As Russell King found out the hard way, a change I did to fix multiplatform
builds with this driver broke the old Assabet/Neponset platform: It turns
out that while the driver is runtime configurable in principle, the
runtime configuration does not cover the specific case of machines that
can not do any 16-bit I/O on the smc91x registers.

The driver currently provides helpers to access 16-bit registers for
architectures that are known at compile-time to only have 8-bit I/O,
but my patch changed it to a runtime flag that never gets consulted
most register accesses.

This introduces new SMC_out16()/SMC_in16 helpers (if anyone can suggest
a better name, I'm glad to modify this) that behaves like SMC_outw()/SMC_inw()
most of the time, but uses a pair of 8-bit accesses on platforms that
have no support for wider register accesses.

Signed-off-by: Arnd Bergmann <a...@arndb.de>
Reported-by: Russell King <li...@armlinux.org.uk>
Fixes: b70661c70830d ("net: smc91x: use run-time configuration on all ARM 
machines")
---
Having bad luck streak with this patch, the version I sent
had a couple of mistakes from the last rebase before sending
it out, this version should actually apply and build.

diff --git a/drivers/net/ethernet/smsc/smc91x.h 
b/drivers/net/ethernet/smsc/smc91x.h
index 1a55c7976df0..497411ed6de2 100644
--- a/drivers/net/ethernet/smsc/smc91x.h
+++ b/drivers/net/ethernet/smsc/smc91x.h
@@ -414,30 +414,32 @@ smc_pxa_dma_insw(void __iomem *ioaddr, struct smc_local 
*lp, int reg, int dma,
 #define SMC_outsl(a, r, p, l)          BUG()
 #endif
 
-#if ! SMC_CAN_USE_16BIT
-
 /*
- * Any 16-bit access is performed with two 8-bit accesses if the hardware
- * can't do it directly. Most registers are 16-bit so those are mandatory.
+ * Any 16-bit register access is performed with two 8-bit accesses if the
+ * hardware can't do it directly.
  */
-#define SMC_outw(x, ioaddr, reg)                                       \
-       do {                                                            \
-               unsigned int __val16 = (x);                             \
-               SMC_outb( __val16, ioaddr, reg );                       \
-               SMC_outb( __val16 >> 8, ioaddr, reg + (1 << SMC_IO_SHIFT));\
-       } while (0)
-#define SMC_inw(ioaddr, reg)                                           \
-       ({                                                              \
-               unsigned int __val16;                                   \
-               __val16 =  SMC_inb( ioaddr, reg );                      \
+#define SMC_out16(x, ioaddr, reg)                                           \
+do {                                                                        \
+       if (SMC_CAN_USE_8BIT && !SMC_16BIT(lp)) {                            \
+               unsigned int __val16 = (x);                                  \
+               SMC_outb(__val16, ioaddr, reg );                             \
+               SMC_outb(__val16 >> 8, ioaddr, reg + (1 << SMC_IO_SHIFT));   \
+       } else {                                                             \
+               SMC_outw(x, ioaddr, reg);                                    \
+       }                                                                    \
+} while (0)
+
+#define SMC_in16(ioaddr, reg)                                               \
+({                                                                          \
+       unsigned int __val16;                                                \
+       if (SMC_CAN_USE_8BIT && !SMC_16BIT(lp)) {                            \
+               __val16 =  SMC_inb( ioaddr, reg );                           \
                __val16 |= SMC_inb( ioaddr, reg + (1 << SMC_IO_SHIFT)) << 8; \
-               __val16;                                                \
-       })
-
-#define SMC_insw(a, r, p, l)           BUG()
-#define SMC_outsw(a, r, p, l)          BUG()
-
-#endif
+       } else {                                                             \
+               __val16 = SMC_inw(ioaddr, reg);                              \
+       }                                                                    \
+       __val16;                                                             \
+})
 
