Applied "spi: fsl-espi: eliminate need for linearization when reading from hardware" to the spi tree

[Mark Brown <broonie@xxxxxxxxxx>]

The patch

   spi: fsl-espi: eliminate need for linearization when reading from hardware

has been applied to the spi tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From dcb425f3ba6ebee4269f68461420246ba9d4ec02 Mon Sep 17 00:00:00 2001
From: Heiner Kallweit <hkallweit1@xxxxxxxxx>
Date: Fri, 25 Nov 2016 23:59:57 +0100
Subject: [PATCH] spi: fsl-espi: eliminate need for linearization when reading
 from hardware

Eliminate need for linearization when reading from the hardware and
write to the transfer buffers directly.

Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
---
 drivers/spi/spi-fsl-espi.c | 77 +++++++++++++++++++++++++++++++++++++---------
 1 file changed, 63 insertions(+), 14 deletions(-)

diff --git a/drivers/spi/spi-fsl-espi.c b/drivers/spi/spi-fsl-espi.c
index 189ab36b787f..e93892dca90a 100644
--- a/drivers/spi/spi-fsl-espi.c
+++ b/drivers/spi/spi-fsl-espi.c
@@ -102,6 +102,9 @@ struct fsl_espi {
 	struct spi_transfer *tx_t;
 	unsigned int tx_pos;
 	bool tx_done;
+	struct spi_transfer *rx_t;
+	unsigned int rx_pos;
+	bool rx_done;
 
 	bool swab;
 	unsigned int rx_len;
@@ -125,6 +128,11 @@ static inline u32 fsl_espi_read_reg(struct fsl_espi *espi, int offset)
 	return ioread32be(espi->reg_base + offset);
 }
 
+static inline u16 fsl_espi_read_reg16(struct fsl_espi *espi, int offset)
+{
+	return ioread16(espi->reg_base + offset);
+}
+
 static inline u8 fsl_espi_read_reg8(struct fsl_espi *espi, int offset)
 {
 	return ioread8(espi->reg_base + offset);
@@ -328,19 +336,53 @@ static void fsl_espi_fill_tx_fifo(struct fsl_espi *espi, u32 events)
 static void fsl_espi_read_rx_fifo(struct fsl_espi *espi, u32 events)
 {
 	u32 rx_fifo_avail = SPIE_RXCNT(events);
+	unsigned int rx_left;
+	void *rx_buf;
 
-	while (rx_fifo_avail >= min(4U, espi->rx_len) && espi->rx_len)
-		if (espi->rx_len >= 4) {
-			*(u32 *)espi->rx = fsl_espi_read_reg(espi, ESPI_SPIRF);
-			espi->rx += 4;
-			espi->rx_len -= 4;
+start:
+	rx_left = espi->rx_t->len - espi->rx_pos;
+	rx_buf = espi->rx_t->rx_buf;
+	while (rx_fifo_avail >= min(4U, rx_left) && rx_left) {
+		if (rx_left >= 4) {
+			u32 val = fsl_espi_read_reg(espi, ESPI_SPIRF);
+
+			if (rx_buf && espi->swab)
+				*(u32 *)(rx_buf + espi->rx_pos) = swahb32(val);
+			else if (rx_buf)
+				*(u32 *)(rx_buf + espi->rx_pos) = val;
+			espi->rx_pos += 4;
+			rx_left -= 4;
 			rx_fifo_avail -= 4;
+		} else if (rx_left >= 2 && rx_buf && espi->swab) {
+			u16 val = fsl_espi_read_reg16(espi, ESPI_SPIRF);
+
+			*(u16 *)(rx_buf + espi->rx_pos) = swab16(val);
+			espi->rx_pos += 2;
+			rx_left -= 2;
+			rx_fifo_avail -= 2;
 		} else {
-			*(u8 *)espi->rx = fsl_espi_read_reg8(espi, ESPI_SPIRF);
-			espi->rx += 1;
-			espi->rx_len -= 1;
+			u8 val = fsl_espi_read_reg8(espi, ESPI_SPIRF);
+
+			if (rx_buf)
+				*(u8 *)(rx_buf + espi->rx_pos) = val;
+			espi->rx_pos += 1;
+			rx_left -= 1;
 			rx_fifo_avail -= 1;
 		}
+	}
+
+	if (!rx_left) {
+		if (list_is_last(&espi->rx_t->transfer_list,
+		    espi->m_transfers)) {
+			espi->rx_done = true;
+			return;
+		}
+		espi->rx_t = list_next_entry(espi->rx_t, transfer_list);
+		espi->rx_pos = 0;
+		/* continue with next transfer if rx fifo is not empty */
+		if (rx_fifo_avail)
+			goto start;
+	}
 }
 
 static void fsl_espi_setup_transfer(struct spi_device *spi,
@@ -375,6 +417,7 @@ static void fsl_espi_setup_transfer(struct spi_device *spi,
 static int fsl_espi_bufs(struct spi_device *spi, struct spi_transfer *t)
 {
 	struct fsl_espi *espi = spi_master_get_devdata(spi->master);
+	unsigned int rx_len = t->len;
 	u32 mask, spcom;
 	int ret;
 
@@ -395,6 +438,7 @@ static int fsl_espi_bufs(struct spi_device *spi, struct spi_transfer *t)
 		spcom |= SPCOM_RXSKIP(espi->rxskip);
 		espi->tx_len = espi->rxskip;
 		espi->rx_len = t->len - espi->rxskip;
+		rx_len = t->len - espi->rxskip;
 		espi->rx = t->rx_buf + espi->rxskip;
 		if (t->rx_nbits == SPI_NBITS_DUAL)
 			spcom |= SPCOM_DO;
@@ -404,7 +448,7 @@ static int fsl_espi_bufs(struct spi_device *spi, struct spi_transfer *t)
 
 	/* enable interrupts */
 	mask = SPIM_DON;
-	if (espi->rx_len > FSL_ESPI_FIFO_SIZE)
+	if (rx_len > FSL_ESPI_FIFO_SIZE)
 		mask |= SPIM_RXT;
 	fsl_espi_write_reg(espi, ESPI_SPIM, mask);
 
@@ -438,6 +482,10 @@ static int fsl_espi_trans(struct spi_message *m, struct spi_transfer *trans)
 				      transfer_list);
 	espi->tx_pos = 0;
 	espi->tx_done = false;
+	espi->rx_t = list_first_entry(&m->transfers, struct spi_transfer,
+				      transfer_list);
+	espi->rx_pos = 0;
+	espi->rx_done = false;
 
 	espi->rxskip = fsl_espi_check_rxskip_mode(m);
 	if (trans->rx_nbits == SPI_NBITS_DUAL && !espi->rxskip) {
@@ -445,6 +493,10 @@ static int fsl_espi_trans(struct spi_message *m, struct spi_transfer *trans)
 		return -EINVAL;
 	}
 
+	/* In RXSKIP mode skip first transfer for reads */
+	if (espi->rxskip)
+		espi->rx_t = list_next_entry(espi->rx_t, transfer_list);
+
 	fsl_espi_copy_to_buf(m, espi);
 	fsl_espi_setup_transfer(spi, trans);
 
@@ -453,9 +505,6 @@ static int fsl_espi_trans(struct spi_message *m, struct spi_transfer *trans)
 	if (trans->delay_usecs)
 		udelay(trans->delay_usecs);
 
-	if (!ret)
-		fsl_espi_copy_from_buf(m, espi);
-
 	return ret;
 }
 
@@ -556,13 +605,13 @@ static void fsl_espi_cleanup(struct spi_device *spi)
 
 static void fsl_espi_cpu_irq(struct fsl_espi *espi, u32 events)
 {
-	if (espi->rx_len)
+	if (!espi->rx_done)
 		fsl_espi_read_rx_fifo(espi, events);
 
 	if (!espi->tx_done)
 		fsl_espi_fill_tx_fifo(espi, events);
 
-	if (!espi->tx_done || espi->rx_len)
+	if (!espi->tx_done || !espi->rx_done)
 		return;
 
 	/* we're done, but check for errors before returning */
-- 
2.10.2

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