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([2402:e280:21d3:2:50bc:8636:2ee8:5158]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a0e2318990sm43179675ad.38.2025.12.15.09.50.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 15 Dec 2025 09:50:47 -0800 (PST) Message-ID: <37d8b0fc-db25-4ce6-89e1-3cd4e447e005@gmail.com> Date: Mon, 15 Dec 2025 23:20:37 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/2] iio: adc: Add support for TI ADS1120 To: David Lechner , jic23@kernel.org Cc: nuno.sa@analog.com, andy@kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org References: <20251109141119.561756-1-ajithanandhan0406@gmail.com> <20251109141119.561756-3-ajithanandhan0406@gmail.com> <5f15284b-159b-4860-b58b-35c624e2539f@baylibre.com> <8e2c73ca-3746-4b2a-9d85-c12b51a69059@gmail.com> <8ad18de5-53cd-49ba-8e84-1e8c7e5bd627@baylibre.com> <15106906-3bcc-4187-87d9-c838fe99b583@gmail.com> <5926ca19-c204-4abc-9e59-86a797b63b5c@baylibre.com> Content-Language: en-US From: Ajith Anandhan In-Reply-To: <5926ca19-c204-4abc-9e59-86a797b63b5c@baylibre.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit >> >> >> Thanks for the pointer. >> >> I did look at reg_shift, but it doesn’t fit this device. With .reg_shift = 2, regmap would send only (reg << 2) (e.g. 0x0c for reg 3). >> >> The ADS1120 requires the command byte to be CMD | (reg << 2) (e.g. 0x20 | 0x0c = 0x2c for an RREG of reg 3). >> >> Similarly, >> >>  .read_flag_mask would produce reg | mask (e.g. 0x03 | 0x20 = 0x23), which is also not the required format. >> >> Unless I’m missing a regmap configuration that can generate (reg << 2) | CMD as a single byte, >> >> a custom regmap bus seems necessary here. Please let me know if there is a way to express this with standard regmap-spi. >> >> >> > Sorry, I didn't read carefully enough. Wouldn't this work though? > > .reg_bits = 2, > .reg_shift = 2, > .read_flag_mask = 0x20, > .write_flag_mask = 0x40, > > > Then a read should be 0x20 | ((reg & 0x3) << 2) and a write should be 0x40 | ((reg & 0x3) << 2). Yes, that works thanks for spelling it out. I missed the reg_bits interaction earlier. I’ll drop the custom regmap bus and switch to standard regmap-spi.