From patchwork Wed Aug 7 19:40:21 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Lechner X-Patchwork-Id: 11082597 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D86251399 for ; Wed, 7 Aug 2019 19:41:30 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C9B1428734 for ; Wed, 7 Aug 2019 19:41:30 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BDD1A288AC; Wed, 7 Aug 2019 19:41:30 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.7 required=2.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AA38C28960 for ; Wed, 7 Aug 2019 19:41:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389498AbfHGTlI (ORCPT ); Wed, 7 Aug 2019 15:41:08 -0400 Received: from vern.gendns.com ([98.142.107.122]:43680 "EHLO vern.gendns.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389462AbfHGTlH (ORCPT ); Wed, 7 Aug 2019 15:41:07 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lechnology.com; s=default; h=References:In-Reply-To:Message-Id:Date:Subject :Cc:To:From:Sender:Reply-To:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=BOAoXWCVXO/tIFxR/DWs3usPoBg4N+kX69B/9ng14rc=; b=Ck2M1o+mXS5KZqT8wCduOrDXb w7QN+pMfEZX5rc4jHHoxzx5POGPIF77iIyhvY759w94Y3RsQmfCfmbQAEyWNiJNcCNGi+4ILezBxD unXufVhkeUiG64lXxLrBq5sPcyPZqpawMApSm4MrmAh9Lxnzks2HjpORW+V8jlS0u90W1OHaQelVq KbOX4mk2Y1TTU8DO7/gLBVx2/Kz8xVZ4K4yf29t7wBgQayJ8zvP20pGN9PbnGanruss6Wgnn/Un4L Um3JlOKBWLXr6L8RCAws4oR9IdKbYrr0kj7xojY1bdZksZbb/lBLt1FPF8zjcJL/5+rhNdH0RVADI 8rBboPaJQ==; Received: from 108-198-5-147.lightspeed.okcbok.sbcglobal.net ([108.198.5.147]:60292 helo=freyr.lechnology.com) by vern.gendns.com with esmtpsa (TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim 4.92) (envelope-from ) id 1hvRnz-00006r-2o; Wed, 07 Aug 2019 15:41:03 -0400 From: David Lechner To: linux-iio@vger.kernel.org, linux-omap@vger.kernel.org Cc: David Lechner , Rob Herring , Mark Rutland , =?utf-8?q?Beno=C3=AEt_Cousson?= , Tony Lindgren , William Breathitt Gray , Thierry Reding , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pwm@vger.kernel.org Subject: [PATCH v2 3/5] counter: new TI eQEP driver Date: Wed, 7 Aug 2019 14:40:21 -0500 Message-Id: <20190807194023.15318-4-david@lechnology.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190807194023.15318-1-david@lechnology.com> References: <20190807194023.15318-1-david@lechnology.com> X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - vern.gendns.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - lechnology.com X-Get-Message-Sender-Via: vern.gendns.com: authenticated_id: davidmain+lechnology.com/only user confirmed/virtual account not confirmed X-Authenticated-Sender: vern.gendns.com: davidmain@lechnology.com X-Source: X-Source-Args: X-Source-Dir: Sender: linux-omap-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This adds a new counter driver for the Texas Instruments Enhanced Quadrature Encoder Pulse (eQEP) module. Only very basic functionality is currently implemented - only enough to be able to read the position. The actual device has many more features which can be added to the driver on an as-needed basis. It is not possible to read the QEPA/B signal values in hardware, so that feature is omitted. The TI_PWMSS kernel option is selected in Kconfig to enable the parent bus, which is needed for power management. Signed-off-by: David Lechner --- v2 changes: - Dropped unused index and strobe signals - Added synapses and actions - Fixed base in of kstrtouint() - Clarifications in commit message MAINTAINERS | 6 + drivers/bus/Kconfig | 2 +- drivers/counter/Kconfig | 12 + drivers/counter/Makefile | 1 + drivers/counter/ti-eqep.c | 460 ++++++++++++++++++++++++++++++++++++++ 5 files changed, 480 insertions(+), 1 deletion(-) create mode 100644 drivers/counter/ti-eqep.c diff --git a/MAINTAINERS b/MAINTAINERS index 783569e3c4b4..53c28d52964c 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -16014,6 +16014,12 @@ S: Maintained F: drivers/media/platform/davinci/ F: include/media/davinci/ +TI ENHANCED QUADRATURE ENCODER PULSE (eQEP) DRIVER +R: David Lechner +L: linux-iio@vger.kernel.org +F: Documentation/devicetree/bindings/counter/ti-eqep.yaml +F: drivers/counter/ti-eqep.c + TI ETHERNET SWITCH DRIVER (CPSW) R: Grygorii Strashko L: linux-omap@vger.kernel.org diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig index 4eeb15839ce0..04db7fce4604 100644 --- a/drivers/bus/Kconfig +++ b/drivers/bus/Kconfig @@ -142,7 +142,7 @@ config TEGRA_GMI config TI_PWMSS bool - default y if (ARCH_OMAP2PLUS) && (PWM_TIECAP || PWM_TIEHRPWM) + default y if (ARCH_OMAP2PLUS) && (PWM_TIECAP || PWM_TIEHRPWM || TI_EQEP) help PWM Subsystem driver support for AM33xx SOC. diff --git a/drivers/counter/Kconfig b/drivers/counter/Kconfig index 2967d0a9ff91..7eeb310f0cda 100644 --- a/drivers/counter/Kconfig +++ b/drivers/counter/Kconfig @@ -49,6 +49,18 @@ config STM32_LPTIMER_CNT To compile this driver as a module, choose M here: the module will be called stm32-lptimer-cnt. +config TI_EQEP + tristate "TI eQEP counter driver" + depends on (SOC_AM33XX || COMPILE_TEST) + select PWM + select REGMAP_MMIO + help + Select this option to enable the Texas Instruments Enhanced Quadrature + Encoder Pulse (eQEP) counter driver. + + To compile this driver as a module, choose M here: the module will be + called ti-eqep. + config FTM_QUADDEC tristate "Flex Timer Module Quadrature decoder driver" depends on HAS_IOMEM && OF diff --git a/drivers/counter/Makefile b/drivers/counter/Makefile index 40d35522937d..55142d1f4c43 100644 --- a/drivers/counter/Makefile +++ b/drivers/counter/Makefile @@ -8,4 +8,5 @@ obj-$(CONFIG_COUNTER) += counter.o obj-$(CONFIG_104_QUAD_8) += 104-quad-8.o obj-$(CONFIG_STM32_TIMER_CNT) += stm32-timer-cnt.o obj-$(CONFIG_STM32_LPTIMER_CNT) += stm32-lptimer-cnt.o +obj-$(CONFIG_TI_EQEP) += ti-eqep.o obj-$(CONFIG_FTM_QUADDEC) += ftm-quaddec.o diff --git a/drivers/counter/ti-eqep.c b/drivers/counter/ti-eqep.c new file mode 100644 index 000000000000..a761b868c12b --- /dev/null +++ b/drivers/counter/ti-eqep.c @@ -0,0 +1,460 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2019 David Lechner + * + * Counter driver for Texas Instruments Enhanced Quadrature Encoder Pulse (eQEP) + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +/* 32-bit registers */ +#define QPOSCNT 0x0 +#define QPOSINIT 0x4 +#define QPOSMAX 0x8 +#define QPOSCMP 0xc +#define QPOSILAT 0x10 +#define QPOSSLAT 0x14 +#define QPOSLAT 0x18 +#define QUTMR 0x1c +#define QUPRD 0x20 + +/* 16-bit registers */ +#define QWDTMR 0x0 /* 0x24 */ +#define QWDPRD 0x2 /* 0x26 */ +#define QDECCTL 0x4 /* 0x28 */ +#define QEPCTL 0x6 /* 0x2a */ +#define QCAPCTL 0x8 /* 0x2c */ +#define QPOSCTL 0xa /* 0x2e */ +#define QEINT 0xc /* 0x30 */ +#define QFLG 0xe /* 0x32 */ +#define QCLR 0x10 /* 0x34 */ +#define QFRC 0x12 /* 0x36 */ +#define QEPSTS 0x14 /* 0x38 */ +#define QCTMR 0x16 /* 0x3a */ +#define QCPRD 0x18 /* 0x3c */ +#define QCTMRLAT 0x1a /* 0x3e */ +#define QCPRDLAT 0x1c /* 0x40 */ + +#define