Re: [RFC 2/2] usb: gadget: composite: parse dt overrides

On 06/26/2012 12:38 AM, Mitch Bradley wrote:

On 6/25/2012 1:49 PM, Rob Herring wrote:

quoted

On 06/25/2012 03:23 PM, Alexandre Pereira da Silva wrote:

quoted

Grab the devicetree node properties to override VendorId, ProductId,
bcdDevice, Manucacturer, Product and SerialNumber

Signed-off-by: Alexandre Pereira da Silva <redacted>
---
  drivers/usb/gadget/composite.c |   31 +++++++++++++++++++++++++++++++
  1 file changed, 31 insertions(+)

Are these bindings documented? I think they should be less generic.
Perhaps prefixed with 'usb-'.

There is precedent for the following properties in the USB node, namely
the device tree that has been used on OLPC systems for the past several
years.  Also, I think that Sun machines from the same timeframe use the
same property names, based on the fact that Sun is using my USB 2.0 OFW
driver code.

Thanks, I wasn't aware of that.

Here's a listing of the properties of a representative USB child device,
in this case a USB FLASH drive.

configuration#           00000001
bulk-out-size            00000200
bulk-out-pipe            00000001
bulk-in-size             00000200
bulk-in-pipe             00000001
serial$                  200435137016ae938861
device$                  Cruzer Mini
vendor$                  SanDisk Corporation
compatible               usb781,5150.20
                         usb781,5150
                         usbif781,class8.6.50
                         usbif781,class8.6
                         usbif781,class8
                         usbif,class8.6.50
                         usbif,class8.6
                         usbif,class8
                         usb,device
vendor-id                00000781
device-id                00005150
release                  00000020
name                     scsi
class                    00000008
subclass                 00000006
protocol                 00000050
high-speed
assigned-address         00000002
reg                      00000003 00000000
#size-cells              00000000
#address-cells           00000001

Note that:

a) The separator in "vendor-id" is hyphen, not underscore, in keeping
with the established property naming convention (except for the
unfortunate "device_type").

b) There is no "usb," prefix, since the presence of this in a device
node that is a child of a USB bus implicitly identifies the kind of ID.
 "vendor-id" and "device-id" in PCI bus child devices is similarly
un-prefixed.

Okay.

c) Some of these property names are defined in
http://www.openfirmware.org/ofwg/bindings/usb/usb-1_0.ps

We should refer back to this as appropriate, but document what is not
standard. Having an example is useful as well. The original doc was
about describing a device to the host. This case is describing the
device to the device. Perhaps these are the same, but if there are
differences we need to capture that.

Rob

quoted

quoted

diff --git a/drivers/usb/gadget/composite.c

b/drivers/usb/gadget/composite.c
index 390749b..f3b480e 100644

--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c

@@ -17,6 +17,7 @@
  #include <linux/module.h>
  #include <linux/device.h>
  #include <linux/utsname.h>
+#include <linux/of.h>

  #include <linux/usb/composite.h>
  #include <asm/unaligned.h>

@@ -1423,6 +1424,7 @@ static int composite_bind(struct usb_gadget

*gadget)
  {
      struct usb_composite_dev    *cdev;
      int                status = -ENOMEM;
+    struct device_node        *np = gadget->dev.of_node;

      cdev = kzalloc(sizeof *cdev, GFP_KERNEL);
      if (!cdev)

@@ -1470,6 +1472,35 @@ static int composite_bind(struct usb_gadget

*gadget)

      cdev->desc = *composite->dev;

+    /* grab overrides from devicetree */

Reading the code, it looks more like the DT entries are defaults rather
than overrides.

quoted

+    if (np) {
+        u32 reg;
+
+        if (!idVendor &&
+            of_property_read_u32(np, "vendor_id", &reg) == 0)
+            idVendor = reg;

if (!idVendor)
    of_property_read_u32(np, "vendor_id", &idVendor);

Rob

quoted

+
+        if (!idProduct &&
+            of_property_read_u32(np, "product_id", &reg) == 0)
+            idProduct = reg;
+
+        if (!bcdDevice &&
+            of_property_read_u32(np, "bcd_device", &reg) == 0)
+            bcdDevice = reg;
+
+        if (!iManufacturer)
+            of_property_read_string(np, "manufacturer",
+                &iManufacturer);
+
+        if (!iProduct)
+            of_property_read_string(np, "product",
+                &iProduct);
+
+        if (!iSerialNumber)
+            of_property_read_string(np, "serial_number",
+                &iSerialNumber);
+    }
+
      /* standardized runtime overrides for device ID data */
      if (idVendor)
          cdev->desc.idVendor = cpu_to_le16(idVendor);

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