[PATCH 1/3 v2] usb: pci-quirks: Add a common mutex for the I/O port pair of SB800

[Zoltan Boszormenyi]

This patch adds a common mutex in the USB PCI quirks code and starts
using it to synchronize access to the I/O port pair 0xcd6 / 0xcd7 on
SB800.

These I/O ports are also used by i2c-piix4 and sp5100_tco, the next
two patches port these drivers to use this common mutex.

v2: No extra header and no wrapper for mutex_lock() / mutex_unlock()

Signed-off-by: Zoltan Boszormenyi <zbos...@pr.hu>
---
 drivers/usb/host/pci-quirks.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/usb/host/pci-quirks.c b/drivers/usb/host/pci-quirks.c
index a9a1e4c..1ef0ada 100644
--- a/drivers/usb/host/pci-quirks.c
+++ b/drivers/usb/host/pci-quirks.c
@@ -279,6 +279,9 @@ bool usb_amd_prefetch_quirk(void)
 }
 EXPORT_SYMBOL_GPL(usb_amd_prefetch_quirk);
 
+DEFINE_MUTEX(sb800_mutex);
+EXPORT_SYMBOL_GPL(sb800_mutex);
+
 /*
  * The hardware normally enables the A-link power management feature, which
  * lets the system lower the power consumption in idle states.
@@ -314,11 +317,13 @@ static void usb_amd_quirk_pll(int disable)
        if (amd_chipset.sb_type.gen == AMD_CHIPSET_SB800 ||
                        amd_chipset.sb_type.gen == AMD_CHIPSET_HUDSON2 ||
                        amd_chipset.sb_type.gen == AMD_CHIPSET_BOLTON) {
+               mutex_lock(&sb800_mutex);
                outb_p(AB_REG_BAR_LOW, 0xcd6);
                addr_low = inb_p(0xcd7);
                outb_p(AB_REG_BAR_HIGH, 0xcd6);
                addr_high = inb_p(0xcd7);
                addr = addr_high << 8 | addr_low;
+               mutex_unlock(&sb800_mutex);
 
                outl_p(0x30, AB_INDX(addr));
                outl_p(0x40, AB_DATA(addr));
-- 
2.9.3