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viafb: Add a simple VX855 DMA engine driver

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This code provides a minimal amount of access to the DMA engine as
needed by the camera driver.  VX855 only; it's guaranteed not to work
on other chipsets, so it won't try.

Cc: ScottFang@viatech.com.cn
Cc: JosephChan@via.com.tw
Cc: Harald Welte <laforge@gnumonks.org>
Acked-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Jonathan Corbet 2010-04-23 10:04:12 -06:00
parent 94dd1a856b
commit 3d28eb42c5
2 changed files with 261 additions and 0 deletions
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232
drivers/video/via/via-core.c
View File

@ -13,6 +13,7 @@
#include "global.h"
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
/*
@ -92,7 +93,238 @@ void viafb_irq_disable(u32 mask)
}
EXPORT_SYMBOL_GPL(viafb_irq_disable);
/* ---------------------------------------------------------------------- */
/*
* Access to the DMA engine. This currently provides what the camera
* driver needs (i.e. outgoing only) but is easily expandable if need
* be.
*/
/*
* There are four DMA channels in the vx855. For now, we only
* use one of them, though. Most of the time, the DMA channel
* will be idle, so we keep the IRQ handler unregistered except
* when some subsystem has indicated an interest.
*/
static int viafb_dma_users;
static DECLARE_COMPLETION(viafb_dma_completion);
/*
* This mutex protects viafb_dma_users and our global interrupt
* registration state; it also serializes access to the DMA
* engine.
*/
static DEFINE_MUTEX(viafb_dma_lock);
/*
* The VX855 DMA descriptor (used for s/g transfers) looks
* like this.
*/
struct viafb_vx855_dma_descr {
u32 addr_low; /* Low part of phys addr */
u32 addr_high; /* High 12 bits of addr */
u32 fb_offset; /* Offset into FB memory */
u32 seg_size; /* Size, 16-byte units */
u32 tile_mode; /* "tile mode" setting */
u32 next_desc_low; /* Next descriptor addr */
u32 next_desc_high;
u32 pad; /* Fill out to 64 bytes */
};
/*
* Flags added to the "next descriptor low" pointers
*/
#define VIAFB_DMA_MAGIC 0x01 /* ??? Just has to be there */
#define VIAFB_DMA_FINAL_SEGMENT 0x02 /* Final segment */
/*
* The completion IRQ handler.
*/
static irqreturn_t viafb_dma_irq(int irq, void *data)
{
int csr;
irqreturn_t ret = IRQ_NONE;
spin_lock(&global_dev.reg_lock);
csr = viafb_mmio_read(VDMA_CSR0);
if (csr & VDMA_C_DONE) {
viafb_mmio_write(VDMA_CSR0, VDMA_C_DONE);
complete(&viafb_dma_completion);
ret = IRQ_HANDLED;
}
spin_unlock(&global_dev.reg_lock);
return ret;
}
/*
* Indicate a need for DMA functionality.
*/
int viafb_request_dma(void)
{
int ret = 0;
/*
* Only VX855 is supported currently.
*/
if (global_dev.chip_type != UNICHROME_VX855)
return -ENODEV;
/*
* Note the new user and set up our interrupt handler
* if need be.
*/
mutex_lock(&viafb_dma_lock);
viafb_dma_users++;
if (viafb_dma_users == 1) {
ret = request_irq(global_dev.pdev->irq, viafb_dma_irq,
IRQF_SHARED, "via-dma", &viafb_dma_users);
if (ret)
viafb_dma_users--;
else
viafb_irq_enable(VDE_I_DMA0TDEN);
}
mutex_unlock(&viafb_dma_lock);
return ret;
}
EXPORT_SYMBOL_GPL(viafb_request_dma);
void viafb_release_dma(void)
{
mutex_lock(&viafb_dma_lock);
viafb_dma_users--;
if (viafb_dma_users == 0) {
viafb_irq_disable(VDE_I_DMA0TDEN);
free_irq(global_dev.pdev->irq, &viafb_dma_users);
}
mutex_unlock(&viafb_dma_lock);
}
EXPORT_SYMBOL_GPL(viafb_release_dma);
#if 0
/*
* Copy a single buffer from FB memory, synchronously. This code works
* but is not currently used.
*/
void viafb_dma_copy_out(unsigned int offset, dma_addr_t paddr, int len)
{
unsigned long flags;
int csr;
mutex_lock(&viafb_dma_lock);
init_completion(&viafb_dma_completion);
/*
* Program the controller.
*/
spin_lock_irqsave(&global_dev.reg_lock, flags);
