spi: core,atmel: convert `word_delay_usecs` -> `word_delay` for spi_device

This change does a conversion from the `word_delay_usecs` -> `word_delay`
for the `spi_device` struct.

This allows users to specify inter-word delays in other unit types
(nano-seconds or clock cycles), depending on how users want.

The Atmel SPI driver is the only current user of the `word_delay_usecs`
field (from the `spi_device` struct).
So, it needed a slight conversion to use the `word_delay` as an `spi_delay`
struct.

In SPI core, the only required mechanism is to update the `word_delay`
information per `spi_transfer`. This requires a bit more logic than before,
because it needs that both delays be converted to a common unit
(nano-seconds) for comparison.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20190926105147.7839-8-alexandru.ardelean@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
index 3ed5e66..1471b04 100644 (file)
--- a/drivers/spi/spi-atmel.c
+++ b/drivers/spi/spi-atmel.c
@@ -1149,12 +1149,31 @@ atmel_spi_pdc_interrupt(int irq, void *dev_id)
        return ret;
 }
 
+static int atmel_word_delay_csr(struct spi_device *spi, struct atmel_spi *as)
+{
+       struct spi_delay *delay = &spi->word_delay;
+       u32 value = delay->value;
+
+       switch (delay->unit) {
+       case SPI_DELAY_UNIT_NSECS:
+               value /= 1000;
+               break;
+       case SPI_DELAY_UNIT_USECS:
+               break;
+       default:
+               return -EINVAL;
+       }
+
+       return (as->spi_clk / 1000000 * value) >> 5;
+}
+
 static int atmel_spi_setup(struct spi_device *spi)
 {
        struct atmel_spi        *as;
        struct atmel_spi_device *asd;
        u32                     csr;
        unsigned int            bits = spi->bits_per_word;
+       int                     word_delay_csr;
 
        as = spi_master_get_devdata(spi->master);
 
@@ -1178,11 +1197,14 @@ static int atmel_spi_setup(struct spi_device *spi)
         */
        csr |= SPI_BF(DLYBS, 0);
 
+       word_delay_csr = atmel_word_delay_csr(spi, as);
+       if (word_delay_csr < 0)
+               return word_delay_csr;
+
        /* DLYBCT adds delays between words.  This is useful for slow devices
         * that need a bit of time to setup the next transfer.
         */
-       csr |= SPI_BF(DLYBCT,
-                       (as->spi_clk / 1000000 * spi->word_delay_usecs) >> 5);
+       csr |= SPI_BF(DLYBCT, word_delay_csr);
 
        asd = spi->controller_state;
        if (!asd) {

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index b69c140..307e440 100644 (file)
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -3281,6 +3281,26 @@ void spi_set_cs_timing(struct spi_device *spi, u8 setup, u8 hold,
 }
 EXPORT_SYMBOL_GPL(spi_set_cs_timing);
 
+static int _spi_xfer_word_delay_update(struct spi_transfer *xfer,
+                                      struct spi_device *spi)
+{
+       int delay1, delay2;
+
+       delay1 = _spi_delay_to_ns(&xfer->word_delay, xfer);
+       if (delay1 < 0)
+               return delay1;
+
+       delay2 = _spi_delay_to_ns(&spi->word_delay, xfer);
+       if (delay2 < 0)
+               return delay2;
+
+       if (delay1 < delay2)
+               memcpy(&xfer->word_delay, &spi->word_delay,
+                      sizeof(xfer->word_delay));
+
+       return 0;
+}
+
 static int __spi_validate(struct spi_device *spi, struct spi_message *message)
 {
        struct spi_controller *ctlr = spi->controller;
@@ -3416,8 +3436,8 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
                                return -EINVAL;
                }
 
-               if (xfer->word_delay_usecs < spi->word_delay_usecs)
-                       xfer->word_delay_usecs = spi->word_delay_usecs;
+               if (_spi_xfer_word_delay_update(xfer, spi))
+                       return -EINVAL;
        }
 
        message->status = -EINPROGRESS;

diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 6cb67ad..ebeb272 100644 (file)
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -139,7 +139,7 @@ extern int spi_delay_exec(struct spi_delay *_delay, struct spi_transfer *xfer);
  *     the spi_master.
  * @cs_gpiod: gpio descriptor of the chipselect line (optional, NULL when
  *     not using a GPIO line)
- * @word_delay_usecs: microsecond delay to be inserted between consecutive
+ * @word_delay: delay to be inserted between consecutive
  *     words of a transfer
  *
  * @statistics: statistics for the spi_device
@@ -189,7 +189,7 @@ struct spi_device {
        const char              *driver_override;
        int                     cs_gpio;        /* LEGACY: chip select gpio */
        struct gpio_desc        *cs_gpiod;      /* chip select gpio desc */
-       uint8_t                 word_delay_usecs; /* inter-word delay */
+       struct spi_delay        word_delay; /* inter-word delay */
 
        /* the statistics */
        struct spi_statistics   statistics;
@@ -781,8 +781,6 @@ extern void spi_res_release(struct spi_controller *ctlr,
  * @delay_usecs: microseconds to delay after this transfer before
  *     (optionally) changing the chipselect status, then starting
  *     the next transfer or completing this @spi_message.
- * @word_delay_usecs: microseconds to inter word delay after each word size
- *     (set by bits_per_word) transmission.
  * @word_delay: inter word delay to be introduced after each word size
  *     (set by bits_per_word) transmission.
  * @effective_speed_hz: the effective SCK-speed that was used to
@@ -897,7 +895,6 @@ struct spi_transfer {
 #define        SPI_NBITS_DUAL          0x02 /* 2bits transfer */
 #define        SPI_NBITS_QUAD          0x04 /* 4bits transfer */
        u8              bits_per_word;
-       u8              word_delay_usecs;
        u16             delay_usecs;
        struct spi_delay        cs_change_delay;
        struct spi_delay        word_delay;