On Fri, May 25, 2018 at 8:19 PM, Radu Pirea [off-list ref] wrote:

This mfd driver is just a wrapper over atmel_serial driver and
spi-at91-usart driver. Selection of one of the drivers is based on a
property from device tree. If the property is not specified, the default
driver is atmel_serial.

+       depends on OF

What makes this driver OF specific?

+#include <linux/of.h>
+#include <linux/of_platform.h>

Ditto.

+#include <linux/pinctrl/pinctrl.h>

How exactly is this used?

+#include <linux/platform_device.h>

+#include <linux/slab.h>

Ditto.

+#include <linux/types.h>

+static int at91_usart_mode_probe(struct platform_device *pdev)
+{
+       struct device_node *np = pdev->dev.of_node;
+       struct mfd_cell cell;
+       u32 opmode;
+       int err;
+

+       err = of_property_read_u32(np, "atmel,usart-mode", &opmode);

Check unified device property API.

+       return mfd_add_devices(&pdev->dev, PLATFORM_DEVID_AUTO, &cell, 1,
+                             NULL, 0, NULL);

No devm_ and no ->remove(). Why to leak resources?

-- 
With Best Regards,
Andy Shevchenko