viafb_mmio_write(VDMA_CSR0, VDMA_C_ENABLE|VDMA_C_DONE);
/* Enable ints; must happen after CSR0 write! */
viafb_mmio_write(VDMA_MR0, VDMA_MR_TDIE);
viafb_mmio_write(VDMA_MARL0, (int) (paddr & 0xfffffff0));
viafb_mmio_write(VDMA_MARH0, (int) ((paddr >> 28) & 0xfff));
/* Data sheet suggests DAR0 should be <<4, but it lies */
viafb_mmio_write(VDMA_DAR0, offset);
viafb_mmio_write(VDMA_DQWCR0, len >> 4);
viafb_mmio_write(VDMA_TMR0, 0);
viafb_mmio_write(VDMA_DPRL0, 0);
viafb_mmio_write(VDMA_DPRH0, 0);
viafb_mmio_write(VDMA_PMR0, 0);
csr = viafb_mmio_read(VDMA_CSR0);
viafb_mmio_write(VDMA_CSR0, VDMA_C_ENABLE|VDMA_C_START);
spin_unlock_irqrestore(&global_dev.reg_lock, flags);
/*
* Now we just wait until the interrupt handler says
* we're done.
*/
wait_for_completion_interruptible(&viafb_dma_completion);
viafb_mmio_write(VDMA_MR0, 0); /* Reset int enable */
mutex_unlock(&viafb_dma_lock);
}
EXPORT_SYMBOL_GPL(viafb_dma_copy_out);
#endif
/*
* Do a scatter/gather DMA copy from FB memory. You must have done
* a successful call to viafb_request_dma() first.
*/
int viafb_dma_copy_out_sg(unsigned int offset, struct scatterlist *sg, int nsg)
{
struct viafb_vx855_dma_descr *descr;
void *descrpages;
dma_addr_t descr_handle;
unsigned long flags;
int i;
struct scatterlist *sgentry;
dma_addr_t nextdesc;
/*
* Get a place to put the descriptors.
*/
descrpages = dma_alloc_coherent(&global_dev.pdev->dev,
nsg*sizeof(struct viafb_vx855_dma_descr),
&descr_handle, GFP_KERNEL);
if (descrpages == NULL) {
dev_err(&global_dev.pdev->dev, "Unable to get descr page.\n");
return -ENOMEM;
}
mutex_lock(&viafb_dma_lock);
/*
* Fill them in.
*/
descr = descrpages;
nextdesc = descr_handle + sizeof(struct viafb_vx855_dma_descr);
for_each_sg(sg, sgentry, nsg, i) {
dma_addr_t paddr = sg_dma_address(sgentry);
descr->addr_low = paddr & 0xfffffff0;
descr->addr_high = ((u64) paddr >> 32) & 0x0fff;
descr->fb_offset = offset;
descr->seg_size = sg_dma_len(sgentry) >> 4;
descr->tile_mode = 0;
descr->next_desc_low = (nextdesc&0xfffffff0) | VIAFB_DMA_MAGIC;
descr->next_desc_high = ((u64) nextdesc >> 32) & 0x0fff;
descr->pad = 0xffffffff; /* VIA driver does this */
offset += sg_dma_len(sgentry);
nextdesc += sizeof(struct viafb_vx855_dma_descr);
descr++;
}
descr[-1].next_desc_low = VIAFB_DMA_FINAL_SEGMENT|VIAFB_DMA_MAGIC;
/*
* Program the engine.
*/
spin_lock_irqsave(&global_dev.reg_lock, flags);
init_completion(&viafb_dma_completion);
viafb_mmio_write(VDMA_DQWCR0, 0);
viafb_mmio_write(VDMA_CSR0, VDMA_C_ENABLE|VDMA_C_DONE);
viafb_mmio_write(VDMA_MR0, VDMA_MR_TDIE | VDMA_MR_CHAIN);
viafb_mmio_write(VDMA_DPRL0, descr_handle | VIAFB_DMA_MAGIC);
viafb_mmio_write(VDMA_DPRH0,
(((u64)descr_handle >> 32) & 0x0fff) | 0xf0000);
(void) viafb_mmio_read(VDMA_CSR0);
viafb_mmio_write(VDMA_CSR0, VDMA_C_ENABLE|VDMA_C_START);
spin_unlock_irqrestore(&global_dev.reg_lock, flags);
/*
* Now we just wait until the interrupt handler says
* we're done. Except that, actually, we need to wait a little
* longer: the interrupts seem to jump the gun a little and we
* get corrupted frames sometimes.
*/
wait_for_completion_timeout(&viafb_dma_completion, 1);
msleep(1);
if ((viafb_mmio_read(VDMA_CSR0)&VDMA_C_DONE) == 0)
printk(KERN_ERR "VIA DMA timeout!\n");
/*
* Clean up and we're done.
*/
viafb_mmio_write(VDMA_CSR0, VDMA_C_DONE);
viafb_mmio_write(VDMA_MR0, 0); /* Reset int enable */
mutex_unlock(&viafb_dma_lock);
dma_free_coherent(&global_dev.pdev->dev,
nsg*sizeof(struct viafb_vx855_dma_descr), descrpages,
descr_handle);
return 0;
}
EXPORT_SYMBOL_GPL(viafb_dma_copy_out_sg);
/* ---------------------------------------------------------------------- */
/*
* Figure out how big our framebuffer memory is. Kind of ugly,
* but evidently we can't trust the information found in the

