From patchwork Wed May 19 09:20:18 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oleksij Rempel X-Patchwork-Id: 443625 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2522C43462 for ; Wed, 19 May 2021 09:20:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B82AF613AA for ; Wed, 19 May 2021 09:20:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345207AbhESJWE (ORCPT ); Wed, 19 May 2021 05:22:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55334 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345221AbhESJV5 (ORCPT ); Wed, 19 May 2021 05:21:57 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D6C05C06138D for ; Wed, 19 May 2021 02:20:33 -0700 (PDT) Received: from dude.hi.pengutronix.de ([2001:67c:670:100:1d::7]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1ljINL-0007kS-RE; Wed, 19 May 2021 11:20:23 +0200 Received: from ore by dude.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1ljINJ-0005Wi-0V; Wed, 19 May 2021 11:20:21 +0200 From: Oleksij Rempel To: Dmitry Torokhov , Rob Herring , Jonathan Cameron Cc: Oleksij Rempel , kernel@pengutronix.de, linux-kernel@vger.kernel.org, linux-input@vger.kernel.org, David Jander , devicetree@vger.kernel.org Subject: [PATCH v3 5/5] Input: resistive-adc-touch: add support for z1 and z2 channels Date: Wed, 19 May 2021 11:20:18 +0200 Message-Id: <20210519092018.21139-6-o.rempel@pengutronix.de> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210519092018.21139-1-o.rempel@pengutronix.de> References: <20210519092018.21139-1-o.rempel@pengutronix.de> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::7 X-SA-Exim-Mail-From: ore@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-input@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-input@vger.kernel.org This patch adds support for the z1 and z2 channels. These are used to calculate the applied pressure. As there is no common order of the individual channels of a resistive touch ADC, support for io-channel-names is added (although the DT bindings stated the driver already supports these). Signed-off-by: Oleksij Rempel --- .../input/touchscreen/resistive-adc-touch.c | 141 ++++++++++++++++-- 1 file changed, 128 insertions(+), 13 deletions(-) diff --git a/drivers/input/touchscreen/resistive-adc-touch.c b/drivers/input/touchscreen/resistive-adc-touch.c index e50af30183f4..470b95ed3569 100644 --- a/drivers/input/touchscreen/resistive-adc-touch.c +++ b/drivers/input/touchscreen/resistive-adc-touch.c @@ -20,7 +20,18 @@ #define DRIVER_NAME "resistive-adc-touch" #define GRTS_DEFAULT_PRESSURE_MIN 50000 +#define GRTS_DEFAULT_PRESSURE_MAX 65535 #define GRTS_MAX_POS_MASK GENMASK(11, 0) +#define GRTS_MAX_CHANNELS 4 + +enum grts_ch_type { + GRTS_CH_NONE = 0, + GRTS_CH_X, + GRTS_CH_Y, + GRTS_CH_PRESSURE, + GRTS_CH_Z1, + GRTS_CH_Z2, +}; /** * struct grts_state - generic resistive touch screen information struct @@ -33,24 +44,61 @@ */ struct grts_state { u32 pressure_min; + u32 x_plate_ohms; bool pressure; struct iio_channel *iio_chans; struct iio_cb_buffer *iio_cb; struct input_dev *input; struct touchscreen_properties prop; + u8 ch[GRTS_MAX_CHANNELS]; }; static int grts_cb(const void *data, void *private) { const u16 *touch_info = data; struct grts_state *st = private; - unsigned int x, y, press = 0x0; + unsigned int x, y, press = 0, z1 = 0, z2; + unsigned int Rt, i; + + for (i = 0; i < ARRAY_SIZE(st->ch) && st->ch[i] != GRTS_CH_NONE; i++) { + switch (st->ch[i]) { + case GRTS_CH_X: + x = touch_info[i]; + break; + case GRTS_CH_Y: + y = touch_info[i]; + break; + case GRTS_CH_PRESSURE: + press = touch_info[i]; + break; + case GRTS_CH_Z1: + z1 = touch_info[i]; + break; + case GRTS_CH_Z2: + z2 = touch_info[i]; + break; + case GRTS_CH_NONE: + break; + } + } - /* channel data coming in buffer in the order below */ - x = touch_info[0]; - y = touch_info[1]; - if (st->pressure) - press = touch_info[2]; + if (z1) { + Rt = z2; + Rt -= z1; + Rt *= st->x_plate_ohms; + Rt = DIV_ROUND_CLOSEST(Rt, 16); + Rt *= x; + Rt /= z1; + Rt = DIV_ROUND_CLOSEST(Rt, 256); + /* + * On increased pressure the resistance (Rt) is decreasing + * so, convert values to make it looks as real pressure. + */ + if (Rt < GRTS_DEFAULT_PRESSURE_MAX) + press = GRTS_DEFAULT_PRESSURE_MAX - Rt; + else + press = 0; + } if ((!x && !y) || (st->pressure && (press < st->pressure_min))) { /* report end of touch */ @@ -94,6 +142,72 @@ static void grts_disable(void *data) iio_channel_release_all_cb(data); } +static int grts_get_properties(struct grts_state *st, struct device *dev) +{ + int idx, error; + + idx = device_property_match_string(dev, "io-channel-names", "x"); + if (idx < 0) + return idx; + + if (idx >= ARRAY_SIZE(st->ch)) + return -EOVERFLOW; + + st->ch[idx] = GRTS_CH_X; + + idx = device_property_match_string(dev, "io-channel-names", "y"); + if (idx < 0) + return idx; + + if (idx >= ARRAY_SIZE(st->ch)) + return -EOVERFLOW; + + st->ch[idx] = GRTS_CH_Y; + + /* pressure is optional */ + idx = device_property_match_string(dev, "io-channel-names", "pressure"); + if (idx >= 0) { + if (idx >= ARRAY_SIZE(st->ch)) + return -EOVERFLOW; + + st->ch[idx] = GRTS_CH_PRESSURE; + st->pressure = true; + + return 0; + } + + /* if no pressure is defined, try optional z1 + z2 */ + idx = device_property_match_string(dev, "io-channel-names", "z1"); + if (idx < 0) + return 0; + + if (idx >= ARRAY_SIZE(st->ch)) + return -EOVERFLOW; + + st->ch[idx] = GRTS_CH_Z1; + + /* if z1 is provided z2 is not optional */ + idx = device_property_match_string(dev, "io-channel-names", "z2"); + if (idx < 0) + return idx; + + if (idx >= ARRAY_SIZE(st->ch)) + return -EOVERFLOW; + + st->ch[idx] = GRTS_CH_Z2; + st->pressure = true; + + error = device_property_read_u32(dev, + "touchscreen-x-plate-ohms", + &st->x_plate_ohms); + if (error) { + dev_err(dev, "can't get touchscreen-x-plate-ohms property\n"); + return error; + } + + return 0; +} + static int grts_probe(struct platform_device *pdev) { struct grts_state *st; @@ -115,12 +229,13 @@ static int grts_probe(struct platform_device *pdev) return error; } - chan = &st->iio_chans[0]; - st->pressure = false; - while (chan && chan->indio_dev) { - if (!strcmp(chan->channel->datasheet_name, "pressure")) - st->pressure = true; - chan++; + if (!device_property_present(dev, "io-channel-names")) + return -ENODEV; + + error = grts_get_properties(st, dev); + if (error) { + dev_err(dev, "Failed to parse properties\n"); + return error; } if (st->pressure) { @@ -148,7 +263,7 @@ static int grts_probe(struct platform_device *pdev) input_set_abs_params(input, ABS_Y, 0, GRTS_MAX_POS_MASK - 1, 0, 0); if (st->pressure) input_set_abs_params(input, ABS_PRESSURE, st->pressure_min, - 0xffff, 0, 0); + GRTS_DEFAULT_PRESSURE_MAX, 0, 0); input_set_capability(input, EV_KEY, BTN_TOUCH);