dma: imx-sdma: make channel0 operations atomic

device_prep_dma_cyclic may be call in audio trigger function which is
atomic context, so we make it atomic too.

 - change channel0 lock to spinlock.
 - Use polling to wait for channel0 finish running.

Signed-off-by: Richard Zhao <richard.zhao@freescale.com>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>

diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
index cd0619a..a472a29 100644 (file)
--- a/drivers/dma/imx-sdma.c
+++ b/drivers/dma/imx-sdma.c
@@ -24,7 +24,7 @@
 #include <linux/mm.h>
 #include <linux/interrupt.h>
 #include <linux/clk.h>
-#include <linux/wait.h>
+#include <linux/delay.h>
 #include <linux/sched.h>
 #include <linux/semaphore.h>
 #include <linux/spinlock.h>
@@ -324,7 +324,7 @@ struct sdma_engine {
        dma_addr_t                      context_phys;
        struct dma_device               dma_device;
        struct clk                      *clk;
-       struct mutex                    channel_0_lock;
+       spinlock_t                      channel_0_lock;
        struct sdma_script_start_addrs  *script_addrs;
 };
 
@@ -402,19 +402,27 @@ static void sdma_enable_channel(struct sdma_engine *sdma, int channel)
 }
 
 /*
- * sdma_run_channel - run a channel and wait till it's done
+ * sdma_run_channel0 - run a channel and wait till it's done
  */
-static int sdma_run_channel(struct sdma_channel *sdmac)
+static int sdma_run_channel0(struct sdma_engine *sdma)
 {
-       struct sdma_engine *sdma = sdmac->sdma;
-       int channel = sdmac->channel;
        int ret;
+       unsigned long timeout = 500;
 
-       init_completion(&sdmac->done);
+       sdma_enable_channel(sdma, 0);
 
-       sdma_enable_channel(sdma, channel);
+       while (!(ret = readl_relaxed(sdma->regs + SDMA_H_INTR) & 1)) {
+               if (timeout-- <= 0)
+                       break;
+               udelay(1);
+       }
 
-       ret = wait_for_completion_timeout(&sdmac->done, HZ);
+       if (ret) {
+               /* Clear the interrupt status */
+               writel_relaxed(ret, sdma->regs + SDMA_H_INTR);
+       } else {
+               dev_err(sdma->dev, "Timeout waiting for CH0 ready\n");
+       }
 
        return ret ? 0 : -ETIMEDOUT;
 }
@@ -426,17 +434,17 @@ static int sdma_load_script(struct sdma_engine *sdma, void *buf, int size,
        void *buf_virt;
        dma_addr_t buf_phys;
        int ret;
-
-       mutex_lock(&sdma->channel_0_lock);
+       unsigned long flags;
 
        buf_virt = dma_alloc_coherent(NULL,
                        size,
                        &buf_phys, GFP_KERNEL);
        if (!buf_virt) {
-               ret = -ENOMEM;
-               goto err_out;
+               return -ENOMEM;
        }
 
+       spin_lock_irqsave(&sdma->channel_0_lock, flags);
+
        bd0->mode.command = C0_SETPM;
        bd0->mode.status = BD_DONE | BD_INTR | BD_WRAP | BD_EXTD;
        bd0->mode.count = size / 2;
@@ -445,12 +453,11 @@ static int sdma_load_script(struct sdma_engine *sdma, void *buf, int size,
 
        memcpy(buf_virt, buf, size);
 
-       ret = sdma_run_channel(&sdma->channel[0]);
+       ret = sdma_run_channel0(sdma);
 
-       dma_free_coherent(NULL, size, buf_virt, buf_phys);
+       spin_unlock_irqrestore(&sdma->channel_0_lock, flags);
 
-err_out:
-       mutex_unlock(&sdma->channel_0_lock);
+       dma_free_coherent(NULL, size, buf_virt, buf_phys);
 
        return ret;
 }
@@ -541,10 +548,6 @@ static void sdma_tasklet(unsigned long data)
 
        complete(&sdmac->done);
 
-       /* not interested in channel 0 interrupts */
-       if (sdmac->channel == 0)
-               return;
-
        if (sdmac->flags & IMX_DMA_SG_LOOP)
                sdma_handle_channel_loop(sdmac);
        else
@@ -557,6 +560,8 @@ static irqreturn_t sdma_int_handler(int irq, void *dev_id)
        unsigned long stat;
 
        stat = readl_relaxed(sdma->regs + SDMA_H_INTR);
+       /* not interested in channel 0 interrupts */
+       stat &= ~1;
        writel_relaxed(stat, sdma->regs + SDMA_H_INTR);
 
        while (stat) {
@@ -662,6 +667,7 @@ static int sdma_load_context(struct sdma_channel *sdmac)
        struct sdma_context_data *context = sdma->context;
        struct sdma_buffer_descriptor *bd0 = sdma->channel[0].bd;
        int ret;
+       unsigned long flags;
 
        if (sdmac->direction == DMA_DEV_TO_MEM) {
                load_address = sdmac->pc_from_device;
@@ -679,7 +685,7 @@ static int sdma_load_context(struct sdma_channel *sdmac)
        dev_dbg(sdma->dev, "event_mask0 = 0x%08x\n", (u32)sdmac->event_mask[0]);
        dev_dbg(sdma->dev, "event_mask1 = 0x%08x\n", (u32)sdmac->event_mask[1]);
 
-       mutex_lock(&sdma->channel_0_lock);
+       spin_lock_irqsave(&sdma->channel_0_lock, flags);
 
        memset(context, 0, sizeof(*context));
        context->channel_state.pc = load_address;
@@ -698,10 +704,9 @@ static int sdma_load_context(struct sdma_channel *sdmac)
        bd0->mode.count = sizeof(*context) / 4;
        bd0->buffer_addr = sdma->context_phys;
        bd0->ext_buffer_addr = 2048 + (sizeof(*context) / 4) * channel;
+       ret = sdma_run_channel0(sdma);
 
-       ret = sdma_run_channel(&sdma->channel[0]);
-
-       mutex_unlock(&sdma->channel_0_lock);
+       spin_unlock_irqrestore(&sdma->channel_0_lock, flags);
 
        return ret;
 }
@@ -1300,7 +1305,7 @@ static int __init sdma_probe(struct platform_device *pdev)
        if (!sdma)
                return -ENOMEM;
 
-       mutex_init(&sdma->channel_0_lock);
+       spin_lock_init(&sdma->channel_0_lock);
 
        sdma->dev = &pdev->dev;