qspi:fsl implement AHB read

The QSPI controller in i.MX 6SoloX and Vybrid supports reading data using
IP register and AHB bus.

The original driver only supports reading data from IP interface. The IC
team suggests to use AHB read which is faster then IP read. Using AHB read,
we can directly memcpy, a "missed" access to the buffer will cause the
controller to clear the buffer and use the SEQID stored in bfgencr register
to initiate a read from flash device.

Since AHB bus is 64 bit width, we can not set MCR register using 32bit. In
order to minimize code change, redefine QSPI_MCR_END_CFD_LE to 64bit Little
endian but not 32bit Little endia.

Introduce a new configuration option CONFIG_SYS_FSL_QSPI_AHB. If want to
use AHB read, just define CONFIG_SYS_FSL_QSPI_AHB. If not, just ignore it.
Actually if Vybrid is migrated to use AHB read, this option can be removed and
IP read function can be discared. The reason to introduce this option
is that only i.MX SOC is tested in my side, no Vybrid platform for me.

In spi_setup_slave, the original piece code to set AHB is deleted, since
Vybrid platform does not use this to intiate AHB read. Instead, add
qspi_init_ahb_read function if defined CONFIG_SYS_FSL_QSPI_AHB.

Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
Reviewed-by: Jagannadha Sutradharudu Teki <jagannadh.teki@gmail.com>

1 files changed, 127 insertions, 10 deletions

diff --git a/drivers/spi/fsl_qspi.c b/drivers/spi/fsl_qspi.c
index ad4f4ce..5e0b069 100644
--- a/drivers/spi/fsl_qspi.c
+++ b/drivers/spi/fsl_qspi.c
@@ -263,6 +263,110 @@ static void qspi_set_lut(struct fsl_qspi *qspi)
 	qspi_write32(&regs->lckcr, QSPI_LCKCR_LOCK);
 }
 
+#if defined(CONFIG_SYS_FSL_QSPI_AHB)
+/*
+ * If we have changed the content of the flash by writing or erasing,
+ * we need to invalidate the AHB buffer. If we do not do so, we may read out
+ * the wrong data. The spec tells us reset the AHB domain and Serial Flash
+ * domain at the same time.
+ */
+static inline void qspi_ahb_invalid(struct fsl_qspi *q)
+{
+	struct fsl_qspi_regs *regs = (struct fsl_qspi_regs *)q->reg_base;
+	u32 reg;
+
+	reg = qspi_read32(&regs->mcr);
+	reg |= QSPI_MCR_SWRSTHD_MASK | QSPI_MCR_SWRSTSD_MASK;
+	qspi_write32(&regs->mcr, reg);
+
+	/*
+	 * The minimum delay : 1 AHB + 2 SFCK clocks.
+	 * Delay 1 us is enough.
+	 */
+	udelay(1);
+
+	reg &= ~(QSPI_MCR_SWRSTHD_MASK | QSPI_MCR_SWRSTSD_MASK);
+	qspi_write32(&regs->mcr, reg);
+}
+
+/* Read out the data from the AHB buffer. */
+static inline void qspi_ahb_read(struct fsl_qspi *q, u8 *rxbuf, int len)
+{
+	struct fsl_qspi_regs *regs = (struct fsl_qspi_regs *)q->reg_base;
+	u32 mcr_reg;
+
+	mcr_reg = qspi_read32(&regs->mcr);
+
+	qspi_write32(&regs->mcr, QSPI_MCR_CLR_RXF_MASK | QSPI_MCR_CLR_TXF_MASK |
+		     QSPI_MCR_RESERVED_MASK | QSPI_MCR_END_CFD_LE);
+
+	/* Read out the data directly from the AHB buffer. */
+	memcpy(rxbuf, (u8 *)(q->amba_base + q->sf_addr), len);
+
+	qspi_write32(&regs->mcr, mcr_reg);
+}
+
+static void qspi_enable_ddr_mode(struct fsl_qspi_regs *regs)
+{
+	u32 reg, reg2;
+
+	reg = qspi_read32(&regs->mcr);
+	/* Disable the module */
+	qspi_write32(&regs->mcr, reg | QSPI_MCR_MDIS_MASK);
+
+	/* Set the Sampling Register for DDR */
+	reg2 = qspi_read32(&regs->smpr);
+	reg2 &= ~QSPI_SMPR_DDRSMP_MASK;
+	reg2 |= (2 << QSPI_SMPR_DDRSMP_SHIFT);
+	qspi_write32(&regs->smpr, reg2);
+
+	/* Enable the module again (enable the DDR too) */
+	reg |= QSPI_MCR_DDR_EN_MASK;
+	/* Enable bit 29 for imx6sx */
+	reg |= (1 << 29);
+
+	qspi_write32(&regs->mcr, reg);
+}
+
+/*
+ * There are two different ways to read out the data from the flash:
+ *  the "IP Command Read" and the "AHB Command Read".
+ *
+ * The IC guy suggests we use the "AHB Command Read" which is faster
+ * then the "IP Command Read". (What's more is that there is a bug in
+ * the "IP Command Read" in the Vybrid.)
+ *
+ * After we set up the registers for the "AHB Command Read", we can use
+ * the memcpy to read the data directly. A "missed" access to the buffer
+ * causes the controller to clear the buffer, and use the sequence pointed
+ * by the QUADSPI_BFGENCR[SEQID] to initiate a read from the flash.
+ */
+static void qspi_init_ahb_read(struct fsl_qspi_regs *regs)
+{
+	/* AHB configuration for access buffer 0/1/2 .*/
+	qspi_write32(&regs->buf0cr, QSPI_BUFXCR_INVALID_MSTRID);
+	qspi_write32(&regs->buf1cr, QSPI_BUFXCR_INVALID_MSTRID);
+	qspi_write32(&regs->buf2cr, QSPI_BUFXCR_INVALID_MSTRID);
+	qspi_write32(&regs->buf3cr, QSPI_BUF3CR_ALLMST_MASK |
+		     (0x80 << QSPI_BUF3CR_ADATSZ_SHIFT));
+
+	/* We only use the buffer3 */
+	qspi_write32(&regs->buf0ind, 0);
+	qspi_write32(&regs->buf1ind, 0);
+	qspi_write32(&regs->buf2ind, 0);
+
+	/*
+	 * Set the default lut sequence for AHB Read.
+	 * Parallel mode is disabled.
+	 */
+	qspi_write32(&regs->bfgencr,
+		     SEQID_FAST_READ << QSPI_BFGENCR_SEQID_SHIFT);
+
+	/*Enable DDR Mode*/
+	qspi_enable_ddr_mode(regs);
+}
+#endif
+
 void spi_init()
 {
 	/* do nothing */
@@ -273,8 +377,8 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
 {
 	struct fsl_qspi *qspi;
 	struct fsl_qspi_regs *regs;
-	u32 reg_val, smpr_val;
-	u32 total_size, seq_id;
+	u32 smpr_val;
+	u32 total_size;
 