QDECCTL_QSRC_SHIFT 14 +#define QDECCTL_QSRC GENMASK(15, 14) +#define QDECCTL_SOEN BIT(13) +#define QDECCTL_SPSEL BIT(12) +#define QDECCTL_XCR BIT(11) +#define QDECCTL_SWAP BIT(10) +#define QDECCTL_IGATE BIT(9) +#define QDECCTL_QAP BIT(8) +#define QDECCTL_QBP BIT(7) +#define QDECCTL_QIP BIT(6) +#define QDECCTL_QSP BIT(5) + +#define QEPCTL_FREE_SOFT GENMASK(15, 14) +#define QEPCTL_PCRM GENMASK(13, 12) +#define QEPCTL_SEI GENMASK(11, 10) +#define QEPCTL_IEI GENMASK(9, 8) +#define QEPCTL_SWI BIT(7) +#define QEPCTL_SEL BIT(6) +#define QEPCTL_IEL GENMASK(5, 4) +#define QEPCTL_PHEN BIT(3) +#define QEPCTL_QCLM BIT(2) +#define QEPCTL_UTE BIT(1) +#define QEPCTL_WDE BIT(0) + +/* EQEP Inputs */ +enum { + TI_EQEP_SIGNAL_QEPA, /* QEPA/XCLK */ + TI_EQEP_SIGNAL_QEPB, /* QEPB/XDIR */ +}; + +/* Position Counter Input Modes */ +enum { + TI_EQEP_COUNT_FUNC_QUAD_COUNT, + TI_EQEP_COUNT_FUNC_DIR_COUNT, + TI_EQEP_COUNT_FUNC_UP_COUNT, + TI_EQEP_COUNT_FUNC_DOWN_COUNT, +}; + +enum { + TI_EQEP_SYNAPSE_ACTION_BOTH_EDGES, + TI_EQEP_SYNAPSE_ACTION_RISING_EDGE, + TI_EQEP_SYNAPSE_ACTION_NONE, +}; + +struct ti_eqep_cnt { + struct counter_device counter; + struct regmap *regmap32; + struct regmap *regmap16; +}; + +static int ti_eqep_count_read(struct counter_device *counter, + struct counter_count *count, + struct counter_count_read_value *val) +{ + struct ti_eqep_cnt *priv = counter->priv; + u32 cnt; + + regmap_read(priv->regmap32, QPOSCNT, &cnt); + counter_count_read_value_set(val, COUNTER_COUNT_POSITION, &cnt); + + return 0; +} + +static int ti_eqep_count_write(struct counter_device *counter, + struct counter_count *count, + struct counter_count_write_value *val) +{ + struct ti_eqep_cnt *priv = counter->priv; + u32 cnt, max; + int err; + + err = counter_count_write_value_get(&cnt, COUNTER_COUNT_POSITION, val); + if (err) + return err; + + regmap_read(priv->regmap32, QPOSMAX, &max); + if (cnt > max) + return -EINVAL; + + return regmap_write(priv->regmap32, QPOSCNT, cnt); +} + +static int ti_eqep_function_get(struct counter_device *counter, + struct counter_count *count, size_t *function) +{ + struct ti_eqep_cnt *priv = counter->priv; + u32 qdecctl; + + regmap_read(priv->regmap16, QDECCTL, &qdecctl); + *function = (qdecctl & QDECCTL_QSRC) >> QDECCTL_QSRC_SHIFT; + + return 0; +} + +static int ti_eqep_function_set(struct counter_device *counter, + struct counter_count *count, size_t function) +{ + struct ti_eqep_cnt *priv = counter->priv; + + return regmap_write_bits(priv->regmap16, QDECCTL, QDECCTL_QSRC, + function << QDECCTL_QSRC_SHIFT); +} + +static int ti_eqep_action_get(struct counter_device *counter, + struct counter_count *count, + struct counter_synapse *synapse, size_t *action) +{ + struct ti_eqep_cnt *priv = counter->priv; + size_t function; + u32 qdecctl; + int err; + + err = ti_eqep_function_get(counter, count, &function); + if (err) + return err; + + switch (function) { + case TI_EQEP_COUNT_FUNC_QUAD_COUNT: + /* In quadrature mode, the rising and falling edge of both + * QEPA and QEPB trigger QCLK. + */ + *action = TI_EQEP_SYNAPSE_ACTION_BOTH_EDGES; + break; + case TI_EQEP_COUNT_FUNC_DIR_COUNT: + /* In direction-count mode only rising edge of QEPA is counted + * and QEPB gives direction. + */ + switch (synapse->signal->id) { + case TI_EQEP_SIGNAL_QEPA: + *action = TI_EQEP_SYNAPSE_ACTION_RISING_EDGE; + break; + default: + *action = TI_EQEP_SYNAPSE_ACTION_NONE; + break; + } + break; + case TI_EQEP_COUNT_FUNC_UP_COUNT: + case