npcx: SPI: add asynchronious transaction APIs

As the finger printer sensor needs multiple SPI transactions in the same
command state without de-asserting the CS pin, this commit implements:
- spi_transaction_async() - does the same thing as the original
  spi_transaction does but keeps asserting the CS pin.
- spi_transaction_flush() - de-assert the CS pin.
- spi_transaction_wait() - a noop function as we don't support SPI DMA.
The original spi_transaction() is hence changed to call
spi_transaction_async() and spi_transaction_flush() to
prevent code duplication.

BRANCH=none
BUG=b:266703380, b:269695617
TEST=Test console commands
spi_flashinfo/spi_flashread/spi_flashwrite/spi_flasherase.
TEST=write a test console command to read the unique ID from flash with
multiple spi_transaction_async() calls + 1 spi_transaction_flush() call.

Change-Id: I3aacef0063a7cf2c1f70dfe2683b67110cdd9f5f
Signed-off-by: Jun Lin <CHLin56@nuvoton.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/4305803
Reviewed-by: Bobby Casey <bobbycasey@google.com>
Tested-by: CH Lin <chlin56@nuvoton.com>
Reviewed-by: David Cross <davidmcross@google.com>
Commit-Queue: David Cross <davidmcross@google.com>

1 files changed, 47 insertions, 23 deletions

diff --git a/chip/npcx/spi.c b/chip/npcx/spi.c
index f152869bc5..f33dfae028 100644
--- a/chip/npcx/spi.c
+++ b/chip/npcx/spi.c
@@ -27,6 +27,9 @@
 
 /* SPI IP as SPI controller */
 #define SPI_CLK 8000000
+
+static struct mutex spi_lock;
+
 /**
  * Clear SPI data buffer.
  *
@@ -106,30 +109,13 @@ int spi_enable(const struct spi_device_t *spi_device, int enable)
 	return EC_SUCCESS;
 }
 
-/**
- * Flush an SPI transaction and receive data from peripheral.
- *
- * @param   spi_device  device to talk to
- * @param   txdata  transfer data
- * @param   txlen   transfer length
- * @param   rxdata  receive data
- * @param   rxlen   receive length
- * @return  success
- * @notes   set controller transaction mode in npcx chip
- */
-int spi_transaction(const struct spi_device_t *spi_device,
-		    const uint8_t *txdata, int txlen, uint8_t *rxdata,
-		    int rxlen)
+int spi_transaction_async(const struct spi_device_t *spi_device,
+			  const uint8_t *txdata, int txlen, uint8_t *rxdata,
+			  int rxlen)
 {
 	int i = 0;
 	enum gpio_signal gpio = spi_device->gpio_cs;
-	static struct mutex spi_lock;
 
-	mutex_lock(&spi_lock);
-	/* Make sure CS# is a GPIO output mode. */
-	gpio_set_flags(gpio, GPIO_OUTPUT);
-	/* Make sure CS# is deselected */
-	gpio_set_level(gpio, 1);
 	/* Cleaning junk data in the buffer */
 	clear_databuf();
 	/* Assert CS# to start transaction */
@@ -159,7 +145,7 @@ int spi_transaction(const struct spi_device_t *spi_device,
 	}
 
 	if (rxlen == SPI_READBACK_ALL)
-		goto terminate;
+		return EC_SUCCESS;
 
 	CPRINTS("write end");
 	/* Reading the data */
@@ -177,14 +163,52 @@ int spi_transaction(const struct spi_device_t *spi_device,
 		CPRINTS("rxdata[i]=%x", rxdata[i]);
 	}
 
-terminate:
+	return EC_SUCCESS;
+}
+
+int spi_transaction_flush(const struct spi_device_t *spi_device)
+{
+	enum gpio_signal gpio = spi_device->gpio_cs;
+
+	/* Making sure if the SPI transaction already finishes */
+	while (IS_BIT_SET(NPCX_SPI_STAT, NPCX_SPI_STAT_BSY))
+		;
 	/* Deassert CS# (high) to end transaction */
 	gpio_set_level(gpio, 1);
-	mutex_unlock(&spi_lock);
 
 	return EC_SUCCESS;
 }
 
+int spi_transaction_wait(const struct spi_device_t *spi_device)
+{
+	return EC_SUCCESS;
+}
+
+/**
+ * Flush an SPI transaction and receive data from peripheral.
+ *
+ * @param   spi_device  device to talk to
+ * @param   txdata  transfer data
+ * @param   txlen   transfer length
+ * @param   rxdata  receive data
+ * @param   rxlen   receive length
+ * @return  success
+ * @notes   set controller transaction mode in npcx chip
+ */
+int spi_transaction(const struct spi_device_t *spi_device,
+		    const uint8_t *txdata, int txlen, uint8_t *rxdata,
+		    int rxlen)
+{
+	int rv;
+
+	mutex_lock(&spi_lock);
+	rv = spi_transaction_async(spi_device, txdata, txlen, rxdata, rxlen);
+	rv |= spi_transaction_flush(spi_device);
+	mutex_unlock(&spi_lock);
+
+	return rv;
+}
+
 /**
  * SPI initial.
  *