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* spi-imx: add support for single burst mode (8,16,32)
@ 2016-05-31  9:40 Chris Ruehl
       [not found] ` <574D5C2B.1000400-CR359r9tUDPXPF5Rlphj1Q@public.gmane.org>
  0 siblings, 1 reply; 10+ messages in thread
From: Chris Ruehl @ 2016-05-31  9:40 UTC (permalink / raw)
  To: linux-spi-u79uwXL29TY76Z2rM5mHXA
  Cc: Fabio Estevam, broonie-DgEjT+Ai2ygdnm+yROfE0A

Hi,

as imx6 using multiple burst to send data to spi slaves and drop the chipselect 
between the words by default my sensor NXP MPL115A1 wasn't working.
The hint comes from a discussion in the Freescale forum from 2013 where Jeff 
Coffman posted his solution for a 3.x kernel.
I'd pick-up the idea behind and develop something which works "so far" with
4.6 and linux-next

Up front - I'm not happy using the xfer->cs_change to get set the single burst
I more likely want add a new xfer bit which allow to dedicated set a single burst.
To replace todays:
         xfer[0].cs_change = 0;
with a
	xfer[0].singleburst = 1;

An other issue with is not yet solved; when I have a odd number of bytes (8 bpw) 
in a transfer, its result in 3 bytes eaten on the start and 0x00 added on the 
tail -

Single file patch - something to view.

Patch v0: add support for imx6 single burst mode.

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index 50769078..3440d0e 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -60,6 +60,8 @@ struct spi_imx_config {
  	unsigned int speed_hz;
  	unsigned int bpw;
  	unsigned int mode;
+	unsigned int len;
+	unsigned int single_burst_mode:1;
  	u8 cs;
  };

@@ -99,11 +101,13 @@ struct spi_imx_data {
  	unsigned int bytes_per_word;

  	unsigned int count;
+	unsigned int rxcount;
  	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 */
+	u8 bits_per_word;

  	/* DMA */
  	bool usedma;
@@ -168,6 +172,191 @@ MXC_SPI_BUF_TX(u16)
  MXC_SPI_BUF_RX(u32)
  MXC_SPI_BUF_TX(u32)

