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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a1f2d699dasm61649665e9.12.2026.10.20.02.13.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Oct 2026 02:13:13 -0700 (PDT) Date: Tue, 20 Oct 2026 10:13:12 +0100 From: David Laight To: Neil Armstrong Cc: Jonathan Cameron , David Lechner , Nuno =?UTF-8?B?U8Oh?= , Andy Shevchenko , Rob Herring , Krzysztof Kozlowski , Conor Dooley , linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hwmon@vger.kernel.org Subject: Re: [PATCH v3 3/3] iio: adc: add driver for the MAX34417 Four-Channel High Dynamic Range Power Accumulator Message-ID: <20261020101312.47d2eaf0@pumpkin> In-Reply-To: <20261013-topic-sm8x50-iio-max34417-adc-v3-3-d3604ae4a229@linaro.org> References: <20261013-topic-sm8x50-iio-max34417-adc-v3-0-d3604ae4a229@linaro.org> <20261013-topic-sm8x50-iio-max34417-adc-v3-3-d3604ae4a229@linaro.org> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 13 Oct 2026 16:07:13 +0200 Neil Armstrong wrote: > The MAX34417 is a specialized current and voltage monitor used to > determine power consumption of portable systems. The driver support > getting the channels voltage, average power and accumulated average > power and energy over an I2C/SMBUS serial interface. > > The MAX34417 datasheet only specified on how to calculate the > accumulated average power, but with the Sample Per Second rate > we can easily get accumulated Energy in mJ. > > By default the IIO driver only supports single-shot Voltage > and Power sensing, but the accumulation can be enabled by > enabling the Energy IIO channel which then enables the > Continuous Accumulation Mode. > > The counter is common to all channels, so when reading a single > channel we will copy all accumulators to registers, so in order > to permit reading individual channels we must accumulate the > other channels in the driver when Continuous Accumulation Mode > is enabled. > > Signed-off-by: Neil Armstrong ... > +#define MAX34417_POWER_READ_LENGTH 8 > +#define MAX34417_POWER_READ_OFFSET 1 ... > +static int max34417_read_acc_power(struct max34417_data *max34417, unsigned int address, > + u64 *acc_power) > +{ > + u8 buf[MAX34417_POWER_READ_LENGTH]; > + int rc; > + > + rc = regmap_noinc_read(max34417->regmap, address, &buf, sizeof(buf)); > + if (rc) > + return rc; > + > + /* Ignore byte0 */ > + *acc_power = get_unaligned_be56(&buf[MAX34417_POWER_READ_OFFSET]); > + > + return 0; > +} I was thinking: struct { u64 pad:8; val:56 } buf; then using bswap64(buf.val) >> 8 on LE. But why not just: u64 buf; and be64toh(buf) & (BITULL(56) - 1) David