ATA bus master DMA, for IDE controllers that can (such as QEMU's PIIX). More...

#include <core/system.h>
#include <core/string.h>
#include <cpu/io.h>
#include <mm/mm.h>
#include <sys/sched.h>
#include <aquila/errno.h>
#include <ata.h>

Data Structures
struct	prd
	A physical region descriptor: one piece of memory to transfer. More...

Macros
#define	BM_CMD 0
#define	BM_STATUS 2
#define	BM_PRDT 4
#define	BM_CMD_START 0x01
#define	BM_CMD_READ 0x08
#define	BM_ST_ACTIVE 0x01
#define	BM_ST_ERROR 0x02
#define	BM_ST_IRQ 0x04
#define	DMA_BUF_SIZE (64 * 1024)
#define	DMA_MAX_SECTORS (DMA_BUF_SIZE / 512)
#define	PRD_EOT 0x8000

Functions
static int	channel_index (struct ata_drive *drive)
	Returns which channel a drive is on: 0 (primary) or 1 (secondary).
static void	dma_complete (struct ata_channel *ch, uint8_t bm_status)
	Ends a transfer: keeps what the controller and the drive say about it, which also acknowledges the interrupt, and marks it done.
void	dma_irq (struct ata_channel *ch)
	Handles a channel's interrupt.
static int	dma_transfer (struct ata_drive *drive, uint64_t lba, size_t count, int write)
	Transfers up to DMA_MAX_SECTORS sectors between the drive and the channel's buffer, and waits until it is done.
static ssize_t	dma_read (struct ata_drive drive, uint64_t lba, size_t count, void buf)
	Reads count sectors from lba on, through the channel's buffer.
static ssize_t	dma_write (struct ata_drive drive, uint64_t lba, size_t count, void buf)
	Writes count sectors from lba on, through the channel's buffer.
int	dma_init (struct ata_drive *drive)
	Sets a drive up for DMA, if both the drive and its channel's controller can do it.

Variables
static struct prd	prdt [2]
static char	dma_buf [2][DMA_BUF_SIZE]

Detailed Description

ATA bus master DMA, for IDE controllers that can (such as QEMU's PIIX).

With DMA, the controller moves a command's data to or from memory itself, and the request sleeps until the drive's interrupt says it is done. With PIO (pio.c), the CPU moves the data a word at a time through an I/O port and polls, which under a hypervisor means an exit to it every time.

Each channel transfers through a buffer of its own, which is physically contiguous and doesn't cross a 64 KiB boundary, as the controller requires. One physical region descriptor (PRD) describes it.

Definition in file dma.c.

Macro Definition Documentation

◆ BM_CMD

#define BM_CMD 0

Definition at line 25 of file dma.c.

Referenced by dma_transfer().

◆ BM_CMD_READ

#define BM_CMD_READ 0x08

Definition at line 30 of file dma.c.

Referenced by dma_transfer().

◆ BM_CMD_START

#define BM_CMD_START 0x01

Definition at line 29 of file dma.c.

Referenced by dma_transfer().

◆ BM_PRDT

#define BM_PRDT 4

Definition at line 27 of file dma.c.

Referenced by dma_transfer().

◆ BM_ST_ACTIVE

#define BM_ST_ACTIVE 0x01

Definition at line 32 of file dma.c.

◆ BM_ST_ERROR

#define BM_ST_ERROR 0x02

Definition at line 33 of file dma.c.

Referenced by dma_complete(), and dma_transfer().

◆ BM_ST_IRQ

#define BM_ST_IRQ 0x04

Definition at line 34 of file dma.c.

Referenced by dma_complete(), dma_irq(), and dma_transfer().

◆ BM_STATUS

#define BM_STATUS 2

Definition at line 26 of file dma.c.

Referenced by dma_complete(), dma_irq(), and dma_transfer().

◆ DMA_BUF_SIZE

#define DMA_BUF_SIZE (64 * 1024)

Definition at line 36 of file dma.c.

◆ DMA_MAX_SECTORS

#define DMA_MAX_SECTORS (DMA_BUF_SIZE / 512)

Definition at line 37 of file dma.c.

Referenced by dma_read(), and dma_write().

◆ PRD_EOT

#define PRD_EOT 0x8000

Definition at line 46 of file dma.c.

Referenced by dma_transfer().

Function Documentation

◆ channel_index()

int channel_index ( struct ata_drive * drive )

static

Returns which channel a drive is on: 0 (primary) or 1 (secondary).

Definition at line 54 of file dma.c.

References channel_index(), and ata_drive::id.

Referenced by channel_index(), dma_read(), dma_transfer(), and dma_write().

◆ dma_complete()

void dma_complete	(	struct ata_channel *	ch,
		uint8_t	bm_status )

static

Ends a transfer: keeps what the controller and the drive say about it, which also acknowledges the interrupt, and marks it done.

Definition at line 61 of file dma.c.

