[PATCH 5/5] Blackfin SPI Driver: Make mmc_spi driver work on Blackfin

From: Bryan Wu
Date: Thu Feb 05 2009 - 05:07:48 EST

From: Wolfgang Muees <wolfgang.mues@xxxxxxxxxxxx>

1. Rewrite of the non-dma data transfer functions to use only ONE
mode of TIMOD (TIMOD=0x1). With TIMOD=0, it was not possible to set
the TX bit pattern. So the TDBR = 0xFFFF inside the read calls won't
work.

2. Clear SPI_RDBR before reading and before duplex transfer. Otherwise
the garbage data in RDBR will get read. Since mmc_spi uses a lot of
duplex transfers, this is the main cause of mmc_spi failure.

3. Poll RXS for transfer completion. Polling SPIF or TXS cannot
guarantee transfer completion. This may interrupt a transfer before
it is finished. Also this may leave garbage data in buffer and
affect next transfer.

[Yi Li <yi.li@xxxxxxxxxx>: add a field "u16 idle_tx_val" in "struct
bfin5xx_spi_chip" to specify the value to transmit if no TX value
is supplied.]

Signed-off-by: Wolfgang Muees <wolfgang.mues@xxxxxxxxxxxx>
Signed-off-by: Yi Li <yi.li@xxxxxxxxxx>
Signed-off-by: Bryan Wu <cooloney@xxxxxxxxxx>
---
arch/blackfin/include/asm/bfin5xx_spi.h | 2 +
drivers/spi/spi_bfin5xx.c | 247 ++++++++++++++-----------------
2 files changed, 110 insertions(+), 139 deletions(-)

diff --git a/arch/blackfin/include/asm/bfin5xx_spi.h b/arch/blackfin/include/asm/bfin5xx_spi.h
index da8b9ca..2202b9d 100644
--- a/arch/blackfin/include/asm/bfin5xx_spi.h
+++ b/arch/blackfin/include/asm/bfin5xx_spi.h
@@ -125,6 +125,8 @@ struct bfin5xx_spi_chip {
u8 cs_change_per_word;
u16 cs_chg_udelay; /* Some devices require 16-bit delays */
u32 cs_gpio;
+ /* Value to send if no TX value is supplied, usually 0x0 or 0xFFFF */
+ u16 idle_tx_val;
};

#endif /* _SPI_CHANNEL_H_ */
diff --git a/drivers/spi/spi_bfin5xx.c b/drivers/spi/spi_bfin5xx.c
index 5089afe..0f6c15a 100644
--- a/drivers/spi/spi_bfin5xx.c
+++ b/drivers/spi/spi_bfin5xx.c
@@ -45,6 +45,9 @@ MODULE_LICENSE("GPL");
#define QUEUE_RUNNING 0
#define QUEUE_STOPPED 1

+/* Value to send if no TX value is supplied */
+#define SPI_IDLE_TXVAL 0x0000
+
struct driver_data {
/* Driver model hookup */
struct platform_device *pdev;
@@ -115,6 +118,7 @@ struct chip_data {
u8 cs_change_per_word;
u16 cs_chg_udelay; /* Some devices require > 255usec delay */
u32 cs_gpio;
+ u16 idle_tx_val;
void (*write) (struct driver_data *);
void (*read) (struct driver_data *);
void (*duplex) (struct driver_data *);
@@ -229,134 +233,126 @@ static void bfin_spi_restore_state(struct driver_data *drv_data)
bfin_spi_cs_active(drv_data, chip);
}

-/* used to kick off transfer in rx mode */
-static unsigned short bfin_spi_dummy_read(struct driver_data *drv_data)
+/* used to kick off transfer in rx mode and read unwanted RX data */
+static inline void bfin_spi_dummy_read(struct driver_data *drv_data)
{
- unsigned short tmp;
- tmp = read_RDBR(drv_data);
- return tmp;
+ (void) read_RDBR(drv_data);
}

static void bfin_spi_null_writer(struct driver_data *drv_data)
{
u8 n_bytes = drv_data->n_bytes;
+ u16 tx_val = drv_data->cur_chip->idle_tx_val;
+
+ /* clear RXS (we check for RXS inside the loop) */
+ bfin_spi_dummy_read(drv_data);

