spi/rspi: Fix 8bit data access, clear buffer

The R8A7790 has QSPI module which added into RSPI together.
The transmit or receive data should be read from or written to
with the longword-, word-, or byte-access width. Modify word-
access to byte-access. In 16-bit data register, QSPI send or
receive datas access from high 8-bit while RSPI send or receive
datas access from low 8-bit on single mode.
Modify to reset transmit-receive buffer data and reading dummy
after data are transmited. RSPI has a TXMD bit on control
register(SPCR) to set transmit-only mode when transmit data or
Full-duplex synchronous mode when receive data. In QSPI the TXMD
bit is not supported, so after transmit data, dummy should be
read and before transmit or receive data the bufer register
should be reset.
This driver is the implementation of send and receive pio only,
DMA is not supported at this time.
Without this patch, it will occur error when transmit and receive

Signed-off-by: Hiep Cao Minh <cm-hiep@jinso.co.jp>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/spi/spi-rspi.c

@@ -198,6 +198,11 @@ static u16 rspi_read16(struct rspi_data *rspi, u16 offset)
 /* optional functions */
 struct spi_ops {
 	int (*set_config_register)(struct rspi_data *rspi, int access_size);
+	int (*send_pio)(struct rspi_data *rspi, struct spi_message *mesg,
+			struct spi_transfer *t);
+	int (*receive_pio)(struct rspi_data *rspi, struct spi_message *mesg,
+			   struct spi_transfer *t);
+
 };
 
 /*
@@ -349,6 +354,43 @@ static int rspi_send_pio(struct rspi_data *rspi, struct spi_message *mesg,
 	return 0;
 }
 
+static int qspi_send_pio(struct rspi_data *rspi, struct spi_message *mesg,
+			 struct spi_transfer *t)
+{
+	int remain = t->len;
+	u8 *data;
+
+	rspi_write8(rspi, SPBFCR_TXRST, QSPI_SPBFCR);
+	rspi_write8(rspi, 0x00, QSPI_SPBFCR);
+
+	data = (u8 *)t->tx_buf;
+	while (remain > 0) {
+
+		if (rspi_wait_for_interrupt(rspi, SPSR_SPTEF, SPCR_SPTIE) < 0) {
+			dev_err(&rspi->master->dev,
+				"%s: tx empty timeout\n", __func__);
+			return -ETIMEDOUT;
+		}
+		rspi_write8(rspi, *data++, RSPI_SPDR);
+
+		if (rspi_wait_for_interrupt(rspi, SPSR_SPRF, SPCR_SPRIE) < 0) {
+			dev_err(&rspi->master->dev,
+				"%s: receive timeout\n", __func__);
+			return -ETIMEDOUT;
+		}
+		rspi_read8(rspi, RSPI_SPDR);
+
+		remain--;
+	}
+
+	/* Waiting for the last transmition */
+	rspi_wait_for_interrupt(rspi, SPSR_SPTEF, SPCR_SPTIE);
+
+	return 0;
+}
+
+#define send_pio(spi, mesg, t) spi->ops->send_pio(spi, mesg, t)
+
 static void rspi_dma_complete(void *arg)
 {
 	struct rspi_data *rspi = arg;
@@ -514,6 +556,51 @@ static int rspi_receive_pio(struct rspi_data *rspi, struct spi_message *mesg,
 	return 0;
 }
 
+static void qspi_receive_init(struct rspi_data *rspi)
+{
+	unsigned char spsr;
+
+	spsr = rspi_read8(rspi, RSPI_SPSR);
+	if (spsr & SPSR_SPRF)
+		rspi_read8(rspi, RSPI_SPDR);   /* dummy read */
+	rspi_write8(rspi, SPBFCR_TXRST | SPBFCR_RXRST, QSPI_SPBFCR);
+	rspi_write8(rspi, 0x00, QSPI_SPBFCR);
+}
+
+static int qspi_receive_pio(struct rspi_data *rspi, struct spi_message *mesg,
+			    struct spi_transfer *t)
+{
+	int remain = t->len;
+	u8 *data;
+
+	qspi_receive_init(rspi);
+
+	data = (u8 *)t->rx_buf;
+	while (remain > 0) {
+
+		if (rspi_wait_for_interrupt(rspi, SPSR_SPTEF, SPCR_SPTIE) < 0) {
+			dev_err(&rspi->master->dev,
+				"%s: tx empty timeout\n", __func__);
+			return -ETIMEDOUT;
+		}
+		/* dummy write for generate clock */
+		rspi_write8(rspi, 0x00, RSPI_SPDR);
+
+		if (rspi_wait_for_interrupt(rspi, SPSR_SPRF, SPCR_SPRIE) < 0) {
+			dev_err(&rspi->master->dev,
+				"%s: receive timeout\n", __func__);
+			return -ETIMEDOUT;
+		}
+		/* SPDR allows 8, 16 or 32-bit access */
+		*data++ = rspi_read8(rspi, RSPI_SPDR);
+		remain--;
+	}
+
+	return 0;
+}
+
+#define receive_pio(spi, mesg, t) spi->ops->receive_pio(spi, mesg, t)
+
 static int rspi_receive_dma(struct rspi_data *rspi, struct spi_transfer *t)
 {
 	struct scatterlist sg, sg_dummy;
@@ -653,7 +740,7 @@ static void rspi_work(struct work_struct *work)
 				if (rspi_is_dma(rspi, t))
 					ret = rspi_send_dma(rspi, t);
 				else
-					ret = rspi_send_pio(rspi, mesg, t);
+					ret = send_pio(rspi, mesg, t);
 				if (ret < 0)
 					goto error;
 			}
@@ -661,7 +748,7 @@ static void rspi_work(struct work_struct *work)
 				if (rspi_is_dma(rspi, t))
 					ret = rspi_receive_dma(rspi, t);
 				else
-					ret = rspi_receive_pio(rspi, mesg, t);
+					ret = receive_pio(rspi, mesg, t);
 				if (ret < 0)
 					goto error;
 			}
@@ -918,10 +1005,14 @@ error1:
 
 static struct spi_ops rspi_ops = {
 	.set_config_register =		rspi_set_config_register,
+	.send_pio =			rspi_send_pio,
+	.receive_pio =			rspi_receive_pio,
 };
 
 static struct spi_ops qspi_ops = {
 	.set_config_register =		qspi_set_config_register,
+	.send_pio =			qspi_send_pio,
+	.receive_pio =			qspi_receive_pio,
 };
 
 static struct platform_device_id spi_driver_ids[] = {