Subject: [PATCH v1 2/2] iio: dac: vf610_dac: Add IIO DAC driver for Vybrid SoC

From: [email-masked] (Jonathan Cameron)
Date: Tue, 9 Feb 2016 22:44:25 +0000

On 09/02/16 05:26, Sanchayan Maity wrote:
> Add driver support for DAC peripheral on Vybrid SoC.
> 
> Signed-off-by: Sanchayan Maity <[email-masked]>
Few minor comments inline.

Jonathan
> ---
>  .../devicetree/bindings/iio/dac/vf610-dac.txt      |  20 ++
>  drivers/iio/dac/Kconfig                            |   8 +
>  drivers/iio/dac/Makefile                           |   1 +
>  drivers/iio/dac/vf610_dac.c                        | 302 +++++++++++++++++++++
>  4 files changed, 331 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/dac/vf610-dac.txt
>  create mode 100644 drivers/iio/dac/vf610_dac.c
> 
> diff --git a/Documentation/devicetree/bindings/iio/dac/vf610-dac.txt b/Documentation/devicetree/bindings/iio/dac/vf610-dac.txt
> new file mode 100644
> index 0000000..97d7a40
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/dac/vf610-dac.txt
> @@ -0,0 +1,20 @@
> +Freescale vf610 Digital to Analog Converter bindings
> +
> +The devicetree bindings are for the new DAC driver written for
> +vf610 SoCs from Freescale.
> +
> +Required properties:
> +- compatible: Should contain "fsl,vf610-dac"
> +- reg: Offset and length of the register set for the device
> +- interrupts: Should contain the interrupt for the device
> +- clocks: The clock is needed by the DAC controller
> +- clock-names: Must contain "dac", matching entry in the clocks property.
> +
> +Example:
> +dac0: dac at 400cc000 {
> +	compatible = "fsl,vf610-dac";
> +	reg = <0x400cc000 0x1000>;
> +	interrupts = <55 IRQ_TYPE_LEVEL_HIGH>;
> +	clock-names = "dac";
> +	clocks = <&clks VF610_CLK_DAC0>;
> +};
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index e701e28..8eb0502 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -196,4 +196,12 @@ config MCP4922
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called mcp4922.
>  
> +config VF610_DAC
> +	tristate "Vybrid vf610 DAC driver"
> +	help
> +	  Say yes here to support Vybrid board digital-to-analog converter.
> +
> +	  This driver can also be built as a module. If so, the module will
> +	  be called vf610_dac.
> +
>  endmenu
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index 63ae056..93feb27 100644
> --- a/drivers/iio/dac/Makefile
> +++ b/drivers/iio/dac/Makefile
> @@ -21,3 +21,4 @@ obj-$(CONFIG_MAX517) += max517.o
>  obj-$(CONFIG_MAX5821) += max5821.o
>  obj-$(CONFIG_MCP4725) += mcp4725.o
>  obj-$(CONFIG_MCP4922) += mcp4922.o
> +obj-$(CONFIG_VF610_DAC) += vf610_dac.o
> diff --git a/drivers/iio/dac/vf610_dac.c b/drivers/iio/dac/vf610_dac.c
> new file mode 100644
> index 0000000..775b349
> --- /dev/null
> +++ b/drivers/iio/dac/vf610_dac.c
> @@ -0,0 +1,302 @@
> +/*
> + * Freescale Vybrid vf610 DAC driver
> + *
> + * Copyright 2016 Toradex AG
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/err.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/slab.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +
> +#define DRIVER_NAME "vf610-dac"
One of my pet hates is having defines like this that add nothing.
Just put it in where it is used (as there is only one place).

