[U-Boot] [RFC] drivers: pci: imx: add imx_pcie_remove function

[Fabio Estevam <festevam@gmail.com>]

Hi Tim,

Thanks for working on this!

[Adding Peter and Jagan on Cc]

On Wed, May 10, 2017 at 1:43 PM, Tim Harvey <tharvey@gateworks.com> wrote:
> There is no dedicated reset signal wired up for the MX6QDL thus if the
> bootloader enables the link we need some special handling to get the core
> back into a state where it is safe to touch it for configuration.
>
> While there has been some special handling in the Linux kernel to do this,
> it was removed in 4.11 thus we need to do it properly in the bootloader
> and therefore without this if you enable PCI in the bootloader you will hang
> while booting the 4.11 kernel.
>
> This was tested on a Gateworks Ventana board.
>
> TODO: what is the right arch specific place to hook the remove function?

Ideally the pcie_imx.c driver should be converted to driver model and
then the .remove can be simply added, just like in Barebox.

Take a look at the following PCI drivers that have already been
converted to the driver model to use as reference:

$ git grep U_BOOT_DRIVER drivers/pci/
drivers/pci/pci-uclass.c:U_BOOT_DRIVER(pci_bridge_drv) = {
drivers/pci/pci-uclass.c:U_BOOT_DRIVER(pci_generic_drv) = {
drivers/pci/pci_sandbox.c:U_BOOT_DRIVER(pci_sandbox) = {
drivers/pci/pci_tegra.c:U_BOOT_DRIVER(pci_tegra) = {
drivers/pci/pci_x86.c:U_BOOT_DRIVER(pci_x86) = {
drivers/pci/pcie_dw_mvebu.c:U_BOOT_DRIVER(pcie_dw_mvebu) = {
drivers/pci/pcie_layerscape.c:U_BOOT_DRIVER(pci_layerscape) = {
drivers/pci/pcie_xilinx.c:U_BOOT_DRIVER(pcie_xilinx) = {