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dmaengine: stm32-dma3: introduce channel semaphore helpers

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Before restoring semaphore status after suspend, introduce new functions
to handle semaphore operations :
- stm32_dma3_get_chan_sem() to take the semaphore
- stm32_dma3_put_chan_sem() to release the semaphore
Also, use a new boolean variable semaphore_taken, which is true when the
semaphore has been taken and false when it has been released.

Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Link: https://patch.msgid.link/20251121-dma3_improv-v2-2-76a207b13ea6@foss.st.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Amelie Delaunay 2025-11-21 14:36:57 +01:00 committed by Vinod Koul
parent 0d41ed4ea4
commit d26eb4a75a
1 changed files with 44 additions and 11 deletions
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55
drivers/dma/stm32/stm32-dma3.c
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@ -288,6 +288,7 @@ struct stm32_dma3_chan {
u32 fifo_size;
u32 max_burst;
bool semaphore_mode;
bool semaphore_taken;
struct stm32_dma3_dt_conf dt_config;
struct dma_slave_config dma_config;
u8 config_set;
@ -1063,11 +1064,50 @@ static irqreturn_t stm32_dma3_chan_irq(int irq, void *devid)
return IRQ_HANDLED;
}
static int stm32_dma3_get_chan_sem(struct stm32_dma3_chan *chan)
{
struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
u32 csemcr, ccid;
csemcr = readl_relaxed(ddata->base + STM32_DMA3_CSEMCR(chan->id));
/* Make an attempt to take the channel semaphore if not already taken */
if (!(csemcr & CSEMCR_SEM_MUTEX)) {
writel_relaxed(CSEMCR_SEM_MUTEX, ddata->base + STM32_DMA3_CSEMCR(chan->id));
csemcr = readl_relaxed(ddata->base + STM32_DMA3_CSEMCR(chan->id));
}
/* Check if channel is under CID1 control */
ccid = FIELD_GET(CSEMCR_SEM_CCID, csemcr);
if (!(csemcr & CSEMCR_SEM_MUTEX) || ccid != CCIDCFGR_CID1)
goto bad_cid;
chan->semaphore_taken = true;
dev_dbg(chan2dev(chan), "under CID1 control (semcr=0x%08x)\n", csemcr);
return 0;
bad_cid:
chan->semaphore_taken = false;
dev_err(chan2dev(chan), "not under CID1 control (in-use by CID%d)\n", ccid);
return -EACCES;
}
static void stm32_dma3_put_chan_sem(struct stm32_dma3_chan *chan)
{
struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
if (chan->semaphore_taken) {
writel_relaxed(0, ddata->base + STM32_DMA3_CSEMCR(chan->id));
chan->semaphore_taken = false;
dev_dbg(chan2dev(chan), "no more under CID1 control\n");
}
}
static int stm32_dma3_alloc_chan_resources(struct dma_chan *c)
{
struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
u32 id = chan->id, csemcr, ccid;
int ret;
ret = pm_runtime_resume_and_get(ddata->dma_dev.dev);
@ -1092,16 +1132,9 @@ static int stm32_dma3_alloc_chan_resources(struct dma_chan *c)
/* Take the channel semaphore */
if (chan->semaphore_mode) {
writel_relaxed(CSEMCR_SEM_MUTEX, ddata->base + STM32_DMA3_CSEMCR(id));
csemcr = readl_relaxed(ddata->base + STM32_DMA3_CSEMCR(id));
ccid = FIELD_GET(CSEMCR_SEM_CCID, csemcr);
/* Check that the channel is well taken */
if (ccid != CCIDCFGR_CID1) {
dev_err(chan2dev(chan), "Not under CID1 control (in-use by CID%d)\n", ccid);
ret = -EPERM;
ret = stm32_dma3_get_chan_sem(chan);
if (ret)
goto err_pool_destroy;
}
dev_dbg(chan2dev(chan), "Under CID1 control (semcr=0x%08x)\n", csemcr);
}
return 0;
@ -1135,7 +1168,7 @@ static void stm32_dma3_free_chan_resources(struct dma_chan *c)
/* Release the channel semaphore */
if (chan->semaphore_mode)
writel_relaxed(0, ddata->base + STM32_DMA3_CSEMCR(chan->id));
stm32_dma3_put_chan_sem(chan);
pm_runtime_put_sync(ddata->dma_dev.dev);