while (drv_data->tx < drv_data->tx_end) {
- write_TDBR(drv_data, 0);
- while ((read_STAT(drv_data) & BIT_STAT_TXS))
- cpu_relax();
+ write_TDBR(drv_data, tx_val);
drv_data->tx += n_bytes;
+ /* wait until transfer finished.
+ checking SPIF or TXS may not guarantee transfer completion */
+ while (!(read_STAT(drv_data) & BIT_STAT_RXS))
+ cpu_relax();
+ /* discard RX data and clear RXS */
+ bfin_spi_dummy_read(drv_data);
}
}

static void bfin_spi_null_reader(struct driver_data *drv_data)
{
u8 n_bytes = drv_data->n_bytes;
+ u16 tx_val = drv_data->cur_chip->idle_tx_val;
+
+ /* discard old RX data and clear RXS */
bfin_spi_dummy_read(drv_data);

while (drv_data->rx < drv_data->rx_end) {
+ write_TDBR(drv_data, tx_val);
+ drv_data->rx += n_bytes;
while (!(read_STAT(drv_data) & BIT_STAT_RXS))
cpu_relax();
bfin_spi_dummy_read(drv_data);
- drv_data->rx += n_bytes;
}
}

static void bfin_spi_u8_writer(struct driver_data *drv_data)
{
- dev_dbg(&drv_data->pdev->dev,
- "cr8-s is 0x%x\n", read_STAT(drv_data));
+ /* clear RXS (we check for RXS inside the loop) */
+ bfin_spi_dummy_read(drv_data);

while (drv_data->tx < drv_data->tx_end) {
- write_TDBR(drv_data, (*(u8 *) (drv_data->tx)));
- while (read_STAT(drv_data) & BIT_STAT_TXS)
+ write_TDBR(drv_data, (*(u8 *) (drv_data->tx++)));
+ /* wait until transfer finished.
+ checking SPIF or TXS may not guarantee transfer completion */
+ while (!(read_STAT(drv_data) & BIT_STAT_RXS))
cpu_relax();
- ++drv_data->tx;
+ /* discard RX data and clear RXS */
+ bfin_spi_dummy_read(drv_data);
}
-
- /* poll for SPI completion before return */
- while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
- cpu_relax();
}

static void bfin_spi_u8_cs_chg_writer(struct driver_data *drv_data)
{
struct chip_data *chip = drv_data->cur_chip;

+ /* clear RXS (we check for RXS inside the loop) */
+ bfin_spi_dummy_read(drv_data);
+
while (drv_data->tx < drv_data->tx_end) {
bfin_spi_cs_active(drv_data, chip);
-
- write_TDBR(drv_data, (*(u8 *) (drv_data->tx)));
- while (read_STAT(drv_data) & BIT_STAT_TXS)
- cpu_relax();
- while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
+ write_TDBR(drv_data, (*(u8 *) (drv_data->tx++)));
+ /* make sure transfer finished before deactiving CS */
+ while (!(read_STAT(drv_data) & BIT_STAT_RXS))
cpu_relax();
-
+ bfin_spi_dummy_read(drv_data);
bfin_spi_cs_deactive(drv_data, chip);
-
- ++drv_data->tx;
}
}

static void bfin_spi_u8_reader(struct driver_data *drv_data)
{
- dev_dbg(&drv_data->pdev->dev,
- "cr-8 is 0x%x\n", read_STAT(drv_data));
-
- /* poll for SPI completion before start */
- while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
- cpu_relax();
-
- /* clear TDBR buffer before read(else it will be shifted out) */
- write_TDBR(drv_data, 0xFFFF);
+ u16 tx_val = drv_data->cur_chip->idle_tx_val;

+ /* discard old RX data and clear RXS */
bfin_spi_dummy_read(drv_data);