29
drivers/video/via/via-core.h
View File

@ -131,4 +131,33 @@ void viafb_irq_disable(u32 mask);
#define VDE_I_LVDSSIEN 0x40000000 /* LVDS Sense enable */
#define VDE_I_ENABLE 0x80000000 /* Global interrupt enable */
/*
* DMA management.
*/
int viafb_request_dma(void);
void viafb_release_dma(void);
/* void viafb_dma_copy_out(unsigned int offset, dma_addr_t paddr, int len); */
int viafb_dma_copy_out_sg(unsigned int offset, struct scatterlist *sg, int nsg);
/*
* DMA Controller registers.
*/
#define VDMA_MR0 0xe00 /* Mod reg 0 */
#define VDMA_MR_CHAIN 0x01 /* Chaining mode */
#define VDMA_MR_TDIE 0x02 /* Transfer done int enable */
#define VDMA_CSR0 0xe04 /* Control/status */
#define VDMA_C_ENABLE 0x01 /* DMA Enable */
#define VDMA_C_START 0x02 /* Start a transfer */
#define VDMA_C_ABORT 0x04 /* Abort a transfer */
#define VDMA_C_DONE 0x08 /* Transfer is done */
#define VDMA_MARL0 0xe20 /* Mem addr low */
#define VDMA_MARH0 0xe24 /* Mem addr high */
#define VDMA_DAR0 0xe28 /* Device address */
#define VDMA_DQWCR0 0xe2c /* Count (16-byte) */
#define VDMA_TMR0 0xe30 /* Tile mode reg */
#define VDMA_DPRL0 0xe34 /* Not sure */
#define VDMA_DPR_IN 0x08 /* Inbound transfer to FB */
#define VDMA_DPRH0 0xe38
#define VDMA_PMR0 (0xe00 + 0x134) /* Pitch mode */
#endif /* __VIA_CORE_H__ */