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@@ -53,3 +53,64 @@
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* P7 ... P0 A7 ... A0 A7 ... A0
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* | Page | Addr MSB | Addr LSB | (DMA registers)
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*
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+ * Address mapping for channels 5-7:
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+ *
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+ * A23 ... A17 A16 A15 ... A9 A8 A7 ... A1 A0 (Physical addresses)
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+ * | ... | \ \ ... \ \ \ ... \ \
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+ * | ... | \ \ ... \ \ \ ... \ (not used)
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+ * | ... | \ \ ... \ \ \ ... \
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+ * P7 ... P1 (0) A7 A6 ... A0 A7 A6 ... A0
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+ * | Page | Addr MSB | Addr LSB | (DMA registers)
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+ *
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+ * Again, channels 5-7 transfer _physical_ words (16 bits), so addresses
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+ * and counts _must_ be word-aligned (the lowest address bit is _ignored_ at
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+ * the hardware level, so odd-byte transfers aren't possible).
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+ *
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+ * Transfer count (_not # bytes_) is limited to 64K, represented as actual
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+ * count - 1 : 64K => 0xFFFF, 1 => 0x0000. Thus, count is always 1 or more,
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+ * and up to 128K bytes may be transferred on channels 5-7 in one operation.
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+ *
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+ */
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+
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+#define MAX_DMA_CHANNELS 8
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+
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+/*
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+ ISA DMA limitations on Alpha platforms,
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+
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+ These may be due to SIO (PCI<->ISA bridge) chipset limitation, or
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+ just a wiring limit.
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+*/
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+
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+/* The maximum address for ISA DMA transfer on Alpha XL, due to an
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+ hardware SIO limitation, is 64MB.
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+*/
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+#define ALPHA_XL_MAX_ISA_DMA_ADDRESS 0x04000000UL
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+
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+/* The maximum address for ISA DMA transfer on RUFFIAN,
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+ due to an hardware SIO limitation, is 16MB.
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+*/
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+#define ALPHA_RUFFIAN_MAX_ISA_DMA_ADDRESS 0x01000000UL
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+
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+/* The maximum address for ISA DMA transfer on SABLE, and some ALCORs,
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+ due to an hardware SIO chip limitation, is 2GB.
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+*/
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+#define ALPHA_SABLE_MAX_ISA_DMA_ADDRESS 0x80000000UL
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+#define ALPHA_ALCOR_MAX_ISA_DMA_ADDRESS 0x80000000UL
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+
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+/*
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+ Maximum address for all the others is the complete 32-bit bus
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+ address space.
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+*/
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+#define ALPHA_MAX_ISA_DMA_ADDRESS 0x100000000UL
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+
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+#ifdef CONFIG_ALPHA_GENERIC
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+# define MAX_ISA_DMA_ADDRESS (alpha_mv.max_isa_dma_address)
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+#else
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+# if defined(CONFIG_ALPHA_XL)
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+# define MAX_ISA_DMA_ADDRESS ALPHA_XL_MAX_ISA_DMA_ADDRESS
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+# elif defined(CONFIG_ALPHA_RUFFIAN)
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+# define MAX_ISA_DMA_ADDRESS ALPHA_RUFFIAN_MAX_ISA_DMA_ADDRESS
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+# elif defined(CONFIG_ALPHA_SABLE)
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+# define MAX_ISA_DMA_ADDRESS ALPHA_SABLE_MAX_ISA_DMA_ADDRESS
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+# elif defined(CONFIG_ALPHA_ALCOR)
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+# define MAX_ISA_DMA_ADDRESS ALPHA_ALCOR_MAX_ISA_DMA_ADDRESS
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