tree 5257b9a01867322f80bfa019ff71b093255bfa8b
parent 902e2e7d482c55395652ff78cb3457fc390b101d
author Takahisa Tanaka <mc74hc00@gmail.com> 1354426398 +0900
committer Wim Van Sebroeck <wim@iguana.be> 1355952309 +0100

watchdog: sp5100_tco: Add SB8x0 chipset support

The current sp5100_tco driver only supports SP5100/SB7x0 chipset, doesn't
support SB8x0 chipset, because current sp5100_tco driver doesn't know that the
offset address for watchdog timer was changed from SB8x0 chipset.

The offset address of SP5100 and SB7x0 chipsets are as follows, quote from the
AMD SB700/710/750 Register Reference Guide (Page 164) and the AMD SP5100
Register Reference Guide (Page 166).

  WatchDogTimerControl 69h
  WatchDogTimerBase0   6Ch
  WatchDogTimerBase1   6Dh
  WatchDogTimerBase2   6Eh
  WatchDogTimerBase3   6Fh

In contrast, the offset address of SB8x0 chipset is as follows, quote from
AMD SB800-Series Southbridges Register Reference Guide (Page 147).

  WatchDogTimerEn      48h
  WatchDogTimerConfig  4Ch

So, In the case of SB8x0 chipset, sp5100_tco reads meaningless MMIO
address (for example, 0xbafe00) from wrong offset address, and the following
message is logged.

   SP5100 TCO timer: mmio address 0xbafe00 already in use

With this patch, sp5100_tco driver supports SB8x0 chipset, and can avoid
iomem resource conflict. The processing of this patch is as follows.

 Step 1) Attempt to get the watchdog base address from indirect I/O (0xCD6
         and 0xCD7).
  - Go to the step 7 if obtained address hasn't conflicted with other
    resource. But, currently, the address (0xfec000f0) conflicts with the
    IOAPIC MMIO address, and the following message is logged.

       SP5100 TCO timer: mmio address 0xfec000f0 already in use

    0xfec000f0 is recommended by AMD BIOS Developer's Guide. So, go to the
    next step.

 Step 2) Attempt to get the SBResource_MMIO base address from AcpiMmioEN (for
         SB8x0,  PM_Reg:24h) or SBResource_MMIO (SP5100/SB7x0, PCI_Reg:9Ch)
         register.
  - Go to the step 7 if these register has enabled by BIOS, and obtained
    address hasn't conflicted with other resource.
  - If above condition isn't true, go to the next step.

 Step 3) Attempt to get the free MMIO address from allocate_resource().
  - Go to the step 7 if these register has enabled by BIOS, and obtained
    address hasn't conflicted with other resource.
  - Driver initialization has failed if obtained address has conflicted
    with other resource, and no 'force_addr' parameter is specified.

 Step 4) Use the specified address If 'force_addr' parameter is specified.
  - allocate_resource() function may fail, when the PCI bridge device occupies
    iomem resource from 0xf0000000 to 0xffffffff. To handle such a case,
    I added 'force_addr' parameter to sp5100_tco driver. With 'force_addr'
    parameter, sp5100_tco driver directly can assign MMIO address for watchdog
    timer from free iomem region. Note that It's dangerous to specify wrong
    address in the 'force_addr' parameter.

      Example of force_addr parameter use
        # cat /proc/iomem
        ...snip...
        fec00000-fec003ff : IOAPIC 0
                                      <--- free MMIO region
        fec10000-fec1001f : pnp 00:0b
        fec20000-fec203ff : IOAPIC 1
        ...snip...
        # cat /etc/modprobe.d/sp5100_tco.conf
        options sp5100_tco force_addr=0xfec00800
        # modprobe sp5100_tco
        # cat /proc/iomem
        ...snip...
        fec00000-fec003ff : IOAPIC 0
        fec00800-fec00807 : SP5100 TCO  <--- watchdog timer MMIO address
        fec10000-fec1001f : pnp 00:0b
        fec20000-fec203ff : IOAPIC 1
        ...snip...
        #

  - Driver initialization has failed if specified address has conflicted
    with other resource.

 Step 5) Disable the watchdog timer
  - To rewrite the watchdog timer register of the chipset, absolutely
    guarantee that the watchdog timer is disabled.

 Step 6) Re-program the watchdog timer MMIO address to chipset.
  - Re-program the obtained MMIO address in Step 3 or Step 4 to chipset via
    indirect I/O (0xCD6 and 0xCD7).

 Step 7) Enable and setup the watchdog timer

This patch has worked fine on my test environment (ASUS M4A89GTD-PRO/USB3 and
DL165G7). therefore I believe that it's no problem to re-program the MMIO
address for watchdog timer to chipset during disabled watchdog. However,
I'm not sure about it, because I don't know much about chipset programming.

So, any comments will be welcome.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=43176
Tested-by: Arkadiusz Miskiewicz <arekm@maven.pl>
Tested-by: Paul Menzel <paulepanter@users.sourceforge.net>
Signed-off-by: Takahisa Tanaka <mc74hc00@gmail.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>