From patchwork Tue Aug 31 07:14:55 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Billy Tsai X-Patchwork-Id: 12466589 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 C22C5C432BE for ; Tue, 31 Aug 2021 07:14:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9973A60200 for ; Tue, 31 Aug 2021 07:14:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239340AbhHaHPq (ORCPT ); Tue, 31 Aug 2021 03:15:46 -0400 Received: from twspam01.aspeedtech.com ([211.20.114.71]:16726 "EHLO twspam01.aspeedtech.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239324AbhHaHPq (ORCPT ); Tue, 31 Aug 2021 03:15:46 -0400 Received: from mail.aspeedtech.com ([192.168.0.24]) by twspam01.aspeedtech.com with ESMTP id 17V6sdx6028275; Tue, 31 Aug 2021 14:54:39 +0800 (GMT-8) (envelope-from billy_tsai@aspeedtech.com) Received: from BillyTsai-pc.aspeed.com (192.168.2.149) by TWMBX02.aspeed.com (192.168.0.24) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Tue, 31 Aug 2021 15:13:36 +0800 From: Billy Tsai To: , , , , , , , , , , , , , CC: Subject: [v5 12/15] iio: adc: aspeed: Add func to set sampling rate. Date: Tue, 31 Aug 2021 15:14:55 +0800 Message-ID: <20210831071458.2334-13-billy_tsai@aspeedtech.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210831071458.2334-1-billy_tsai@aspeedtech.com> References: <20210831071458.2334-1-billy_tsai@aspeedtech.com> MIME-Version: 1.0 X-Originating-IP: [192.168.2.149] X-ClientProxiedBy: TWMBX02.aspeed.com (192.168.0.24) To TWMBX02.aspeed.com (192.168.0.24) X-DNSRBL: X-MAIL: twspam01.aspeedtech.com 17V6sdx6028275 Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org Add the function to set the sampling rate and keep the sampling period for a driver used to wait the fresh value. In addition, since the ADC clock is required when initializing the ADC device, move clk_prepare_enable ahead of the initialization phase. Signed-off-by: Billy Tsai --- drivers/iio/adc/aspeed_adc.c | 59 ++++++++++++++++++++++++------------ 1 file changed, 40 insertions(+), 19 deletions(-) diff --git a/drivers/iio/adc/aspeed_adc.c b/drivers/iio/adc/aspeed_adc.c index 349377b9fac0..1333d7a88427 100644 --- a/drivers/iio/adc/aspeed_adc.c +++ b/drivers/iio/adc/aspeed_adc.c @@ -73,6 +73,12 @@ #define ASPEED_ADC_INIT_POLLING_TIME 500 #define ASPEED_ADC_INIT_TIMEOUT 500000 +/* + * When the sampling rate is too high, the ADC may not have enough charging + * time, resulting in a low voltage value. Thus, the default uses a slow + * sampling rate for most use cases. + */ +#define ASPEED_ADC_DEF_SAMPLING_RATE 65000 struct aspeed_adc_model_data { const char *model_name; @@ -96,6 +102,7 @@ struct aspeed_adc_data { struct clk_hw *clk_scaler; struct reset_control *rst; int vref_mv; + u32 sample_period_ns; }; #define ASPEED_CHAN(_idx, _data_reg_addr) { \ @@ -127,6 +134,24 @@ static const struct iio_chan_spec aspeed_adc_iio_channels[] = { ASPEED_CHAN(15, 0x2E), }; +static int aspeed_adc_set_sampling_rate(struct iio_dev *indio_dev, u32 rate) +{ + struct aspeed_adc_data *data = iio_priv(indio_dev); + + if (rate < data->model_data->min_sampling_rate || + rate > data->model_data->max_sampling_rate) + return -EINVAL; + /* Each sampling needs 12 clocks to convert.*/ + clk_set_rate(data->clk_scaler->clk, rate * ASPEED_CLOCKS_PER_SAMPLE); + rate = clk_get_rate(data->clk_scaler->clk); + data->sample_period_ns = DIV_ROUND_UP_ULL( + (u64)NSEC_PER_SEC * ASPEED_CLOCKS_PER_SAMPLE, rate); + dev_dbg(data->dev, "Adc clock = %d sample period = %d ns", rate, + data->sample_period_ns); + + return 0; +} + static int aspeed_adc_read_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan, int *val, int *val2, long mask) @@ -157,17 +182,9 @@ static int aspeed_adc_write_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan, int val, int val2, long mask) { - struct aspeed_adc_data *data = iio_priv(indio_dev); - switch (mask) { case IIO_CHAN_INFO_SAMP_FREQ: - if (val < data->model_data->min_sampling_rate || - val > data->model_data->max_sampling_rate) - return -EINVAL; - - clk_set_rate(data->clk_scaler->clk, - val * ASPEED_CLOCKS_PER_SAMPLE); - return 0; + return aspeed_adc_set_sampling_rate(indio_dev, val); case IIO_CHAN_INFO_SCALE: case IIO_CHAN_INFO_RAW: @@ -409,6 +426,20 @@ static int aspeed_adc_probe(struct platform_device *pdev) if (ret) return ret; + ret = clk_prepare_enable(data->clk_scaler->clk); + if (ret) + return ret; + + ret = devm_add_action_or_reset(data->dev, + aspeed_adc_clk_disable_unprepare, + data->clk_scaler->clk); + if (ret) + return ret; + + ret = aspeed_adc_set_sampling_rate(indio_dev, ASPEED_ADC_DEF_SAMPLING_RATE); + if (ret) + return ret; + if (data->model_data->wait_init_sequence) { adc_engine_control_reg_val = readl(data->base + ASPEED_REG_ENGINE_CONTROL); @@ -436,16 +467,6 @@ static int aspeed_adc_probe(struct platform_device *pdev) } /* Start all channels in normal mode. */ - ret = clk_prepare_enable(data->clk_scaler->clk); - if (ret) - return ret; - - ret = devm_add_action_or_reset(data->dev, - aspeed_adc_clk_disable_unprepare, - data->clk_scaler->clk); - if (ret) - return ret; - adc_engine_control_reg_val = readl(data->base + ASPEED_REG_ENGINE_CONTROL); adc_engine_control_reg_val |=