> +
> +#define VF610_DACx_STATCTRL		0x20
> +
> +#define VF610_DAC_DACEN			BIT(15)
> +#define VF610_DAC_DACRFS		BIT(14)
> +#define VF610_DAC_LPEN			BIT(11)
> +
> +#define VF610_DAC_DAT0(x)		((x) & 0xFFF)
> +
> +enum conversion_mode_sel {
> +	VF610_DAC_CONV_HIGH_POWER,
> +	VF610_DAC_CONV_LOW_POWER,
> +};
> +
> +struct vf610_dac {
> +	struct clk *clk;
> +	struct device *dev;
> +	enum conversion_mode_sel conv_mode;
> +	void __iomem *regs;
> +	int irq;
> +};
> +
> +static int vf610_dac_init(struct vf610_dac *info)
> +{
> +	int val;
> +
> +	info->conv_mode = VF610_DAC_CONV_LOW_POWER;
> +	val = VF610_DAC_DACEN | VF610_DAC_DACRFS |
> +		VF610_DAC_LPEN;
> +	writel(val, info->regs + VF610_DACx_STATCTRL);
> +
> +	return 0;
> +}
> +
> +static int vf610_set_conversion_mode(struct iio_dev *indio_dev,
> +				const struct iio_chan_spec *chan,
> +				unsigned int mode)
> +{
> +	struct vf610_dac *info = iio_priv(indio_dev);
> +	int val;
> +
> +	mutex_lock(&indio_dev->mlock);
> +	info->conv_mode = mode;
> +	val = readl(info->regs + VF610_DACx_STATCTRL);
> +	if (mode)
> +		val |= VF610_DAC_LPEN;
> +	else
> +		val &= ~VF610_DAC_LPEN;
> +	writel(val, info->regs + VF610_DACx_STATCTRL);
> +	mutex_unlock(&indio_dev->mlock);
> +
> +	return 0;
> +}
> +
> +static int vf610_get_conversion_mode(struct iio_dev *indio_dev,
> +				const struct iio_chan_spec *chan)
> +{
> +	struct vf610_dac *info = iio_priv(indio_dev);
> +
> +	return info->conv_mode;
> +}
> +
> +static const char * const vf610_conv_modes[] = { "high-power", "low-power"};
> +
> +static const struct iio_enum vf610_conversion_mode = {
> +	.items = vf610_conv_modes,
> +	.num_items = ARRAY_SIZE(vf610_conv_modes),
> +	.get = vf610_get_conversion_mode,
> +	.set = vf610_set_conversion_mode,
> +};
> +
> +static const struct iio_chan_spec_ext_info vf610_ext_info[] = {
> +	IIO_ENUM("conversion_mode", IIO_SHARED_BY_DIR,
This will amke it called out_conversion_mode. Does it actually
make sense, rather than IIO_SHARED_BY_ALL which would just
be conversion_mode?  Doesn't really matter either way.
> +		&vf610_conversion_mode),
> +	{},
> +};
> +
> +#define VF610_DAC_CHAN(_chan_type) { \
> +	.type = (_chan_type), \
> +	.indexed = -1, \
> +	.output = 1, \
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
> +	.ext_info = vf610_ext_info, \
> +}
> +
> +static const struct iio_chan_spec vf610_dac_iio_channels[] = {
> +	VF610_DAC_CHAN(IIO_VOLTAGE),
> +};
> +
> +static int vf610_read_raw(struct iio_dev *indio_dev,
> +			struct iio_chan_spec const *chan,
> +			int *val, int *val2,
> +			long mask)
> +{
> +	struct vf610_dac *info = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		*val = VF610_DAC_DAT0(readl(info->regs));
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		/*
> +		 * DACRFS is always 1 for valid reference and typical
> +		 * reference voltage as per Vybrid datasheet is 3.3V
> +		 * from section 9.1.2.1 of Vybrid datasheet
> +		 */
> +		*val = 3300 /* mV */;
> +		*val2 = 12;
Looks at least superficially right to me - I'm being lazy and not reading
the datasheet on this occasion!
> +		return IIO_VAL_FRACTIONAL_LOG2;
> +
> +	default:
> +		break;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int vf610_write_raw(struct iio_dev *indio_dev,
> +			struct iio_chan_spec const *chan,
> +			int val, int val2,
> +			long mask)
> +{
> +	struct vf610_dac *info = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		mutex_lock(&indio_dev->mlock);
> +		writel(VF610_DAC_DAT0(val), info->regs);
> +		mutex_unlock(&indio_dev->mlock);
> +		return 0;
> +
> +	default:
> +		break;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static const struct iio_info vf610_dac_iio_info = {
> +	.driver_module = THIS_MODULE,
> +	.read_raw = &vf610_read_raw,
> +	.write_raw = &vf610_write_raw,
> +};
> +
> +static const struct of_device_id vf610_dac_match[] = {
> +	{ .compatible = "fsl,vf610-dac", },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, vf610_dac_match);
> +
> +static int vf610_dac_probe(struct platform_device *pdev)
> +{
> +	struct iio_dev *indio_dev;
> +	struct vf610_dac *info;
> +	struct resource *mem;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&pdev->dev,
> +					sizeof(struct vf610_dac));
> +	if (!indio_dev) {
> +		dev_err(&pdev->dev, "Failed allocating iio device\n");
> +		return -ENOMEM;
> +	}
> +
> +	info = iio_priv(indio_dev);
> +	info->dev = &pdev->dev;
> +
> +	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	info->regs = devm_ioremap_resource(&pdev->dev, mem);
> +	if (IS_ERR(info->regs))
> +		return PTR_ERR(info->regs);
> +
> +	info->clk = devm_clk_get(&pdev->dev, "dac");
> +	if (IS_ERR(info->clk)) {
> +		dev_err(&pdev->dev, "failed getting clock, err = %ld\n",
> +			PTR_ERR(info->clk));
> +		return PTR_ERR(info->clk);
> +	}
> +
> +	platform_set_drvdata(pdev, indio_dev);
> +
> +	indio_dev->name = dev_name(&pdev->dev);
> +	indio_dev->dev.parent = &pdev->dev;
> +	indio_dev->dev.of_node = pdev->dev.of_node;
> +	indio_dev->info = &vf610_dac_iio_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = vf610_dac_iio_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(vf610_dac_iio_channels);
> +
> +	ret = clk_prepare_enable(info->clk);
> +	if (ret) {
> +		dev_err(&pdev->dev,
> +			"Could not prepare or enable the clock\n");
> +		return ret;
> +	}
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Couldn't register the device\n");
> +		goto error_iio_device_register;
> +	}
> +
> +	vf610_dac_init(info);
Peter already pointed this out, but iio_device_register is responsible
for exposing an IIO device to the rest of the system (userspace and
in kernel client driverS) so it should not be called until everything is
ready.  You might just get a read before we get to the init call here.
> +
> +	return 0;
> +
> +error_iio_device_register:
> +	clk_disable_unprepare(info->clk);
> +
> +	return ret;
> +}
> +
> +static int vf610_dac_remove(struct platform_device *pdev)
> +{
> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +	struct vf610_dac *info = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
> +	clk_disable_unprepare(info->clk);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int vf610_dac_suspend(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
> +	struct vf610_dac *info = iio_priv(indio_dev);
> +	int val;
> +
Given this is presumably 'kind of' the oposite of the
init below, for clear balance I'd break this out to
a vf610_dac_exit function.

