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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/blackfin/lib/ins.S
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/*

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 * arch/blackfin/lib/ins.S - ins{bwl} using hardware loops

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 *

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 * Copyright 2004-2008 Analog Devices Inc.

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 * Copyright (C) 2005 Bas Vermeulen, BuyWays BV <[email protected]>

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 * Licensed under the GPL-2 or later.

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 */

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#include <linux/linkage.h>

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#include <asm/blackfin.h>

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.align 2

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#ifdef CONFIG_IPIPE

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# define DO_CLI \

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	[--sp] = rets; \

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	[--sp] = (P5:0); \

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	sp += -12; \

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	call ___ipipe_disable_root_irqs_hw; \

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	sp += 12; \

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	(P5:0) = [sp++];

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# define CLI_INNER_NOP

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#else

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# define DO_CLI cli R3;

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# define CLI_INNER_NOP nop; nop; nop;

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#endif

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#ifdef CONFIG_IPIPE

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# define DO_STI \

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	sp += -12; \

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	call ___ipipe_enable_root_irqs_hw; \

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	sp += 12; \

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2:	rets = [sp++];

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#else

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# define DO_STI 2: sti R3;

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#endif

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#ifdef CONFIG_BFIN_INS_LOWOVERHEAD

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# define CLI_OUTER DO_CLI;

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# define STI_OUTER DO_STI;

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# define CLI_INNER 1:

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# if ANOMALY_05000416

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#  define STI_INNER nop; 2: nop;

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# else

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#  define STI_INNER 2:

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# endif

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#else

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# define CLI_OUTER

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# define STI_OUTER

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# define CLI_INNER 1: DO_CLI; CLI_INNER_NOP;

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# define STI_INNER DO_STI;

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#endif

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/*

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 * Reads on the Blackfin are speculative. In Blackfin terms, this means they

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 * can be interrupted at any time (even after they have been issued on to the

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 * external bus), and re-issued after the interrupt occurs.

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 *

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 * If a FIFO is sitting on the end of the read, it will see two reads,

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 * when the core only sees one. The FIFO receives the read which is cancelled,

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 * and not delivered to the core.

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 *

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 * To solve this, interrupts are turned off before reads occur to I/O space.

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 * There are 3 versions of all these functions

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 *  - turns interrupts off every read (higher overhead, but lower latency)

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 *  - turns interrupts off every loop (low overhead, but longer latency)

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 *  - DMA version, which do not suffer from this issue. DMA versions have

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 *      different name (prefixed by dma_ ), and are located in

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 *      ../kernel/bfin_dma_5xx.c

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 * Using the dma related functions are recommended for transferring large

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 * buffers in/out of FIFOs.

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 */

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#define COMMON_INS(func, ops) \

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ENTRY(_ins##func) \

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	P0 = R0;	/* P0 = port */ \

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	CLI_OUTER;	/* 3 instructions before first read access */ \

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	P1 = R1;	/* P1 = address */ \

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	P2 = R2;	/* P2 = count */ \

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	SSYNC; \

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 \

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	LSETUP(1f, 2f) LC0 = P2; \

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	CLI_INNER; \

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	ops; \

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	STI_INNER; \

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 \

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	STI_OUTER; \

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	RTS; \

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ENDPROC(_ins##func)

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COMMON_INS(l, \

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	R0 = [P0]; \

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	[P1++] = R0; \

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)

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COMMON_INS(w, \

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	R0 = W[P0]; \

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	W[P1++] = R0; \

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)

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COMMON_INS(w_8, \

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	R0 = W[P0]; \

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	B[P1++] = R0; \

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	R0 = R0 >> 8; \

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	B[P1++] = R0; \

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)

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COMMON_INS(b, \

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	R0 = B[P0]; \

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	B[P1++] = R0; \

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)

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COMMON_INS(l_16, \

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	R0 = [P0]; \

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	W[P1++] = R0; \

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	R0 = R0 >> 16; \

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	W[P1++] = R0; \

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)

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