From patchwork Fri Jul 23 08:16:18 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Billy Tsai X-Patchwork-Id: 12395503 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,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 4A136C4338F for ; Fri, 23 Jul 2021 08:16:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2DA4260E8E for ; Fri, 23 Jul 2021 08:16:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234030AbhGWHf2 (ORCPT ); Fri, 23 Jul 2021 03:35:28 -0400 Received: from twspam01.aspeedtech.com ([211.20.114.71]:29947 "EHLO twspam01.aspeedtech.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234348AbhGWHf2 (ORCPT ); Fri, 23 Jul 2021 03:35:28 -0400 Received: from mail.aspeedtech.com ([192.168.0.24]) by twspam01.aspeedtech.com with ESMTP id 16N7x6Su041951; Fri, 23 Jul 2021 15:59:06 +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; Fri, 23 Jul 2021 16:15:40 +0800 From: Billy Tsai To: , , , , , , , , , , , CC: Subject: [v2 5/8] iio: adc: aspeed: Add func to set sampling rate. Date: Fri, 23 Jul 2021 16:16:18 +0800 Message-ID: <20210723081621.29477-6-billy_tsai@aspeedtech.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210723081621.29477-1-billy_tsai@aspeedtech.com> References: <20210723081621.29477-1-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 16N7x6Su041951 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 lastest value. Signed-off-by: Billy Tsai --- drivers/iio/adc/aspeed_adc.c | 48 +++++++++++++++++++++++++----------- 1 file changed, 33 insertions(+), 15 deletions(-) diff --git a/drivers/iio/adc/aspeed_adc.c b/drivers/iio/adc/aspeed_adc.c index 84f079195375..bb6100228cae 100644 --- a/drivers/iio/adc/aspeed_adc.c +++ b/drivers/iio/adc/aspeed_adc.c @@ -55,6 +55,12 @@ #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, default use slow sampling + * rate for most user case. + */ +#define ASPEED_ADC_DEF_SAMPLING_RATE 65000 enum aspeed_adc_version { aspeed_adc_ast2400, @@ -77,6 +83,7 @@ struct aspeed_adc_data { struct clk_hw *clk_scaler; struct reset_control *rst; int vref; + u32 sample_period_ns; }; #define ASPEED_CHAN(_idx, _data_reg_addr) { \ @@ -108,6 +115,26 @@ 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); + const struct aspeed_adc_model_data *model_data = + of_device_get_match_data(data->dev); + + if (rate < model_data->min_sampling_rate || + rate > model_data->max_sampling_rate) + return -EINVAL; + /* Each sampling needs 12 clocks to covert.*/ + 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) @@ -138,19 +165,9 @@ 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); - const struct aspeed_adc_model_data *model_data = - of_device_get_match_data(data->dev); - switch (mask) { case IIO_CHAN_INFO_SAMP_FREQ: - if (val < model_data->min_sampling_rate || - val > 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: @@ -302,6 +319,10 @@ static int aspeed_adc_probe(struct platform_device *pdev) goto reset_error; } reset_control_deassert(data->rst); + ret = clk_prepare_enable(data->clk_scaler->clk); + if (ret) + goto clk_enable_error; + aspeed_adc_set_sampling_rate(indio_dev, ASPEED_ADC_DEF_SAMPLING_RATE); ret = aspeed_adc_vref_config(pdev); if (ret) @@ -327,9 +348,6 @@ static int aspeed_adc_probe(struct platform_device *pdev) goto poll_timeout_error; } - ret = clk_prepare_enable(data->clk_scaler->clk); - if (ret) - goto clk_enable_error; adc_engine_control_reg_val = readl(data->base + ASPEED_REG_ENGINE_CONTROL); /* Start all channels in normal mode. */ @@ -354,8 +372,8 @@ static int aspeed_adc_probe(struct platform_device *pdev) iio_register_error: writel(ASPEED_ADC_OPERATION_MODE_POWER_DOWN, data->base + ASPEED_REG_ENGINE_CONTROL); - clk_disable_unprepare(data->clk_scaler->clk); vref_config_error: + clk_disable_unprepare(data->clk_scaler->clk); clk_enable_error: poll_timeout_error: reset_control_assert(data->rst);