- while (drv_data->rx < drv_data->rx_end - 1) {
+ while (drv_data->rx < drv_data->rx_end) {
+ write_TDBR(drv_data, tx_val);
while (!(read_STAT(drv_data) & BIT_STAT_RXS))
cpu_relax();
- *(u8 *) (drv_data->rx) = read_RDBR(drv_data);
- ++drv_data->rx;
+ *(u8 *) (drv_data->rx++) = read_RDBR(drv_data);
}
-
- while (!(read_STAT(drv_data) & BIT_STAT_RXS))
- cpu_relax();
- *(u8 *) (drv_data->rx) = read_SHAW(drv_data);
- ++drv_data->rx;
}

static void bfin_spi_u8_cs_chg_reader(struct driver_data *drv_data)
{
struct chip_data *chip = drv_data->cur_chip;
+ u16 tx_val = chip->idle_tx_val;
+
+ /* discard old RX data and clear RXS */
+ bfin_spi_dummy_read(drv_data);

while (drv_data->rx < drv_data->rx_end) {
bfin_spi_cs_active(drv_data, chip);
- read_RDBR(drv_data); /* kick off */
-
+ write_TDBR(drv_data, tx_val);
while (!(read_STAT(drv_data) & BIT_STAT_RXS))
cpu_relax();
- while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
- cpu_relax();
-
- *(u8 *) (drv_data->rx) = read_SHAW(drv_data);
+ *(u8 *) (drv_data->rx++) = read_RDBR(drv_data);
bfin_spi_cs_deactive(drv_data, chip);
-
- ++drv_data->rx;
}
}

static void bfin_spi_u8_duplex(struct driver_data *drv_data)
{
- /* in duplex mode, clk is triggered by writing of TDBR */
+ /* discard old RX data and clear RXS */
+ bfin_spi_dummy_read(drv_data);
+
while (drv_data->rx < drv_data->rx_end) {
- write_TDBR(drv_data, (*(u8 *) (drv_data->tx)));
- while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
- cpu_relax();
+ write_TDBR(drv_data, (*(u8 *) (drv_data->tx++)));
while (!(read_STAT(drv_data) & BIT_STAT_RXS))
cpu_relax();
- *(u8 *) (drv_data->rx) = read_RDBR(drv_data);
- ++drv_data->rx;
- ++drv_data->tx;
+ *(u8 *) (drv_data->rx++) = read_RDBR(drv_data);
}
}

@@ -364,130 +360,102 @@ static void bfin_spi_u8_cs_chg_duplex(struct driver_data *drv_data)
{
struct chip_data *chip = drv_data->cur_chip;

+ /* discard old RX data and clear RXS */
+ bfin_spi_dummy_read(drv_data);
+
while (drv_data->rx < drv_data->rx_end) {
bfin_spi_cs_active(drv_data, chip);
-
- write_TDBR(drv_data, (*(u8 *) (drv_data->tx)));
-
- while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
- cpu_relax();
+ write_TDBR(drv_data, (*(u8 *) (drv_data->tx++)));
while (!(read_STAT(drv_data) & BIT_STAT_RXS))
cpu_relax();
- *(u8 *) (drv_data->rx) = read_RDBR(drv_data);
-
+ *(u8 *) (drv_data->rx++) = read_RDBR(drv_data);
bfin_spi_cs_deactive(drv_data, chip);
-
- ++drv_data->rx;
- ++drv_data->tx;
}
}

static void bfin_spi_u16_writer(struct driver_data *drv_data)
{
- dev_dbg(&drv_data->pdev->dev,
- "cr16 is 0x%x\n", read_STAT(drv_data));
+ /* clear RXS (we check for RXS inside the loop) */
+ bfin_spi_dummy_read(drv_data);

while (drv_data->tx < drv_data->tx_end) {
write_TDBR(drv_data, (*(u16 *) (drv_data->tx)));
- while ((read_STAT(drv_data) & BIT_STAT_TXS))
- cpu_relax();
drv_data->tx += 2;
+ /* wait until transfer finished.
+ checking SPIF or TXS may not guarantee transfer completion */
+ while (!(read_STAT(drv_data) & BIT_STAT_RXS))
+ cpu_relax();
+ /* discard RX data and clear RXS */
+ bfin_spi_dummy_read(drv_data);
}
-
- /* poll for SPI completion before return */
- while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
- cpu_relax();
}

static void bfin_spi_u16_cs_chg_writer(struct driver_data *drv_data)
{
struct chip_data *chip = drv_data->cur_chip;

