[POWERPC] Add workaround for MPICs with broken register reads

Some versions of PWRficient 1682M have an interrupt controller in which
the first register in each pair for interrupt sources doesn't always
read with the right polarity/sense values.

To work around this, keep a software copy of the register instead.  Since
it's not modified from the mpic itself, it's a feasible solution.  Still,
keep it under a config option to avoid wasting memory on other platforms.

Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>

diff --git a/arch/powerpc/platforms/Kconfig b/arch/powerpc/platforms/Kconfig
index 065f3b19d6c749ea902700601482afaed8b0f59b..78a7edac577f355845bf7835aef0f6094bb6c4a7 100644 (file)
--- a/arch/powerpc/platforms/Kconfig
+++ b/arch/powerpc/platforms/Kconfig
@@ -137,6 +137,16 @@ config MPIC_U3_HT_IRQS
        depends on PPC_MAPLE
        default y
 
+config MPIC_BROKEN_REGREAD
+       bool
+       depends on MPIC
+       help
+         This option enables a MPIC driver workaround for some chips
+         that have a bug that causes some interrupt source information
+         to not read back properly. It is safe to use on other chips as
+         well, but enabling it uses about 8KB of memory to keep copies
+         of the register contents in software.
+
 config IBMVIO
        depends on PPC_PSERIES || PPC_ISERIES
        bool

diff --git a/arch/powerpc/platforms/pasemi/Kconfig b/arch/powerpc/platforms/pasemi/Kconfig
index 95cd90fd81c74f3ed38dd61766787afb0987965b..117d90aa500840336f1bca64827b3e3c2049e7e4 100644 (file)
--- a/arch/powerpc/platforms/pasemi/Kconfig
+++ b/arch/powerpc/platforms/pasemi/Kconfig
@@ -5,6 +5,7 @@ config PPC_PASEMI
        select MPIC
        select PPC_UDBG_16550
        select PPC_NATIVE
+       select MPIC_BROKEN_REGREAD
        help
          This option enables support for PA Semi's PWRficient line
          of SoC processors, including PA6T-1682M

diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index 25a81f73cecf021ea8d3a6bc470a0ef6c769005f..8de29f28b4c7a6da03f749760b7777dc7356977b 100644 (file)
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c
@@ -228,8 +228,13 @@ static inline u32 _mpic_irq_read(struct mpic *mpic, unsigned int src_no, unsigne
        unsigned int    isu = src_no >> mpic->isu_shift;
        unsigned int    idx = src_no & mpic->isu_mask;
 
-       return _mpic_read(mpic->reg_type, &mpic->isus[isu],
-                         reg + (idx * MPIC_INFO(IRQ_STRIDE)));
+#ifdef CONFIG_MPIC_BROKEN_REGREAD
+       if (reg == 0)
+               return mpic->isu_reg0_shadow[idx];
+       else
+#endif
+               return _mpic_read(mpic->reg_type, &mpic->isus[isu],
+                                 reg + (idx * MPIC_INFO(IRQ_STRIDE)));
 }
 
 static inline void _mpic_irq_write(struct mpic *mpic, unsigned int src_no,
@@ -240,6 +245,11 @@ static inline void _mpic_irq_write(struct mpic *mpic, unsigned int src_no,
 
        _mpic_write(mpic->reg_type, &mpic->isus[isu],
                    reg + (idx * MPIC_INFO(IRQ_STRIDE)), value);
+
+#ifdef CONFIG_MPIC_BROKEN_REGREAD
+       if (reg == 0)
+               mpic->isu_reg0_shadow[idx] = value;
+#endif
 }
 
 #define mpic_read(b,r)         _mpic_read(mpic->reg_type,&(b),(r))

diff --git a/include/asm-powerpc/mpic.h b/include/asm-powerpc/mpic.h
index 0eb3ab9ec2bbf5b559907ead942610591269bacd..edb4a7c8450626009f1585096cbd783525f3fda4 100644 (file)
--- a/include/asm-powerpc/mpic.h
+++ b/include/asm-powerpc/mpic.h
@@ -306,6 +306,10 @@ struct mpic
        unsigned long           *hwirq_bitmap;
 #endif
 
+#ifdef CONFIG_MPIC_BROKEN_REGREAD
+       u32                     isu_reg0_shadow[MPIC_MAX_IRQ_SOURCES];
+#endif
+
        /* link */
        struct mpic             *next;