spi: stm32: Simplify stm32h7_spi_prepare_fthlv()

Simplify stm32h7_spi_prepare_fthlv() function implementation,
no functional change intended.
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Alain Volmat <alain.volmat@st.com>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Cc: Amelie Delaunay <amelie.delaunay@st.com>
Cc: Antonio Borneo <antonio.borneo@st.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Roman Guskov <rguskov@dh-electronics.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-stm32@st-md-mailman.stormreply.com
To: linux-spi@vger.kernel.org
Link: https://lore.kernel.org/r/20210104123114.261596-1-marex@denx.deSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-stm32.c

@@ -473,34 +473,14 @@ static int stm32_spi_prepare_mbr(struct stm32_spi *spi, u32 speed_hz,
  */
 static u32 stm32h7_spi_prepare_fthlv(struct stm32_spi *spi, u32 xfer_len)
 {
-	u32 fthlv, half_fifo, packet;
+	u32 packet, bpw;
 
 	/* data packet should not exceed 1/2 of fifo space */
-	half_fifo = (spi->fifo_size / 2);
-
-	/* data_packet should not exceed transfer length */
-	if (half_fifo > xfer_len)
-		packet = xfer_len;
-	else
-		packet = half_fifo;
-
-	if (spi->cur_bpw <= 8)
-		fthlv = packet;
-	else if (spi->cur_bpw <= 16)
-		fthlv = packet / 2;
-	else
-		fthlv = packet / 4;
+	packet = clamp(xfer_len, 1U, spi->fifo_size / 2);
 
 	/* align packet size with data registers access */
-	if (spi->cur_bpw > 8)
-		fthlv += (fthlv % 2) ? 1 : 0;
-	else
-		fthlv += (fthlv % 4) ? (4 - (fthlv % 4)) : 0;
-
-	if (!fthlv)
-		fthlv = 1;
-
-	return fthlv;
+	bpw = DIV_ROUND_UP(spi->cur_bpw, 8);
+	return DIV_ROUND_UP(packet, bpw);
 }
 
 /**