[U-Boot] [PATCH V2 2/6] spi: omap3: add support for more word lengths

Nikita Kiryanov
2013-10-16T14:23:25Z

Current implementation only supports 8 bit word lengths, even though
omap3 can handle anything between 4 and 32.

Update the spi interface to support changing the SPI word length,
and implement it in omap3_spi driver to support the full range of
possible word lengths.
This implementation is backwards compatible by defaulting to the old
behavior of 8 bit word lengths.
Also, it required a change to the omap3_spi non static I/O functions,
but since they are not used anywhere else, no collateral changes are required.

Cc: Tom Rini <trini@ti.com>
Cc: Jagannadha Sutradharudu Teki <jagannadh.teki@gmail.com>
Cc: Igor Grinberg <grinberg@compulab.co.il>
Signed-off-by: Nikita Kiryanov <nikita@compulab.co.il>
---
Changes in V2:
- Removed semicolon from #define SPI_DEFAULT_WORDLEN (Gerhard Sittig,
Igor Grinberg)
- Moved wordlen to generic spi_slave struct, and added generic
implementation for spi_set_wordlen which only updates the struct without
touching the hardware (Igor Grinberg)
- Update wordlen in hardware just before doing SPI transactions, not
when changing wordlen (Igor Grinberg)
- OMAP3 specific check of wordlen value from old implementation of
spi_set_wordlen moved to xfer. It refines the more general check done
in the new spi_set_wordlen.
- Fixed comment style in spi.h following a rebase on top of latest
U-Boot

drivers/spi/omap3_spi.c | 69 +++++++++++++++++++++++++++++++++++--------------
drivers/spi/omap3_spi.h | 8 +++---
drivers/spi/spi.c | 13 ++++++++++
include/spi.h | 16 ++++++++++++
4 files changed, 82 insertions(+), 24 deletions(-)

diff --git a/drivers/spi/omap3_spi.c b/drivers/spi/omap3_spi.c
index 116276c..a3ad056 100644
--- a/drivers/spi/omap3_spi.c
+++ b/drivers/spi/omap3_spi.c
@@ -20,7 +20,6 @@
#include <asm/io.h>
#include "omap3_spi.h"

-#define WORD_LEN 8
#define SPI_WAIT_TIMEOUT 3000000

static void spi_reset(struct omap3_spi_slave *ds)
@@ -185,7 +184,7 @@ int spi_claim_bus(struct spi_slave *slave)

/* wordlength */
conf &= ~OMAP3_MCSPI_CHCONF_WL_MASK;
- conf |= (WORD_LEN - 1) << 7;
+ conf |= (ds->slave.wordlen - 1) << 7;

/* set chipselect polarity; manage with FORCE */
if (!(ds->mode & SPI_CS_HIGH))
@@ -223,7 +222,7 @@ void spi_release_bus(struct spi_slave *slave)
spi_reset(ds);
}

-int omap3_spi_write(struct spi_slave *slave, unsigned int len, const u8 *txp,
+int omap3_spi_write(struct spi_slave *slave, unsigned int len, const void *txp,
unsigned long flags)
{
struct omap3_spi_slave *ds = to_omap3_spi(slave);
@@ -234,7 +233,8 @@ int omap3_spi_write(struct spi_slave *slave, unsigned int len, const u8 *txp,
/* Enable the channel */
omap3_spi_set_enable(ds,OMAP3_MCSPI_CHCTRL_EN);

- chconf &= ~OMAP3_MCSPI_CHCONF_TRM_MASK;
+ chconf &= ~(OMAP3_MCSPI_CHCONF_TRM_MASK | OMAP3_MCSPI_CHCONF_WL_MASK);
+ chconf |= (ds->slave.wordlen - 1) << 7;
chconf |= OMAP3_MCSPI_CHCONF_TRM_TX_ONLY;
chconf |= OMAP3_MCSPI_CHCONF_FORCE;
omap3_spi_write_chconf(ds,chconf);
@@ -250,7 +250,13 @@ int omap3_spi_write(struct spi_slave *slave, unsigned int len, const u8 *txp,
}
}
/* Write the data */
- writel(txp[i], &ds->regs->channel[ds->slave.cs].tx);
+ unsigned int *tx = &ds->regs->channel[ds->slave.cs].tx;
+ if (ds->slave.wordlen > 16)
+ writel(((u32 *)txp)[i], tx);
+ else if (ds->slave.wordlen > 8)
+ writel(((u16 *)txp)[i], tx);
+ else
+ writel(((u8 *)txp)[i], tx);
}

/* wait to finish of transfer */
@@ -268,7 +274,7 @@ int omap3_spi_write(struct spi_slave *slave, unsigned int len, const u8 *txp,
return 0;
}

