[PATCH 1/2] dmaengine: hsu: Export hsu_dma_get_status()
From: Chuah Kim Tatt
Date: Fri May 13 2016 - 04:17:06 EST
From: "Chuah, Kim Tatt" <kim.tatt.chuah@xxxxxxxxx>
To allow other code to safely read DMA Channel Status Register (where
the register attribute for Channel Error, Descriptor Time Out &
Descriptor Done fields are read-clear), export hsu_dma_get_status().
hsu_dma_irq() is renamed to hsu_dma_do_irq() and requires Status
Register value to be passed in.
Signed-off-by: Chuah, Kim Tatt <kim.tatt.chuah@xxxxxxxxx>
---
drivers/dma/hsu/hsu.c | 90 +++++++++++++++++++++++++++++---------
drivers/dma/hsu/pci.c | 11 ++++-
drivers/tty/serial/8250/8250_mid.c | 22 +++++++---
include/linux/dma/hsu.h | 14 ++++--
4 files changed, 106 insertions(+), 31 deletions(-)
diff --git a/drivers/dma/hsu/hsu.c b/drivers/dma/hsu/hsu.c
index f8c5cd5..c5f21ef 100644
--- a/drivers/dma/hsu/hsu.c
+++ b/drivers/dma/hsu/hsu.c
@@ -126,28 +126,33 @@ static void hsu_dma_start_transfer(struct hsu_dma_chan *hsuc)
hsu_dma_start_channel(hsuc);
}
-static u32 hsu_dma_chan_get_sr(struct hsu_dma_chan *hsuc)
-{
- unsigned long flags;
- u32 sr;
-
- spin_lock_irqsave(&hsuc->vchan.lock, flags);
- sr = hsu_chan_readl(hsuc, HSU_CH_SR);
- spin_unlock_irqrestore(&hsuc->vchan.lock, flags);
-
- return sr & ~(HSU_CH_SR_DESCE_ANY | HSU_CH_SR_CDESC_ANY);
-}
-
-irqreturn_t hsu_dma_irq(struct hsu_dma_chip *chip, unsigned short nr)
+/*
+ * hsu_dma_get_status() - get DMA channel status
+ * @chip: HSUART DMA chip
+ * @nr: DMA channel number
+ * @status: pointer for DMA Channel Status Register value
+ *
+ * Description:
+ * The function reads and clears the DMA Channel Status Register, checks
+ * if it was a timeout interrupt and returns a corresponding value.
+ *
+ * Caller should provide a valid pointer for the DMA Channel Status
+ * Register value that will be returned in @status.
+ *
+ * Return:
+ * 1 for DMA timeout status, 0 for other DMA status, or error code for
+ * invalid parameters or no interrupt pending.
+ */
+int hsu_dma_get_status(struct hsu_dma_chip *chip, unsigned short nr,
+ u32 *status)
{
struct hsu_dma_chan *hsuc;
- struct hsu_dma_desc *desc;
unsigned long flags;
u32 sr;
/* Sanity check */
if (nr >= chip->hsu->nr_channels)
- return IRQ_NONE;
+ return -EINVAL;
hsuc = &chip->hsu->chan[nr];
@@ -155,22 +160,65 @@ irqreturn_t hsu_dma_irq(struct hsu_dma_chip *chip, unsigned short nr)
* No matter what situation, need read clear the IRQ status
* There is a bug, see Errata 5, HSD 2900918
*/
- sr = hsu_dma_chan_get_sr(hsuc);
+ spin_lock_irqsave(&hsuc->vchan.lock, flags);
+ sr = hsu_chan_readl(hsuc, HSU_CH_SR);
+ spin_unlock_irqrestore(&hsuc->vchan.lock, flags);
+
+ /* Check if any interrupt is pending */
+ sr &= ~(HSU_CH_SR_DESCE_ANY | HSU_CH_SR_CDESC_ANY);
if (!sr)
- return IRQ_NONE;
+ return -EIO;
/* Timeout IRQ, need wait some time, see Errata 2 */
if (sr & HSU_CH_SR_DESCTO_ANY)
udelay(2);
+ /*
+ * At this point, at least one of Descriptor Time Out, Channel Error
+ * or Descriptor Done bits must be set. Clear the Descriptor Time Out
+ * bits and if sr is still non-zero, it must be channel error or
+ * descriptor done which are higher priority than timeout and handled
+ * in hsu_dma_do_irq(). Else, it must be a timeout.
+ */
sr &= ~HSU_CH_SR_DESCTO_ANY;
- if (!sr)
- return IRQ_HANDLED;
+
+ *status = sr;
+
+ return sr ? 0 : 1;
+}
+EXPORT_SYMBOL_GPL(hsu_dma_get_status);
+
+/*
+ * hsu_dma_do_irq() - DMA interrupt handler
+ * @chip: HSUART DMA chip
+ * @nr: DMA channel number
+ * @status: Channel Status Register value
+ *
+ * Description:
+ * This function handles Channel Error and Descriptor Done interrupts.
+ * This function should be called after determining that the DMA interrupt
+ * is not a normal timeout interrupt, ie. hsu_dma_get_status() returned 0.
+ *
+ * Return:
+ * IRQ_NONE for invalid channel number, IRQ_HANDLED otherwise.
