[U-Boot] [PATCH 17/33] x86: Add ISA DMA implementation

[Bin Meng]

Hi Simon,

On Wed, Nov 12, 2014 at 8:18 AM, Simon Glass <sjg at chromium.org> wrote:
> Add simple init for the ISA DMA settings.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
>  arch/x86/include/asm/isa_dma.h | 14 +++++++++++
>  arch/x86/lib/Makefile          |  1 +
>  arch/x86/lib/isa_dma.c         | 56 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 71 insertions(+)
>  create mode 100644 arch/x86/include/asm/isa_dma.h
>  create mode 100644 arch/x86/lib/isa_dma.c
>
> diff --git a/arch/x86/include/asm/isa_dma.h b/arch/x86/include/asm/isa_dma.h
> new file mode 100644
> index 0000000..69c6a84
> --- /dev/null
> +++ b/arch/x86/include/asm/isa_dma.h
> @@ -0,0 +1,14 @@
> +/*
> + * From Coreboot
> + * Copyright (C) 2014 Google, Inc
> + * Copyright (C) 2008-2009 coresystems GmbH
> + *
> + * SPDX-License-Identifier:    GPL-2.0
> + */
> +
> +#ifndef __ASM_ISA_DMA_H
> +#define _ASM_ISA_DMA_H
> +
> +void isa_dma_init(void);
> +
> +#endif
> diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
> index 2d75f9f..622ef08 100644
> --- a/arch/x86/lib/Makefile
> +++ b/arch/x86/lib/Makefile
> @@ -11,6 +11,7 @@ obj-y += gcc.o
>  obj-y += i8259.o
>  obj-y  += init_helpers.o
>  obj-y  += interrupts.o
> +obj-y += isa_dma.o
>  obj-$(CONFIG_SYS_PCAT_INTERRUPTS) += pcat_interrupts.o
>  obj-$(CONFIG_SYS_PCAT_TIMER) += pcat_timer.o
>  obj-$(CONFIG_PCI) += pci_type1.o
> diff --git a/arch/x86/lib/isa_dma.c b/arch/x86/lib/isa_dma.c
> new file mode 100644
> index 0000000..36d6ee5
> --- /dev/null
> +++ b/arch/x86/lib/isa_dma.c
> @@ -0,0 +1,56 @@
> +/*
> + * From Coreboot
> + * Copyright (C) 2014 Google, Inc
> + * Copyright (C) 2008-2009 coresystems GmbH
> + *
> + * SPDX-License-Identifier:    GPL-2.0
> + */
> +
> +#include <common.h>
> +#include <asm/io.h>
> +#include <asm/isa_dma.h>
> +
> +/* DMA controller registers */
> +#define DMA1_CMD_REG           0x08    /* command register (w) */
> +#define DMA1_STAT_REG          0x08    /* status register (r) */
> +#define DMA1_REQ_REG            0x09    /* request register (w) */
> +#define DMA1_MASK_REG          0x0A    /* single-channel mask (w) */
> +#define DMA1_MODE_REG          0x0B    /* mode register (w) */
> +#define DMA1_CLEAR_FF_REG      0x0C    /* clear pointer flip-flop (w) */
> +#define DMA1_TEMP_REG           0x0D    /* Temporary Register (r) */
> +#define DMA1_RESET_REG         0x0D    /* Master Clear (w) */
> +#define DMA1_CLR_MASK_REG       0x0E    /* Clear Mask */
> +#define DMA1_MASK_ALL_REG       0x0F    /* all-channels mask (w) */
> +
> +#define DMA2_CMD_REG           0xD0    /* command register (w) */
> +#define DMA2_STAT_REG          0xD0    /* status register (r) */
> +#define DMA2_REQ_REG            0xD2    /* request register (w) */
> +#define DMA2_MASK_REG          0xD4    /* single-channel mask (w) */
> +#define DMA2_MODE_REG          0xD6    /* mode register (w) */
> +#define DMA2_CLEAR_FF_REG      0xD8    /* clear pointer flip-flop (w) */
> +#define DMA2_TEMP_REG           0xDA    /* Temporary Register (r) */
> +#define DMA2_RESET_REG         0xDA    /* Master Clear (w) */
> +#define DMA2_CLR_MASK_REG       0xDC    /* Clear Mask */
> +#define DMA2_MASK_ALL_REG       0xDE    /* all-channels mask (w) */
> +
> +/* I/O to memory, no autoinit, increment, single mode */
> +#define DMA_MODE_READ  0x44
> +/* memory to I/O, no autoinit, increment, single mode */
> +#define DMA_MODE_WRITE 0x48
> +#define DMA_MODE_CASCADE 0xC0   /* pass thru DREQ->HRQ, DACK<-HLDA only */
> +
> +#define DMA_AUTOINIT   0x10
> +
> +void isa_dma_init(void)
> +{
> +       /*
> +        * slave at 0x00 - 0x0f
> +        * master at 0xc0 - 0xdf
> +        * 0x80 - 0x8f DMA page registers
> +        * DMA: 0x00, 0x02, 0x4, 0x06 base address for DMA channel
> +        */
> +       outb(0, DMA1_RESET_REG);
> +       outb(0, DMA2_RESET_REG);
> +       outb(DMA_MODE_CASCADE, DMA2_MODE_REG);
> +       outb(0, DMA2_MASK_REG);
> +}
> --

Why is this whole patch needed? Is there any U-Boot driver that
depends on this driver to initialize the DMA to work correctly? If
not, I'd suggest we drop this patch.

Regards,
Bin