 #if !defined(SMC_insw) || !defined(SMC_outsw)
 #define SMC_insw(a, r, p, l)           BUG()
@@ -927,113 +929,113 @@ static const char * chip_ids[ 16 ] =  {
                        SMC_outw((x) << 8, ioaddr, INT_REG(lp));        \
        } while (0)
 
-#define SMC_CURRENT_BANK(lp)   SMC_inw(ioaddr, BANK_SELECT)
+#define SMC_CURRENT_BANK(lp)   SMC_in16(ioaddr, BANK_SELECT)
 
 #define SMC_SELECT_BANK(lp, x)                                 \
        do {                                                            \
                if (SMC_MUST_ALIGN_WRITE(lp))                           \
                        SMC_outl((x)<<16, ioaddr, 12<<SMC_IO_SHIFT);    \
                else                                                    \
-                       SMC_outw(x, ioaddr, BANK_SELECT);               \
+                       SMC_out16(x, ioaddr, BANK_SELECT);              \
        } while (0)
 
-#define SMC_GET_BASE(lp)               SMC_inw(ioaddr, BASE_REG(lp))
+#define SMC_GET_BASE(lp)       SMC_in16(ioaddr, BASE_REG(lp))
 
-#define SMC_SET_BASE(lp, x)            SMC_outw(x, ioaddr, BASE_REG(lp))
+#define SMC_SET_BASE(lp, x)    SMC_out16(x, ioaddr, BASE_REG(lp))
 
-#define SMC_GET_CONFIG(lp)     SMC_inw(ioaddr, CONFIG_REG(lp))
+#define SMC_GET_CONFIG(lp)     SMC_in16(ioaddr, CONFIG_REG(lp))
 
-#define SMC_SET_CONFIG(lp, x)  SMC_outw(x, ioaddr, CONFIG_REG(lp))
+#define SMC_SET_CONFIG(lp, x)  SMC_out16(x, ioaddr, CONFIG_REG(lp))
 
-#define SMC_GET_COUNTER(lp)    SMC_inw(ioaddr, COUNTER_REG(lp))
+#define SMC_GET_COUNTER(lp)    SMC_in16(ioaddr, COUNTER_REG(lp))
 
-#define SMC_GET_CTL(lp)                SMC_inw(ioaddr, CTL_REG(lp))
+#define SMC_GET_CTL(lp)                SMC_in16(ioaddr, CTL_REG(lp))
 
-#define SMC_SET_CTL(lp, x)             SMC_outw(x, ioaddr, CTL_REG(lp))
+#define SMC_SET_CTL(lp, x)     SMC_out16(x, ioaddr, CTL_REG(lp))
 
-#define SMC_GET_MII(lp)                SMC_inw(ioaddr, MII_REG(lp))
+#define SMC_GET_MII(lp)                SMC_in16(ioaddr, MII_REG(lp))
 
-#define SMC_GET_GP(lp)         SMC_inw(ioaddr, GP_REG(lp))
+#define SMC_GET_GP(lp)         SMC_in16(ioaddr, GP_REG(lp))
 
 #define SMC_SET_GP(lp, x)                                              \
        do {                                                            \
                if (SMC_MUST_ALIGN_WRITE(lp))                           \
                        SMC_outl((x)<<16, ioaddr, SMC_REG(lp, 8, 1));   \
                else                                                    \
-                       SMC_outw(x, ioaddr, GP_REG(lp));                \
+                       SMC_out16(x, ioaddr, GP_REG(lp));               \
        } while (0)
 
-#define SMC_SET_MII(lp, x)             SMC_outw(x, ioaddr, MII_REG(lp))
+#define SMC_SET_MII(lp, x)     SMC_out16(x, ioaddr, MII_REG(lp))
 
-#define SMC_GET_MIR(lp)                SMC_inw(ioaddr, MIR_REG(lp))
+#define SMC_GET_MIR(lp)                SMC_in16(ioaddr, MIR_REG(lp))
 
