IB/ipath: Lock and always use shadow copies of GPIO register

The new LED blinking interface adds more contention for the
unprotected GPIO pins that were already shared, though not commonly at
the same time.  We add locks to the accesses to these pins so that
Read-Modify-Write is now safe.  Some of these locks are added at
interrupt context, so we shadow the registers which drive and inspect
these pins to avoid the mmio read/writes.  This mitigates the effects
of the locks and hastens us through the interrupt.

Add locking and always use shadows for registers controlling GPIO pins
(ExtCtrl and GPIOout). The use of shadows implies doing less I/O,
which can make I2C operation too fast on some platforms. An explicit
udelay(1) in SCL manipulation fixes that.

Signed-off-by: Michael Albaugh <michael.albaugh@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/infiniband/hw/ipath/ipath_kernel.h b/drivers/infiniband/hw/ipath/ipath_kernel.h
index 2f39db7df31c..bd1088a99891 100644
--- a/drivers/infiniband/hw/ipath/ipath_kernel.h
+++ b/drivers/infiniband/hw/ipath/ipath_kernel.h
@@ -399,6 +399,8 @@ struct ipath_devdata {
         u64 ipath_gpio_out;
         /* shadow the gpio mask register */
         u64 ipath_gpio_mask;
+        /* shadow the gpio output enable, etc... */
+        u64 ipath_extctrl;
         /* kr_revision shadow */
         u64 ipath_revision;
         /*
@@ -473,8 +475,6 @@ struct ipath_devdata {
         u32 ipath_cregbase;
         /* shadow the control register contents */
         u32 ipath_control;
-        /* shadow the gpio output contents */
-        u32 ipath_extctrl;
         /* PCI revision register (HTC rev on FPGA) */
         u32 ipath_pcirev;
 
@@ -576,6 +576,9 @@ struct ipath_devdata {
         u64 ipath_gpio_sda;
         u64 ipath_gpio_scl;
 
+        /* lock for doing RMW of shadows/regs for ExtCtrl and GPIO */
+        spinlock_t ipath_gpio_lock;
+
         /* used to override LED behavior */
         u8 ipath_led_override;  /* Substituted for normal value, if non-zero */
         u16 ipath_led_override_timeoff; /* delta to next timer event */