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Wed, 5 Aug 2026 05:44:20 -0400 From: Andrei Stancovici To: =?UTF-8?q?Nuno=20S=C3=A1?= , Michael Hennerich , Jonathan Cameron , "David Lechner" , Andy Shevchenko , "Rob Herring" , Krzysztof Kozlowski , "Conor Dooley" , Liam Beguin , , , , CC: Andrei Stancovici Subject: [PATCH 1/3] dt-bindings: iio: adc: lltc,ltc2497: add LTC2499 to title Date: Wed, 5 Aug 2026 12:41:27 +0300 Message-ID: <20260805094135.11762-2-andrei.stancovici@analog.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260805094135.11762-1-andrei.stancovici@analog.com> References: <20260805094135.11762-1-andrei.stancovici@analog.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ADIRuleOP-NewSCL: Rule Triggered X-Proofpoint-Spam-Info: AW1haW4tMjYwODA1MDA3NyBTYWx0ZWRfXw9y4GM0Em1mh /LjgGF/cpXv9e/2oIR8fWT2iLz+/aQmdBrXLfF9PRDg5/5vJ5iuW/vRNr3jegH4Egdk8oOM/OPT sn6URWJlxCOQTM74nyKlT9JPISrC8YM5QuM5YHXFFtcL+08oQZg4 X-Authority-Analysis: v=2.4 cv=bcFbluPB c=1 sm=1 tr=0 ts=6a7305fa cx=c_pps a=3WNzaoukacrqR9RwcOSAdA==:117 a=3WNzaoukacrqR9RwcOSAdA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=0sLvza09kfJOxVLZPwjg:22 a=Z0pTeXoby7EwIRygza74:22 a=gEfo2CItAAAA:8 a=gAnH3GRIAAAA:8 a=EP9JJrKyo648RTWUWkgA:9 a=sptkURWiP4Gy88Gu7hUp:22 X-Proofpoint-ORIG-GUID: QuOt6v58gEgNxYcd_PgfjqZLch5AKOKH X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODA1MDA3NyBTYWx0ZWRfX1J0zXDt9amur JRTq4vNW7dKn6L+Rw2rXPcQBcd32a85QFf9HY6zTAnNA0oPa/FB39kUR3+2FOaH7oCmb9dF7Rkf giJ9ykdKOPF9HQZbbMD8StWK4dqglqE4icRO3v5PUr6Vqkce70VhOYVfa0PuBd9oSZ+V/C7QxoD dRDCUFL1NrJHE6ym1kKQ1PuiHIp9hgsuOzNZsL3LnrI5h8Eg6tnpgr6VQpKtJse3ehOXGK3/8Ll fmot9r1WJ3H2qu5hQaiN0aMGO3mxRAQDt2YEXvfI4lG2C/m/0Ru6lzrHRhDlf4GVUsU2DL/pzt3 8TGiAD60W6twh6EPAZ+G+n1A3xnwQJJvyhAqn+Stg8dlRkkJbvqwqidF6hVGf4ohNhyA8ccX7ak pnYBa4orvCtK/XFcltXvSi/96Kl0f8yWneMXkm6gYy78ERZab142RKyx36ojlt6XGFvqtJDZh0d rA2+n6M+WxBCuo9kmKg== X-Proofpoint-GUID: QuOt6v58gEgNxYcd_PgfjqZLch5AKOKH X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-05_03,2026-08-04_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 phishscore=0 impostorscore=0 priorityscore=1501 clxscore=1015 bulkscore=0 lowpriorityscore=0 malwarescore=0 adultscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608050077 Content-Type: text/plain; charset="utf-8" The LTC2499 is already listed in the compatible enum and covered by the description, but was missing from the binding title. Add it so the title matches the set of devices the schema documents. No schema or property change is needed. Signed-off-by: Andrei Stancovici Acked-by: Rob Herring (Arm) --- Documentation/devicetree/bindings/iio/adc/lltc,ltc2497.yaml | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Documentation/devicetree/bindings/iio/adc/lltc,ltc2497.yaml b/= Documentation/devicetree/bindings/iio/adc/lltc,ltc2497.yaml index c884b6e03767..8aa1ba0a8728 100644 --- a/Documentation/devicetree/bindings/iio/adc/lltc,ltc2497.yaml +++ b/Documentation/devicetree/bindings/iio/adc/lltc,ltc2497.yaml @@ -4,7 +4,7 @@ $id: http://devicetree.org/schemas/iio/adc/lltc,ltc2497.yaml# $schema: http://devicetree.org/meta-schemas/core.yaml# =20 -title: Linear Technology / Analog Devices LTC2497 and LTC2309 ADC +title: Linear Technology / Analog Devices LTC2497, LTC2499 and LTC2309 ADC =20 maintainers: - Michael Hennerich --=20 2.43.0 From nobody Fri Oct 2 04:27:49 2026 Received: from mx0b-00128a01.pphosted.com (mx0a-00128a01.pphosted.com [148.163.135.77]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 37C4E405862; 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Wed, 5 Aug 2026 05:44:24 -0400 From: Andrei Stancovici To: =?UTF-8?q?Nuno=20S=C3=A1?