From mboxrd@z Thu Jan 1 00:00:00 1970 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=-18.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 EAE29C433F5 for ; Wed, 22 Sep 2021 10:53:51 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id AE03F610A1 for ; Wed, 22 Sep 2021 10:53:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org AE03F610A1 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=aspeedtech.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:CC:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=L/LqJEGb4xnCaO41tmaTNrfRunnX17PgIcH+TiabVp0=; b=L50w5WFsrPu1EI HbPIGjDKBIGzt46rHKRGM5E1uf/u6hm0l7B0ztWBsA/vnBq3B8FvW6hcyqlc9NJPzFQn04wjAAV1G qC7MZSV53uCPeFv+tsKfJQgFy5mUe7sUHX0pj8ciinKEocun7ufzYvQh/EetQhc1r9zCSi+poDn0o s9xNQKwBn90How847Jt3Nc12wajpzG3hw7I+X9wIBG2TgLTs8R+6S/Up7X45h0aS1atV8knx9XI8N Dy6w8j4kOocsstVvqIsAZf/OIYVt0jguNrtMs46aXQwxEiC1gnfgGUNdz1OgpCePtEjTQNOyvt6ST uLliIvh7J3B/mkRItx/g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mSzqO-0087Xk-Me; Wed, 22 Sep 2021 10:51:17 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mSzav-007qgZ-1O for linux-arm-kernel@bombadil.infradead.org; Wed, 22 Sep 2021 10:35:17 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Type:Content-Transfer-Encoding :MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:CC:To:From: Sender:Reply-To:Content-ID:Content-Description; bh=/n3s0Q6mzjuOItlrUxGG8SbwZJRPX9T+mZ3y7Ik/4ns=; b=i6fdRnC7oGeDDC1h0DNGqGe1Wr omqjuWjms9DhTbz+GjPd+Di/jwRhkN3C/yj1UEhehyA6cKGV6ctQvhNYMkSPp64FhXAfDAYlHbbcn cS7DUS29XS8BHRa7HWCbs0bw/0StQTNrZeyYxXEIaemCwbgtq0xvY509InXlBwz4dHqVTPEMGvkNo L9gNs1VXH9O80sKpi98heOo4WajH3OGOWqagVlI0iYCI/G52Qw7RKTs5YYnfGtnOi/RMiextPtvtZ F9c6Zng4Wzf/psrweRADnNbe9AB15VvS1iji512sCZTyliAr6xP9m7MTJbW5DDHXWumt4lNYR5RRX UAzpWZ/g==; Received: from twspam01.aspeedtech.com ([211.20.114.71]) by desiato.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mSxQD-004x9Q-W5 for linux-arm-kernel@lists.infradead.org; Wed, 22 Sep 2021 08:16:08 +0000 Received: from mail.aspeedtech.com ([192.168.0.24]) by twspam01.aspeedtech.com with ESMTP id 18M7sdVP099796; Wed, 22 Sep 2021 15:54:39 +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; Wed, 22 Sep 2021 16:14:57 +0800 From: Billy Tsai To: , , , , , , , , , , , , , CC: Subject: [v7 09/11] iio: adc: aspeed: Add compensation phase. Date: Wed, 22 Sep 2021 16:15:18 +0800 Message-ID: <20210922081520.30580-10-billy_tsai@aspeedtech.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210922081520.30580-1-billy_tsai@aspeedtech.com> References: <20210922081520.30580-1-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 18M7sdVP099796 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210922_091606_586288_12C695E0 X-CRM114-Status: GOOD ( 18.42 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org This patch adds a compensation phase to improve the accuracy of ADC measurement. This is the built-in function through input half of the reference voltage to get the ADC offset. Signed-off-by: Billy Tsai --- drivers/iio/adc/aspeed_adc.c | 54 +++++++++++++++++++++++++++++++++++- 1 file