From patchwork Thu May 23 09:07:35 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fabien Lahoudere X-Patchwork-Id: 10957139 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 E5A5614B6 for ; Thu, 23 May 2019 09:08:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C1E7327F2B for ; Thu, 23 May 2019 09:08:09 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B581E27F82; Thu, 23 May 2019 09:08:09 +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=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham 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 19E3C27F2B for ; Thu, 23 May 2019 09:08:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729996AbfEWJII (ORCPT ); Thu, 23 May 2019 05:08:08 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:34588 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726913AbfEWJII (ORCPT ); Thu, 23 May 2019 05:08:08 -0400 Received: from laptop.home (unknown [IPv6:2a01:cb19:8ad6:900:42dd:dd1c:19ee:7c60]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: aragua) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id BC331280175; Thu, 23 May 2019 10:08:05 +0100 (BST) From: Fabien Lahoudere Cc: kernel@collabora.com, Fabien Lahoudere , Nick Vaccaro , Jonathan Cameron , Hartmut Knaack , Lars-Peter Clausen , Peter Meerwald-Stadler , Benson Leung , Enric Balletbo i Serra , Guenter Roeck , Lee Jones , Gwendal Grignou , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/3] iio: common: cros_ec_sensors: support protocol v3 message Date: Thu, 23 May 2019 11:07:35 +0200 Message-Id: X-Mailer: git-send-email 2.19.2 In-Reply-To: References: MIME-Version: 1.0 To: unlisted-recipients:; (no To-header on input) Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Version 3 of the EC protocol provides min and max frequencies and fifo size for EC sensors. Signed-off-by: Fabien Lahoudere Signed-off-by: Nick Vaccaro --- .../cros_ec_sensors/cros_ec_sensors_core.c | 83 ++++++++++++++++++- .../linux/iio/common/cros_ec_sensors_core.h | 4 + include/linux/mfd/cros_ec_commands.h | 21 +++++ 3 files changed, 107 insertions(+), 1 deletion(-) diff --git a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c index 719a0df5aeeb..ac53ea32c1b1 100644 --- a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c +++ b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c @@ -25,6 +25,67 @@ static char *cros_ec_loc[] = { [MOTIONSENSE_LOC_MAX] = "unknown", }; +static void get_default_min_max_freq(enum motionsensor_type type, + u32 *min_freq, + u32 *max_freq) +{ + switch (type) { + case MOTIONSENSE_TYPE_ACCEL: + case MOTIONSENSE_TYPE_GYRO: + *min_freq = 12500; + *max_freq = 100000; + break; + case MOTIONSENSE_TYPE_MAG: + *min_freq = 5000; + *max_freq = 25000; + break; + case MOTIONSENSE_TYPE_PROX: + case MOTIONSENSE_TYPE_LIGHT: + *min_freq = 100; + *max_freq = 50000; + break; + case MOTIONSENSE_TYPE_BARO: + *min_freq = 250; + *max_freq = 20000; + break; + case MOTIONSENSE_TYPE_ACTIVITY: + default: + *min_freq = 0; + *max_freq = 0; + break; + } +} + +static int cros_ec_get_host_cmd_version_mask(struct cros_ec_device *ec_dev, + u16 cmd_offset, u16 cmd, u32 *mask) +{ + struct { + struct cros_ec_command msg; + union { + struct ec_params_get_cmd_versions params; + struct ec_response_get_cmd_versions resp; + }; + } __packed buf; + struct ec_params_get_cmd_versions *params = &buf.params; + struct ec_response_get_cmd_versions *resp = &buf.resp; + struct cros_ec_command *msg = &buf.msg; + int ret; + + memset(&buf, 0, sizeof(buf)); + msg->command = EC_CMD_GET_CMD_VERSIONS + cmd_offset; + msg->insize = sizeof(*resp); + msg->outsize = sizeof(*params); + params->cmd = cmd; + ret = cros_ec_cmd_xfer_status(ec_dev, msg); + if (ret >= 0) { + if (msg->result == EC_RES_SUCCESS) + *mask = resp->version_mask; + else + *mask = 0; + } + return ret; +} + int cros_ec_sensors_core_init(struct platform_device *pdev, struct iio_dev *indio_dev, bool physical_device) @@ -33,6 +94,8 @@ int cros_ec_sensors_core_init(struct platform_device *pdev, struct cros_ec_sensors_core_state *state = iio_priv(indio_dev); struct cros_ec_dev *ec = dev_get_drvdata(pdev->dev.parent); struct cros_ec_sensor_platform *sensor_platform = dev_get_platdata(dev); + u32 ver_mask; + int ret; platform_set_drvdata(pdev, indio_dev); @@ -47,8 +110,16 @@ int cros_ec_sensors_core_init(struct platform_device *pdev, mutex_init(&state->cmd_lock); + /* determine what version of MOTIONSENSE CMD EC has */ + ret = cros_ec_get_host_cmd_version_mask(state->ec, + ec->cmd_offset, + EC_CMD_MOTION_SENSE_CMD, + &ver_mask); + if (ret < 0 || ver_mask == 0) + return -ENODEV; + /* Set up the host command structure. */ - state->msg->version = 2; + state->msg->version = fls(ver_mask) - 1; state->msg->command = EC_CMD_MOTION_SENSE_CMD + ec->cmd_offset; state->msg->outsize = sizeof(struct ec_params_motion_sense); @@ -66,6 +137,16 @@ int cros_ec_sensors_core_init(struct platform_device *pdev, } state->type = state->resp->info.type; state->loc = state->resp->info.location; + if (state->msg->version < 3) { + get_default_min_max_freq(state->resp->info.type, + &state->min_freq, + &state->max_freq); + } else { + state->min_freq = + state->resp->info_3.min_frequency; + state->max_freq = + state->resp->info_3.max_frequency; + } } return 0; diff --git a/include/linux/iio/common/cros_ec_sensors_core.h b/include/linux/iio/common/cros_ec_sensors_core.h index ce16445411ac..32fd08bbcf52 100644 --- a/include/linux/iio/common/cros_ec_sensors_core.h +++ b/include/linux/iio/common/cros_ec_sensors_core.h @@ -78,6 +78,10 @@ struct cros_ec_sensors_core_state { unsigned long scan_mask, s16 *data); int curr_sampl_freq; + + /* Min and Max Sampling Frequency in mHz */ + u32 min_freq; + u32 max_freq; }; /** diff --git a/include/linux/mfd/cros_ec_commands.h b/include/linux/mfd/cros_ec_commands.h index dcec96f01879..db2e3a9a656e 100644 --- a/include/linux/mfd/cros_ec_commands.h +++ b/include/linux/mfd/cros_ec_commands.h @@ -1744,6 +1744,27 @@ struct ec_response_motion_sense { uint8_t chip; } info; + /* Used for MOTIONSENSE_CMD_INFO version 3 */ + struct __ec_todo_unpacked { + /* Should be element of enum motionsensor_type. */ + uint8_t type; + + /* Should be element of enum motionsensor_location. */ + uint8_t location; + + /* Should be element of enum motionsensor_chip. */ + uint8_t chip; + + /* Minimum sensor sampling frequency */ + uint32_t min_frequency; + + /* Maximum sensor sampling frequency */ + uint32_t max_frequency; + + /* Reserved field */ + uint32_t reserved; + } info_3; + /* Used for MOTIONSENSE_CMD_DATA */ struct ec_response_motion_sensor_data data; From patchwork Thu May 23 09:07:36 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fabien Lahoudere X-Patchwork-Id: 10957141 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 A6F9814B6 for ; Thu, 23 May 2019 09:08:19 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8514F26AE3 for ; Thu, 23 May 2019 09:08:19 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 78C5927F7F; Thu, 23 May 2019 09:08:19 +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=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham 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 BF19926AE3 for ; Thu, 23 May 2019 09:08:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726913AbfEWJIR (ORCPT ); Thu, 23 May 2019 05:08:17 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:34600 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726429AbfEWJIR (ORCPT ); Thu, 23 May 2019 05:08:17 -0400 Received: from laptop.home (unknown [IPv6:2a01:cb19:8ad6:900:42dd:dd1c:19ee:7c60]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: aragua) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id 3860D26C4A5; Thu, 23 May 2019 10:08:15 +0100 (BST) From: Fabien Lahoudere Cc: kernel@collabora.com, Fabien Lahoudere , Jonathan Cameron , Hartmut Knaack , Lars-Peter Clausen , Peter Meerwald-Stadler , Benson Leung , Enric Balletbo i Serra , Guenter Roeck , Lee Jones , Gwendal Grignou , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 2/3] iio: common: cros_ec_sensors: add sysfs attribute for frequencies Date: Thu, 23 May 2019 11:07:36 +0200 Message-Id: X-Mailer: git-send-email 2.19.2 In-Reply-To: References: MIME-Version: 1.0 To: unlisted-recipients:; (no To-header on input) Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP In order to provide minimum and maximum frequencies for each sensors, we use a standard API (sampling_frequency_available) to provide them to userland. As cros_ec_sensors_core_init do not manage default attrs, we change the signature to let all kind of sensors to provide "struct iio_info" with their callback. This change impact drivers using that function. Then cros_ec_* sensors provides frequencies