= , Michael Hennerich , Jonathan Cameron , "David Lechner" , Andy Shevchenko , "Rob Herring" , Krzysztof Kozlowski , "Conor Dooley" , Liam Beguin , , , , CC: Andrei Stancovici Subject: [PATCH 2/3] iio: adc: ltc2497: add LTC2499 internal temperature channel Date: Wed, 5 Aug 2026 12:41:28 +0300 Message-ID: <20260805094135.11762-3-andrei.stancovici@analog.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260805094135.11762-1-andrei.stancovici@analog.com> References: <20260805094135.11762-1-andrei.stancovici@analog.com> 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: quoted-printable X-ADIRuleOP-NewSCL: Rule Triggered X-Proofpoint-GUID: 0XySsyFRMezSeQ1mXzQu3mgNylNLIjMd X-Proofpoint-Spam-Info: AW1haW4tMjYwODA1MDA3NyBTYWx0ZWRfX1Mt6fmhXt1s7 DkWlgfolEdTqtTPcuPBBxgC0hb1PfihrbaAnyljf376ZDN29Mh9SLFQLqvXDtZOtwu9rV/Xmz4V lJgOMwaPgFwINdNKCV28flP4cE3g11sBFugG2KHQbbH4v+5UnSVc X-Authority-Analysis: v=2.4 cv=aY9RWxot c=1 sm=1 tr=0 ts=6a7305fd cx=c_pps a=3WNzaoukacrqR9RwcOSAdA==:117 a=3WNzaoukacrqR9RwcOSAdA==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=0sLvza09kfJOxVLZPwjg:22 a=N--XFCr6TIEc_64PeIT2:22 a=gAnH3GRIAAAA:8 a=zsLNtPQ2y0leb1ljye4A:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: 0XySsyFRMezSeQ1mXzQu3mgNylNLIjMd X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODA1MDA3NyBTYWx0ZWRfXzf8fUc0XQXcG FhhdKlk5ZYi0F9aB+g3oJ4efzj5RjUWw7SenfIjZSSCtBiu7Q0miNate2A51QPPN2yL8hks+xGV C8TNHJytVO8tTmYvMpl29qg4RJxgSGzIPpBb/kFfbV6jRFZc/5v0lPMmBjvmLOnzg5AGvameNVV r9KlFjhrHdXHeAGSKlZmZSxVrKHieEcJR+aGWx2inHjXoKT6w1VCJ9zBCJ58+Po1yc32ZNWANL9 ctnRFRlWbubnhy4F0PS9IN9r0+eVyvF8be8tMoMsTPBgNlxBZsz/tc4bPznBOYXvMn72lEES2FG 2o8O3BFc1VoXBn7jHbM5APS1At8Oktrt/4K/Aj76o3jknEwPXQfoeQpI0GPYI34Aahp1qSuLAmk jeMaf99DYmbR+IbIv3KdeAypdN3FKqZP0fd9ZcDJTPKqhsOYsBQilg+QjMmuQ2k+BO096bcWVf0 hDJccYPK/5+xn3vPtqg== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-05_03,2026-08-04_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 bulkscore=0 impostorscore=0 spamscore=0 suspectscore=0 lowpriorityscore=0 phishscore=0 clxscore=1015 adultscore=0 priorityscore=1501 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608050077 The LTC2499 has an internal PTAT (proportional to absolute temperature) sensor that is activated by a second I2C configuration byte (EN2 | IM). Expose it as an IIO_TEMP channel providing raw, scale and offset so the standard IIO formula T[m=C2=B0C] =3D (raw + offset) * scale reconstructs the temperature. The PTAT sensor yields the absolute temperature as T(K) =3D DATAOUT24 * Vref / 1570 (Vref in volts) The raw value exported here is sign-extended and normalised to 2^(resolution + 1) =3D=3D 2^25, i.e. raw =3D 2 * DATAOUT24, so on the IIO milli-degree-Celsius convention scale[m=C2=B0C/LSB] =3D Vref_uV / 3140000 offset =3D -273150 * 3140000 / Vref_uV The scale and offset are derived from the reference voltage returned by regulator_get_voltage(); its error is propagated as before, so a board that fails to describe vref-supply gets a clear read error instead of a silently wrong temperature. No board-specific reference value is assumed in the driver. The single temperature channel is appended as the last