spi: imx: dynamic burst length adjust for PIO mode
previously burst length (BURST_LENGTH) is always set to equal
to bits_per_word, causes a 10us gap between each word in
transfer, which significantly affects performance.
This patch uses 32 bits transfer to simulate lower bits transfer,
and adjusts burst length runtimely to use biggeest burst length
as possible to reduce the gaps in transfer for PIO mode.
Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index 930e475..cc808a1 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -56,6 +56,7 @@
/* The maximum bytes that a sdma BD can transfer.*/
#define MAX_SDMA_BD_BYTES (1 << 15)
+#define MX51_ECSPI_CTRL_MAX_BURST 512
enum spi_imx_devtype {
IMX1_CSPI,
@@ -77,6 +78,7 @@
void (*reset)(struct spi_imx_data *);
bool has_dmamode;
unsigned int fifo_size;
+ bool dynamic_burst;
enum spi_imx_devtype devtype;
};
@@ -97,12 +99,14 @@
unsigned int bits_per_word;
unsigned int spi_drctl;
- unsigned int count;
+ unsigned int count, remainder;
void (*tx)(struct spi_imx_data *);
void (*rx)(struct spi_imx_data *);
void *rx_buf;
const void *tx_buf;
unsigned int txfifo; /* number of words pushed in tx FIFO */
+ unsigned int dynamic_burst, read_u32;
+ unsigned int word_mask;
/* DMA */
bool usedma;
@@ -231,6 +235,7 @@
return false;
spi_imx->wml = i;
+ spi_imx->dynamic_burst = 0;
return true;
}
@@ -245,6 +250,7 @@
#define MX51_ECSPI_CTRL_PREDIV_OFFSET 12
#define MX51_ECSPI_CTRL_CS(cs) ((cs) << 18)
#define MX51_ECSPI_CTRL_BL_OFFSET 20
+#define MX51_ECSPI_CTRL_BL_MASK (0xfff << 20)
#define MX51_ECSPI_CONFIG 0x0c
#define MX51_ECSPI_CONFIG_SCLKPHA(cs) (1 << ((cs) + 0))
@@ -272,6 +278,102 @@
#define MX51_ECSPI_TESTREG 0x20
#define MX51_ECSPI_TESTREG_LBC BIT(31)
+static void spi_imx_buf_rx_swap_u32(struct spi_imx_data *spi_imx)
+{
+ unsigned int val = readl(spi_imx->base + MXC_CSPIRXDATA);
+ unsigned int bytes_per_word;
+
+ if (spi_imx->rx_buf) {
+#ifdef __LITTLE_ENDIAN
+ bytes_per_word = spi_imx_bytes_per_word(spi_imx->bits_per_word);
+ if (bytes_per_word == 1)
+ val = cpu_to_be32(val);
+ else if (bytes_per_word == 2)
+ val = (val << 16) | (val >> 16);
+#endif
+ val &= spi_imx->word_mask;
+ *(u32 *)spi_imx->rx_buf = val;
+ spi_imx->rx_buf += sizeof(u32);
+ }
+}
+
+static void spi_imx_buf_rx_swap(struct spi_imx_data *spi_imx)
+{
+ unsigned int bytes_per_word;
+
+ bytes_per_word = spi_imx_bytes_per_word(spi_imx->bits_per_word);
+ if (spi_imx->read_u32) {
+ spi_imx_buf_rx_swap_u32(spi_imx);
+ return;
+ }
+
+ if (bytes_per_word == 1)
+ spi_imx_buf_rx_u8(spi_imx);
+ else if (bytes_per_word == 2)
+ spi_imx_buf_rx_u16(spi_imx);
+}
+
+static void spi_imx_buf_tx_swap_u32(struct spi_imx_data *spi_imx)
+{
+ u32 val = 0;
+ unsigned int bytes_per_word;
+
+ if (spi_imx->tx_buf) {
+ val = *(u32 *)spi_imx->tx_buf;
+ val &= spi_imx->word_mask;
+ spi_imx->tx_buf += sizeof(u32);
+ }
+
+ spi_imx->count -= sizeof(u32);
+#ifdef __LITTLE_ENDIAN
+ bytes_per_word = spi_imx_bytes_per_word(spi_imx->bits_per_word);
+
+ if (bytes_per_word == 1)
+ val = cpu_to_be32(val);
+ else if (bytes_per_word == 2)
+ val = (val << 16) | (val >> 16);
+#endif
+ writel(val, spi_imx->base + MXC_CSPITXDATA);
+}
+
+static void spi_imx_buf_tx_swap(struct spi_imx_data *spi_imx)
+{
+ u32 ctrl, val;
+ unsigned int bytes_per_word;
+
+ if (spi_imx->count == spi_imx->remainder) {
+ ctrl = readl(spi_imx->base + MX51_ECSPI_CTRL);