 	if (bus >= ARRAY_SIZE(spi_bases))
 		return NULL;
@@ -329,13 +433,9 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
 	qspi_write32(&regs->smpr, smpr_val);
 	qspi_write32(&regs->mcr, QSPI_MCR_RESERVED_MASK);
 
-	seq_id = 0;
-	reg_val = qspi_read32(&regs->bfgencr);
-	reg_val &= ~QSPI_BFGENCR_SEQID_MASK;
-	reg_val |= (seq_id << QSPI_BFGENCR_SEQID_SHIFT);
-	reg_val &= ~QSPI_BFGENCR_PAR_EN_MASK;
-	qspi_write32(&regs->bfgencr, reg_val);
-
+#ifdef CONFIG_SYS_FSL_QSPI_AHB
+	qspi_init_ahb_read(regs);
+#endif
 	return &qspi->slave;
 }
 
@@ -426,6 +526,8 @@ static void qspi_op_rdid(struct fsl_qspi *qspi, u32 *rxbuf, u32 len)
 	qspi_write32(&regs->mcr, mcr_reg);
 }
 
+#ifndef CONFIG_SYS_FSL_QSPI_AHB
+/* If not use AHB read, read data from ip interface */
 static void qspi_op_read(struct fsl_qspi *qspi, u32 *rxbuf, u32 len)
 {
 	struct fsl_qspi_regs *regs = (struct fsl_qspi_regs *)qspi->reg_base;
@@ -469,6 +571,7 @@ static void qspi_op_read(struct fsl_qspi *qspi, u32 *rxbuf, u32 len)
 
 	qspi_write32(&regs->mcr, mcr_reg);
 }
+#endif
 
 static void qspi_op_write(struct fsl_qspi *qspi, u8 *txbuf, u32 len)
 {
@@ -643,8 +746,13 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
 	}
 
 	if (din) {
-		if (qspi->cur_seqid == QSPI_CMD_FAST_READ)
+		if (qspi->cur_seqid == QSPI_CMD_FAST_READ) {
+#ifdef CONFIG_SYS_FSL_QSPI_AHB
+			qspi_ahb_read(qspi, din, bytes);
+#else
 			qspi_op_read(qspi, din, bytes);
+#endif
+		}
 		else if (qspi->cur_seqid == QSPI_CMD_RDID)
 			qspi_op_rdid(qspi, din, bytes);
 		else if (qspi->cur_seqid == QSPI_CMD_RDSR)
@@ -658,6 +766,15 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
 #endif
 	}
 
+#ifdef CONFIG_SYS_FSL_QSPI_AHB
+	if ((qspi->cur_seqid == QSPI_CMD_SE) ||
+	    (qspi->cur_seqid == QSPI_CMD_PP) ||
+	    (qspi->cur_seqid == QSPI_CMD_BE_4K) ||
+	    (qspi->cur_seqid == QSPI_CMD_WREAR) ||
+	    (qspi->cur_seqid == QSPI_CMD_BRWR))
+		qspi_ahb_invalid(qspi);
+#endif
+
 	return 0;
 }