+ */
+irqreturn_t hsu_dma_do_irq(struct hsu_dma_chip *chip, unsigned short nr,
+ u32 status)
+{
+ struct hsu_dma_chan *hsuc;
+ struct hsu_dma_desc *desc;
+ unsigned long flags;
+
+ /* Sanity check */
+ if (nr >= chip->hsu->nr_channels)
+ return IRQ_NONE;
+
+ hsuc = &chip->hsu->chan[nr];
spin_lock_irqsave(&hsuc->vchan.lock, flags);
desc = hsuc->desc;
if (desc) {
- if (sr & HSU_CH_SR_CHE) {
+ if (status & HSU_CH_SR_CHE) {
desc->status = DMA_ERROR;
} else if (desc->active < desc->nents) {
hsu_dma_start_channel(hsuc);
@@ -184,7 +232,7 @@ irqreturn_t hsu_dma_irq(struct hsu_dma_chip *chip, unsigned short nr)
return IRQ_HANDLED;
}
-EXPORT_SYMBOL_GPL(hsu_dma_irq);
+EXPORT_SYMBOL_GPL(hsu_dma_do_irq);
static struct hsu_dma_desc *hsu_dma_alloc_desc(unsigned int nents)
{
diff --git a/drivers/dma/hsu/pci.c b/drivers/dma/hsu/pci.c
index e2db76b..9916058 100644
--- a/drivers/dma/hsu/pci.c
+++ b/drivers/dma/hsu/pci.c
@@ -27,13 +27,20 @@ static irqreturn_t hsu_pci_irq(int irq, void *dev)
{
struct hsu_dma_chip *chip = dev;
u32 dmaisr;
+ u32 status;
unsigned short i;
irqreturn_t ret = IRQ_NONE;
+ int err;
dmaisr = readl(chip->regs + HSU_PCI_DMAISR);
for (i = 0; i < chip->hsu->nr_channels; i++) {
- if (dmaisr & 0x1)
- ret |= hsu_dma_irq(chip, i);
+ if (dmaisr & 0x1) {
+ err = hsu_dma_get_status(chip, i, &status);
+ if (err > 0)
+ ret |= IRQ_HANDLED;
+ else if (err == 0)
+ ret |= hsu_dma_do_irq(chip, i, status);
+ }
dmaisr >>= 1;
}
diff --git a/drivers/tty/serial/8250/8250_mid.c b/drivers/tty/serial/8250/8250_mid.c
index 86379a7..b218ff5 100644
--- a/drivers/tty/serial/8250/8250_mid.c
+++ b/drivers/tty/serial/8250/8250_mid.c
@@ -97,12 +97,24 @@ static int dnv_handle_irq(struct uart_port *p)
{
struct mid8250 *mid = p->private_data;
unsigned int fisr = serial_port_in(p, INTEL_MID_UART_DNV_FISR);
+ u32 status;
int ret = IRQ_NONE;
-
- if (fisr & BIT(2))
- ret |= hsu_dma_irq(&mid->dma_chip, 1);
- if (fisr & BIT(1))
- ret |= hsu_dma_irq(&mid->dma_chip, 0);
+ int err;
+
+ if (fisr & BIT(2)) {
+ err = hsu_dma_get_status(&mid->dma_chip, 1, &status);
+ if (err > 0)
+ ret |= IRQ_HANDLED;
+ else if (err == 0)
+ ret |= hsu_dma_do_irq(&mid->dma_chip, 1, status);
+ }
+ if (fisr & BIT(1)) {
+ err = hsu_dma_get_status(&mid->dma_chip, 0, &status);
+ if (err > 0)
+ ret |= IRQ_HANDLED;
+ else if (err == 0)
+ ret |= hsu_dma_do_irq(&mid->dma_chip, 0, status);
+ }
if (fisr & BIT(0))
ret |= serial8250_handle_irq(p, serial_port_in(p, UART_IIR));
return ret;
diff --git a/include/linux/dma/hsu.h b/include/linux/dma/hsu.h
index 79df69d..aaff68e 100644
--- a/include/linux/dma/hsu.h
+++ b/include/linux/dma/hsu.h
@@ -39,14 +39,22 @@ struct hsu_dma_chip {
#if IS_ENABLED(CONFIG_HSU_DMA)
/* Export to the internal users */
-irqreturn_t hsu_dma_irq(struct hsu_dma_chip *chip, unsigned short nr);
+int hsu_dma_get_status(struct hsu_dma_chip *chip, unsigned short nr,
+ u32 *status);
+irqreturn_t hsu_dma_do_irq(struct hsu_dma_chip *chip, unsigned short nr,
+ u32 status);
/* Export to the platform drivers */
int hsu_dma_probe(struct hsu_dma_chip *chip);
int hsu_dma_remove(struct hsu_dma_chip *chip);
#else
-static inline irqreturn_t hsu_dma_irq(struct hsu_dma_chip *chip,
- unsigned short nr)
+static inline int hsu_dma_get_status(struct hsu_dma_chip *chip,
+ unsigned short nr, u32 *status)
+{
+ return 0;
+}
+static inline irqreturn_t hsu_dma_do_irq(struct hsu_dma_chip *chip,
+ unsigned short nr, u32 status)
{
return IRQ_NONE;
}
--
1.9.1