drivers: dac: added driver for Microchip MCP4725 (38ed9c88) · Commits · Wenxi XU / zephyr

drivers/dac/CMakeLists.txt

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		@@ -9,4 +9,5 @@ zephyr_library_sources_ifdef(CONFIG_DAC_SAM0 dac_sam0.c)
		zephyr_library_sources_ifdef(CONFIG_DAC_DACX0508 dac_dacx0508.c)
		zephyr_library_sources_ifdef(CONFIG_DAC_DACX3608 dac_dacx3608.c)
		zephyr_library_sources_ifdef(CONFIG_DAC_SHELL dac_shell.c)
		zephyr_library_sources_ifdef(CONFIG_DAC_MCP4725 dac_mcp4725.c)
		zephyr_library_sources_ifdef(CONFIG_USERSPACE dac_handlers.c)

drivers/dac/Kconfig

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		@@ -34,4 +34,6 @@ source "drivers/dac/Kconfig.dacx0508"

		source "drivers/dac/Kconfig.dacx3608"

		source "drivers/dac/Kconfig.mcp4725"

		endif # DAC

drivers/dac/Kconfig.mcp4725

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		# DAC configuration options

		# Copyright (c) 2021 Laird Connectivity
		#
		# SPDX-License-Identifier: Apache-2.0

		config DAC_MCP4725
		bool "Microchip MCP4725 DAC driver"
		depends on I2C
		help
		Enable the driver for the Microchip MCP4725.

		if DAC_MCP4725

		config DAC_MCP4725_INIT_PRIORITY
		int "Init priority"
		default 80
		help
		MCP4725 DAC device driver initialization priority.

		endif # DAC_MCP4725

drivers/dac/dac_mcp4725.c

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		/*
		* Copyright (c) 2021 Laird Connectivity
		*
		* SPDX-License-Identifier: Apache-2.0
		*/
		#define DT_DRV_COMPAT microchip_mcp4725

		#include <zephyr.h>
		#include <drivers/i2c.h>
		#include <drivers/dac.h>
		#include <logging/log.h>

		LOG_MODULE_REGISTER(dac_mcp4725, CONFIG_DAC_LOG_LEVEL);

		/* Information in this file comes from MCP4725 datasheet revision D
		* found at https://ww1.microchip.com/downloads/en/DeviceDoc/22039d.pdf
		*/

		/* Defines for field values in MCP4725 DAC register */
		#define MCP4725_DAC_MAX_VAL 0xFFF

		#define MCP4725_FAST_MODE_POWER_DOWN_POS 4U
		#define MCP4725_FAST_MODE_DAC_UPPER_VAL_POS 8U
		#define MCP4725_FAST_MODE_DAC_UPPER_VAL_MASK 0xF
		#define MCP4725_FAST_MODE_DAC_LOWER_VAL_MASK 0xFF

		#define MCP4725_READ_RDY_POS 7U
		#define MCP4725_READ_RDY_MASK (0x1 << MCP4725_READ_RDY_POS)

		/* After writing eeprom, the MCP4725 can be in a busy state for 25 - 50ms
		* See section 1.0 of MCP4725 datasheet, 'Electrical Characteristics'
		*/
		#define MCP4725_BUSY_TIMEOUT_MS 60U

		struct mcp4725_config {
		const struct device *i2c_dev;
		uint16_t i2c_addr;
		};

		/* Read mcp4725 and check RDY status bit */
		static int mcp4725_wait_until_ready(const struct device *dev, uint16_t i2c_addr)
		{
		uint8_t rx_data[5];
		bool mcp4725_ready = false;
		int ret;
		int32_t timeout = k_uptime_get_32() + MCP4725_BUSY_TIMEOUT_MS;

		/* Wait until RDY bit is set or return error if timer exceeds MCP4725_BUSY_TIMEOUT_MS */
		while (!mcp4725_ready) {
		ret = i2c_read(dev, rx_data, sizeof(rx_data), i2c_addr);

		if (ret == 0) {
		mcp4725_ready = rx_data[0] & MCP4725_READ_RDY_MASK;
		} else {
		/* I2C error */
		return ret;
		}

		if (k_uptime_get_32() > timeout) {
		return -ETIMEDOUT;
		}
		}

		return 0;
		}

		/* MCP4725 is a single channel 12 bit DAC */
		static int mcp4725_channel_setup(const struct device *dev,
		const struct dac_channel_cfg *channel_cfg)
		{
		if (channel_cfg->channel_id != 0) {
		return -EINVAL;
		}

		if (channel_cfg->resolution != 12) {
		return -ENOTSUP;
		}

		return 0;
		}

		static int mcp4725_write_value(const struct device *dev, uint8_t channel,
		uint32_t value)
		{
		const struct mcp4725_config config = (struct mcp4725_config )dev->config;
		uint8_t tx_data[2];
		int ret;

		if (channel != 0) {
		return -EINVAL;
		}

		/* Check value isn't over 12 bits */
		if (value > MCP4725_DAC_MAX_VAL) {
		return -ENOTSUP;
		}

		/* WRITE_MODE_FAST message format (2 bytes):
		*
		* \|\| 15 14 \| 13 12 \| 11 10 9 8 \|\| 7 6 5 4 3 2 1 0 \|\|
		* \|\| Fast mode (0) \| Power-down bits (0) \| DAC value[11:8] \|\| DAC value[7:0] \|\|
		*/
		tx_data[0] = ((value >> MCP4725_FAST_MODE_DAC_UPPER_VAL_POS) &
		MCP4725_FAST_MODE_DAC_UPPER_VAL_MASK);
		tx_data[1] = (value & MCP4725_FAST_MODE_DAC_LOWER_VAL_MASK);
		ret = i2c_write(config->i2c_dev, tx_data, sizeof(tx_data),
		config->i2c_addr);

		return ret;
		}

		static int dac_mcp4725_init(const struct device *dev)
		{
		const struct mcp4725_config *config = dev->config;

		if (!device_is_ready(config->i2c_dev)) {
		LOG_ERR("I2C device not found");
		return -EINVAL;
		}

		/* Check we can read a 'RDY' bit from this device */
		if (mcp4725_wait_until_ready(config->i2c_dev, config->i2c_addr)) {
		return -EBUSY;
		}

		return 0;
		}

		static const struct dac_driver_api mcp4725_driver_api = {
		.channel_setup = mcp4725_channel_setup,
		.write_value = mcp4725_write_value,
		};


		#define INST_DT_MCP4725(index) \
		static const struct mcp4725_config mcp4725_config_##index = { \
		.i2c_dev = DEVICE_DT_GET(DT_INST_BUS(index)), \
		.i2c_addr = DT_INST_REG_ADDR(index) \
		}; \
		\
		DEVICE_DT_INST_DEFINE(index, dac_mcp4725_init, \
		device_pm_control_nop, \
		NULL, \
		&mcp4725_config_##index, POST_KERNEL, \
		CONFIG_DAC_MCP4725_INIT_PRIORITY, \
		&mcp4725_driver_api);

		DT_INST_FOREACH_STATUS_OKAY(INST_DT_MCP4725);

dts/bindings/dac/microchip,mcp4725.yaml

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		# Copyright (c) 2021 Laird Connectivity
		# SPDX-License-Identifier: Apache-2.0

		description: Microchip MCP4725 12-bit DAC

		compatible: "microchip,mcp4725"

		include: [dac-controller.yaml, i2c-device.yaml]

		properties:
		"#io-channel-cells":
		const: 1

		io-channel-cells:
		- output

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