-#define SMC_SET_MIR(lp, x)             SMC_outw(x, ioaddr, MIR_REG(lp))
+#define SMC_SET_MIR(lp, x)     SMC_out16(x, ioaddr, MIR_REG(lp))
 
-#define SMC_GET_MMU_CMD(lp)    SMC_inw(ioaddr, MMU_CMD_REG(lp))
+#define SMC_GET_MMU_CMD(lp)    SMC_in16(ioaddr, MMU_CMD_REG(lp))
 
-#define SMC_SET_MMU_CMD(lp, x) SMC_outw(x, ioaddr, MMU_CMD_REG(lp))
+#define SMC_SET_MMU_CMD(lp, x) SMC_out16(x, ioaddr, MMU_CMD_REG(lp))
 
-#define SMC_GET_FIFO(lp)               SMC_inw(ioaddr, FIFO_REG(lp))
+#define SMC_GET_FIFO(lp)       SMC_in16(ioaddr, FIFO_REG(lp))
 
-#define SMC_GET_PTR(lp)                SMC_inw(ioaddr, PTR_REG(lp))
+#define SMC_GET_PTR(lp)                SMC_in16(ioaddr, PTR_REG(lp))
 
 #define SMC_SET_PTR(lp, x)                                             \
        do {                                                            \
                if (SMC_MUST_ALIGN_WRITE(lp))                           \
                        SMC_outl((x)<<16, ioaddr, SMC_REG(lp, 4, 2));   \
                else                                                    \
-                       SMC_outw(x, ioaddr, PTR_REG(lp));               \
+                       SMC_out16(x, ioaddr, PTR_REG(lp));              \
        } while (0)
 
-#define SMC_GET_EPH_STATUS(lp) SMC_inw(ioaddr, EPH_STATUS_REG(lp))
+#define SMC_GET_EPH_STATUS(lp) SMC_in16(ioaddr, EPH_STATUS_REG(lp))
 
-#define SMC_GET_RCR(lp)                SMC_inw(ioaddr, RCR_REG(lp))
+#define SMC_GET_RCR(lp)                SMC_in16(ioaddr, RCR_REG(lp))
 
-#define SMC_SET_RCR(lp, x)             SMC_outw(x, ioaddr, RCR_REG(lp))
+#define SMC_SET_RCR(lp, x)     SMC_out16(x, ioaddr, RCR_REG(lp))
 
-#define SMC_GET_REV(lp)                SMC_inw(ioaddr, REV_REG(lp))
+#define SMC_GET_REV(lp)                SMC_in16(ioaddr, REV_REG(lp))
 
-#define SMC_GET_RPC(lp)                SMC_inw(ioaddr, RPC_REG(lp))
+#define SMC_GET_RPC(lp)                SMC_in16(ioaddr, RPC_REG(lp))
 
 #define SMC_SET_RPC(lp, x)                                             \
        do {                                                            \
                if (SMC_MUST_ALIGN_WRITE(lp))                           \
                        SMC_outl((x)<<16, ioaddr, SMC_REG(lp, 8, 0));   \
                else                                                    \
-                       SMC_outw(x, ioaddr, RPC_REG(lp));               \
+                       SMC_out16(x, ioaddr, RPC_REG(lp));              \
        } while (0)
 
-#define SMC_GET_TCR(lp)                SMC_inw(ioaddr, TCR_REG(lp))
+#define SMC_GET_TCR(lp)                SMC_in16(ioaddr, TCR_REG(lp))
 
-#define SMC_SET_TCR(lp, x)             SMC_outw(x, ioaddr, TCR_REG(lp))
+#define SMC_SET_TCR(lp, x)     SMC_out16(x, ioaddr, TCR_REG(lp))
 
