OpenWRT on Ebox3300 (IV): Adding patches

In this part, we will deal with enabling not functioning parts of our device. We’ve already noticed, that there are no disks seen and ethernet controller is also not visible. The second is quite easily resolved by selecting appropriate options in the OpenWRT menuconfig. However the first thing is going to be more interesting, as we will be creating patch to the OpenWRT build tree itself. The solution to these hardware problems I’ve found on this blog.

The ethernet controller

First, we deal with ethernet controller. The controller on board is based on the RDC R6040 device. So we will need r6040 kernel module. It’s location in OpenWRT’s menuconfig is Kernel modules > Network Devices > kmod-r6040. We simply select it to build and that’s all. When we rebuild our image we will hopefully get our working ethernet device in ifconfig and in dmesg we will get something like this:

[    7.082793] r6040: RDC R6040 NAPI net driver,version 0.28 (07Oct2011)
[    7.096384] libphy: r6040_eth_mii: probed
[    7.101049] r6040 0000:00:08.0: attached PHY driver [Generic PHY] (mii_bus:phy_addr=0000:00:08.0-0:01)

There is a slight problem with this device (it sometimes fails to enumerate - at least in my case), but I will get back to it later on.

The IDE controller

As far as disks are concerned, it’s going to be more complicated. According to blog, which I provided link above, the needed driver is in kernel. However, driver is not assigned to the specific hardware ID our device uses. So we have to add this ID to the driver headers in order to correctly identify it.

The correct way to add a patch to OpenWRT build tree is using the tool named quilt (which is great tool to work with patches - used by Linux kernel maintainers). The procedure is described on official OpenWRT wiki. We are going to use the procedure described in Adding or editing kernel patches section.

Adding the kernel patch

Procedure looks like this (of course we need quilt, so install it ;)):

• First we need to prepare our kernel tree in order to add changes:

make target/linux/{clean,prepare} V=s QUILT=1

• Then we go to build directory and prepare our patch:
  • The build_dir is for version of OpenWRT I use. On different version, however, it should be similar.
  • Patch name (for kernel patches) must be constructed that way: {platform,generic}/[number]-[name_of_patch].patch. Our patch is of platform type.

cd build_dir/target-i386_i486_uClibc-0.9.33.2/linux-x86_generic/linux-3.10.49/
quilt push -a
quilt new platform/170-rdc_d1011_ids.patch

• Next we edit the files:

  Note: quilt edit uses editor, which can be set in ~/.quiltrc as EDITOR= variable.

quilt edit drivers/ata/pata_it821x.c
quilt edit include/linux/pci_ids.h

• We make our changes visible in patch by using quilt refresh command.
• We may see what changes are being applied to the patch using quilt diff:

# quilt diff

--- a/drivers/ata/pata_it821x.c
+++ b/drivers/ata/pata_it821x.c
@@ -957,6 +957,7 @@ static const struct pci_device_id it821x
        { PCI_VDEVICE(ITE, PCI_DEVICE_ID_ITE_8211), },
        { PCI_VDEVICE(ITE, PCI_DEVICE_ID_ITE_8212), },
        { PCI_VDEVICE(RDC, PCI_DEVICE_ID_RDC_D1010), },
+       { PCI_VDEVICE(RDC, PCI_DEVICE_ID_RDC_D1011), },

        { },
 };
--- a/include/linux/pci_ids.h
+++ b/include/linux/pci_ids.h
@@ -2328,6 +2328,7 @@
 #define PCI_DEVICE_ID_RDC_R6060                0x6060
 #define PCI_DEVICE_ID_RDC_R6061                0x6061
 #define PCI_DEVICE_ID_RDC_D1010                0x1010
+#define PCI_DEVICE_ID_RDC_D1011                0x1011

 #define PCI_VENDOR_ID_LENOVO           0x17aa

As we can see, only those two lines are needed in order to enable our device in the driver.

• To add our patch to the main OpenWRT buildroot we need to run this command from root directory:

make target/linux/update package/index V=s

• After that we can run again make target/linux/{clean,prepare} V=s QUILT=1 and see if our changes are added. We may also check, if the patch is in the patch dir, in this case: target/linux/x86/patches-3.10.

Adding the device to OpenWRT menuconfig

After the necessary modification we have to enable correct kernel module in OpenWRT menuconfig, but there is no appropriate option. So we must add one.

It is quite straightforward. The necessary change must be done in the package/kernel/linux/modules/block.mk file. It will add kernel module in Kernel modules > Block Devices > kmod-ata-core > kmod-ata-pata-821x.

This piece of code should be added under this submenu:

define AddDepends/ata
    SUBMENU:=$(BLOCK_MENU)
    DEPENDS+=kmod-ata-core $(1)
endef

Here is the lines we should add:

@@ -116,6 +116,17 @@ endef
 $(eval $(call KernelPackage,ata-nvidia-sata))


+define KernelPackage/ata-pata-821x
+  TITLE:=IT8211/2 PATA support
+  KCONFIG:=CONFIG_PATA_IT821X
+  FILES:=$(LINUX_DIR)/drivers/ata/pata_it821x.ko
+  AUTOLOAD:=$(call AutoLoad,41,pata_it821x,1)
+  $(call AddDepends/ata)
+endef
+
+$(eval $(call KernelPackage,ata-pata-821x))
+
+
 define KernelPackage/ata-pdc202xx-old
   SUBMENU:=$(BLOCK_MENU)
   TITLE:=Older Promise PATA controller support

After those changes, we should have necessary option available and also we should have visible disks (as sda, sdb, etc.) when we rebuild image with correct module selected.

Let’s check with dmesg:

[    0.157099] libata version 3.00 loaded.
[    0.996951] pata_it821x 0000:00:0c.0: setting latency timer to 64
[    1.000347] scsi0 : pata_it821x
[    1.004775] scsi1 : pata_it821x
[    1.009032] ata1: PATA max UDMA/133 cmd 0x1f0 ctl 0x3f6 bmdma 0xef00 irq 14
[    1.016821] ata2: PATA max UDMA/133 cmd 0x170 ctl 0x376 bmdma 0xef08 irq 15
[    1.300693] ata1.00: ATA-6: 2GU2M     RDC SD-IDE HOST CONTROLLER, 01000000, max UDMA/133
[    1.309761] ata1.00: 3921920 sectors, multi 0: LBA
[    1.315323] ata1.00: limited to UDMA/33 due to 40-wire cable
[    1.322155] ata1.00: configured for UDMA/33
[    1.539471] ata2.00: CFA: TOSHIBA THNCF512MQG, 3.00, max PIO4
[    1.545879] ata2.00: 1000944 sectors, multi 1: LBA
[    1.589460] ata2.00: configured for PIO4

Disks should be visible under /dev. My µSD card is seen as sda and CF card as sdb. So far, so good.

Summary

After those changes, we should be able to use the ethernet device, as well as memory cards as IDE drives. In the next part we deal with adding Ebox3300 target to OpenWRT build tree and we will look into networking facilities.