"); > + > + if (!touchdev->ts_workqueue) { > + ret = PTR_ERR(touchdev->ts_workqueue); > + dev_err(dev, > + "Failed creating vf50-ts-touch workqueue %d\n", ret); > + return ret; > + } This should go away with the threaded IRQ. > + > + touchdev->channels = iio_channel_get_all(dev); > + if (IS_ERR(touchdev->channels)) > + return PTR_ERR(touchdev->channels); > + > + dev_info(dev, "Attached colibri-vf50-ts driver successfully\n"); Please drop, you should see message from input core about the new device already. > + > + return 0; > +} > + > +static int vf50_ts_remove(struct platform_device *pdev) > +{ > + struct vf50_touch_device *touchdev = platform_get_drvdata(pdev); > + > + destroy_workqueue(touchdev->ts_workqueue); > + iio_channel_release_all(touchdev->channels); > + > + return 0; > +} > + > +static const struct of_device_id vf50_touch_of_match[] = { > + { .compatible = "toradex,vf50-touchctrl", }, > + { } > +}; > +MODULE_DEVICE_TABLE(of, vf50_touch_of_match); > + > +static struct platform_driver __refdata vf50_touch_driver = { Why do you need __refdata? > + .driver = { > + .name = "toradex,vf50_touchctrl", > + .of_match_table = vf50_touch_of_match, > + }, > + .probe = vf50_ts_probe, > + .remove = vf50_ts_remove, > + .prevent_deferred_probe = false, Deferrals are enabled by default. > +}; > + > +module_platform_driver(vf50_touch_driver); > + > +module_param(min_pressure, int, 0600); > +MODULE_PARM_DESC(min_pressure, "Minimum pressure for touch detection"); I'd rather let userspace figure out what it recognizes as valid touch. > +MODULE_AUTHOR("Sanchayan Maity"); > +MODULE_DESCRIPTION("Colibri VF50 Touchscreen driver"); > +MODULE_LICENSE("GPL v2"); > +MODULE_VERSION(DRV_VERSION); Thanks. -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/