+ ctrl &= ~MX51_ECSPI_CTRL_BL_MASK;
+ if (spi_imx->count > MX51_ECSPI_CTRL_MAX_BURST) {
+ spi_imx->remainder = spi_imx->count %
+ MX51_ECSPI_CTRL_MAX_BURST;
+ val = MX51_ECSPI_CTRL_MAX_BURST * 8 - 1;
+ } else if (spi_imx->count >= sizeof(u32)) {
+ spi_imx->remainder = spi_imx->count % sizeof(u32);
+ val = (spi_imx->count - spi_imx->remainder) * 8 - 1;
+ } else {
+ spi_imx->remainder = 0;
+ val = spi_imx->bits_per_word - 1;
+ spi_imx->read_u32 = 0;
+ }
+
+ ctrl |= (val << MX51_ECSPI_CTRL_BL_OFFSET);
+ writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL);
+ }
+
+ if (spi_imx->count >= sizeof(u32)) {
+ spi_imx_buf_tx_swap_u32(spi_imx);
+ return;
+ }
+
+ bytes_per_word = spi_imx_bytes_per_word(spi_imx->bits_per_word);
+
+ if (bytes_per_word == 1)
+ spi_imx_buf_tx_u8(spi_imx);
+ else if (bytes_per_word == 2)
+ spi_imx_buf_tx_u16(spi_imx);
+}
+
/* MX51 eCSPI */
static unsigned int mx51_ecspi_clkdiv(struct spi_imx_data *spi_imx,
unsigned int fspi, unsigned int *fres)
@@ -698,6 +800,7 @@
.reset = mx1_reset,
.fifo_size = 8,
.has_dmamode = false,
+ .dynamic_burst = false,
.devtype = IMX1_CSPI,
};
@@ -709,6 +812,7 @@
.reset = mx21_reset,
.fifo_size = 8,
.has_dmamode = false,
+ .dynamic_burst = false,
.devtype = IMX21_CSPI,
};
@@ -721,6 +825,7 @@
.reset = mx21_reset,
.fifo_size = 8,
.has_dmamode = false,
+ .dynamic_burst = false,
.devtype = IMX27_CSPI,
};
@@ -732,6 +837,7 @@
.reset = mx31_reset,
.fifo_size = 8,
.has_dmamode = false,
+ .dynamic_burst = false,
.devtype = IMX31_CSPI,
};
@@ -744,6 +850,7 @@
.reset = mx31_reset,
.fifo_size = 8,
.has_dmamode = true,
+ .dynamic_burst = false,
.devtype = IMX35_CSPI,
};
@@ -755,6 +862,7 @@
.reset = mx51_ecspi_reset,
.fifo_size = 64,
.has_dmamode = true,
+ .dynamic_burst = true,
.devtype = IMX51_ECSPI,
};
@@ -827,6 +935,8 @@
while (spi_imx->txfifo < spi_imx->devtype_data->fifo_size) {
if (!spi_imx->count)
break;
+ if (spi_imx->txfifo && (spi_imx->count == spi_imx->remainder))
+ break;
spi_imx->tx(spi_imx);
spi_imx->txfifo++;
}
@@ -920,15 +1030,37 @@
spi_imx->speed_hz = t->speed_hz;
/* Initialize the functions for transfer */
- if (spi_imx->bits_per_word <= 8) {
- spi_imx->rx = spi_imx_buf_rx_u8;
- spi_imx->tx = spi_imx_buf_tx_u8;
- } else if (spi_imx->bits_per_word <= 16) {
- spi_imx->rx = spi_imx_buf_rx_u16;
- spi_imx->tx = spi_imx_buf_tx_u16;
+ if (spi_imx->devtype_data->dynamic_burst) {
+ u32 mask;
+
+ spi_imx->dynamic_burst = 0;
+ spi_imx->remainder = 0;
+ spi_imx->read_u32 = 1;
+
+ mask = (1 << spi_imx->bits_per_word) - 1;
+ spi_imx->rx = spi_imx_buf_rx_swap;
+ spi_imx->tx = spi_imx_buf_tx_swap;
+ spi_imx->dynamic_burst = 1;
+ spi_imx->remainder = t->len;
+
+ if (spi_imx->bits_per_word <= 8)
+ spi_imx->word_mask = mask << 24 | mask << 16
+ | mask << 8 | mask;
+ else if (spi_imx->bits_per_word <= 16)
+ spi_imx->word_mask = mask << 16 | mask;
+ else
+ spi_imx->word_mask = mask;
} else {
- spi_imx->rx = spi_imx_buf_rx_u32;
- spi_imx->tx = spi_imx_buf_tx_u32;
+ if (spi_imx->bits_per_word <= 8) {
+ spi_imx->rx = spi_imx_buf_rx_u8;
+ spi_imx->tx = spi_imx_buf_tx_u8;
+ } else if (spi_imx->bits_per_word <= 16) {
+ spi_imx->rx = spi_imx_buf_rx_u16;
+ spi_imx->tx = spi_imx_buf_tx_u16;
+ } else {
+ spi_imx->rx = spi_imx_buf_rx_u32;
+ spi_imx->tx = spi_imx_buf_tx_u32;
+ }
}
if (spi_imx_can_dma(spi_imx->bitbang.master, spi, t))