[PATCH v7 0/2] add mcf54415 DAC driver

[PATCH v7 0/2] add mcf54415 DAC driver

[Angelo Dureghello]

This patchset adds a minimalistic DAC driver for the NXP mcf54415/6/7/8
builtin DACs.

Currently the driver enables the raw write only. Feature as dma, sync, or
format are not supoprted for this version.

Additional options suppoerted by the DAC module will be added to the driver
later on, as needed.

The same patchset prepares the m68k/coldfire architecture to support
the driver.

Below some basic tests done on stmark2 mcf54415-based board, voltage check
on DAC0 and DAC1:

~ # cd /sys/bus/iio/devices/iio:device0/
/sys/bus/iio/devices/iio:device0 # ls
name               out_voltage_scale  uevent
out_voltage_raw    subsystem
/sys/bus/iio/devices/iio:device0 # cat name
mcf54415
/sys/bus/iio/devices/iio:device0 # echo 4095 > out_voltage_raw 
/sys/bus/iio/devices/iio:device0 # echo 2048 > out_voltage_raw 
/sys/bus/iio/devices/iio:device0 # echo 4096 > out_voltage_raw 
sh: write error: Invalid argument
/sys/bus/iio/devices/iio:device0 # cat out_voltage_raw 
2048
/sys/bus/iio/devices/iio:device0 # 

Same behavior for /sys/bus/iio/devices/iio:device1.

Generated a sine wave by shell script, sine shape is good.

is actually in progress:

Note: this patchset depends on mew mcf_read/mcf_write implementation that
Link: https://lore.kernel.org/linux-m68k/209d0653-6386-4b64-9e15-e358f84453ab@app.fastmail.com/T/#t
Link: https://lore.kernel.org/linux-m68k/20260506142644.3234270-2-gerg@kernel.org/
---
Changes in v7:
- keeping changelog in each single patch, where any
- Link to v6: https://patch.msgid.link/20260618-wip-stmark2-dac-v6-0-48761dbb96d7@baylibre.com

Changes in v6:
- Removed patches 1 to 8, already pushed in m68knommu for-next by
  Greg Ungerer <gerg@linux-m68k.org>
- keeping changelog in each single patch, where any
- Link to v5: https://patch.msgid.link/20260610-wip-stmark2-dac-v5-0-b76b83366d5c@baylibre.com

Changes in v5:
- keeping changelog in each single patch, where any
- Link to v4: https://patch.msgid.link/20260531-wip-stmark2-dac-v4-0-7e65ab4215dd@baylibre.com

Changes in v4:
- keeping changelog in each single patch, where any
- Link to v3: https://patch.msgid.link/20260522-wip-stmark2-dac-v3-0-16be0ad35a67@baylibre.com

Changes in v3:
- keeping changelog in each single patch, where any
- Link to v2: https://patch.msgid.link/20260513-wip-stmark2-dac-v2-0-fcdae50cf51a@baylibre.com

Changes in v2:
- keeping changelog in each single patch, where any
- Link to v1: https://patch.msgid.link/20260504-wip-stmark2-dac-v1-0-874c36a4910d@baylibre.com

To: Jonathan Cameron <jic23@kernel.org>
To: David Lechner <dlechner@baylibre.com>
To: Nuno Sá <nuno.sa@analog.com>
To: Andy Shevchenko <andy@kernel.org>
To: Geert Uytterhoeven <geert@linux-m68k.org>
To: Maxime Coquelin <mcoquelin.stm32@gmail.com>
To: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-iio@vger.kernel.org
Cc: linux-m68k@lists.linux-m68k.org
Cc: linux-stm32@st-md-mailman.stormreply.com
Cc: linux-arm-kernel@lists.infradead.org

---
Angelo Dureghello (2):
      iio: dac: add mcf54415 DAC
      m68k: defconfig: update stmark2 defconfig

 arch/m68k/configs/stmark2_defconfig |   2 +
 drivers/iio/dac/Kconfig             |  11 +++
 drivers/iio/dac/Makefile            |   1 +
 drivers/iio/dac/mcf54415_dac.c      | 180 ++++++++++++++++++++++++++++++++++++
 4 files changed, 194 insertions(+)
---
base-commit: bc5a85a5441632f4bd7acd38620fdcbe4852a44f
change-id: 20260430-wip-stmark2-dac-7060f49dd94f

Best regards,
--  
Angelo Dureghello <adureghello@baylibre.com>

[PATCH v7 1/2] iio: dac: add mcf54415 DAC

[Angelo Dureghello]

From: Angelo Dureghello <adureghello@baylibre.com>

Add basic version of mcf54415 DAC driver. DAC is embedded in the SoC and
DAC configuration registers are mapped in the internal IO address space.

The DAC accepts a 12-bit digital signal and creates a monotonic 12-bit
analog output varying from DAC_VREFL to DAC_VREFH. The DAC module
consists of a conversion unit, an output amplifier, and the associated
digital control blocks. Default register values for DAC_VREFL and DAC_VREFH
are respectively 0 and 0xfff, left untouched in this initial version.