range in sysfs like this: [min step max] Signed-off-by: Fabien Lahoudere --- .../common/cros_ec_sensors/cros_ec_sensors.c | 6 +-- .../cros_ec_sensors/cros_ec_sensors_core.c | 38 +++++++++++++++++++ drivers/iio/light/cros_ec_light_prox.c | 6 +-- drivers/iio/pressure/cros_ec_baro.c | 6 +-- .../linux/iio/common/cros_ec_sensors_core.h | 4 +- 5 files changed, 50 insertions(+), 10 deletions(-) diff --git a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c index 17af4e0fd5f8..a0ecee15a6c8 100644 --- a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c +++ b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c @@ -172,7 +172,7 @@ static int cros_ec_sensors_write(struct iio_dev *indio_dev, return ret; } -static const struct iio_info ec_sensors_info = { +static struct iio_info ec_sensors_info = { .read_raw = &cros_ec_sensors_read, .write_raw = &cros_ec_sensors_write, }; @@ -195,11 +195,11 @@ static int cros_ec_sensors_probe(struct platform_device *pdev) if (!indio_dev) return -ENOMEM; - ret = cros_ec_sensors_core_init(pdev, indio_dev, true); + ret = cros_ec_sensors_core_init(pdev, indio_dev, &ec_sensors_info, + true); if (ret) return ret; - indio_dev->info = &ec_sensors_info; state = iio_priv(indio_dev); for (channel = state->channels, i = CROS_EC_SENSOR_X; i < CROS_EC_SENSOR_MAX_AXIS; i++, channel++) { diff --git a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c index ac53ea32c1b1..08fb5d3dc7b5 100644 --- a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c +++ b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c @@ -10,6 +10,7 @@ #include #include #include +#include #include #include #include @@ -86,8 +87,42 @@ static int cros_ec_get_host_cmd_version_mask(struct cros_ec_device *ec_dev, return ret; } +/** + * cros_ec_sensors_read_freq() - sysfs function to get available frequencies + * @dev: Device structure for this device. + * @attr: Description of the attribute. + * @buf: Incoming string + * + * The later modes are only relevant to the ring buffer - and depend on current + * mode. Note that data sheet gives rather wide tolerances for these so integer + * division will give good enough answer and not all chips have them specified + * at all. + **/ +static ssize_t cros_ec_sensors_read_freq(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct iio_dev *indio_dev = dev_to_iio_dev(dev); + struct cros_ec_sensors_core_state *state = iio_priv(indio_dev); + + return snprintf(buf, PAGE_SIZE, "[%d 1 %d]\n", state->min_freq, + state->max_freq); +} + +static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(cros_ec_sensors_read_freq); + +static struct attribute *cros_ec_sensors_attributes[] = { + &iio_dev_attr_sampling_frequency_available.dev_attr.attr, + NULL, +}; + +static const struct attribute_group cros_ec_sensors_attribute_group = { + .attrs = cros_ec_sensors_attributes, +}; + int cros_ec_sensors_core_init(struct platform_device *pdev, struct iio_dev *indio_dev, + struct iio_info *info, bool physical_device) { struct device *dev = &pdev->dev; @@ -149,6 +184,9 @@ int cros_ec_sensors_core_init(struct platform_device *pdev, } } + info->attrs = &cros_ec_sensors_attribute_group; + indio_dev->info = info; + return 0; } EXPORT_SYMBOL_GPL(cros_ec_sensors_core_init); diff --git a/drivers/iio/light/cros_ec_light_prox.c b/drivers/iio/light/cros_ec_light_prox.c index 308ee6ff2e22..1772e339cf14 100644 --- a/drivers/iio/light/cros_ec_light_prox.c +++ b/drivers/iio/light/cros_ec_light_prox.c @@ -161,7 +161,7 @@ static int cros_ec_light_prox_write(struct iio_dev *indio_dev, return ret; } -static const struct iio_info cros_ec_light_prox_info = { +static struct iio_info cros_ec_light_prox_info = { .read_raw = &cros_ec_light_prox_read, .write_raw = &cros_ec_light_prox_write, }; @@ -184,11 +184,11 @@ static int cros_ec_light_prox_probe(struct platform_device *pdev) if (!indio_dev) return -ENOMEM; - ret = cros_ec_sensors_core_init(pdev, indio_dev, true); + ret = cros_ec_sensors_core_init(pdev, indio_dev, + &cros_ec_light_prox_info, true); if (ret) return ret; - indio_dev->info = &cros_ec_light_prox_info; state = iio_priv(indio_dev); state->core.type = state->core.resp->info.type; state->core.loc = state->core.resp->info.location; diff --git a/drivers/iio/pressure/cros_ec_baro.c b/drivers/iio/pressure/cros_ec_baro.c index 034ce98d6e97..cd3be0f16226 100644 --- a/drivers/iio/pressure/cros_ec_baro.c +++ b/drivers/iio/pressure/cros_ec_baro.c @@ -107,7 +107,7 @@ static int cros_ec_baro_write(struct iio_dev *indio_dev, return ret; } -static const struct iio_info cros_ec_baro_info = { +static struct iio_info cros_ec_baro_info = { .read_raw = &cros_ec_baro_read, .write_raw = &cros_ec_baro_write, }; @@ -130,11 +130,11 @@ static int cros_ec_baro_probe(struct platform_device *pdev) if (!indio_dev) return -ENOMEM; - ret = cros_ec_sensors_core_init(pdev, indio_dev, true); + ret = cros_ec_sensors_core_init(pdev, indio_dev, &cros_ec_baro_info, + true); if (ret) return ret; - indio_dev->info = &cros_ec_baro_info; state = iio_priv(indio_dev); state->core.type = state->core.resp->info.type; state->core.loc = state->core.resp->info.location; diff --git a/include/linux/iio/common/cros_ec_sensors_core.h b/include/linux/iio/common/cros_ec_sensors_core.h index 32fd08bbcf52..f170a72ac08d 100644 --- a/include/linux/iio/common/cros_ec_sensors_core.h +++ b/include/linux/iio/common/cros_ec_sensors_core.h @@ -114,12 +114,14 @@ struct platform_device; * cros_ec_sensors_core_init() - basic initialization of the core structure * @pdev: platform device created for the sensors * @indio_dev: iio device structure of the device + * @info: iio info structure with read and write callback * @physical_device: true if the device refers to a physical device * * Return: 0 on success, -errno on failure. */ int cros_ec_sensors_core_init(struct platform_device *pdev, - struct iio_dev *indio_dev, bool physical_device); + struct iio_dev *indio_dev, struct iio_info *info, + bool physical_device); /** * cros_ec_sensors_capture() - the trigger handler function From patchwork Thu May 23 09:07:37 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fabien Lahoudere X-Patchwork-Id: 10957143 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 AFF461395 for ; Thu, 23 May 2019 09:08:27 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8F19F26AE3 for ; Thu, 23 May 2019 09:08:27 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 82C4F27F7F; Thu, 23 May 2019 09:08:27 +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=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham 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 2745B26AE3 for ; Thu, 23 May 2019 09:08:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730236AbfEWJI0 (ORCPT ); Thu, 23 May 2019 05:08:26 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:34608 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726429AbfEWJI0 (ORCPT ); Thu, 23 May 2019 05:08:26 -0400 Received: from laptop.home (unknown [IPv6:2a01:cb19:8ad6:900:42dd:dd1c:19ee:7c60]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: aragua) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id B74EC280175; Thu, 23 May 2019 10:08:24 +0100 (BST) From: Fabien Lahoudere Cc: kernel@collabora.com, Fabien Lahoudere , Jonathan Cameron , Hartmut Knaack , Lars-Peter Clausen , Peter Meerwald-Stadler , Benson Leung , Enric Balletbo i Serra , Guenter Roeck , Lee Jones , Gwendal Grignou , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 3/3] docs: iio: add precision about sampling_frequency_available Date: Thu, 23 May 2019 11:07:37 +0200 Message-Id: X-Mailer: git-send-email 2.19.2 In-Reply-To: References: MIME-Version: 1.0 To: unlisted-recipients:; (no To-header on input) Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The documentation give some exemple on what format can be expected from sampling_frequency_available sysfs attribute Signed-off-by: Fabien Lahoudere --- Documentation/ABI/testing/sysfs-bus-iio | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio index 6aef7dbbde44..680451695422 100644 --- a/Documentation/ABI/testing/sysfs-bus-iio +++ b/Documentation/ABI/testing/sysfs-bus-iio @@ -61,8 +61,11 @@ What: /sys/bus/iio/devices/triggerX/sampling_frequency_available KernelVersion: 2.6.35 Contact: linux-iio@vger.kernel.org Description: - When the internal sampling clock can only take a small - discrete set of values, this file lists those available. + When the internal sampling clock can only take a specific set of + frequencies, we can specify the available values with: + - a small discrete set of values like "0 2 4 6 8" + - a range with minimum, step and maximum frequencies like + "[min step max]" What: /sys/bus/iio/devices/iio:deviceX/oversampling_ratio KernelVersion: 2.6.38