-int omap3_spi_read(struct spi_slave *slave, unsigned int len, u8 *rxp,
+int omap3_spi_read(struct spi_slave *slave, unsigned int len, void *rxp,
unsigned long flags)
{
struct omap3_spi_slave *ds = to_omap3_spi(slave);
@@ -279,7 +285,8 @@ int omap3_spi_read(struct spi_slave *slave, unsigned int len, u8 *rxp,
/* Enable the channel */
omap3_spi_set_enable(ds,OMAP3_MCSPI_CHCTRL_EN);

- chconf &= ~OMAP3_MCSPI_CHCONF_TRM_MASK;
+ chconf &= ~(OMAP3_MCSPI_CHCONF_TRM_MASK | OMAP3_MCSPI_CHCONF_WL_MASK);
+ chconf |= (ds->slave.wordlen - 1) << 7;
chconf |= OMAP3_MCSPI_CHCONF_TRM_RX_ONLY;
chconf |= OMAP3_MCSPI_CHCONF_FORCE;
omap3_spi_write_chconf(ds,chconf);
@@ -302,7 +309,13 @@ int omap3_spi_read(struct spi_slave *slave, unsigned int len, u8 *rxp,
omap3_spi_set_enable(ds,OMAP3_MCSPI_CHCTRL_DIS);

/* Read the data */
- rxp[i] = readl(&ds->regs->channel[ds->slave.cs].rx);
+ unsigned int *rx = &ds->regs->channel[ds->slave.cs].rx;
+ if (ds->slave.wordlen > 16)
+ ((u32 *)rxp)[i] = readl(rx);
+ else if (ds->slave.wordlen > 8)
+ ((u16 *)rxp)[i] = (u16)readl(rx);
+ else
+ ((u8 *)rxp)[i] = (u8)readl(rx);
}

if (flags & SPI_XFER_END) {
@@ -314,8 +327,8 @@ int omap3_spi_read(struct spi_slave *slave, unsigned int len, u8 *rxp,
}

/*McSPI Transmit Receive Mode*/
-int omap3_spi_txrx(struct spi_slave *slave,
- unsigned int len, const u8 *txp, u8 *rxp, unsigned long flags)
+int omap3_spi_txrx(struct spi_slave *slave, unsigned int len,
+ const void *txp, void *rxp, unsigned long flags)
{
struct omap3_spi_slave *ds = to_omap3_spi(slave);
int timeout = SPI_WAIT_TIMEOUT;
@@ -327,7 +340,8 @@ int omap3_spi_txrx(struct spi_slave *slave,
omap3_spi_set_enable(ds,OMAP3_MCSPI_CHCTRL_EN);

/*set TRANSMIT-RECEIVE Mode*/
- chconf &= ~OMAP3_MCSPI_CHCONF_TRM_MASK;
+ chconf &= ~(OMAP3_MCSPI_CHCONF_TRM_MASK | OMAP3_MCSPI_CHCONF_WL_MASK);
+ chconf |= (ds->slave.wordlen - 1) << 7;
chconf |= OMAP3_MCSPI_CHCONF_FORCE;
omap3_spi_write_chconf(ds,chconf);

@@ -344,7 +358,13 @@ int omap3_spi_txrx(struct spi_slave *slave,
}
}
/* Write the data */
- writel(txp[i], &ds->regs->channel[ds->slave.cs].tx);
+ unsigned int *tx = &ds->regs->channel[ds->slave.cs].tx;
+ if (ds->slave.wordlen > 16)
+ writel(((u32 *)txp)[i], tx);
+ else if (ds->slave.wordlen > 8)
+ writel(((u16 *)txp)[i], tx);
+ else
+ writel(((u8 *)txp)[i], tx);

/*Read: wait for RX containing data (RXS == 1)*/
while (!(readl(&ds->regs->channel[ds->slave.cs].chstat) &
@@ -356,7 +376,13 @@ int omap3_spi_txrx(struct spi_slave *slave,
}
}
/* Read the data */
- rxp[i] = readl(&ds->regs->channel[ds->slave.cs].rx);
+ unsigned int *rx = &ds->regs->channel[ds->slave.cs].rx;
+ if (ds->slave.wordlen > 16)
+ ((u32 *)rxp)[i] = readl(rx);
+ else if (ds->slave.wordlen > 8)
+ ((u16 *)rxp)[i] = (u16)readl(rx);
+ else
+ ((u8 *)rxp)[i] = (u8)readl(rx);
}
/* Disable the channel */
omap3_spi_set_enable(ds,OMAP3_MCSPI_CHCTRL_DIS);
@@ -375,14 +401,17 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
{
struct omap3_spi_slave *ds = to_omap3_spi(slave);
unsigned int len;
- const u8 *txp = dout;
- u8 *rxp = din;
int ret = -1;

