Blackfin SPI Driver: Make mmc_spi driver work on Blackfin

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@analog.com>: 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@auerswald.de>
Signed-off-by: Yi Li <yi.li@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/blackfin/include/asm/bfin5xx_spi.h b/arch/blackfin/include/asm/bfin5xx_spi.h
index 8c5f8a9..aaeb4df 100644 (file)
--- 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 6aa084e..e1d9eae 100644 (file)
--- 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;
@@ -112,6 +115,7 @@ 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 *);
@@ -226,134 +230,126 @@ 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);
        }
 }
 
@@ -361,130 +357,102 @@ 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;
        }
 }
 
@@ -492,20 +460,18 @@ 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);
        }
 }
 
@@ -682,6 +648,13 @@ 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;
@@ -837,9 +810,6 @@ static void bfin_spi_pump_transfers(unsigned long data)
                                                        (unsigned long) (drv_data->rx +
                                                        drv_data->len_in_bytes));
 
-                       /* clear tx reg soformer data is not shifted out */
-                       write_TDBR(drv_data, 0xFFFF);
-
                        dma_config |= WNR;
                        dma_start_addr = (unsigned long)drv_data->rx;
                        cr |= BIT_CTL_TIMOD_DMA_RX | BIT_CTL_SENDOPT;
@@ -881,6 +851,11 @@ 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 +863,6 @@ 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 +872,6 @@ 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 +881,6 @@ 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 +900,6 @@ static void bfin_spi_pump_transfers(unsigned long data)
                }
                /* Schedule next transfer tasklet */
                tasklet_schedule(&drv_data->pump_transfers);
-
        }
 }
 
@@ -1092,6 +1057,7 @@ 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 */