entry of the shared channel array and excluded via num_channels for parts without an internal sensor, so the existing LTC2497 channel layout and device name are unchanged. The LTC2499 latches its converter configuration from the second command byte and only re-evaluates it when that byte has EN2 set. EN2 | IM selects the internal temperature sensor. Because a single-byte command, or a second byte with EN2 =3D 0, means "keep previous", a one-byte channel select cannot pull the device back out of temperature mode: after a temperature read every subsequent voltage read would keep returning the PTAT result instead of the selected input. Temperature support is therefore only correct if the voltage path also emits a second command byte that re-selects an external input. Send two-byte commands for all conversions on parts that have the sensor (has_temp): temperature: EN2 | IM voltage: EN2 (IM =3D 0 -> external input) The LTC2497 and LTC2496, which lack the second-byte mechanism, keep using the original single-byte channel select and are unchanged. Signed-off-by: Andrei Stancovici --- drivers/iio/adc/ltc2497-core.c | 54 +++++++++++++++++++++++++++++++--- drivers/iio/adc/ltc2497.c | 31 +++++++++++++++++++ drivers/iio/adc/ltc2497.h | 12 ++++++++ 3 files changed, 93 insertions(+), 4 deletions(-) diff --git a/drivers/iio/adc/ltc2497-core.c b/drivers/iio/adc/ltc2497-core.c index 2dc5c7044269..4ca7271ca007 100644 --- a/drivers/iio/adc/ltc2497-core.c +++ b/drivers/iio/adc/ltc2497-core.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include #include @@ -95,10 +96,43 @@ static int ltc2497core_read_raw(struct iio_dev *indio_d= ev, if (ret < 0) return ret; =20 - *val =3D ret / 1000; - *val2 =3D ddata->chip_info->resolution + 1; - - return IIO_VAL_FRACTIONAL_LOG2; + switch (chan->type) { + case IIO_TEMP: + /* + * raw is normalised to 2^(resolution + 1), i.e. + * raw =3D 2 * DATAOUT24, so the PTAT scale (datasheet + * Vref / 1570 per kelvin) doubles its denominator and, + * in m=C2=B0C, becomes Vref_uV / 3140000. + */ + *val =3D ret; + *val2 =3D 3140000; + return IIO_VAL_FRACTIONAL; + case IIO_VOLTAGE: + *val =3D ret / 1000; + *val2 =3D ddata->chip_info->resolution + 1; + return IIO_VAL_FRACTIONAL_LOG2; + default: + return -EINVAL; + } + + case IIO_CHAN_INFO_OFFSET: + switch (chan->type) { + case IIO_TEMP: + ret =3D regulator_get_voltage(ddata->ref); + if (ret < 0) + return ret; + /* + * 0 =C2=B0C =3D=3D 273.15 K must map to raw + offset such that + * (raw + offset) * scale =3D=3D 0 m=C2=B0C, i.e. + * offset =3D -273150 / scale + * =3D -273150 * 3140000 / Vref_uV + * Computed in 64-bit to avoid overflow. + */ + *val =3D div_s64(-273150LL * 3140000, ret); + return IIO_VAL_INT; + default: + return -EINVAL; + } =20 default: return -EINVAL; @@ -126,6 +160,14 @@ static int ltc2497core_read_raw(struct iio_dev *indio_= dev, .differential =3D 1, \ } =20 +#define LTC2497_TEMP_CHANNEL { \ + .type =3D IIO_TEMP, \ + .address =3D LTC2497_TEMP_ADDR, \ + .info_mask_separate =3D BIT(IIO_CHAN_INFO_RAW) | \ + BIT(IIO_CHAN_INFO_SCALE) | \ + BIT(IIO_CHAN_INFO_OFFSET), \ +} + static const struct iio_chan_spec ltc2497core_channel[] =3D { LTC2497_CHAN(0, LTC2497_SGL, "CH0"), LTC2497_CHAN(1, LTC2497_SGL, "CH1"), @@ -159,6 +201,7 @@ static const struct iio_chan_spec ltc2497core_channel[]= =3D { LTC2497_CHAN_DIFF(5, LTC2497_DIFF | LTC2497_SIGN), LTC2497_CHAN_DIFF(6, LTC2497_DIFF | LTC2497_SIGN), LTC2497_CHAN_DIFF(7, LTC2497_DIFF | LTC2497_SIGN), + LTC2497_TEMP_CHANNEL, }; =20 static const struct iio_info ltc2497core_info =3D { @@ -184,6 +227,9 @@ int ltc2497core_probe(struct device *dev, struct iio_de= v *indio_dev) indio_dev->modes =3D INDIO_DIRECT_MODE; indio_dev->channels =3D ltc2497core_channel; indio_dev->num_channels =3D ARRAY_SIZE(ltc2497core_channel); + /* Only the ltc2499 has a temperature channel; it is the last entry. */ + if (!ddata->chip_info->has_temp) + indio_dev->num_channels--; =20 ret =3D ddata->result_and_measure(ddata, LTC2497_CONFIG_DEFAULT, NULL); if (ret < 0) diff --git a/drivers/iio/adc/ltc2497.c b/drivers/iio/adc/ltc2497.c index c1668b5a351e..2ff53b292f74 100644 --- a/drivers/iio/adc/ltc2497.c +++ b/drivers/iio/adc/ltc2497.c @@ -84,6 +84,36 @@ static int ltc2497_result_and_measure(struct ltc2497core= _driverdata *ddata, return 0; } =20 + /* + * Parts with the internal PTAT sensor (LTC2499) latch their converter + * configuration via a second command byte and only re-evaluate it when + * that byte has EN2 set; a single byte, or a second byte with EN2 =3D 0, + * means "keep previous". A one-byte channel select therefore cannot pull + * the device back out of temperature mode, so a voltage read after a + * temperature read would keep returning the PTAT result. Always drive the + * second byte with EN2 set on these parts: IM | temperature-rejection for + * a temperature read, EN2 alone (IM =3D 0) to (re)select an external inp= ut. + */ + if (ddata->chip_info->has_temp) { + u8 cmd[2]; + + if (address =3D=3D LTC2497_TEMP_ADDR) { + cmd[0] =3D LTC2497_ENABLE | LTC2497_CONFIG_DEFAULT; + cmd[1] =3D LTC2499_EN2 | LTC2499_IM; + } else { + cmd[0] =3D LTC2497_ENABLE | address; + cmd[1] =3D LTC2499_EN2; + } + + ret =3D i2c_master_send(st->client, cmd, sizeof(cmd)); + if (ret < 0) { + dev_err(&st->client->dev, "i2c transfer failed: %pe\n", + ERR_PTR(ret)); + return ret; + } + return 0; + } + ret =3D i2c_smbus_write_byte(st->client, LTC2497_ENABLE | address); if (ret) @@ -137,6 +167,7 @@ static const struct ltc2497_chip_info ltc2497_info[] = =3D { [TYPE_LTC2499] =3D { .resolution =3D 24, .name =3D "ltc2499", + .has_temp =3D true, }, }; =20 diff --git a/drivers/iio/adc/ltc2497.h b/drivers/iio/adc/ltc2497.h index 64e81c95a3dd..1da2cfec3b6a 100644 --- a/drivers/iio/adc/ltc2497.h +++ b/drivers/iio/adc/ltc2497.h @@ -4,9 +4,21 @@ #define LTC2497_CONFIG_DEFAULT LTC2497_ENABLE #define LTC2497_CONVERSION_TIME_MS 150ULL =20 +/* + * Sentinel passed as `address` to result_and_measure() to request a + * temperature conversion instead of a voltage channel. 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charset="utf-8" The LTC2499 supports a 2x output rate (SPD bit in the second configuration byte). In 2x mode the offset auto-calibration is disabled, roughly doubling the conversion rate (~13.6Hz vs ~6.8Hz in simultaneous 50/60Hz rejection) while leaving linearity and full-scale errors unchanged (datasheet). During a temperature measurement the part always converts at 1x regardless of SPD. Expose the rate through the standard sampling_frequency / sampling_frequency_available ABI on the voltage channels only: SPD is ignored for temperature conversions, so the temperature channel deliberately carries no SAMP_FREQ attribute. A new has_speed_mode capability flag gates the feature (LTC2499); the two-byte command