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authorMike Frysinger <vapier@gentoo.org>2009-10-09 22:18:12 +0000
committerMike Frysinger <vapier@gentoo.org>2009-12-15 00:14:18 -0500
commitd2e015d65fc692475b8513259d6afacd2cded8e8 (patch)
treee296f8daa8a7ba957d0ae080c71212f77172d382 /arch
parentadfc046740b4161cbb1f0a3ea0d4200e21113489 (diff)
Blackfin: convert DMA mutex to an atomic and drop redundant code
The DMA channel status field was encoding redundant info wrt the DMA MMR config register, and it was doing an incomplete job of checking all DMA channels (some drivers write directly to the config register). So drop the tristate field in favor of a binary atomic field. This simplifies the code in general, removes the implicit need for sleeping, and forces the suspend code to handle all channels properly. Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/blackfin/include/asm/dma.h17
-rw-r--r--arch/blackfin/kernel/bfin_dma_5xx.c31
2 files changed, 13 insertions, 35 deletions
diff --git a/arch/blackfin/include/asm/dma.h b/arch/blackfin/include/asm/dma.h
index c9a59622e23..e3c0dfa73d1 100644
--- a/arch/blackfin/include/asm/dma.h
+++ b/arch/blackfin/include/asm/dma.h
@@ -10,6 +10,7 @@
#include <linux/interrupt.h>
#include <mach/dma.h>
+#include <asm/atomic.h>
#include <asm/blackfin.h>
#include <asm/page.h>
@@ -19,11 +20,6 @@
* Generic DMA Declarations
*
****************************************************************************/
-enum dma_chan_status {
- DMA_CHANNEL_FREE,
- DMA_CHANNEL_REQUESTED,
- DMA_CHANNEL_ENABLED,
-};
/*-------------------------
* config reg bits value
@@ -104,11 +100,9 @@ struct dma_register {
};
-struct mutex;
struct dma_channel {
- struct mutex dmalock;
const char *device_id;
- enum dma_chan_status chan_status;
+ atomic_t chan_status;
volatile struct dma_register *regs;
struct dmasg *sg; /* large mode descriptor */
unsigned int irq;
@@ -220,24 +214,19 @@ static inline void set_dma_sg(unsigned int channel, struct dmasg *sg, int ndsize
static inline int dma_channel_active(unsigned int channel)
{
- if (dma_ch[channel].chan_status == DMA_CHANNEL_FREE)
- return 0;
- else
- return 1;
+ return atomic_read(&dma_ch[channel].chan_status);
}
static inline void disable_dma(unsigned int channel)
{
dma_ch[channel].regs->cfg &= ~DMAEN;
SSYNC();
- dma_ch[channel].chan_status = DMA_CHANNEL_REQUESTED;
}
static inline void enable_dma(unsigned int channel)
{
dma_ch[channel].regs->curr_x_count = 0;
dma_ch[channel].regs->curr_y_count = 0;
dma_ch[channel].regs->cfg |= DMAEN;
- dma_ch[channel].chan_status = DMA_CHANNEL_ENABLED;
}
void free_dma(unsigned int channel);
int request_dma(unsigned int channel, const char *device_id);
diff --git a/arch/blackfin/kernel/bfin_dma_5xx.c b/arch/blackfin/kernel/bfin_dma_5xx.c
index 3946aff4f41..639dcee5611 100644
--- a/arch/blackfin/kernel/bfin_dma_5xx.c
+++ b/arch/blackfin/kernel/bfin_dma_5xx.c
@@ -37,9 +37,8 @@ static int __init blackfin_dma_init(void)
printk(KERN_INFO "Blackfin DMA Controller\n");
for (i = 0; i < MAX_DMA_CHANNELS; i++) {
- dma_ch[i].chan_status = DMA_CHANNEL_FREE;
+ atomic_set(&dma_ch[i].chan_status, 0);
dma_ch[i].regs = dma_io_base_addr[i];
- mutex_init(&(dma_ch[i].dmalock));
}
/* Mark MEMDMA Channel 0 as requested since we're using it internally */
request_dma(CH_MEM_STREAM0_DEST, "Blackfin dma_memcpy");
@@ -60,7 +59,7 @@ static int proc_dma_show(struct seq_file *m, void *v)
int i;
for (i = 0; i < MAX_DMA_CHANNELS; ++i)
- if (dma_ch[i].chan_status != DMA_CHANNEL_FREE)
+ if (dma_channel_active(i))
seq_printf(m, "%2d: %s\n", i, dma_ch[i].device_id);
return 0;
@@ -107,20 +106,11 @@ int request_dma(unsigned int channel, const char *device_id)
}
#endif
- mutex_lock(&(dma_ch[channel].dmalock));
-
- if ((dma_ch[channel].chan_status == DMA_CHANNEL_REQUESTED)
- || (dma_ch[channel].chan_status == DMA_CHANNEL_ENABLED)) {
- mutex_unlock(&(dma_ch[channel].dmalock));
+ if (atomic_cmpxchg(&dma_ch[channel].chan_status, 0, 1)) {
pr_debug("DMA CHANNEL IN USE \n");
return -EBUSY;
- } else {
- dma_ch[channel].chan_status = DMA_CHANNEL_REQUESTED;
- pr_debug("DMA CHANNEL IS ALLOCATED \n");
}
- mutex_unlock(&(dma_ch[channel].dmalock));
-
#ifdef CONFIG_BF54x
if (channel >= CH_UART2_RX && channel <= CH_UART3_TX) {
unsigned int per_map;
@@ -149,7 +139,7 @@ EXPORT_SYMBOL(request_dma);
int set_dma_callback(unsigned int channel, irq_handler_t callback, void *data)
{
BUG_ON(channel >= MAX_DMA_CHANNELS ||
- dma_ch[channel].chan_status == DMA_CHANNEL_FREE);
+ !atomic_read(&dma_ch[channel].chan_status));
if (callback != NULL) {
int ret;
@@ -184,7 +174,7 @@ void free_dma(unsigned int channel)
{
pr_debug("freedma() : BEGIN \n");
BUG_ON(channel >= MAX_DMA_CHANNELS ||
- dma_ch[channel].chan_status == DMA_CHANNEL_FREE);
+ !atomic_read(&dma_ch[channel].chan_status));
/* Halt the DMA */
disable_dma(channel);
@@ -194,9 +184,7 @@ void free_dma(unsigned int channel)
free_irq(dma_ch[channel].irq, dma_ch[channel].data);
/* Clear the DMA Variable in the Channel */
- mutex_lock(&(dma_ch[channel].dmalock));
- dma_ch[channel].chan_status = DMA_CHANNEL_FREE;
- mutex_unlock(&(dma_ch[channel].dmalock));
+ atomic_set(&dma_ch[channel].chan_status, 0);
pr_debug("freedma() : END \n");
}
@@ -210,13 +198,14 @@ int blackfin_dma_suspend(void)
{
int i;
- for (i = 0; i < MAX_DMA_SUSPEND_CHANNELS; ++i) {
- if (dma_ch[i].chan_status == DMA_CHANNEL_ENABLED) {
+ for (i = 0; i < MAX_DMA_CHANNELS; ++i) {
+ if (dma_ch[i].regs->cfg & DMAEN) {
printk(KERN_ERR "DMA Channel %d failed to suspend\n", i);
return -EBUSY;
}
- dma_ch[i].saved_peripheral_map = dma_ch[i].regs->peripheral_map;
+ if (i < MAX_DMA_SUSPEND_CHANNELS)
+ dma_ch[i].saved_peripheral_map = dma_ch[i].regs->peripheral_map;
}
return 0;