drivers: dac: add mcp4728 driver

MCP4728 is a 12-bit, Quad Digital-to-Analog Converter with EEPROM Memory.
Controlled via I2C interface.

Signed-off-by: Marek Janus <marek.janus@grinn-global.com>

drivers/dac/CMakeLists.txt

@@ -11,5 +11,6 @@ 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_DAC_MCP4728		dac_mcp4728.c)
 zephyr_library_sources_ifdef(CONFIG_DAC_GD32		dac_gd32.c)
 zephyr_library_sources_ifdef(CONFIG_USERSPACE		dac_handlers.c)

drivers/dac/Kconfig

@@ -44,6 +44,8 @@ source "drivers/dac/Kconfig.dacx3608"
 
 source "drivers/dac/Kconfig.mcp4725"
 
+source "drivers/dac/Kconfig.mcp4728"
+
 source "drivers/dac/Kconfig.gd32"
 
 endif # DAC

drivers/dac/Kconfig.mcp4728

@@ -0,0 +1,9 @@
+# Copyright 2021 Grinn
+#
+# SPDX-License-Identifier: Apache-2.0
+
+config DAC_MCP4728
+	bool "Microchip MCP4728 DAC driver"
+	depends on I2C && DAC
+	help
+	Enable driver for the Microchip MCP4728.

drivers/dac/dac_mcp4728.c

@@ -0,0 +1,110 @@
+/*
+ * Copyright 2021 Grinn
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT microchip_mcp4728
+
+#include <zephyr.h>
+#include <drivers/dac.h>
+#include <drivers/i2c.h>
+#include <logging/log.h>
+
+LOG_MODULE_REGISTER(dac_mcp4728, CONFIG_DAC_LOG_LEVEL);
+
+#define MCP4728_MAX_CHANNEL			4U
+#define MCP4728_RESOLUTION			0xC
+#define MCP4728_DAC_MAX_VAL			((1U << MCP4728_RESOLUTION) - 1U)
+#define MCP4728_MULTI_WRITE_CMD_VAL		8U
+#define MCP4728_MULTI_WRITE_CMD_POS		3U
+#define MCP4728_MULTI_WRITE_CHANNEL_POS		1U
+#define MCP4728_MULTI_WRITE_REFERENCE_POS	7U
+#define MCP4728_MULTI_WRITE_POWER_DOWN_POS	5U
+#define MCP4728_MULTI_WRITE_POWER_DOWN_MASK	0X3
+#define MCP4728_MULTI_WRITE_GAIN_POS		4U
+#define MCP4728_MULTI_WRITE_DAC_UPPER_VAL_POS	8U
+#define MCP4728_MULTI_WRITE_DAC_UPPER_VAL_MASK	0xF
+#define MCP4728_MULTI_WRITE_DAC_LOWER_VAL_MASK	0xFF
+
+struct mcp4728_config {
+	struct i2c_dt_spec bus;
+	uint8_t power_down[MCP4728_MAX_CHANNEL];
+	uint8_t voltage_reference[MCP4728_MAX_CHANNEL];
+	uint8_t gain[MCP4728_MAX_CHANNEL];
+};
+
+static int mcp4728_channel_setup(const struct device *dev,
+				const struct dac_channel_cfg *channel_cfg)
+{
+	if (channel_cfg->channel_id >= MCP4728_MAX_CHANNEL) {
+		return -ENOTSUP;
+	}
+
+	if (channel_cfg->resolution != MCP4728_RESOLUTION) {
+		return -ENOTSUP;
+	}
+
+	return 0;
+}
+
+static int mcp4728_write_value(const struct device *dev, uint8_t channel, uint32_t value)
+{
+	const struct mcp4728_config *config = (struct mcp4728_config *)dev->config;
+	uint8_t tx_data[3];
+	int ret;
+
+	if (channel >= MCP4728_MAX_CHANNEL) {
+		return -ENOTSUP;
+	}
+
+	if (value > MCP4728_DAC_MAX_VAL) {
+		return -ENOTSUP;
+	}
+
+	/* Multi-Write Command: Write Multiple DAC Input Registers. */
+	tx_data[0] = (MCP4728_MULTI_WRITE_CMD_VAL << MCP4728_MULTI_WRITE_CMD_POS) |
+			(channel << MCP4728_MULTI_WRITE_CHANNEL_POS);
+	tx_data[1] = (config->voltage_reference[channel] << MCP4728_MULTI_WRITE_REFERENCE_POS) |
+			((config->power_down[channel] & MCP4728_MULTI_WRITE_POWER_DOWN_MASK)
+			<< MCP4728_MULTI_WRITE_POWER_DOWN_POS) |
+			((config->gain[channel] << MCP4728_MULTI_WRITE_GAIN_POS)) |
+			((value >> MCP4728_MULTI_WRITE_DAC_UPPER_VAL_POS) &
+			MCP4728_MULTI_WRITE_DAC_UPPER_VAL_MASK);
+	tx_data[2] = (value & MCP4728_MULTI_WRITE_DAC_LOWER_VAL_MASK);
+	ret = i2c_write_dt(&config->bus, tx_data, sizeof(tx_data));
+
+	return ret;
+}
+
+static int dac_mcp4728_init(const struct device *dev)
+{
+	const struct mcp4728_config *config = dev->config;
+
+	if (!device_is_ready(config->bus.bus)) {
+		LOG_ERR("%s device not found", config->bus.bus->name);
+		return -ENODEV;
+	}
+	return 0;
+}
+
+static const struct dac_driver_api mcp4728_driver_api = {
+	.channel_setup = mcp4728_channel_setup,
+	.write_value = mcp4728_write_value,
+};
+
+#define INST_DT_MCP4728(index)							\
+	static const struct mcp4728_config mcp4728_config_##index = {		\
+		.bus = I2C_DT_SPEC_INST_GET(index),				\
+		.power_down = DT_INST_PROP(index, power_down_mode),		\
+		.voltage_reference = DT_INST_PROP(index, voltage_reference),	\
+		.gain = DT_INST_PROP_OR(index, gain, {0}),			\
+	};									\
+										\
+	DEVICE_DT_INST_DEFINE(index, dac_mcp4728_init, NULL, NULL,		\
+				&mcp4728_config_##index,			\
+				POST_KERNEL,					\
+				CONFIG_DAC_INIT_PRIORITY,			\
+				&mcp4728_driver_api);
+
+DT_INST_FOREACH_STATUS_OKAY(INST_DT_MCP4728);

dts/bindings/dac/microchip,mcp4728.yaml

@@ -0,0 +1,44 @@
+description: Microchip MCP4728 12-bit 4-channel DAC
+
+compatible: "microchip,mcp4728"
+
+include: [dac-controller.yaml, i2c-device.yaml]
+
+properties:
+    "#io-channel-cells":
+      const: 1
+
+    voltage_reference:
+      type: array
+      required: true
+      description: |
+        DAC voltage reference select.
+        0 - Vdd
+        1 - Internal voltage reference (2.048V)
+        Note: array entries correspond to the successive channels
+
+    power_down_mode:
+      type: array
+      required: true
+      description: |
+        Power-down mode select.
+        0 - normal mode
+        1 - Vout is loaded with 1 kOhm resistor to ground
+        2 - Vout is loaded 100 kOhm resistor to ground
+        3 - Vout is loaded with 500 kOhm resistor to ground
+        Note: with values bigger than 0 most of channel circuits are powered off
+        Note: array entries correspond to the successive channels
+
+    gain:
+      type: array
+      required: false
+      default: [0, 0, 0, 0]
+      description: |
+        Gain selection bit.
+        0 = x1 (gain of 1)
+        1 = x2 (gain of 2)
+        Note: applicable only when internal Vref is selected
+        Note: array entries correspond to the successive channels
+
+io-channel-cells:
+    - output