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

On Tue, 9 Feb 2016, Sanchayan Maity wrote:

Add driver support for DAC peripheral on Vybrid SoC.

comments below
 

the last sentence is not quite clear; is the comma needed?

VF610_ prefix

+
+#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_ prefix

+	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)

should be void, or check the return value

+{
+	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)

mode should be enum conversion_mode_sel?

+{
+	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,

return of type enum conversion_mode_sel?

+				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"};

this should be documented in sysfs-bus-iio-vf610; maybe high-power should 
be high-speed

probably this interface should have been exposed as a settable 
conversion rate

+
+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,
+		&vf610_conversion_mode),
+	{},
+};
+
+#define VF610_DAC_CHAN(_chan_type) { \
+	.type = (_chan_type), \
+	.indexed = -1, \

indexed should be 0 (or not specified) if no indexing is to be used

+	.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;
+		return IIO_VAL_FRACTIONAL_LOG2;
+
+	default:
+		break;

just return -EINVAL here?
and remove it below below

+	}
+
+	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 here should save two lines

+	}
+
+	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",

"Failed getting ..."

+			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);

there is a race here, move _dac_init() before _register()
return value is not checked (or use void)

+
+	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;
+
+	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 <sanchayan.maity@toradex.com");
+MODULE_DESCRIPTION("Freescale VF610 DAC driver");
+MODULE_LICENSE("GPL v2");

-- 

Peter Meerwald-Stadler
+43-664-2444418 (mobile)