5 files changed, 71 insertions, 39 deletions

diff --git a/arch/powerpc/sysdev/bestcomm/ata.c b/arch/powerpc/sysdev/bestcomm/ata.c
index 1f5258fb38c3..901c9f91e5dd 100644
--- a/arch/powerpc/sysdev/bestcomm/ata.c
+++ b/arch/powerpc/sysdev/bestcomm/ata.c
@@ -61,6 +61,9 @@ bcom_ata_init(int queue_len, int maxbufsize)
         struct bcom_ata_var *var;
         struct bcom_ata_inc *inc;
 
+        /* Prefetch breaks ATA DMA.  Turn it off for ATA DMA */
+        bcom_disable_prefetch();
+
         tsk = bcom_task_alloc(queue_len, sizeof(struct bcom_ata_bd), 0);
         if (!tsk)
                 return NULL;
diff --git a/arch/powerpc/sysdev/bestcomm/ata.h b/arch/powerpc/sysdev/bestcomm/ata.h
index 10982769c465..0b2371811334 100644
--- a/arch/powerpc/sysdev/bestcomm/ata.h
+++ b/arch/powerpc/sysdev/bestcomm/ata.h
@@ -16,22 +16,15 @@
 
 struct bcom_ata_bd {
         u32     status;
-        u32     dst_pa;
         u32     src_pa;
+        u32     dst_pa;
 };
 
-extern struct bcom_task *
-bcom_ata_init(int queue_len, int maxbufsize);
-
-extern void
-bcom_ata_rx_prepare(struct bcom_task *tsk);
-
-extern void
-bcom_ata_tx_prepare(struct bcom_task *tsk);
-
-extern void
-bcom_ata_reset_bd(struct bcom_task *tsk);
-
+extern struct bcom_task * bcom_ata_init(int queue_len, int maxbufsize);
+extern void bcom_ata_rx_prepare(struct bcom_task *tsk);
+extern void bcom_ata_tx_prepare(struct bcom_task *tsk);
+extern void bcom_ata_reset_bd(struct bcom_task *tsk);
+extern void bcom_ata_release(struct bcom_task *tsk);
 
 #endif /* __BESTCOMM_ATA_H__ */
 
diff --git a/arch/powerpc/sysdev/bestcomm/bestcomm.c b/arch/powerpc/sysdev/bestcomm/bestcomm.c
index 446c9ea85b30..378ebd9aac18 100644
--- a/arch/powerpc/sysdev/bestcomm/bestcomm.c
+++ b/arch/powerpc/sysdev/bestcomm/bestcomm.c
@@ -279,7 +279,6 @@ bcom_engine_init(void)
         int task;
         phys_addr_t tdt_pa, ctx_pa, var_pa, fdt_pa;
         unsigned int tdt_size, ctx_size, var_size, fdt_size;
-        u16 regval;
 
         /* Allocate & clear SRAM zones for FDT, TDTs, contexts and vars/incs */
         tdt_size = BCOM_MAX_TASKS * sizeof(struct bcom_tdt);
@@ -331,10 +330,8 @@ bcom_engine_init(void)
         out_8(&bcom_eng->regs->ipr[BCOM_INITIATOR_ALWAYS], BCOM_IPR_ALWAYS);
 
         /* Disable COMM Bus Prefetch on the original 5200; it's broken */
-        if ((mfspr(SPRN_SVR) & MPC5200_SVR_MASK) == MPC5200_SVR) {
-                regval = in_be16(&bcom_eng->regs->PtdCntrl);
-                out_be16(&bcom_eng->regs->PtdCntrl,  regval | 1);
-        }
+        if ((mfspr(SPRN_SVR) & MPC5200_SVR_MASK) == MPC5200_SVR)
+                bcom_disable_prefetch();
 
         /* Init lock */
         spin_lock_init(&bcom_eng->lock);
diff --git a/arch/powerpc/sysdev/bestcomm/bestcomm.h b/arch/powerpc/sysdev/bestcomm/bestcomm.h
index c960a8b49655..23a95f80dfdb 100644
--- a/arch/powerpc/sysdev/bestcomm/bestcomm.h
+++ b/arch/powerpc/sysdev/bestcomm/bestcomm.h
@@ -16,8 +16,19 @@
 #ifndef __BESTCOMM_H__
 #define __BESTCOMM_H__
 
-struct bcom_bd; /* defined later on ... */
-
+/**
+ * struct bcom_bd - Structure describing a generic BestComm buffer descriptor
+ * @status: The current status of this buffer. Exact meaning depends on the
+ *          task type
+ * @data: An array of u32 extra data.  Size of array is task dependant.
+ *
+ * Note: Don't dereference a bcom_bd pointer as an array.  The size of the
+ *       bcom_bd is variable.  Use bcom_get_bd() instead.
+ */
+struct bcom_bd {
+        u32     status;
+        u32     data[0];        /* variable payload size */
+};
 
 /* ======================================================================== */
 /* Generic task management                                                   */
@@ -84,17 +95,6 @@ bcom_get_task_irq(struct bcom_task *tsk) {
 /* BD based tasks helpers                                                   */
 /* ======================================================================== */
 
