From patchwork Mon Sep 13 07:53:34 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Billy Tsai X-Patchwork-Id: 12488057 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 43138C433EF for ; Mon, 13 Sep 2021 07:51:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2F97F60FDA for ; Mon, 13 Sep 2021 07:51:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237739AbhIMHxB (ORCPT ); Mon, 13 Sep 2021 03:53:01 -0400 Received: from twspam01.aspeedtech.com ([211.20.114.71]:40273 "EHLO twspam01.aspeedtech.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237788AbhIMHxB (ORCPT ); Mon, 13 Sep 2021 03:53:01 -0400 Received: from mail.aspeedtech.com ([192.168.0.24]) by twspam01.aspeedtech.com with ESMTP id 18D7VMhl004723; Mon, 13 Sep 2021 15:31:22 +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; Mon, 13 Sep 2021 15:51:07 +0800 From: Billy Tsai To: , , , , , , , , , , , , , CC: Subject: [v6 08/11] iio: adc: aspeed: Add func to set sampling rate. Date: Mon, 13 Sep 2021 15:53:34 +0800 Message-ID: <20210913075337.19991-9-billy_tsai@aspeedtech.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210913075337.19991-1-billy_tsai@aspeedtech.com> References: <20210913075337.19991-1-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 18D7VMhl004723 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 | 58 ++++++++++++++++++++++++------------ 1 file changed, 39 insertions(+), 19 deletions(-) diff --git a/drivers/iio/adc/aspeed_adc.c b/drivers/iio/adc/aspeed_adc.c index 262b5f80c728..cf1e0be9d11f 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: @@ -392,6 +409,19 @@ 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; + adc_engine_control_reg_val = readl(data->base + ASPEED_REG_ENGINE_CONTROL); adc_engine_control_reg_val |= @@ -418,16 +448,6 @@ static int aspeed_adc_probe(struct platform_device *pdev) 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; - /* Start all channels in normal mode. */ adc_engine_control_reg_val = readl(data->base + ASPEED_REG_ENGINE_CONTROL);