 #ifndef SMC_GET_MAC_ADDR
 #define SMC_GET_MAC_ADDR(lp, addr)                                     \
        do {                                                            \
                unsigned int __v;                                       \
-               __v = SMC_inw(ioaddr, ADDR0_REG(lp));                   \
+               __v = SMC_in16(ioaddr, ADDR0_REG(lp));                  \
                addr[0] = __v; addr[1] = __v >> 8;                      \
-               __v = SMC_inw(ioaddr, ADDR1_REG(lp));                   \
+               __v = SMC_in16(ioaddr, ADDR1_REG(lp));                  \
                addr[2] = __v; addr[3] = __v >> 8;                      \
-               __v = SMC_inw(ioaddr, ADDR2_REG(lp));                   \
+               __v = SMC_in16(ioaddr, ADDR2_REG(lp));                  \
                addr[4] = __v; addr[5] = __v >> 8;                      \
        } while (0)
 #endif
 
 #define SMC_SET_MAC_ADDR(lp, addr)                                     \
        do {                                                            \
-               SMC_outw(addr[0]|(addr[1] << 8), ioaddr, ADDR0_REG(lp)); \
-               SMC_outw(addr[2]|(addr[3] << 8), ioaddr, ADDR1_REG(lp)); \
-               SMC_outw(addr[4]|(addr[5] << 8), ioaddr, ADDR2_REG(lp)); \
+               SMC_out16(addr[0]|(addr[1] << 8), ioaddr, ADDR0_REG(lp)); \
+               SMC_out16(addr[2]|(addr[3] << 8), ioaddr, ADDR1_REG(lp)); \
+               SMC_out16(addr[4]|(addr[5] << 8), ioaddr, ADDR2_REG(lp)); \
        } while (0)
 
 #define SMC_SET_MCAST(lp, x)                                           \
        do {                                                            \
                const unsigned char *mt = (x);                          \
-               SMC_outw(mt[0] | (mt[1] << 8), ioaddr, MCAST_REG1(lp)); \
-               SMC_outw(mt[2] | (mt[3] << 8), ioaddr, MCAST_REG2(lp)); \
-               SMC_outw(mt[4] | (mt[5] << 8), ioaddr, MCAST_REG3(lp)); \
-               SMC_outw(mt[6] | (mt[7] << 8), ioaddr, MCAST_REG4(lp)); \
+               SMC_out16(mt[0] | (mt[1] << 8), ioaddr, MCAST_REG1(lp)); \
+               SMC_out16(mt[2] | (mt[3] << 8), ioaddr, MCAST_REG2(lp)); \
+               SMC_out16(mt[4] | (mt[5] << 8), ioaddr, MCAST_REG3(lp)); \
+               SMC_out16(mt[6] | (mt[7] << 8), ioaddr, MCAST_REG4(lp)); \
        } while (0)
 
 #define SMC_PUT_PKT_HDR(lp, status, length)                            \
@@ -1042,8 +1044,8 @@ static const char * chip_ids[ 16 ] =  {
                        SMC_outl((status) | (length)<<16, ioaddr,       \
                                 DATA_REG(lp));                 \
                else {                                                  \
-                       SMC_outw(status, ioaddr, DATA_REG(lp)); \
-                       SMC_outw(length, ioaddr, DATA_REG(lp)); \
+                       SMC_out16(status, ioaddr, DATA_REG(lp));        \
+                       SMC_out16(length, ioaddr, DATA_REG(lp));        \
                }                                                       \
        } while (0)
 
@@ -1054,8 +1056,8 @@ static const char * chip_ids[ 16 ] =  {
                        (status) = __val & 0xffff;                      \
                        (length) = __val >> 16;                         \
                } else {                                                \
-                       (status) = SMC_inw(ioaddr, DATA_REG(lp));       \
-                       (length) = SMC_inw(ioaddr, DATA_REG(lp));       \
+                       (status) = SMC_in16(ioaddr, DATA_REG(lp));      \
+                       (length) = SMC_in16(ioaddr, DATA_REG(lp));      \
                }                                                       \
        } while (0)
 

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