This initial version of the driver is minimalistic, "output raw" only, to
be extended in the future. DMA and external sync are disabled, default mode
is high speed, default format is right-justified 12-bit on 16-bit word.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Angelo Dureghello <adureghello@baylibre.com>
---
Changes in v2:
- remove tests from commit message, moved to patch 0
- remove additional blank lines
- remove dead code and unused definitions
- use regmap
- add limit check on raw write
- non functional style fixes
- add COMPILE_TEST to Kconfig
Changes in v3:
- add comments where needed
- code style changes
- remove unneeded variables
- use regmap_set_bits where possible
- remove macro not needed to define a single channel
- set up regmap to big_endian accesses for next patches that will come,
  that will adjust ColdFire readx/writex as standard LE (links in 0/x).
- add return value check on regmap calls
- sashiko: remove unneeded .io_port from regmap init.
- sashiko: add select REGMAP_MMIO in Kconfig
Changes in v4:
- remove unused includes
- sashiko: return "ret" as regmap_read ret value in case of error
- sashiko: using u32 as regmap_read value
- use local variable in mcf54415_dac_init() for better readability
- sashiko: check mcf54415_dac_init return value also in resume()
Changes in v5:
- commit syntax fixes
- minor code style fixes
- use include <linux/type.h>
- removed unneeded cast
- disable clock in case of DAC init error
- use unsigned int for regmap_read and GENMASK for masking 12 bits
- add id table to match "mcfdac" platform device name
Changes in v6:
- removed pm ops, can't be tested for mcf54415 with mmu enabled
- Kconfig desc line rewrap
- minor coding style fixes
Changes in v7:
- remove unused includes
- remove unneeded call to platform_set_drvdata()
---
 drivers/iio/dac/Kconfig        |  11 +++
 drivers/iio/dac/Makefile       |   1 +
 drivers/iio/dac/mcf54415_dac.c | 180 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 192 insertions(+)

diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index 657c68e75542..ebf7144f922a 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -527,6 +527,17 @@ config MAX5821
 	  Say yes here to build support for Maxim MAX5821
 	  10 bits DAC.
 
