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[200.61.172.117]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-3537cacb5e9sm13009650eec.20.2026.10.09.23.53.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Oct 2026 23:53:45 -0700 (PDT) From: Kurt Borja Date: Sat, 10 Oct 2026 03:52:45 -0300 Subject: [PATCH v5 06/10] iio: adc: ti-ads1262: support input chopping Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261010-ads126x-v5-6-49e331cb2fed@gmail.com> References: <20261010-ads126x-v5-0-49e331cb2fed@gmail.com> In-Reply-To: <20261010-ads126x-v5-0-49e331cb2fed@gmail.com> To: Kurt Borja , Jonathan Cameron , Rob Herring , Krzysztof Kozlowski , Conor Dooley , David Lechner Cc: =?utf-8?q?Nuno_S=C3=A1?= , Andy Shevchenko , linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=3240; i=kuurtb@gmail.com; h=from:subject:message-id; bh=dIjt8nwdTss/bhvR/VsQb/EXL6ivNKMpYRbB1ZzbmXo=; b=kA0DAAoWFmBDOPSf1GYByyZiAGrJ4Oait7mMTMA4MGTYlatrqswcZ8sCDSkSGJidd6JLjCXPO 4h1BAAWCgAdFiEEh2Ci9uJabu1OwFXfFmBDOPSf1GYFAmrJ4OYACgkQFmBDOPSf1GbfVAEA8NJZ 5Rd7VzJasMWFIupSIwiW4kHbh1uIQZWNeR+X96oBALDwvFEDzxYdnuQSn3OtTp4iHTzlIXHwwLc P9Ly1VlQC X-Developer-Key: i=kuurtb@gmail.com; a=openpgp; fpr=54D3BE170AEF777983C3C63B57E3B6585920A69A Enable per-channel input chopping via the "input-chopping" property. As the device withholds the first conversion in chop mode, single reads are taken in CONTINUOUS run mode with a brief start/stop pulse, as recommended by the datasheet (Section 9.4.1.2). Reviewed-by: David Lechner Signed-off-by: Kurt Borja --- drivers/iio/adc/ti-ads1262.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/drivers/iio/adc/ti-ads1262.c b/drivers/iio/adc/ti-ads1262.c index 98d147f120c4..938e26075302 100644 --- a/drivers/iio/adc/ti-ads1262.c +++ b/drivers/iio/adc/ti-ads1262.c @@ -205,6 +205,7 @@ struct ads1262_channel { u8 ref_n; bool ref_reversal; bool is_resistance; + bool input_chop; size_t num_scales; int scales[ADS1262_GAIN_COUNT][2]; }; @@ -456,7 +457,7 @@ static int ads1262_dev_stop(struct ads1262 *st) return ret; } -static int ads1262_dev_start_one(struct ads1262 *st) +static int ads1262_dev_start_one(struct ads1262 *st, u8 runmode) { int ret; @@ -464,7 +465,7 @@ static int ads1262_dev_start_one(struct ads1262 *st) if (ret) return ret; - if (st->start_gpiod) { + if (runmode == ADS1262_RUNMODE_CONTINUOUS || st->start_gpiod) { /* * The START pulse timing requirement is 4 clock cycles, at the * minimum clock rate this is 4 microseconds. @@ -512,7 +513,9 @@ static int ads1262_channel_enable(struct ads1262 *st, guard(mutex)(&st->chan_lock); ret = regmap_update_bits(st->regmap, ADS1262_MODE0_REG, + ADS1262_MODE0_INPUT_CHOP_MASK | ADS1262_MODE0_REFREV_MASK, + FIELD_PREP(ADS1262_MODE0_INPUT_CHOP_MASK, chan->input_chop) | FIELD_PREP(ADS1262_MODE0_REFREV_MASK, chan->ref_reversal)); if (ret) return ret; @@ -553,13 +556,26 @@ static int ads1262_channel_read(struct iio_dev *indio_dev, const struct iio_chan_spec *spec, __be32 *val) { struct ads1262 *st = iio_priv(indio_dev); + struct ads1262_channel *chan = &st->channels[spec->scan_index]; + u8 runmode; int ret; IIO_DEV_ACQUIRE_DIRECT_MODE(indio_dev, claim); if (IIO_DEV_ACQUIRE_FAILED(claim)) return -EBUSY; - ret = ads1262_set_runmode(st, ADS1262_RUNMODE_PULSE); + /* + * When a channel has chop mode or IDAC rotation mode, the first + * conversion is always withheld so the datasheet suggests using the + * CONTINUOUS mode and briefly starting and stopping conversions to + * achieve the same effect (Section 9.4.1.2). + */ + if (chan->input_chop) + runmode = ADS1262_RUNMODE_CONTINUOUS; + else + runmode = ADS1262_RUNMODE_PULSE; + + ret = ads1262_set_runmode(st, runmode); if (ret) return ret; @@ -569,7 +585,7 @@ static int ads1262_channel_read(struct iio_dev *indio_dev, reinit_completion(&st->drdy); - ret = ads1262_dev_start_one(st); + ret = ads1262_dev_start_one(st, runmode); if (ret) return ret; @@ -1316,6 +1332,7 @@ static int ads1262_parse_channel_node(struct ads1262 *st, } } + chan->input_chop = fwnode_property_read_bool(node, "input-chopping"); chan->ref_reversal = fwnode_property_read_bool(node, "ti,reference-reversal"); return 0; -- 2.55.0