TI_EQEP_COUNT_FUNC_DOWN_COUNT: + /* In up/down-count modes only QEPA is counted and QEPB is not + * used. + */ + switch (synapse->signal->id) { + case TI_EQEP_SIGNAL_QEPA: + err = regmap_read(priv->regmap16, QDECCTL, &qdecctl); + if (err) + return err; + + if (qdecctl & QDECCTL_XCR) + *action = TI_EQEP_SYNAPSE_ACTION_BOTH_EDGES; + else + *action = TI_EQEP_SYNAPSE_ACTION_RISING_EDGE; + break; + default: + *action = TI_EQEP_SYNAPSE_ACTION_NONE; + break; + } + break; + } + + return 0; +} + +static const struct counter_ops ti_eqep_counter_ops = { + .count_read = ti_eqep_count_read, + .count_write = ti_eqep_count_write, + .function_get = ti_eqep_function_get, + .function_set = ti_eqep_function_set, + .action_get = ti_eqep_action_get, +}; + +static ssize_t ti_eqep_position_ceiling_read(struct counter_device *counter, + struct counter_count *count, + void *ext_priv, char *buf) +{ + struct ti_eqep_cnt *priv = counter->priv; + u32 qposmax; + + regmap_read(priv->regmap32, QPOSMAX, &qposmax); + + return sprintf(buf, "%u\n", qposmax); +} + +static ssize_t ti_eqep_position_ceiling_write(struct counter_device *counter, + struct counter_count *count, + void *ext_priv, const char *buf, + size_t len) +{ + struct ti_eqep_cnt *priv = counter->priv; + int err; + u32 res; + + err = kstrtouint(buf, 0, &res); + if (err < 0) + return err; + + regmap_write(priv->regmap32, QPOSMAX, res); + + return len; +} + +static ssize_t ti_eqep_position_floor_read(struct counter_device *counter, + struct counter_count *count, + void *ext_priv, char *buf) +{ + struct ti_eqep_cnt *priv = counter->priv; + u32 qposinit; + + regmap_read(priv->regmap32, QPOSINIT, &qposinit); + + return sprintf(buf, "%u\n", qposinit); +} + +static ssize_t ti_eqep_position_floor_write(struct counter_device *counter, + struct counter_count *count, + void *ext_priv, const char *buf, + size_t len) +{ + struct ti_eqep_cnt *priv = counter->priv; + int err; + u32 res; + + err = kstrtouint(buf, 0, &res); + if (err < 0) + return err; + + regmap_write(priv->regmap32, QPOSINIT, res); + + return len; +} + +static ssize_t ti_eqep_position_enable_read(struct counter_device *counter, + struct counter_count *count, + void *ext_priv, char *buf) +{ + struct ti_eqep_cnt *priv = counter->priv; + u32 qepctl; + + regmap_read(priv->regmap16, QEPCTL, &qepctl); + + return sprintf(buf, "%u\n", !!(qepctl & QEPCTL_PHEN)); +} + +static ssize_t ti_eqep_position_enable_write(struct counter_device *counter, + struct counter_count *count, + void *ext_priv, const char *buf, + size_t len) +{ + struct ti_eqep_cnt *priv = counter->priv; + int err; + bool res; + + err = kstrtobool(buf, &res); + if (err < 0) + return err; + + regmap_write_bits(priv->regmap16, QEPCTL, QEPCTL_PHEN, res ? -1 : 0); + + return len; +} + +static struct counter_count_ext ti_eqep_position_ext[] = { + { + .name = "ceiling", + .read = ti_eqep_position_ceiling_read, + .write = ti_eqep_position_ceiling_write, + }, + { + .name = "floor", + .read = ti_eqep_position_floor_read, + .write = ti_eqep_position_floor_write, + }, + { + .name = "enable", + .read = ti_eqep_position_enable_read, + .write = ti_eqep_position_enable_write, + }, +}; + +static struct counter_signal ti_eqep_signals[] = { + [TI_EQEP_SIGNAL_QEPA] = { + .id = TI_EQEP_SIGNAL_QEPA, + .name = "QEPA" + }, + [TI_EQEP_SIGNAL_QEPB] = { + .id = TI_EQEP_SIGNAL_QEPB, + .name = "QEPB" + }, +}; + +static const enum counter_count_function