+ /* clear RXS (we check for RXS inside the loop) */
+ bfin_spi_dummy_read(drv_data);
+
while (drv_data->tx < drv_data->tx_end) {
bfin_spi_cs_active(drv_data, chip);
-
write_TDBR(drv_data, (*(u16 *) (drv_data->tx)));
- while ((read_STAT(drv_data) & BIT_STAT_TXS))
- cpu_relax();
- while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
+ drv_data->tx += 2;
+ /* make sure transfer finished before deactiving CS */
+ while (!(read_STAT(drv_data) & BIT_STAT_RXS))
cpu_relax();
-
+ bfin_spi_dummy_read(drv_data);
bfin_spi_cs_deactive(drv_data, chip);
-
- drv_data->tx += 2;
}
}

static void bfin_spi_u16_reader(struct driver_data *drv_data)
{
- dev_dbg(&drv_data->pdev->dev,
- "cr-16 is 0x%x\n", read_STAT(drv_data));
-
- /* poll for SPI completion before start */
- while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
- cpu_relax();
-
- /* clear TDBR buffer before read(else it will be shifted out) */
- write_TDBR(drv_data, 0xFFFF);
+ u16 tx_val = drv_data->cur_chip->idle_tx_val;

+ /* discard old RX data and clear RXS */
bfin_spi_dummy_read(drv_data);

- while (drv_data->rx < (drv_data->rx_end - 2)) {
+ while (drv_data->rx < drv_data->rx_end) {
+ write_TDBR(drv_data, tx_val);
while (!(read_STAT(drv_data) & BIT_STAT_RXS))
cpu_relax();
*(u16 *) (drv_data->rx) = read_RDBR(drv_data);
drv_data->rx += 2;
}
-
- while (!(read_STAT(drv_data) & BIT_STAT_RXS))
- cpu_relax();
- *(u16 *) (drv_data->rx) = read_SHAW(drv_data);
- drv_data->rx += 2;
}

static void bfin_spi_u16_cs_chg_reader(struct driver_data *drv_data)
{
struct chip_data *chip = drv_data->cur_chip;
+ u16 tx_val = chip->idle_tx_val;

- /* poll for SPI completion before start */
- while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
- cpu_relax();
-
- /* clear TDBR buffer before read(else it will be shifted out) */
- write_TDBR(drv_data, 0xFFFF);
-
- bfin_spi_cs_active(drv_data, chip);
+ /* discard old RX data and clear RXS */
bfin_spi_dummy_read(drv_data);

- while (drv_data->rx < drv_data->rx_end - 2) {
- bfin_spi_cs_deactive(drv_data, chip);
-
+ while (drv_data->rx < drv_data->rx_end) {
+ bfin_spi_cs_active(drv_data, chip);
+ write_TDBR(drv_data, tx_val);
while (!(read_STAT(drv_data) & BIT_STAT_RXS))
cpu_relax();
- bfin_spi_cs_active(drv_data, chip);
*(u16 *) (drv_data->rx) = read_RDBR(drv_data);
drv_data->rx += 2;
+ bfin_spi_cs_deactive(drv_data, chip);
}
- bfin_spi_cs_deactive(drv_data, chip);
-
- while (!(read_STAT(drv_data) & BIT_STAT_RXS))
- cpu_relax();
- *(u16 *) (drv_data->rx) = read_SHAW(drv_data);
- drv_data->rx += 2;
}

static void bfin_spi_u16_duplex(struct driver_data *drv_data)
{
- /* in duplex mode, clk is triggered by writing of TDBR */
- while (drv_data->tx < drv_data->tx_end) {
+ /* discard old RX data and clear RXS */
+ bfin_spi_dummy_read(drv_data);
+
+ while (drv_data->rx < drv_data->rx_end) {
write_TDBR(drv_data, (*(u16 *) (drv_data->tx)));
- while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
- cpu_relax();
+ drv_data->tx += 2;
while (!(read_STAT(drv_data) & BIT_STAT_RXS))
cpu_relax();
*(u16 *) (drv_data->rx) = read_RDBR(drv_data);
drv_data->rx += 2;
- drv_data->tx += 2;
}
}