path is now taken for has_temp || has_speed_mode, since both features need the second config byte. The conversion-time wait becomes mode dependent: 150ms at 1x, 76ms at 2x (datasheet t_CONV max, simultaneous rejection, rounded up). The wait is keyed on the conversion currently in flight, whose duration is fixed by the mode that was active when it started - not by the newly selected mode. This matters on a 1x->2x switch: a 1x conversion may still be running when the first 2x read arrives, and reprogramming the device before it finishes would be NACKed with -EIO. Timing is centralized in ltc2497core_conv_time_ms() so a future FA/FB rejection-mode selection can extend it into a [rejection][speed] lookup without touching callers. LTC2496/LTC2497 (no speed mode) keep the single-byte path and the unchanged 150ms wait. Validated on a live LTC2499: 20 reads take ~3.1s at 1x and ~1.6s at 2x (~0.5x, no -EIO), voltage and temperature readings stay sane in both modes, and the temperature/voltage interleave (sticky-PTAT) regression still passes at 1x and 2x. Signed-off-by: Andrei Stancovici --- drivers/iio/adc/ltc2497-core.c | 169 +++++++++++++++++++++++++++++++-- drivers/iio/adc/ltc2497.c | 24 +++-- drivers/iio/adc/ltc2497.h | 24 ++++- 3 files changed, 200 insertions(+), 17 deletions(-) diff --git a/drivers/iio/adc/ltc2497-core.c b/drivers/iio/adc/ltc2497-core.c index 4ca7271ca007..68b53a983e05 100644 --- a/drivers/iio/adc/ltc2497-core.c +++ b/drivers/iio/adc/ltc2497-core.c @@ -7,12 +7,14 @@ */ =20 #include +#include #include #include #include #include #include #include +#include =20 #include "ltc2497.h" =20 @@ -20,24 +22,57 @@ #define LTC2497_DIFF 0 #define LTC2497_SIGN BIT(3) =20 -static int ltc2497core_wait_conv(struct ltc2497core_driverdata *ddata) +/* + * Output-rate modes, indexed by ltc2497core_driverdata.sped_2x + * (0 =3D 1x, the power-on default; 1 =3D 2x, LTC2499 only). The advertis= ed + * sampling_frequency and the conversion-time budget are two views of the = same + * mode, so they are kept in lock-step here and can never drift apart. On= ly the + * two simultaneous 50/60Hz rejection rates are reachable today; adding FA= /FB + * rejection selection later turns this into a [rejection][speed] lookup w= ithout + * changing any caller. + */ +static const int ltc2497core_samp_freq_avail[] =3D { + 6, 800000, /* 1x: ~6.8 Hz (1 / t_CONV_1 typ 146.9ms) */ + 13, 600000, /* 2x: ~13.6 Hz (1 / t_CONV_2 typ 73.6ms) */ +}; + +static const unsigned int ltc2497core_conv_time_ms_tbl[] =3D { + LTC2497_CONV_TIME_1X_MS, /* 1x */ + LTC2499_CONV_TIME_2X_MS, /* 2x */ +}; + +static unsigned int ltc2497core_conv_time_ms(struct ltc2497core_driverdata= *ddata, + u8 address) +{ + /* + * SPD is ignored by the part during a temperature measurement: it + * always converts at 1x, so budget the 1x time regardless of the + * selected voltage-channel mode. + */ + if (address =3D=3D LTC2497_TEMP_ADDR) + return ltc2497core_conv_time_ms_tbl[0]; + + return ltc2497core_conv_time_ms_tbl[ddata->sped_2x]; +} + +static int ltc2497core_wait_conv(struct ltc2497core_driverdata *ddata, + unsigned int conv_time_ms) { s64 time_elapsed; =20 time_elapsed =3D ktime_ms_delta(ktime_get(), ddata->time_prev); =20 - if (time_elapsed < LTC2497_CONVERSION_TIME_MS) { + if (time_elapsed < conv_time_ms) { /* delay if conversion time not passed * since last read or write */ - if (msleep_interruptible( - LTC2497_CONVERSION_TIME_MS - time_elapsed)) + if (msleep_interruptible(conv_time_ms - time_elapsed)) return -ERESTARTSYS; =20 return 0; } =20 - if (time_elapsed - LTC2497_CONVERSION_TIME_MS <=3D 0) { + if (time_elapsed - conv_time_ms <=3D 0) { /* We're in automatic mode - * so the last reading is still not outdated */ @@ -49,9 +84,18 @@ static int ltc2497core_wait_conv(struct ltc2497core_driv= erdata *ddata) =20 static int ltc2497core_read(struct ltc2497core_driverdata *ddata, u8 addre= ss, int *val) { + unsigned int conv_time_ms =3D ltc2497core_conv_time_ms(ddata, address); int ret; =20 - ret =3D ltc2497core_wait_conv(ddata); + /* + * Wait for the conversion currently in flight, whose duration was fixed + * by the mode active when it was started (ddata->conv_time_prev). This + * can be longer than the freshly selected mode's time - e.g. a 1x + * conversion is still running when the first 2x read arrives after a + * sampling_frequency change - and reprogramming the device before it + * finishes would be NACKed (-EIO). + */ + ret =3D ltc2497core_wait_conv(ddata, ddata->conv_time_prev); if (ret < 0) return ret; =20 @@ -61,7 +105,9 @@ static int ltc2497core_read(struct ltc2497core_driverdat= a *ddata, u8 address, in return ret; ddata->addr_prev =3D address; =20 - if (msleep_interruptible(LTC2497_CONVERSION_TIME_MS)) + /* The reprogram above starts a conversion in the new mode. */ + ddata->conv_time_prev =3D conv_time_ms; + if (msleep_interruptible(conv_time_ms)) return -ERESTARTSYS; } =20 @@ -70,6 +116,8 @@ static int ltc2497core_read(struct ltc2497core_driverdat= a *ddata, u8 address, in return ret; =20 ddata->time_prev =3D ktime_get(); + /* The read above auto-starts the next conversion in the current mode. */ + ddata->conv_time_prev =3D conv_time_ms; =20 return ret; } @@ -134,6 +182,81 @@ static int ltc2497core_read_raw(struct iio_dev *indio_= dev, return -EINVAL; } =20 + case IIO_CHAN_INFO_SAMP_FREQ: + /* + * Only advertised on the voltage channels of parts with a speed + * mode; the sampling frequency is a property of the selected 1x/2x + * mode, not of an individual conversion. + */ + mutex_lock(&ddata->lock); + *val =3D ltc2497core_samp_freq_avail[ddata->sped_2x * 2]; + *val2 =3D ltc2497core_samp_freq_avail[ddata->sped_2x * 2 + 1]; + mutex_unlock(&ddata->lock); + + return IIO_VAL_INT_PLUS_MICRO; + + default: + return -EINVAL; + } +} + +static int ltc2497core_read_avail(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + const int **vals, int *type, int *length, + long mask) +{ + switch (mask) { + case IIO_CHAN_INFO_SAMP_FREQ: + *vals =3D ltc2497core_samp_freq_avail; + *type =3D IIO_VAL_INT_PLUS_MICRO; + *length =3D ARRAY_SIZE(ltc2497core_samp_freq_avail); + return IIO_AVAIL_LIST; + + default: + return -EINVAL; + } +} + +static int ltc2497core_write_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int val, int val2, long mask) +{ + struct ltc2497core_driverdata *ddata =3D iio_priv(indio_dev); + bool sped_2x; + int i; + + switch (mask) { + case IIO_CHAN_INFO_SAMP_FREQ: + /* Match the (val, val2) pair against the advertised rates. */ + for (i =3D 0; i < ARRAY_SIZE(ltc2497core_samp_freq_avail); i +=3D 2) { + if (val =3D=3D ltc2497core_samp_freq_avail[i] && + val2 =3D=3D ltc2497core_samp_freq_avail[i + 1]) + break; + } + if (i >=3D ARRAY_SIZE(ltc2497core_samp_freq_avail)) + return -EINVAL; + + sped_2x =3D i / 