[PATCH] spi: sun6i: Allow transfers larger than FIFO size
Icenowy Zheng
icenowy at aosc.xyz
Mon Mar 6 04:14:43 PST 2017
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 at aosc.xyz>
---
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;
}
--
2.11.1
More information about the linux-arm-kernel
mailing list