| Message ID | 1441709851-25261-8-git-send-email-bmeng.cn@gmail.com |
|---|---|
| State | Superseded |
| Delegated to: | Simon Glass |
| Headers | show |
Hi Bin, On Tuesday, 8 September 2015, Bin Meng <bmeng.cn@gmail.com> wrote: > > Document porting considerations for Intel Quark based board, > including MRC parameters and PCIe initialization. > > Signed-off-by: Bin Meng <bmeng.cn@gmail.com> > > --- > > doc/README.x86 | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+) Some nits below. Acked-by: Simon Glass <sjg@chromium.org> > > > diff --git a/doc/README.x86 b/doc/README.x86 > index 5f9c46f..f76db7f 100644 > --- a/doc/README.x86 > +++ b/doc/README.x86 > @@ -733,6 +733,29 @@ Example output: > PCI_BDF(0, 3, 0) INTA PIRQA > ... > > +Porting Hints > +------------- > + > +Quark-specific considerations: > + > +To port U-Boot on other Intel Quark SoC based board, something needs to be taken To port U-Boot to other boards based on the Intel Quark SoC, a few things need to be taken care of > > +care of. The first important part is the Memory Reference Code (MRC) parameters. > +Quark MRC supports memory-down configuration only. All these MRC parameters are > +supplied via board device tree. To get started, first copy the MRC section of via the board > > +arch/x86/dts/galileo.dts to your board's device tree, then change these values > +by consulting board manuals or your hardware vendor. Available MRC parameter > +values are listed in include/dt-bindings/mrc/quark.h. The other tricky part is > +with PCIe. Quark SoC integrates two PCIe root ports, but by default it is held > +in reset after power on. In U-Boot, PCIe initialization is properly handled as > +per Quark's firmware writer guide. In your board support codes, you need provide > +two routines to aid PCIe initialization, which are: board_assert_perst() and > +board_deassert_perst(). The two routines need implement board-specific mechanism implement a board-specific > > +to assert/deassert PCIe PERST# pin. Care must be taken that in those routines > +that any APIs that may trigger PCI enumeration process are strictly forbidden, > +as any access to PCIe root port's configuration registers will cause system hang > +while it is held in reset. For more details, check how it is implemented by the > +Intel Galileo board supported codes in board/intel/galileo/galileo.c. > + > TODO List > --------- > - Audio > -- > 1.8.2.1 > Regards, Simon
diff --git a/doc/README.x86 b/doc/README.x86 index 5f9c46f..f76db7f 100644 --- a/doc/README.x86 +++ b/doc/README.x86 @@ -733,6 +733,29 @@ Example output: PCI_BDF(0, 3, 0) INTA PIRQA ... +Porting Hints +------------- + +Quark-specific considerations: + +To port U-Boot on other Intel Quark SoC based board, something needs to be taken +care of. The first important part is the Memory Reference Code (MRC) parameters. +Quark MRC supports memory-down configuration only. All these MRC parameters are +supplied via board device tree. To get started, first copy the MRC section of +arch/x86/dts/galileo.dts to your board's device tree, then change these values +by consulting board manuals or your hardware vendor. Available MRC parameter +values are listed in include/dt-bindings/mrc/quark.h. The other tricky part is +with PCIe. Quark SoC integrates two PCIe root ports, but by default it is held +in reset after power on. In U-Boot, PCIe initialization is properly handled as +per Quark's firmware writer guide. In your board support codes, you need provide +two routines to aid PCIe initialization, which are: board_assert_perst() and +board_deassert_perst(). The two routines need implement board-specific mechanism +to assert/deassert PCIe PERST# pin. Care must be taken that in those routines +that any APIs that may trigger PCI enumeration process are strictly forbidden, +as any access to PCIe root port's configuration registers will cause system hang +while it is held in reset. For more details, check how it is implemented by the +Intel Galileo board supported codes in board/intel/galileo/galileo.c. + TODO List --------- - Audio
Document porting considerations for Intel Quark based board, including MRC parameters and PCIe initialization. Signed-off-by: Bin Meng <bmeng.cn@gmail.com> --- doc/README.x86 | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+)