- if (bitlen % 8)
+ if (ds->slave.wordlen < 4 || ds->slave.wordlen > 32) {
+ printf("omap3_spi: invalid wordlen %d\n", ds->slave.wordlen);
+ return -1;
+ }
+
+ if (bitlen % ds->slave.wordlen)
return -1;

- len = bitlen / 8;
+ len = bitlen / ds->slave.wordlen;

if (bitlen == 0) { /* only change CS */
int chconf = readl(&ds->regs->channel[ds->slave.cs].chconf);
@@ -400,11 +429,11 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
ret = 0;
} else {
if (dout != NULL && din != NULL)
- ret = omap3_spi_txrx(slave, len, txp, rxp, flags);
+ ret = omap3_spi_txrx(slave, len, dout, din, flags);
else if (dout != NULL)
- ret = omap3_spi_write(slave, len, txp, flags);
+ ret = omap3_spi_write(slave, len, dout, flags);
else if (din != NULL)
- ret = omap3_spi_read(slave, len, rxp, flags);
+ ret = omap3_spi_read(slave, len, din, flags);
}
return ret;
}
diff --git a/drivers/spi/omap3_spi.h b/drivers/spi/omap3_spi.h
index 01537b6..ab7cd84 100644
--- a/drivers/spi/omap3_spi.h
+++ b/drivers/spi/omap3_spi.h
@@ -99,11 +99,11 @@ static inline struct omap3_spi_slave *to_omap3_spi(struct spi_slave *slave)
return container_of(slave, struct omap3_spi_slave, slave);
}

-int omap3_spi_txrx(struct spi_slave *slave, unsigned int len, const u8 *txp,
- u8 *rxp, unsigned long flags);
-int omap3_spi_write(struct spi_slave *slave, unsigned int len, const u8 *txp,
+int omap3_spi_txrx(struct spi_slave *slave, unsigned int len, const void *txp,
+ void *rxp, unsigned long flags);
+int omap3_spi_write(struct spi_slave *slave, unsigned int len, const void *txp,
unsigned long flags);
-int omap3_spi_read(struct spi_slave *slave, unsigned int len, u8 *rxp,
+int omap3_spi_read(struct spi_slave *slave, unsigned int len, void *rxp,
unsigned long flags);

#endif /* _OMAP3_SPI_H_ */
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index ea39d1a..b76a26c 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -8,6 +8,18 @@
#include <malloc.h>
#include <spi.h>

+int spi_set_wordlen(struct spi_slave *slave, unsigned int wordlen)
+{
+ if (wordlen == 0 || wordlen > 32) {
+ printf("spi: invalid wordlen %d\n", wordlen);
+ return -1;
+ }
+
+ slave->wordlen = wordlen;
+
+ return 0;
+}
+
void *spi_do_alloc_slave(int offset, int size, unsigned int bus,
unsigned int cs)
{
@@ -20,6 +32,7 @@ void *spi_do_alloc_slave(int offset, int size, unsigned int bus,
slave = (struct spi_slave *)(ptr + offset);
slave->bus = bus;
slave->cs = cs;
+ slave->wordlen = SPI_DEFAULT_WORDLEN;
}

return ptr;
diff --git a/include/spi.h b/include/spi.h
index ad9248b..67da75c 100644
--- a/include/spi.h
+++ b/include/spi.h
@@ -33,6 +33,8 @@
/* Header byte that marks the start of the message */
#define SPI_PREAMBLE_END_BYTE 0xec

+#define SPI_DEFAULT_WORDLEN 8
+
/**
* struct spi_slave - Representation of a SPI slave
*
@@ -40,6 +42,7 @@
*
* @bus: ID of the bus that the slave is attached to.
* @cs: ID of the chip select connected to the slave.
+ * @wordlen: Size of SPI word in number of bits
* @max_write_size: If non-zero, the maximum number of bytes which can
* be written at once, excluding command bytes.
* @memory_map: Address of read-only SPI flash access.
@@ -47,6 +50,7 @@
struct spi_slave {
unsigned int bus;
unsigned int cs;
+ unsigned int wordlen;
unsigned int max_write_size;
void *memory_map;
};
@@ -153,6 +157,18 @@ int spi_claim_bus(struct spi_slave *slave);
void spi_release_bus(struct spi_slave *slave);

/**
+ * Set the word length for SPI transactions
+ *
+ * Set the word length (number of bits per word) for SPI transactions.
+ *
+ * @slave: The SPI slave
+ * @wordlen: The number of bits in a word
+ *
+ * Returns: 0 on success, -1 on failure.
+ */
+int spi_set_wordlen(struct spi_slave *slave, unsigned int wordlen);
+
+/**
* SPI transfer
*
* This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
--
1.8.1.2