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([103.187.64.31]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7992d09ace5sm9030616b3a.53.2025.10.12.10.31.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 12 Oct 2025 10:31:07 -0700 (PDT) From: Shrikant Raskar To: jic23@kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org Cc: dlechner@baylibre.com, nuno.sa@analog.com, andy@kernel.org, matt@ranostay.sg, skhan@linuxfoundation.org, david.hunter.linux@gmail.com, linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linux.dev, Shrikant Raskar Subject: [PATCH v3 2/2] iio: health: max30100: Make LED pulse-width configurable via DT Date: Sun, 12 Oct 2025 23:00:35 +0530 Message-ID: <20251012173035.12536-3-raskar.shree97@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251012173035.12536-1-raskar.shree97@gmail.com> References: <20251012173035.12536-1-raskar.shree97@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel-mentees@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The required LED pulse width depends on board-specific optical and mechanical design, which affects measurement accuracy and power use. Making it configurable via Device Tree allows each platform to define an appropriate value instead of relying on a hardcoded default. If unspecified, the driver defaults to 1600 us for backward compatibility. Tested on: Raspberry Pi 3B + MAX30100 breakout board. Reviewed-by: Nuno Sa Signed-off-by: Shrikant Raskar --- Changelog: Changes since v2: - Reorder SPO2_CONFIG register defines by bit position (lowest to highest). - Add missing header file for FIELD_PREP() macro. - Add Reviewed-by tag. Link to v2: https://lore.kernel.org/all/20251008031737.7321-3-raskar.shree97@gmail.com/ --- drivers/iio/health/max30100.c | 38 ++++++++++++++++++++++++++++++++--- 1 file changed, 35 insertions(+), 3 deletions(-) diff --git a/drivers/iio/health/max30100.c b/drivers/iio/health/max30100.c index 814f521e47ae..3d441013893c 100644 --- a/drivers/iio/health/max30100.c +++ b/drivers/iio/health/max30100.c @@ -5,7 +5,6 @@ * Copyright (C) 2015, 2018 * Author: Matt Ranostay * - * TODO: enable pulse length controls via device tree properties */ #include @@ -18,6 +17,7 @@ #include #include #include +#include #include #include #include @@ -52,9 +52,13 @@ #define MAX30100_REG_MODE_CONFIG_PWR BIT(7) #define MAX30100_REG_SPO2_CONFIG 0x07 +#define MAX30100_REG_SPO2_CONFIG_PW_MASK GENMASK(1, 0) +#define MAX30100_REG_SPO2_CONFIG_200US 0x0 +#define MAX30100_REG_SPO2_CONFIG_400US 0x1 +#define MAX30100_REG_SPO2_CONFIG_800US 0x2 +#define MAX30100_REG_SPO2_CONFIG_1600US 0x3 #define MAX30100_REG_SPO2_CONFIG_100HZ BIT(2) #define MAX30100_REG_SPO2_CONFIG_HI_RES_EN BIT(6) -#define MAX30100_REG_SPO2_CONFIG_1600US 0x3 #define MAX30100_REG_LED_CONFIG 0x09 #define MAX30100_REG_LED_CONFIG_LED_MASK 0x0f @@ -306,19 +310,47 @@ static int max30100_led_init(struct max30100_data *data) MAX30100_REG_LED_CONFIG_LED_MASK, reg); } +static int max30100_get_pulse_width(unsigned int pwidth_us) +{ + switch (pwidth_us) { + case 200: + return MAX30100_REG_SPO2_CONFIG_200US; + case 400: + return MAX30100_REG_SPO2_CONFIG_400US; + case 800: + return MAX30100_REG_SPO2_CONFIG_800US; + case 1600: + return MAX30100_REG_SPO2_CONFIG_1600US; + default: + return -EINVAL; + } +} + static int max30100_chip_init(struct max30100_data *data) { int ret; + int pulse_width; + /* set default LED pulse-width to 1600 us */ + unsigned int pulse_us = 1600; + struct device *dev = &data->client->dev; /* setup LED current settings */ ret = max30100_led_init(data); if (ret) return ret; + /* Read LED pulse-width-us from DT */ + device_property_read_u32(dev, "maxim,pulse-width-us", &pulse_us); + + pulse_width = max30100_get_pulse_width(pulse_us); + if (pulse_width < 0) + return dev_err_probe(dev, pulse_width, "invalid LED pulse-width %uus\n", pulse_us); + /* enable hi-res SPO2 readings at 100Hz */ ret = regmap_write(data->regmap, MAX30100_REG_SPO2_CONFIG, MAX30100_REG_SPO2_CONFIG_HI_RES_EN | - MAX30100_REG_SPO2_CONFIG_100HZ); + MAX30100_REG_SPO2_CONFIG_100HZ | + FIELD_PREP(MAX30100_REG_SPO2_CONFIG_PW_MASK, pulse_width)); if (ret) return ret; -- 2.43.0