-/**
- * struct bcom_bd - Structure describing a generic BestComm buffer descriptor
- * @status: The current status of this buffer. Exact meaning depends on the
- *          task type
- * @data: An array of u32 whose meaning depends on the task type.
- */
-struct bcom_bd {
-        u32     status;
-        u32     data[1];        /* variable, but at least 1 */
-};
-
 #define BCOM_BD_READY   0x40000000ul
 
 /** _bcom_next_index - Get next input index.
@@ -140,15 +140,31 @@ bcom_queue_full(struct bcom_task *tsk)
 }
 
 /**
+ * bcom_get_bd - Get a BD from the queue
+ * @tsk: The BestComm task structure
+ * index: Index of the BD to fetch
+ */
+static inline struct bcom_bd
+*bcom_get_bd(struct bcom_task *tsk, unsigned int index)
+{
+        /* A cast to (void*) so the address can be incremented by the
+         * real size instead of by sizeof(struct bcom_bd) */
+        return ((void *)tsk->bd) + (index * tsk->bd_size);
+}
+
+/**
  * bcom_buffer_done - Checks if a BestComm 
  * @tsk: The BestComm task structure
  */
 static inline int
 bcom_buffer_done(struct bcom_task *tsk)
 {
+        struct bcom_bd *bd;
         if (bcom_queue_empty(tsk))
                 return 0;
-        return !(tsk->bd[tsk->outdex].status & BCOM_BD_READY);
+
+        bd = bcom_get_bd(tsk, tsk->outdex);
+        return !(bd->status & BCOM_BD_READY);
 }
 
 /**
@@ -160,16 +176,21 @@ bcom_buffer_done(struct bcom_task *tsk)
 static inline struct bcom_bd *
 bcom_prepare_next_buffer(struct bcom_task *tsk)
 {
-        tsk->bd[tsk->index].status = 0; /* cleanup last status */
-        return &tsk->bd[tsk->index];
+        struct bcom_bd *bd;
+
+        bd = bcom_get_bd(tsk, tsk->index);
+        bd->status = 0; /* cleanup last status */
+        return bd;
 }
 
 static inline void
 bcom_submit_next_buffer(struct bcom_task *tsk, void *cookie)
 {
+        struct bcom_bd *bd = bcom_get_bd(tsk, tsk->index);
+
         tsk->cookie[tsk->index] = cookie;
         mb();   /* ensure the bd is really up-to-date */
-        tsk->bd[tsk->index].status |= BCOM_BD_READY;
+        bd->status |= BCOM_BD_READY;
         tsk->index = _bcom_next_index(tsk);
         if (tsk->flags & BCOM_FLAGS_ENABLE_TASK)
                 bcom_enable(tsk);
@@ -179,10 +200,12 @@ static inline void *
 bcom_retrieve_buffer(struct bcom_task *tsk, u32 *p_status, struct bcom_bd **p_bd)
 {
         void *cookie = tsk->cookie[tsk->outdex];
+        struct bcom_bd *bd = bcom_get_bd(tsk, tsk->outdex);
+
         if (p_status)
-                *p_status = tsk->bd[tsk->outdex].status;
+                *p_status = bd->status;
         if (p_bd)
-                *p_bd = &tsk->bd[tsk->outdex];
+                *p_bd = bd;
         tsk->outdex = _bcom_next_outdex(tsk);
         return cookie;
 }
diff --git a/arch/powerpc/sysdev/bestcomm/bestcomm_priv.h b/arch/powerpc/sysdev/bestcomm/bestcomm_priv.h
index 866a2915ef2f..eb0d1c883c31 100644
--- a/arch/powerpc/sysdev/bestcomm/bestcomm_priv.h
+++ b/arch/powerpc/sysdev/bestcomm/bestcomm_priv.h
@@ -198,8 +198,8 @@ struct bcom_task_header {
 #define BCOM_IPR_SCTMR_1        2
 #define BCOM_IPR_FEC_RX         6
 #define BCOM_IPR_FEC_TX         5
-#define BCOM_IPR_ATA_RX         4
-#define BCOM_IPR_ATA_TX         3
+#define BCOM_IPR_ATA_RX         7
+#define BCOM_IPR_ATA_TX         7
 #define BCOM_IPR_SCPCI_RX       2
 #define BCOM_IPR_SCPCI_TX       2
 #define BCOM_IPR_PSC3_RX        2
@@ -241,6 +241,22 @@ extern void bcom_set_initiator(int task, int initiator);
 
 #define TASK_ENABLE             0x8000
 
+/**
+ * bcom_disable_prefetch - Hook to disable bus prefetching
+ *
+ * ATA DMA and the original MPC5200 need this due to silicon bugs.  At the
+ * moment disabling prefetch is a one-way street.  There is no mechanism
+ * in place to turn prefetch back on after it has been disabled.  There is
+ * no reason it couldn't be done, it would just be more complex to implement.
+ */
+static inline void bcom_disable_prefetch(void)
+{
+        u16 regval;
+
+        regval = in_be16(&bcom_eng->regs->PtdCntrl);
+        out_be16(&bcom_eng->regs->PtdCntrl, regval | 1);
+};
+
 static inline void
 bcom_enable_task(int task)
 {