+static void spi_imx_buf_rx_sb(struct spi_imx_data *spi_imx)
+{
+    unsigned int val = readl(spi_imx->base + MXC_CSPIRXDATA);
+    dev_dbg(spi_imx->dev, "%s: rxcount: %u val:0x%08x\n",
+	    __func__, spi_imx->rxcount , val);
+    if (spi_imx->rxcount>=4) {
+	    if (spi_imx->rx_buf) {
+		    if (spi_imx->bits_per_word==32) {
+			    spi_imx_buf_rx_u32(spi_imx);
+		    } else if (spi_imx->bits_per_word==16) {
+			    *(u16 *)spi_imx->rx_buf = (val>>16);
+			    spi_imx->rx_buf += sizeof(u16);
+			    *(u16 *)spi_imx->rx_buf = val;
+			    spi_imx->rx_buf += sizeof(u16);
+		    } else {
+			    *(u8 *)spi_imx->rx_buf = (val>>24);
+			    spi_imx->rx_buf += sizeof(u8);
+			    *(u8 *)spi_imx->rx_buf = (val>>16);
+			    spi_imx->rx_buf += sizeof(u8);
+			    *(u8 *)spi_imx->rx_buf = (val>>8);
+			    spi_imx->rx_buf += sizeof(u8);
+			    *(u8 *)spi_imx->rx_buf = val;
+			    spi_imx->rx_buf += sizeof(u8);
+		    }
+	    }
+	    spi_imx->rxcount-=4;
+    }
+    else if (spi_imx->rxcount==3) {
+	    if (spi_imx->rx_buf) {
+		    if (spi_imx->bits_per_word==32) {
+			    *(u8 *)spi_imx->rx_buf = val>>24;
+			    spi_imx->rx_buf += sizeof(u8);
+			    *(u8 *)spi_imx->rx_buf = val>>16;
+			    spi_imx->rx_buf += sizeof(u8);
+			    *(u8 *)spi_imx->rx_buf = val>>8;
+			    spi_imx->rx_buf += sizeof(u8);
+		    } else if (spi_imx->bits_per_word==16) {
+			    *(u16 *)spi_imx->rx_buf = (val>>16);
+			    spi_imx->rx_buf += sizeof(u16);
+			    *(u8 *)spi_imx->rx_buf = val>>8;
+			    spi_imx->rx_buf += sizeof(u8);
+		    } else {
+			    *(u8 *)spi_imx->rx_buf = (val>>16);
+			    spi_imx->rx_buf += sizeof(u8);
+			    *(u8 *)spi_imx->rx_buf = (val>>8);
+			    spi_imx->rx_buf += sizeof(u8);
+			    *(u8 *)spi_imx->rx_buf = val;
+			    spi_imx->rx_buf += sizeof(u8);
+		    }
+	    }
+	    spi_imx->rxcount-=3;
+    }
+    else if (spi_imx->rxcount==2) {
+	    if (spi_imx->rx_buf) {
+		    if (spi_imx->bits_per_word==32) {
+			    *(u8 *)spi_imx->rx_buf = val>>24;
+			    spi_imx->rx_buf += sizeof(u8);
+			    *(u8 *)spi_imx->rx_buf = val>>16;
+			    spi_imx->rx_buf += sizeof(u8);
+		    } else if (spi_imx->bits_per_word==16) {
+			    spi_imx_buf_rx_u16(spi_imx);
+		    } else {
+			    *(u8 *)spi_imx->rx_buf = (val>>8);
+			    spi_imx->rx_buf += sizeof(u8);
+			    *(u8 *)spi_imx->rx_buf = val;
+			    spi_imx->rx_buf += sizeof(u8);
+		    }
+	    }
+	    spi_imx->rxcount-=2;
+    }
+    else if (spi_imx->rxcount==1) {
+	    if (spi_imx->rx_buf) {
+		    if (spi_imx->bits_per_word==32) {
+			    *(u8 *)spi_imx->rx_buf = val>>24;
+		    } else if (spi_imx->bits_per_word==16) {
+			    *(u8 *)spi_imx->rx_buf = val>>8;
+		    } else {
+			    spi_imx_buf_rx_u8(spi_imx);
+		    }
+	    }
+	    spi_imx->rxcount-=1;
+    }
+}
+
+static void spi_imx_buf_tx_sb(struct spi_imx_data *spi_imx)
+{
+	unsigned int val = 0;
+	dev_dbg(spi_imx->dev, "%s: txcount: %u ptr:0x%08x\n",
+		__func__, spi_imx->count ,*(u32 *)spi_imx->tx_buf);
+	if (spi_imx->count>=4) {
+		if (spi_imx->bits_per_word==32) {
+			spi_imx_buf_tx_u32(spi_imx);
+		} else {
+			if (spi_imx->tx_buf) {
+				if (spi_imx->bits_per_word==16) {
+					val = *(u16 *)spi_imx->tx_buf<<16;
+					spi_imx->tx_buf += sizeof(u16);
+					val |= *(u16 *)spi_imx->tx_buf;
+					spi_imx->tx_buf += sizeof(u16);
+				} else {
+					val = *(u8 *)spi_imx->tx_buf<<24;
+					spi_imx->tx_buf += sizeof(u8);
+					val |= *(u8 *)spi_imx->tx_buf<<16;
+					spi_imx->tx_buf += sizeof(u8);
+					val |= *(u8 *)spi_imx->tx_buf<<8;
+					spi_imx->tx_buf += sizeof(u8);
+					val |= *(u8 *)spi_imx->tx_buf;
+					spi_imx->tx_buf += sizeof(u8);
+				}
+				writel(val, spi_imx->base + MXC_CSPITXDATA);
+			}
+			spi_imx->count -= 4;
+		}
+	}
+	else if (spi_imx->count==3) {
+		if (spi_imx->tx_buf) {
+			if (spi_imx->bits_per_word==32) {
+				val = *(u8 *)spi_imx->tx_buf<<24;
+				spi_imx->tx_buf += sizeof(u8);
+				val |= *(u8 *)spi_imx->tx_buf<<16;
+				spi_imx->tx_buf += sizeof(u8);
+				val |= *(u8 *)spi_imx->tx_buf<<8;
+				spi_imx->tx_buf += sizeof(u8);
+
+			} else if (spi_imx->bits_per_word==16) {
+				val = *(u8 *)spi_imx->tx_buf<<24;
+				spi_imx->tx_buf += sizeof(u8);
+				val |= *(u8 *)spi_imx->tx_buf<<16;
+				spi_imx->tx_buf += sizeof(u8);
+				val |= *(u8 *)spi_imx->tx_buf;
+				spi_imx->tx_buf += sizeof(u8);
+
+			} else {
+				val = *(u8 *)spi_imx->tx_buf<<16;
+				spi_imx->tx_buf += sizeof(u8);
+				val |= *(u8 *)spi_imx->tx_buf<<8;
+				spi_imx->tx_buf += sizeof(u8);
+				val |= *(u8 *)spi_imx->tx_buf;
+				spi_imx->tx_buf += sizeof(u8);
+			}
+			writel(val, spi_imx->base + MXC_CSPITXDATA);
+		}
+		spi_imx->count -= 3;
+	}
+	else if (spi_imx->count==2) {
+		if (spi_imx->bits_per_word==16) {
+			spi_imx_buf_tx_u16(spi_imx);
+		} else {
+			if (spi_imx->tx_buf) {
+				if (spi_imx->bits_per_word==32) {
+					val = *(u8 *)spi_imx->tx_buf<<24;
+					spi_imx->tx_buf += sizeof(u8);
+					val |= *(u8 *)spi_imx->tx_buf<<16;
+					spi_imx->tx_buf += sizeof(u8);
+				} else {
+					val = *(u8 *)spi_imx->tx_buf<<8;
+					spi_imx->tx_buf += sizeof(u8);
+					val |= *(u8 *)spi_imx->tx_buf;
+					spi_imx->tx_buf += sizeof(u8);
+				}
+				writel(val, spi_imx->base + MXC_CSPITXDATA);
+			}
+			spi_imx->count -= 2;
+		}
+	}
+	else if (spi_imx->count==1) {
+		if (spi_imx->bits_per_word==8){
+			spi_imx_buf_tx_u8(spi_imx);
+		} else {
+			if (spi_imx->tx_buf) {
+				if (spi_imx->bits_per_word==32) {
+					val = *(u8 *)spi_imx->tx_buf<<24;
+					spi_imx->tx_buf += sizeof(u8);
+				} else if (spi_imx->bits_per_word==16) {
+					val = *(u8 *)spi_imx->tx_buf<<8;
+					spi_imx->tx_buf += sizeof(u8);
+				}
+				writel(val, spi_imx->base + MXC_CSPITXDATA);
+			}
+			spi_imx->count -= 1;
+		}
+	}
+}
+
+
  /* First entry is reserved, second entry is valid only if SDHC_SPIEN is set
   * (which is currently not the case in this driver)
   */
@@ -357,9 +546,49 @@ static int __maybe_unused mx51_ecspi_config(struct 
spi_imx_data *spi_imx,
  	/* set chip select to use */
  	ctrl |= MX51_ECSPI_CTRL_CS(config->cs);