References ATA_REG_STATUS, ata_channel::base, ata_channel::bm, BM_ST_ERROR, BM_ST_IRQ, BM_STATUS, ata_channel::bm_status, dma_complete(), ata_channel::done, io_in8(), io_out8(), and ata_channel::status.

Referenced by dma_complete(), dma_irq(), and dma_transfer().

◆ dma_init()

int dma_init ( struct ata_drive * drive )

Sets a drive up for DMA, if both the drive and its channel's controller can do it.

Parameters

drive the drive

Returns: 0 if the drive uses DMA now, or -ENODEV if it can't

Definition at line 195 of file dma.c.

References ioaddr::addr, ATA_CAP_DMA, ata_channel::bm, ata_drive::capabilities, ata_drive::channel, dma_init(), dma_read(), dma_write(), ata_drive::read, and ata_drive::write.

Referenced by ata_probe(), and dma_init().

◆ dma_irq()

void dma_irq ( struct ata_channel * ch )

Handles a channel's interrupt.

If it ends a DMA transfer, the request waiting for it wakes up; otherwise (PIO polls) reading the drive's status acknowledges it.

Parameters

ch	the channel

Definition at line 76 of file dma.c.

References ioaddr::addr, ATA_REG_STATUS, ata_channel::base, ata_channel::bm, BM_ST_IRQ, BM_STATUS, dma_complete(), dma_irq(), io_in8(), ata_channel::irq_wait, and waitq_wakeup_nopoll().

Referenced by ata_irq(), and dma_irq().

◆ dma_read()

ssize_t dma_read	(	struct ata_drive *	drive,
		uint64_t	lba,
		size_t	count,
		void *	buf )

static

Reads count sectors from lba on, through the channel's buffer.

Returns 0 or a negative errno.

Definition at line 144 of file dma.c.

References channel_index(), dma_buf, DMA_MAX_SECTORS, dma_read(), dma_transfer(), memcpy(), and MIN.

Referenced by dma_init(), and dma_read().

◆ dma_transfer()

int dma_transfer	(	struct ata_drive *	drive,
		uint64_t	lba,
		size_t	count,
		int	write )

static

Transfers up to DMA_MAX_SECTORS sectors between the drive and the channel's buffer, and waits until it is done.

Returns 0, or -EIO if the controller or the drive reports an error.

Definition at line 93 of file dma.c.

References prd::addr, ATA_CMD_READ_DMA, ATA_CMD_READ_DMA_EXT, ATA_CMD_WRITE_DMA, ATA_CMD_WRITE_DMA_EXT, ATA_MODE_LBA48, ATA_REG_CMD, ata_setup(), ATA_STATUS_DF, ATA_STATUS_ERR, ata_drive::base, ata_channel::bm, BM_CMD, BM_CMD_READ, BM_CMD_START, BM_PRDT, BM_ST_ERROR, BM_ST_IRQ, BM_STATUS, ata_channel::bm_status, ata_drive::channel, channel_index(), curthread, dma_buf, dma_complete(), dma_transfer(), ata_channel::done, prd::flags, ata_drive::id, io_in8(), io_out32(), io_out8(), ata_channel::irq_wait, LMA, ata_drive::mode, PRD_EOT, prdt, printk(), sched_running, prd::size, ata_channel::status, and waitq_sleep_unint().

Referenced by dma_read(), dma_transfer(), and dma_write().

◆ dma_write()

ssize_t dma_write	(	struct ata_drive *	drive,
		uint64_t	lba,
		size_t	count,
		void *	buf )

static

Writes count sectors from lba on, through the channel's buffer.

Returns 0 or a negative errno.

Definition at line 167 of file dma.c.

References channel_index(), dma_buf, DMA_MAX_SECTORS, dma_transfer(), dma_write(), memcpy(), and MIN.

Referenced by dma_init(), and dma_write().

Variable Documentation

◆ dma_buf

char dma_buf[2][DMA_BUF_SIZE]

static

Definition at line 51 of file dma.c.

Referenced by dma_read(), dma_transfer(), and dma_write().

◆ prdt

struct prd prdt[2]

static

Definition at line 50 of file dma.c.

Referenced by dma_transfer().

Data Structures

Macros

Functions

Variables

Detailed Description

Macro Definition Documentation

◆ BM_CMD

◆ BM_CMD_READ

◆ BM_CMD_START

◆ BM_PRDT

◆ BM_ST_ACTIVE

◆ BM_ST_ERROR

◆ BM_ST_IRQ

◆ BM_STATUS

◆ DMA_BUF_SIZE

◆ DMA_MAX_SECTORS

◆ PRD_EOT

Function Documentation

◆ channel_index()

◆ dma_complete()

◆ dma_init()

◆ dma_irq()

◆ dma_read()

◆ dma_transfer()

◆ dma_write()

Variable Documentation

◆ dma_buf

◆ prdt