2; + + mutex_lock(&ddata->lock); + ddata->sped_2x =3D sped_2x; + /* + * The new speed only takes effect once the second command byte + * is reprogrammed, so force the next read to reprogram rather + * than reuse the value already latched for this address. + * LTC2497_CONFIG_DEFAULT is not a valid channel/temperature + * address, so it is a safe re-arm sentinel (as used at probe). + * + * A conversion started under the old speed may still be in + * flight; its own duration (conv_time_prev), not the new mode's, + * still gates the next reprogram, so the timing state is left + * untouched here. + */ + ddata->addr_prev =3D LTC2497_CONFIG_DEFAULT; + mutex_unlock(&ddata->lock); + + return 0; + default: return -EINVAL; } @@ -206,6 +329,8 @@ static const struct iio_chan_spec ltc2497core_channel[]= =3D { =20 static const struct iio_info ltc2497core_info =3D { .read_raw =3D ltc2497core_read_raw, + .read_avail =3D ltc2497core_read_avail, + .write_raw =3D ltc2497core_write_raw, }; =20 int ltc2497core_probe(struct device *dev, struct iio_dev *indio_dev) @@ -231,6 +356,34 @@ int ltc2497core_probe(struct device *dev, struct iio_d= ev *indio_dev) if (!ddata->chip_info->has_temp) indio_dev->num_channels--; =20 + /* + * Parts with a speed mode expose in_voltage_sampling_frequency / + * _available on the voltage channels only. SPD is ignored during a + * temperature measurement, so the temperature channel deliberately + * carries no SAMP_FREQ attribute. Patch a private copy of the shared + * channel array so parts without a speed mode stay untouched. + */ + if (ddata->chip_info->has_speed_mode) { + struct iio_chan_spec *channels; + unsigned int i; + + channels =3D devm_kmemdup(dev, ltc2497core_channel, + sizeof(ltc2497core_channel), GFP_KERNEL); + if (!channels) + return -ENOMEM; + + for (i =3D 0; i < indio_dev->num_channels; i++) { + if (channels[i].type !=3D IIO_VOLTAGE) + continue; + channels[i].info_mask_shared_by_type |=3D + BIT(IIO_CHAN_INFO_SAMP_FREQ); + channels[i].info_mask_shared_by_type_available |=3D + BIT(IIO_CHAN_INFO_SAMP_FREQ); + } + + indio_dev->channels =3D channels; + } + ret =3D ddata->result_and_measure(ddata, LTC2497_CONFIG_DEFAULT, NULL); if (ret < 0) return ret; @@ -255,6 +408,8 @@ int ltc2497core_probe(struct device *dev, struct iio_de= v *indio_dev) =20 ddata->addr_prev =3D LTC2497_CONFIG_DEFAULT; ddata->time_prev =3D ktime_get(); + /* Power-on default mode is 1x; a conversion is already in flight. */ + ddata->conv_time_prev =3D LTC2497_CONV_TIME_1X_MS; =20 mutex_init(&ddata->lock); =20 diff --git a/drivers/iio/adc/ltc2497.c b/drivers/iio/adc/ltc2497.c index 2ff53b292f74..3fc31d418cf4 100644 --- a/drivers/iio/adc/ltc2497.c +++ b/drivers/iio/adc/ltc2497.c @@ -85,16 +85,19 @@ static int ltc2497_result_and_measure(struct ltc2497cor= e_driverdata *ddata, } =20 /* - * Parts with the internal PTAT sensor (LTC2499) latch their converter - * configuration via a second command byte and only re-evaluate it when - * that byte has EN2 set; a single byte, or a second byte with EN2 =3D 0, - * means "keep previous". A one-byte channel select therefore cannot pull - * the device back out of temperature mode, so a voltage read after a - * temperature read would keep returning the PTAT result. Always drive the - * second byte with EN2 set on these parts: IM | temperature-rejection for - * a temperature read, EN2 alone (IM =3D 0) to (re)select an external