spi: bcm2835aux: support effective_speed_hz

Setting spi_transfer->effective_speed_hz in transfer_one so that
it can get used in cs_change_delay configured with delay as a muliple
of SPI clock cycles.
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/20200709074120.110069-3-mkl@pengutronix.deSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-bcm2835aux.c

@@ -345,7 +345,7 @@ static int bcm2835aux_spi_transfer_one(struct spi_master *master,
 				       struct spi_transfer *tfr)
 {
 	struct bcm2835aux_spi *bs = spi_master_get_devdata(master);
-	unsigned long spi_hz, clk_hz, speed, spi_used_hz;
+	unsigned long spi_hz, clk_hz, speed;
 	unsigned long hz_per_byte, byte_limit;
 
 	/* calculate the registers to handle
@@ -374,7 +374,7 @@ static int bcm2835aux_spi_transfer_one(struct spi_master *master,
 	/* set the new speed */
 	bs->cntl[0] |= speed << BCM2835_AUX_SPI_CNTL0_SPEED_SHIFT;
 
-	spi_used_hz = clk_hz / (2 * (speed + 1));
+	tfr->effective_speed_hz = clk_hz / (2 * (speed + 1));
 
 	/* set transmit buffers and length */
 	bs->tx_buf = tfr->tx_buf;
@@ -391,7 +391,7 @@ static int bcm2835aux_spi_transfer_one(struct spi_master *master,
 	 * 30 µs per 300,000 Hz of bus clock.
 	 */
 	hz_per_byte = polling_limit_us ? (9 * 1000000) / polling_limit_us : 0;
-	byte_limit = hz_per_byte ? spi_used_hz / hz_per_byte : 1;
+	byte_limit = hz_per_byte ? tfr->effective_speed_hz / hz_per_byte : 1;
 
 	/* run in polling mode for short transfers */
 	if (tfr->len < byte_limit)