Also opens up the question of whether it makes sense to make
this same write in the remove function above.

> +	val = readl(info->regs + VF610_DACx_STATCTRL);
> +	val &= ~VF610_DAC_DACEN;
> +	writel(val, info->regs + VF610_DACx_STATCTRL);
> +
> +	clk_disable_unprepare(info->clk);
> +
> +	return 0;
> +}
> +
> +static int vf610_dac_resume(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
> +	struct vf610_dac *info = iio_priv(indio_dev);
> +	int ret;
> +
> +	ret = clk_prepare_enable(info->clk);
> +	if (ret)
> +		return ret;
> +
> +	vf610_dac_init(info);
> +
> +	return 0;
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(vf610_dac_pm_ops, vf610_dac_suspend, vf610_dac_resume);
> +
> +static struct platform_driver vf610_dac_driver = {
> +	.probe          = vf610_dac_probe,
> +	.remove         = vf610_dac_remove,
> +	.driver         = {
> +		.name   = DRIVER_NAME,
> +		.of_match_table = vf610_dac_match,
> +		.pm     = &vf610_dac_pm_ops,
> +	},
> +};
> +module_platform_driver(vf610_dac_driver);
> +
> +MODULE_AUTHOR("Sanchayan Maity <[email-masked]");
> +MODULE_DESCRIPTION("Freescale VF610 DAC driver");
> +MODULE_LICENSE("GPL v2");
>