inp= ut. + * Parts with a second config byte (LTC2499: internal PTAT sensor and/or + * the 2x speed mode) latch their converter configuration from that byte + * and only re-evaluate it when EN2 is set; a single byte, or a second + * byte with EN2 =3D 0, means "keep previous". A one-byte channel select + * therefore cannot pull the device back out of temperature mode, so a + * voltage read after a temperature read would keep returning the PTAT + * result. Always drive the second byte with EN2 set on these parts: + * - temperature read: IM =3D 1 (SPD is ignored by the part in + * temperature mode and is left 0 here); + * - voltage read: IM =3D 0 (external input), plus SPD when 2x is + * selected. */ - if (ddata->chip_info->has_temp) { + if (ddata->chip_info->has_temp || ddata->chip_info->has_speed_mode) { u8 cmd[2]; =20 if (address =3D=3D LTC2497_TEMP_ADDR) { @@ -103,6 +106,8 @@ static int ltc2497_result_and_measure(struct ltc2497cor= e_driverdata *ddata, } else { cmd[0] =3D LTC2497_ENABLE | address; cmd[1] =3D LTC2499_EN2; + if (ddata->sped_2x) + cmd[1] |=3D LTC2499_SPD; } =20 ret =3D i2c_master_send(st->client, cmd, sizeof(cmd)); @@ -168,6 +173,7 @@ static const struct ltc2497_chip_info ltc2497_info[] = =3D { .resolution =3D 24, .name =3D "ltc2499", .has_temp =3D true, + .has_speed_mode =3D true, }, }; =20 diff --git a/drivers/iio/adc/ltc2497.h b/drivers/iio/adc/ltc2497.h index 1da2cfec3b6a..5707ee3ff8a5 100644 --- a/drivers/iio/adc/ltc2497.h +++ b/drivers/iio/adc/ltc2497.h @@ -2,7 +2,19 @@ =20 #define LTC2497_ENABLE 0xA0 #define LTC2497_CONFIG_DEFAULT LTC2497_ENABLE -#define LTC2497_CONVERSION_TIME_MS 150ULL + +/* + * Worst-case conversion times (datasheet t_CONV max). The driver only ev= er + * programs simultaneous 50/60Hz rejection (FA/FB selection is not impleme= nted), + * so only those two rates are listed. The 1x value also covers the + * LTC2496/LTC2497, which have no speed mode. + * + * The 2x mode (LTC2499_SPD, LTC2499 only) disables the offset auto-calibr= ation + * to roughly double the output rate; adding the 2x wait time is what make= s the + * SPD control actually faster. + */ +#define LTC2497_CONV_TIME_1X_MS 150ULL /* t_CONV_1 simult. max 149.9 */ +#define LTC2499_CONV_TIME_2X_MS 76ULL /* t_CONV_2 simult. max 75.1 */ =20 /* * Sentinel passed as `address` to result_and_measure() to request a @@ -14,11 +26,13 @@ /* Second config-byte bits (LTC2499 / LTC2493 only) */ #define LTC2499_EN2 BIT(7) /* enable second config byte */ #define LTC2499_IM BIT(6) /* 1 =3D measure internal temp sensor */ +#define LTC2499_SPD BIT(3) /* 1 =3D 2x output rate (offset cal off) */ =20 struct ltc2497_chip_info { u32 resolution; const char *name; bool has_temp; + bool has_speed_mode; /* SPD bit in the 2nd config byte (LTC2499/LTC2493) = */ }; =20 struct ltc2497core_driverdata { @@ -28,6 +42,14 @@ struct ltc2497core_driverdata { struct mutex lock; const struct ltc2497_chip_info *chip_info; u8 addr_prev; + bool sped_2x; /* SPD: false =3D 1x (default), true =3D 2x */ + /* + * Conversion time (ms) of the conversion currently in flight. It is + * fixed by the mode active when that conversion was started, which + * differs from the newly selected mode for the first read after a + * sampling_frequency change. + */ + unsigned int conv_time_prev; int (*result_and_measure)(struct ltc2497core_driverdata *ddata, u8 address, int *val); }; --=20 2.43.0