-	ctrl |= (config->bpw - 1) << MX51_ECSPI_CTRL_BL_OFFSET;
+	/* set single/multible burst parameters */
+	if (config->single_burst_mode>0) {
+		reg = 0;
+		spi_imx->rx = spi_imx_buf_rx_sb;
+		spi_imx->tx = spi_imx_buf_tx_sb;
+		spi_imx->rxcount = config->len;
+		spi_imx->bits_per_word = config->bpw;
+
+		/* calculate the Burst Length,
+		   refer to 21.7.3 Control Register (ECSPIx_CONREG)
+		   for details.
+		 */
+		switch (config->len%4)
+		{
+		case 1:
+			ctrl |= 7 << MX51_ECSPI_CTRL_BL_OFFSET;
+			reg = (config->len-1) / 4;
+			break;
+		case 2:
+			ctrl |= 15 << MX51_ECSPI_CTRL_BL_OFFSET;
+			reg = (config->len-2) / 4;
+			break;
+		case 3:
+			ctrl |= 23 << MX51_ECSPI_CTRL_BL_OFFSET;
+			reg = (config->len-3) / 4;
+			break;
+		case 0:
+			ctrl |= 31 << MX51_ECSPI_CTRL_BL_OFFSET;
+			reg = (config->len-4) / 4;
+			break;
+		}
+
+		if (reg>0)
+			ctrl |= reg << (MX51_ECSPI_CTRL_BL_OFFSET + 5);

