m68k: mac: Fix IOP status/control register writes

[ Upstream commit 931fc82a6aaf4e2e4a5490addaa6a090d78c24a7 ]

When writing values to the IOP status/control register make sure those
values do not have any extraneous bits that will clear interrupt flags.

To place the SCC IOP into bypass mode would be desirable but this is not
achieved by writing IOP_DMAINACTIVE | IOP_RUN | IOP_AUTOINC | IOP_BYPASS
to the control register. Drop this ineffective register write.

Remove the flawed and unused iop_bypass() function. Make use of the
unused iop_stop() function.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Stan Johnson <userm57@yahoo.com>
Cc: Joshua Thompson <funaho@jurai.org>
Link: https://lore.kernel.org/r/09bcb7359a1719a18b551ee515da3c4c3cf709e6.1590880333.git.fthain@telegraphics.com.au
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/m68k/mac/iop.c b/arch/m68k/mac/iop.c
index 8209a74fbdebc80e6d40392e66d0a7df3df80b64..cb516cacc819b7a07d77423fe8b857bf244ee254 100644 (file)
--- a/arch/m68k/mac/iop.c
+++ b/arch/m68k/mac/iop.c
@@ -173,7 +173,7 @@ static __inline__ void iop_writeb(volatile struct mac_iop *iop, __u16 addr, __u8
 
 static __inline__ void iop_stop(volatile struct mac_iop *iop)
 {
-       iop->status_ctrl &= ~IOP_RUN;
+       iop->status_ctrl = IOP_AUTOINC;
 }
 
 static __inline__ void iop_start(volatile struct mac_iop *iop)
@@ -181,14 +181,9 @@ static __inline__ void iop_start(volatile struct mac_iop *iop)
        iop->status_ctrl = IOP_RUN | IOP_AUTOINC;
 }
 
-static __inline__ void iop_bypass(volatile struct mac_iop *iop)
-{
-       iop->status_ctrl |= IOP_BYPASS;
-}
-
 static __inline__ void iop_interrupt(volatile struct mac_iop *iop)
 {
-       iop->status_ctrl |= IOP_IRQ;
+       iop->status_ctrl = IOP_IRQ | IOP_RUN | IOP_AUTOINC;
 }
 
 static int iop_alive(volatile struct mac_iop *iop)
@@ -239,7 +234,6 @@ void __init iop_preinit(void)
                } else {
                        iop_base[IOP_NUM_SCC] = (struct mac_iop *) SCC_IOP_BASE_QUADRA;
                }
-               iop_base[IOP_NUM_SCC]->status_ctrl = 0x87;
                iop_scc_present = 1;
        } else {
                iop_base[IOP_NUM_SCC] = NULL;
@@ -251,7 +245,7 @@ void __init iop_preinit(void)
                } else {
                        iop_base[IOP_NUM_ISM] = (struct mac_iop *) ISM_IOP_BASE_QUADRA;
                }
-               iop_base[IOP_NUM_ISM]->status_ctrl = 0;
+               iop_stop(iop_base[IOP_NUM_ISM]);
                iop_ism_present = 1;
        } else {
                iop_base[IOP_NUM_ISM] = NULL;