spi: spi-fsl-lpspi: support effective_speed_hz

Setting spi_transfer->effective_speed_hz in transfer_one so that
SPI client driver can use it.

Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20240930093056.93418-4-wahrenst@gmx.net
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: lategoodbye

drivers/spi/spi-fsl-lpspi.c

@@ -92,6 +92,7 @@ struct lpspi_config {
 	u8 prescale;
 	u16 mode;
 	u32 speed_hz;
+	u32 effective_speed_hz;
 };
 
 struct fsl_lpspi_data {
@@ -351,6 +352,9 @@ static int fsl_lpspi_set_bitrate(struct fsl_lpspi_data *fsl_lpspi)
 	writel(scldiv | (scldiv << 8) | ((scldiv >> 1) << 16),
 					fsl_lpspi->base + IMX7ULP_CCR);
 
+	fsl_lpspi->config.effective_speed_hz = perclk_rate / (scldiv + 2) *
+					       (1 << prescale);
+
 	dev_dbg(fsl_lpspi->dev, "perclk=%u, speed=%u, prescale=%u, scldiv=%d\n",
 		perclk_rate, config.speed_hz, prescale, scldiv);
 
@@ -750,6 +754,8 @@ static int fsl_lpspi_transfer_one(struct spi_controller *controller,
 	if (ret < 0)
 		return ret;
 
+	t->effective_speed_hz = fsl_lpspi->config.effective_speed_hz;
+
 	fsl_lpspi_set_cmd(fsl_lpspi);
 	fsl_lpspi->is_first_byte = false;