changed, 53 insertions(+), 1 deletion(-) diff --git a/drivers/iio/adc/aspeed_adc.c b/drivers/iio/adc/aspeed_adc.c index f2226ba3144d..efda76fa0aa1 100644 --- a/drivers/iio/adc/aspeed_adc.c +++ b/drivers/iio/adc/aspeed_adc.c @@ -103,6 +103,7 @@ struct aspeed_adc_data { struct reset_control *rst; int vref_mv; u32 sample_period_ns; + int cv; }; #define ASPEED_CHAN(_idx, _data_reg_addr) { \ @@ -112,7 +113,8 @@ struct aspeed_adc_data { .address = (_data_reg_addr), \ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \ - BIT(IIO_CHAN_INFO_SAMP_FREQ), \ + BIT(IIO_CHAN_INFO_SAMP_FREQ) | \ + BIT(IIO_CHAN_INFO_OFFSET), \ } static const struct iio_chan_spec aspeed_adc_iio_channels[] = { @@ -134,6 +136,51 @@ static const struct iio_chan_spec aspeed_adc_iio_channels[] = { ASPEED_CHAN(15, 0x2E), }; +static int aspeed_adc_compensation(struct iio_dev *indio_dev) +{ + struct aspeed_adc_data *data = iio_priv(indio_dev); + u32 index, adc_raw = 0; + u32 adc_engine_control_reg_val; + + adc_engine_control_reg_val = + readl(data->base + ASPEED_REG_ENGINE_CONTROL); + adc_engine_control_reg_val &= ~ASPEED_ADC_OP_MODE; + adc_engine_control_reg_val |= + (FIELD_PREP(ASPEED_ADC_OP_MODE, ASPEED_ADC_OP_MODE_NORMAL) | + ASPEED_ADC_ENGINE_ENABLE); + /* + * Enable compensating sensing: + * After that, the input voltage of ADC will force to half of the reference + * voltage. So the expected reading raw data will become half of the max + * value. We can get compensating value = 0x200 - ADC read raw value. + * It is recommended to average at least 10 samples to get a final CV. + */ + writel(adc_engine_control_reg_val | ASPEED_ADC_CTRL_COMPENSATION | + ASPEED_ADC_CTRL_CHANNEL_ENABLE(0), + data->base + ASPEED_REG_ENGINE_CONTROL); + /* + * After enable compensating sensing mode need to wait some time for ADC stable + * Experiment result is 1ms. + */ + mdelay(1); + + for (index = 0; index < 16; index++) { + /* + * Waiting for the sampling period ensures that the value acquired + * is fresh each time. + */ + ndelay(data->sample_period_ns); + adc_raw += readw(data->base + aspeed_adc_iio_channels[0].address); + } + adc_raw >>= 4; + data->cv = BIT(ASPEED_RESOLUTION_BITS - 1) - adc_raw; + writel(adc_engine_control_reg_val, + data->base + ASPEED_REG_ENGINE_CONTROL); + dev_dbg(data->dev, "Compensating value = %d\n", data->cv); + + return 0; +} + static int aspeed_adc_set_sampling_rate(struct iio_dev *indio_dev, u32 rate) { struct aspeed_adc_data *data = iio_priv(indio_dev); @@ -163,6 +210,10 @@ static int aspeed_adc_read_raw(struct iio_dev *indio_dev, *val = readw(data->base + chan->address); return IIO_VAL_INT; + case IIO_CHAN_INFO_OFFSET: + *val = data->cv; + return IIO_VAL_INT; + case IIO_CHAN_INFO_SCALE: *val = data->vref_mv; *val2 = ASPEED_RESOLUTION_BITS; @@ -448,6 +499,7 @@ static int aspeed_adc_probe(struct platform_device *pdev) return ret; } + aspeed_adc_compensation(indio_dev); /* Start all channels in normal mode. */ adc_engine_control_reg_val = readl(data->base + ASPEED_REG_ENGINE_CONTROL); -- 2.25.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel