Applied "spi: sun6i: Allow transfers larger than FIFO size" to the spi tree

[Mark Brown <broonie@xxxxxxxxxx>]

The patch

   spi: sun6i: Allow transfers larger than FIFO size

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 913f536c6c18a2e19e32f06971101c1d0ae3739c Mon Sep 17 00:00:00 2001
From: Icenowy Zheng <icenowy@xxxxxxxx>
Date: Mon, 6 Mar 2017 20:14:43 +0800
Subject: [PATCH] spi: sun6i: Allow transfers larger than FIFO size

The spi-sun6i driver have the same problem that spi-sun4i used to have
-- SPI transfers are limited to one FIFO depth.

This commit fixes this problem in the same way it's fixed in spi-sun4i.
See commit 196737912da5 ("spi: sun4i: Allow transfers larger than FIFO size")
for more information.

The sun6i SPI controllers features changeable interrupt trigger level, but I
set it to 3/4 of fifo depth, as same as the the sun4i SPI controllers.

Signed-off-by: Icenowy Zheng <icenowy@xxxxxxxx>
Acked-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
---
 drivers/spi/spi-sun6i.c | 90 ++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 81 insertions(+), 9 deletions(-)

diff --git a/drivers/spi/spi-sun6i.c b/drivers/spi/spi-sun6i.c
index e3114832c485..6e9ca93db9bf 100644
--- a/drivers/spi/spi-sun6i.c
+++ b/drivers/spi/spi-sun6i.c
@@ -46,13 +46,19 @@
 #define SUN6I_TFR_CTL_XCH			BIT(31)
 
 #define SUN6I_INT_CTL_REG		0x10
+#define SUN6I_INT_CTL_RF_RDY			BIT(0)
+#define SUN6I_INT_CTL_TF_ERQ			BIT(4)
 #define SUN6I_INT_CTL_RF_OVF			BIT(8)
 #define SUN6I_INT_CTL_TC			BIT(12)
 
 #define SUN6I_INT_STA_REG		0x14
 
 #define SUN6I_FIFO_CTL_REG		0x18
+#define SUN6I_FIFO_CTL_RF_RDY_TRIG_LEVEL_MASK	0xff
+#define SUN6I_FIFO_CTL_RF_RDY_TRIG_LEVEL_BITS	0
 #define SUN6I_FIFO_CTL_RF_RST			BIT(15)
+#define SUN6I_FIFO_CTL_TF_ERQ_TRIG_LEVEL_MASK	0xff
+#define SUN6I_FIFO_CTL_TF_ERQ_TRIG_LEVEL_BITS	16
 #define SUN6I_FIFO_CTL_TF_RST			BIT(31)
 
 #define SUN6I_FIFO_STA_REG		0x1c
@@ -68,14 +74,16 @@
 #define SUN6I_CLK_CTL_CDR1(div)			(((div) & SUN6I_CLK_CTL_CDR1_MASK) << 8)
 #define SUN6I_CLK_CTL_DRS			BIT(12)
 
+#define SUN6I_MAX_XFER_SIZE		0xffffff
+
 #define SUN6I_BURST_CNT_REG		0x30
-#define SUN6I_BURST_CNT(cnt)			((cnt) & 0xffffff)
+#define SUN6I_BURST_CNT(cnt)			((cnt) & SUN6I_MAX_XFER_SIZE)
 
 #define SUN6I_XMIT_CNT_REG		0x34
-#define SUN6I_XMIT_CNT(cnt)			((cnt) & 0xffffff)
+#define SUN6I_XMIT_CNT(cnt)			((cnt) & SUN6I_MAX_XFER_SIZE)
 
 #define SUN6I_BURST_CTL_CNT_REG		0x38
-#define SUN6I_BURST_CTL_CNT_STC(cnt)		((cnt) & 0xffffff)
+#define SUN6I_BURST_CTL_CNT_STC(cnt)		((cnt) & SUN6I_MAX_XFER_SIZE)
 
 #define SUN6I_TXDATA_REG		0x200
 #define SUN6I_RXDATA_REG		0x300
@@ -105,6 +113,31 @@ static inline void sun6i_spi_write(struct sun6i_spi *sspi, u32 reg, u32 value)
 	writel(value, sspi->base_addr + reg);
 }
 
+static inline u32 sun6i_spi_get_tx_fifo_count(struct sun6i_spi *sspi)
+{
+	u32 reg = sun6i_spi_read(sspi, SUN6I_FIFO_STA_REG);
+
+	reg >>= SUN6I_FIFO_STA_TF_CNT_BITS;
+
+	return reg & SUN6I_FIFO_STA_TF_CNT_MASK;
+}
+
+static inline void sun6i_spi_enable_interrupt(struct sun6i_spi *sspi, u32 mask)
+{
+	u32 reg = sun6i_spi_read(sspi, SUN6I_INT_CTL_REG);
+
+	reg |= mask;
+	sun6i_spi_write(sspi, SUN6I_INT_CTL_REG, reg);
+}
+
+static inline void sun6i_spi_disable_interrupt(struct sun6i_spi *sspi, u32 mask)
+{
+	u32 reg = sun6i_spi_read(sspi, SUN6I_INT_CTL_REG);
+
+	reg &= ~mask;
+	sun6i_spi_write(sspi, SUN6I_INT_CTL_REG, reg);
+}
+
 static inline void sun6i_spi_drain_fifo(struct sun6i_spi *sspi, int len)
 {
 	u32 reg, cnt;
@@ -127,10 +160,13 @@ static inline void sun6i_spi_drain_fifo(struct sun6i_spi *sspi, int len)
 
 static inline void sun6i_spi_fill_fifo(struct sun6i_spi *sspi, int len)
 {
+	u32 cnt;
 	u8 byte;
 
-	if (len > sspi->len)
-		len = sspi->len;
+	/* See how much data we can fit */
+	cnt = sspi->fifo_depth - sun6i_spi_get_tx_fifo_count(sspi);
+
+	len = min3(len, (int)cnt, sspi->len);
 
 	while (len--) {
 		byte = sspi->tx_buf ? *sspi->tx_buf++ : 0;
@@ -170,12 +206,12 @@ static int sun6i_spi_transfer_one(struct spi_master *master,
 	struct sun6i_spi *sspi = spi_master_get_devdata(master);
 	unsigned int mclk_rate, div, timeout;
 	unsigned int start, end, tx_time;
+	unsigned int trig_level;
 	unsigned int tx_len = 0;
 	int ret = 0;
 	u32 reg;
 
-	/* We don't support transfer larger than the FIFO */
-	if (tfr->len > sspi->fifo_depth)
+	if (tfr->len > SUN6I_MAX_XFER_SIZE)
 		return -EINVAL;
 
 	reinit_completion(&sspi->done);
@@ -191,6 +227,17 @@ static int sun6i_spi_transfer_one(struct spi_master *master,
 			SUN6I_FIFO_CTL_RF_RST | SUN6I_FIFO_CTL_TF_RST);
 
 	/*
+	 * Setup FIFO interrupt trigger level
+	 * Here we choose 3/4 of the full fifo depth, as it's the hardcoded
+	 * value used in old generation of Allwinner SPI controller.
+	 * (See spi-sun4i.c)
+	 */
+	trig_level = sspi->fifo_depth / 4 * 3;
+	sun6i_spi_write(sspi, SUN6I_FIFO_CTL_REG,
+			(trig_level << SUN6I_FIFO_CTL_RF_RDY_TRIG_LEVEL_BITS) |
+			(trig_level << SUN6I_FIFO_CTL_TF_ERQ_TRIG_LEVEL_BITS));
+
+	/*
 	 * Setup the transfer control register: Chip Select,
 	 * polarities, etc.
 	 */
@@ -274,6 +321,10 @@ static int sun6i_spi_transfer_one(struct spi_master *master,
 
 	/* Enable the interrupts */
 	sun6i_spi_write(sspi, SUN6I_INT_CTL_REG, SUN6I_INT_CTL_TC);
+	sun6i_spi_enable_interrupt(sspi, SUN6I_INT_CTL_TC |
+					 SUN6I_INT_CTL_RF_RDY);
+	if (tx_len > sspi->fifo_depth)
+		sun6i_spi_enable_interrupt(sspi, SUN6I_INT_CTL_TF_ERQ);
 
 	/* Start the transfer */
 	reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);
@@ -293,8 +344,6 @@ static int sun6i_spi_transfer_one(struct spi_master *master,
 		goto out;
 	}
 
-	sun6i_spi_drain_fifo(sspi, sspi->fifo_depth);
-
 out:
 	sun6i_spi_write(sspi, SUN6I_INT_CTL_REG, 0);
 
@@ -309,10 +358,33 @@ static irqreturn_t sun6i_spi_handler(int irq, void *dev_id)
 	/* Transfer complete */
 	if (status & SUN6I_INT_CTL_TC) {
 		sun6i_spi_write(sspi, SUN6I_INT_STA_REG, SUN6I_INT_CTL_TC);
+		sun6i_spi_drain_fifo(sspi, sspi->fifo_depth);
 		complete(&sspi->done);
 		return IRQ_HANDLED;
 	}
 
+	/* Receive FIFO 3/4 full */
+	if (status & SUN6I_INT_CTL_RF_RDY) {
+		sun6i_spi_drain_fifo(sspi, SUN6I_FIFO_DEPTH);
+		/* Only clear the interrupt _after_ draining the FIFO */
+		sun6i_spi_write(sspi, SUN6I_INT_STA_REG, SUN6I_INT_CTL_RF_RDY);
+		return IRQ_HANDLED;
+	}
+
+	/* Transmit FIFO 3/4 empty */
+	if (status & SUN6I_INT_CTL_TF_ERQ) {
+		sun6i_spi_fill_fifo(sspi, SUN6I_FIFO_DEPTH);
+
+		if (!sspi->len)
+			/* nothing left to transmit */
+			sun6i_spi_disable_interrupt(sspi, SUN6I_INT_CTL_TF_ERQ);
+
+		/* Only clear the interrupt _after_ re-seeding the FIFO */
+		sun6i_spi_write(sspi, SUN6I_INT_STA_REG, SUN6I_INT_CTL_TF_ERQ);
+
+		return IRQ_HANDLED;
+	}
+
 	return IRQ_NONE;
 }
 
-- 
2.11.0

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