ti_eqep_position_functions[] = { + [TI_EQEP_COUNT_FUNC_QUAD_COUNT] = COUNTER_COUNT_FUNCTION_QUADRATURE_X4, + [TI_EQEP_COUNT_FUNC_DIR_COUNT] = COUNTER_COUNT_FUNCTION_PULSE_DIRECTION, + [TI_EQEP_COUNT_FUNC_UP_COUNT] = COUNTER_COUNT_FUNCTION_INCREASE, + [TI_EQEP_COUNT_FUNC_DOWN_COUNT] = COUNTER_COUNT_FUNCTION_DECREASE, +}; + +static const enum counter_synapse_action ti_eqep_position_synapse_actions[] = { + [TI_EQEP_SYNAPSE_ACTION_BOTH_EDGES] = COUNTER_SYNAPSE_ACTION_BOTH_EDGES, + [TI_EQEP_SYNAPSE_ACTION_RISING_EDGE] = COUNTER_SYNAPSE_ACTION_RISING_EDGE, + [TI_EQEP_SYNAPSE_ACTION_NONE] = COUNTER_SYNAPSE_ACTION_NONE, +}; + +static struct counter_synapse ti_eqep_position_synapses[] = { + { + .action = TI_EQEP_SYNAPSE_ACTION_BOTH_EDGES, + .actions_list = ti_eqep_position_synapse_actions, + .num_actions = ARRAY_SIZE(ti_eqep_position_synapse_actions), + .signal = &ti_eqep_signals[TI_EQEP_SIGNAL_QEPA], + }, + { + .action = TI_EQEP_SYNAPSE_ACTION_BOTH_EDGES, + .actions_list = ti_eqep_position_synapse_actions, + .num_actions = ARRAY_SIZE(ti_eqep_position_synapse_actions), + .signal = &ti_eqep_signals[TI_EQEP_SIGNAL_QEPB], + }, +}; + +static struct counter_count ti_eqep_counts[] = { + { + .id = 0, + .name = "QPOSCNT", + .functions_list = ti_eqep_position_functions, + .num_functions = ARRAY_SIZE(ti_eqep_position_functions), + .synapses = ti_eqep_position_synapses, + .num_synapses = ARRAY_SIZE(ti_eqep_position_synapses), + .ext = ti_eqep_position_ext, + .num_ext = ARRAY_SIZE(ti_eqep_position_ext), + }, +}; + +static const struct regmap_config ti_eqep_regmap32_config = { + .name = "32-bit", + .reg_bits = 32, + .val_bits = 32, + .reg_stride = 4, + .max_register = 0x24, +}; + +static const struct regmap_config ti_eqep_regmap16_config = { + .name = "16-bit", + .reg_bits = 16, + .val_bits = 16, + .reg_stride = 2, + .max_register = 0x1e, +}; + +static int ti_eqep_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct ti_eqep_cnt *priv; + struct resource *res; + void __iomem *base; + + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + base = devm_ioremap_resource(dev, res); + if (IS_ERR(base)) + return PTR_ERR(base); + + priv->regmap32 = devm_regmap_init_mmio(dev, base, + &ti_eqep_regmap32_config); + if (IS_ERR(priv->regmap32)) + return PTR_ERR(priv->regmap32); + + priv->regmap16 = devm_regmap_init_mmio(dev, base + 0x24, + &ti_eqep_regmap16_config); + if (IS_ERR(priv->regmap16)) + return PTR_ERR(priv->regmap16); + + priv->counter.name = dev_name(dev); + priv->counter.parent = dev; + priv->counter.ops = &ti_eqep_counter_ops; + priv->counter.counts = ti_eqep_counts; + priv->counter.num_counts = ARRAY_SIZE(ti_eqep_counts); + priv->counter.signals = ti_eqep_signals; + priv->counter.num_signals = ARRAY_SIZE(ti_eqep_signals); + priv->counter.priv = priv; + + pm_runtime_enable(dev); + pm_runtime_get(dev); + + return devm_counter_register(dev, &priv->counter); +} + +static int ti_eqep_remove(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + + pm_runtime_put(dev), + pm_runtime_disable(dev); + + return 0; +} + +static const struct of_device_id ti_eqep_of_match[] = { + { .compatible = "ti,am3352-eqep", }, + { }, +}; +MODULE_DEVICE_TABLE(of, ti_eqep_of_match); + +static struct platform_driver ti_eqep_driver = { + .probe = ti_eqep_probe, + .remove = ti_eqep_remove, + .driver = { + .name = "ti-eqep-cnt", + .of_match_table = ti_eqep_of_match, + }, +}; +module_platform_driver(ti_eqep_driver); + +MODULE_AUTHOR("David Lechner "); +MODULE_DESCRIPTION("TI eQEP counter driver"); +MODULE_LICENSE("GPL v2");