Re: [PATCH v2 3/5] misc: eeprom_93xx46: Implement eeprom_93xx46 DT bindings.

On 21.11.2015 06:40, Cory Tusar wrote:

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On 11/19/2015 12:50 AM, Vladimir Zapolskiy wrote:

quoted

Hi Cory,

On 19.11.2015 05:29, Cory Tusar wrote:

quoted

This commit implements bindings in the eeprom_93xx46 driver allowing
device word size and read-only attributes to be specified via
devicetree.

Signed-off-by: Cory Tusar <cory.tusar-J6Z/VSE8EyIAspv4Qr0y0gC/G2K4zDHf@public.gmane.org>
---
 drivers/misc/eeprom/eeprom_93xx46.c | 62 +++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/drivers/misc/eeprom/eeprom_93xx46.c b/drivers/misc/eeprom/eeprom_93xx46.c
index e1bf0a5..1f29d9a 100644
--- a/drivers/misc/eeprom/eeprom_93xx46.c
+++ b/drivers/misc/eeprom/eeprom_93xx46.c

@@ -13,6 +13,8 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
 #include <linux/slab.h>
 #include <linux/spi/spi.h>
 #include <linux/sysfs.h>

@@ -294,12 +296,71 @@ static ssize_t eeprom_93xx46_store_erase(struct device *dev,
 }
 static DEVICE_ATTR(erase, S_IWUSR, NULL, eeprom_93xx46_store_erase);
 
+#ifdef CONFIG_OF
+static const struct of_device_id eeprom_93xx46_of_table[] = {
+	{ .compatible = "eeprom-93xx46", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, eeprom_93xx46_of_table);
+

Please move this declaration closer to struct spi_driver
eeprom_93xx46_driver below.

As Andrew noted in his follow-up, it's used in the function immediately
after this declaration.  Seems logical to leave it here?

IMO no, see my comment below.

quoted

Also you can avoid #ifdef here, if you write

   .of_match_table = of_match_ptr(eeprom_93xx46_of_table)

Will change this to use of_match_ptr().

quoted

Whenever possible please avoid #ifdef's in .c files.

Agreed.  #ifdef CONFIG_OF still seems to be fairly pervasive though...?

In my opinion it is better to avoid it, and many nice drivers don't have
#ifdef CONFIG_OF.

quoted

quoted

+static int eeprom_93xx46_probe_dt(struct spi_device *spi)
+{
+	struct device_node *np = spi->dev.of_node;
+	struct eeprom_93xx46_platform_data *pd;
+	u32 tmp;
+	int ret;
+
+	if (!of_match_device(eeprom_93xx46_of_table, &spi->dev))
+		return 0;

This check above is redundant, please remove it.

Imagine, how can you get here !of_match_device(..) condition, if you
have driver initialization from a valid device node?

quoted

quoted

+
+	pd = devm_kzalloc(&spi->dev, sizeof(*pd), GFP_KERNEL);
+	if (!pd)
+		return -ENOMEM;
+
+	ret = of_property_read_u32(np, "data-size", &tmp);
+	if (ret < 0) {
+		dev_err(&spi->dev, "data-size property not found\n");
+		goto error_free;

Because you use devm_* resource allocation in .probe, just return error.

Will fix.

quoted

Plus I would suggest to change "data-size" property to an optional one,
here I mean that if it is omitted, then by default consider pd->flags |=
EE_ADDR8.

I don't see such an assumption as safe...data word size is an inherent
property of the device (or the way it's strapped on a given platform),
and should be required for proper operation.

Ok.

quoted

quoted

+	}
+
+	if (tmp == 8) {
+		pd->flags |= EE_ADDR8;
+	} else if (tmp == 16) {
+		pd->flags |= EE_ADDR16;
+	} else {
+		dev_err(&spi->dev, "invalid data-size (%d)\n", tmp);
+		goto error_free;

Same here.

Will fix.

quoted

quoted

+	}
+
+	if (of_property_read_bool(np, "read-only"))
+		pd->flags |= EE_READONLY;
+
+	spi->dev.platform_data = pd;
+
+	return 1;

On success please return 0.

Fixed.

quoted

quoted

+error_free:
+	devm_kfree(&spi->dev, pd);
+	return ret;
+}
+
+#else
+static inline int eeprom_93xx46_probe_dt(struct spi_device *spi)
+{
+	return 0;
+}
+#endif
+

I actually don't see a point to have #ifdef CONFIG_OF here.

Instead please add a check for !spi->dev.of_node at the beginning of
eeprom_93xx46_probe_dt() or in .probe()

How about...

	if (IS_ENABLED(CONFIG_OF) && spi->dev.of_node) {
		err = eeprom_93xx46_probe_dt(spi);
		if (err < 0)
			return err;
	}

...at the beginning of eeprom_93xx46_probe() (as below)?

	if (spi->dev.of_node) {
		err = eeprom_93xx46_probe_dt(spi);
		if (err < 0)
			return err;
	}

is good enough.

Condition (!IS_ENABLED(CONFIG_OF) && spi->dev.of_node) is always false.

quoted

quoted

 static int eeprom_93xx46_probe(struct spi_device *spi)
 {
 	struct eeprom_93xx46_platform_data *pd;
 	struct eeprom_93xx46_dev *edev;
 	int err;
 
+	err = eeprom_93xx46_probe_dt(spi);
+	if (err < 0)
+		return err;
+
 	pd = spi->dev.platform_data;
 	if (!pd) {
 		dev_err(&spi->dev, "missing platform data\n");

@@ -370,6 +431,7 @@ static int eeprom_93xx46_remove(struct spi_device *spi)
 static struct spi_driver eeprom_93xx46_driver = {
 	.driver = {
 		.name	= "93xx46",
+		.of_match_table = eeprom_93xx46_of_table,
 	},
 	.probe		= eeprom_93xx46_probe,
 	.remove		= eeprom_93xx46_remove,

--
With best wishes,
Vladimir
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