-	cfg |= MX51_ECSPI_CONFIG_SBBCTRL(config->cs);
+		cfg &= ~(MX51_ECSPI_CONFIG_SBBCTRL(config->cs));
+
+		dev_dbg(spi_imx->dev, "Single Burst reg:0x%08x cfg:0x%08x ctrl:0x%08x\n"
+			, reg, cfg, ctrl);
+	} else {
+		ctrl |= (config->bpw - 1) << MX51_ECSPI_CTRL_BL_OFFSET;
+		cfg |= MX51_ECSPI_CONFIG_SBBCTRL(config->cs);
+	}

  	if (config->mode & SPI_CPHA)
  		cfg |= MX51_ECSPI_CONFIG_SCLKPHA(config->cs);
@@ -861,6 +1090,8 @@ static int spi_imx_setupxfer(struct spi_device *spi,
  	config.speed_hz  = t ? t->speed_hz : spi->max_speed_hz;
  	config.mode = spi->mode;
  	config.cs = spi->chip_select;
+	config.len = t->len;
+	config.single_burst_mode = ~(t->cs_change);

  	if (!config.speed_hz)
  		config.speed_hz = spi->max_speed_hz;





Regards
Chris

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^ permalink raw reply related	[flat|nested] 10+ messages in thread

end of thread, other threads:[~2016-06-01  6:39 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2016-05-31  9:40 spi-imx: add support for single burst mode (8,16,32) Chris Ruehl
     [not found] ` <574D5C2B.1000400-CR359r9tUDPXPF5Rlphj1Q@public.gmane.org>
2016-05-31 10:43   ` Fabio Estevam
     [not found]     ` <CAOMZO5CiW3J+naHfitjv59i4xisYB1R3ATs2qvz4mLh_FMyf+g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-05-31 11:06       ` Sascha Hauer
     [not found]         ` <20160531110608.GG31666-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2016-06-01  1:54           ` Chris Ruehl
     [not found]             ` <574E405F.9090000-CR359r9tUDPXPF5Rlphj1Q@public.gmane.org>
2016-06-01  6:30               ` Sascha Hauer
     [not found]                 ` <20160601063029.GB11074-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2016-06-01  6:39                   ` Chris Ruehl
2016-05-31 11:20   ` Vladimir Zapolskiy
     [not found]     ` <574D7366.5050203-nmGgyN9QBj3QT0dZR+AlfA@public.gmane.org>
2016-06-01  1:48       ` Chris Ruehl
2016-05-31 13:08   ` Mark Brown
     [not found]     ` <20160531130828.GB29837-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2016-06-01  1:58       ` Chris Ruehl

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