+config MCF54415_DAC
+	tristate "NXP MCF54415 DAC driver"
+	depends on M5441x || COMPILE_TEST
+	select REGMAP_MMIO
+	help
+	  Say yes here if you want to build support for NXP ColdFire
+	  MCF54415/6/7/8 12-bit DAC module.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called mcf54415_dac.
+
 config MCP4725
 	tristate "MCP4725/6 DAC driver"
 	depends on I2C
diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
index 003431798498..5d20d37e44ce 100644
--- a/drivers/iio/dac/Makefile
+++ b/drivers/iio/dac/Makefile
@@ -52,6 +52,7 @@ obj-$(CONFIG_MAX517) += max517.o
 obj-$(CONFIG_MAX22007) += max22007.o
 obj-$(CONFIG_MAX5522) += max5522.o
 obj-$(CONFIG_MAX5821) += max5821.o
+obj-$(CONFIG_MCF54415_DAC) += mcf54415_dac.o
 obj-$(CONFIG_MCP4725) += mcp4725.o
 obj-$(CONFIG_MCP4728) += mcp4728.o
 obj-$(CONFIG_MCP47FEB02) += mcp47feb02.o
diff --git a/drivers/iio/dac/mcf54415_dac.c b/drivers/iio/dac/mcf54415_dac.c
new file mode 100644
index 000000000000..e2c12241a534
--- /dev/null
+++ b/drivers/iio/dac/mcf54415_dac.c
@@ -0,0 +1,180 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * NXP mcf54415 DAC driver
+ *
+ * Copyright 2026 BayLibre - adureghello@baylibre.com
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+
+#include <linux/iio/iio.h>
+
+#define MCF54415_DAC_CR			0x00
+#define MCF54415_DAC_CR_PDN		BIT(0)
+#define MCF54415_DAC_CR_HSLS		BIT(6)
+#define MCF54415_DAC_CR_WMLVL		GENMASK(9, 8)
+#define MCF54415_DAC_CR_FILT		BIT(12)
+
+#define MCF54415_DAC_DATA		0x02
+
+struct mcf54415_dac {
+	struct regmap *map;
+	struct clk *clk;
+};
+
+static const struct regmap_config mcf54415_dac_regmap_config = {
+	.reg_bits = 16,
+	.reg_stride = 2,
+	.val_bits = 16,
+	.max_register = 0x0c, /* DACX_FILTCNT,  R.M. Table 30-2 */
+	.val_format_endian = REGMAP_ENDIAN_BIG,
+	.reg_format_endian = REGMAP_ENDIAN_BIG,
+};
+
+static int mcf54415_dac_init(struct mcf54415_dac *info)
+{
+	u16 val = MCF54415_DAC_CR_FILT | FIELD_PREP(MCF54415_DAC_CR_WMLVL, 1);
+	int ret;
+
+	/* Fixed defaults and enable DAC (bit 0 set to 0) */
+	ret = regmap_write(info->map, MCF54415_DAC_CR, val);
+	if (ret)
+		return ret;
+
+	/* DAC is ready after 12us, from RM table 40-3  */
+	fsleep(12);
+
+	return 0;
+}
+
+static void mcf54415_dac_exit(void *data)
+{
+	struct mcf54415_dac *info = data;
+
+	regmap_set_bits(info->map, MCF54415_DAC_CR, MCF54415_DAC_CR_PDN);
+}
+
+static const struct iio_chan_spec mcf54415_dac_iio_channel = {
+	.type = IIO_VOLTAGE,
+	.output = 1,
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+};
+
+static int mcf54415_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val, int *val2, long mask)
+{
+	struct mcf54415_dac *info = iio_priv(indio_dev);
+	unsigned int reg;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = regmap_read(info->map, MCF54415_DAC_DATA, &reg);
+		if (ret)
+			return ret;
+		*val = reg & GENMASK(11, 0);
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		/* Reference voltage as per ColdFire datasheet is 3.3V */
+		*val = 3300 /* mV */;
+		*val2 = 12;
+		return IIO_VAL_FRACTIONAL_LOG2;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int mcf54415_write_raw(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan,
+			      int val, int val2, long mask)
+{
+	struct mcf54415_dac *info = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		/* Check based on RM 30.3.2 (DACn_DATA) reg. resolution */
+		if (val < 0 || val > 4095)
+			return -EINVAL;
+		return regmap_write(info->map, MCF54415_DAC_DATA, val);
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info mcf54415_dac_iio_info = {
+	.read_raw = &mcf54415_read_raw,
+	.write_raw = &mcf54415_write_raw,
+};
+
+static int mcf54415_dac_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct iio_dev *indio_dev;
+	struct mcf54415_dac *info;
+	void __iomem *regs;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*info));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	info = iio_priv(indio_dev);
+
+	regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(regs))
+		return dev_err_probe(dev, PTR_ERR(regs), "failed to get io regs\n");
+
+	info->map = devm_regmap_init_mmio(dev, regs, &mcf54415_dac_regmap_config);
+	if (IS_ERR(info->map))
+		return PTR_ERR(info->map);
+
+	info->clk = devm_clk_get_enabled(dev, "dac");
+	if (IS_ERR(info->clk))
+		return dev_err_probe(dev, PTR_ERR(info->clk), "failed getting clock\n");
+
+	indio_dev->name = "mcf54415";
+	indio_dev->info = &mcf54415_dac_iio_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = &mcf54415_dac_iio_channel;
+	indio_dev->num_channels = 1;
+
+	ret = mcf54415_dac_init(info);
+	if (ret)
+		return ret;
+
+	ret = devm_add_action_or_reset(dev, mcf54415_dac_exit, info);
+	if (ret)
+		return ret;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct platform_device_id mcf54415_dac_ids[] = {
+	{ .name = "mcfdac" },
+	{ }
+};
+MODULE_DEVICE_TABLE(platform, mcf54415_dac_ids);
+
+static struct platform_driver mcf54415_dac_driver = {
+	.driver = {
+		.name = "mcf54415_dac",
+	},
+	.probe = mcf54415_dac_probe,
+	.id_table = mcf54415_dac_ids,
+};
+module_platform_driver(mcf54415_dac_driver);
+
+MODULE_AUTHOR("Angelo Dureghello <angelo@kernel-space.org>");
+MODULE_DESCRIPTION("NXP MCF54415 DAC driver");
+MODULE_LICENSE("GPL");

-- 
2.54.0

[PATCH v7 2/2] m68k: defconfig: update stmark2 defconfig

[Angelo Dureghello]

From: Angelo Dureghello <adureghello@baylibre.com>

Update stmark2 defconfig enabling MCF5441X DACs.

Signed-off-by: Angelo Dureghello <adureghello@baylibre.com>
---
Changes for v5:
- move this patch after new Kconfig symbols are added
---
 arch/m68k/configs/stmark2_defconfig | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/m68k/configs/stmark2_defconfig b/arch/m68k/configs/stmark2_defconfig
index b3fb95f73a95..3941113bc60b 100644
--- a/arch/m68k/configs/stmark2_defconfig
+++ b/arch/m68k/configs/stmark2_defconfig
@@ -76,6 +76,8 @@ CONFIG_DMADEVICES=y
 CONFIG_MCF_EDMA=y
 # CONFIG_VIRTIO_MENU is not set
 # CONFIG_VHOST_MENU is not set
+CONFIG_IIO=y
+CONFIG_MCF54415_DAC=y
 CONFIG_EXT2_FS=y
 CONFIG_EXT2_FS_XATTR=y
 CONFIG_EXT2_FS_POSIX_ACL=y

-- 
2.54.0

Re: [PATCH v7 0/2] add mcf54415 DAC driver

[Jonathan Cameron]

On Wed, 01 Jul 2026 16:17:22 +0200
Angelo Dureghello <adureghello@baylibre.com> wrote:

> This patchset adds a minimalistic DAC driver for the NXP mcf54415/6/7/8
> builtin DACs.
Applied patch 1 to the testing branch of iio.git.

Thanks,

Jonathan