@@ -495,20 +463,18 @@ static void bfin_spi_u16_cs_chg_duplex(struct driver_data *drv_data)
{
struct chip_data *chip = drv_data->cur_chip;

- while (drv_data->tx < drv_data->tx_end) {
- bfin_spi_cs_active(drv_data, chip);
+ /* discard old RX data and clear RXS */
+ bfin_spi_dummy_read(drv_data);

+ while (drv_data->rx < drv_data->rx_end) {
+ bfin_spi_cs_active(drv_data, chip);
write_TDBR(drv_data, (*(u16 *) (drv_data->tx)));
- while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
- cpu_relax();
+ drv_data->tx += 2;
while (!(read_STAT(drv_data) & BIT_STAT_RXS))
cpu_relax();
*(u16 *) (drv_data->rx) = read_RDBR(drv_data);
-
- bfin_spi_cs_deactive(drv_data, chip);
-
drv_data->rx += 2;
- drv_data->tx += 2;
+ bfin_spi_cs_deactive(drv_data, chip);
}
}

@@ -685,6 +651,13 @@ static void bfin_spi_pump_transfers(unsigned long data)
return;
}

+ if (transfer->len == 0) {
+ /* Move to next transfer of this msg */
+ message->state = bfin_spi_next_transfer(drv_data);
+ /* Schedule next transfer tasklet */
+ tasklet_schedule(&drv_data->pump_transfers);
+ }
+
if (transfer->tx_buf != NULL) {
drv_data->tx = (void *)transfer->tx_buf;
drv_data->tx_end = drv_data->tx + transfer->len;
@@ -881,6 +854,11 @@ static void bfin_spi_pump_transfers(unsigned long data)
/* IO mode write then read */
dev_dbg(&drv_data->pdev->dev, "doing IO transfer\n");

+ /* we always use SPI_WRITE mode. SPI_READ mode
+ seems to have problems with setting up the
+ output value in TDBR prior to the transfer. */
+ write_CTRL(drv_data, (cr | CFG_SPI_WRITE));
+
if (full_duplex) {
/* full duplex mode */
BUG_ON((drv_data->tx_end - drv_data->tx) !=
@@ -888,9 +866,6 @@ static void bfin_spi_pump_transfers(unsigned long data)
dev_dbg(&drv_data->pdev->dev,
"IO duplex: cr is 0x%x\n", cr);

- /* set SPI transfer mode */
- write_CTRL(drv_data, (cr | CFG_SPI_WRITE));
-
drv_data->duplex(drv_data);

if (drv_data->tx != drv_data->tx_end)
@@ -900,9 +875,6 @@ static void bfin_spi_pump_transfers(unsigned long data)
dev_dbg(&drv_data->pdev->dev,
"IO write: cr is 0x%x\n", cr);

- /* set SPI transfer mode */
- write_CTRL(drv_data, (cr | CFG_SPI_WRITE));
-
drv_data->write(drv_data);

if (drv_data->tx != drv_data->tx_end)
@@ -912,9 +884,6 @@ static void bfin_spi_pump_transfers(unsigned long data)
dev_dbg(&drv_data->pdev->dev,
"IO read: cr is 0x%x\n", cr);

- /* set SPI transfer mode */
- write_CTRL(drv_data, (cr | CFG_SPI_READ));
-
drv_data->read(drv_data);
if (drv_data->rx != drv_data->rx_end)
tranf_success = 0;
@@ -934,7 +903,6 @@ static void bfin_spi_pump_transfers(unsigned long data)
}
/* Schedule next transfer tasklet */
tasklet_schedule(&drv_data->pump_transfers);
-
}
}

@@ -1154,6 +1122,7 @@ static int bfin_spi_setup(struct spi_device *spi)
chip->cs_change_per_word = chip_info->cs_change_per_word;
chip->cs_chg_udelay = chip_info->cs_chg_udelay;
chip->cs_gpio = chip_info->cs_gpio;
+ chip->idle_tx_val = chip_info->idle_tx_val;
}

/* translate common spi framework into our register */
--
1.5.6.3
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