spi: fsl-dspi: Set max_speed_hz for master

Calculate and update max speed from bus clock for SoCs
using DSPI IP.

The bus clock factor's are taken from the data sheets
of respective SoCs.
Signed-off-by: NBhuvanchandra DV <bhuvanchandra.dv@toradex.com>
Acked-by: NStefan Agner <stefan@agner.ch>
Signed-off-by: NMark Brown <broonie@kernel.org>

drivers/spi/spi-fsl-dspi.c

@@ -121,18 +121,22 @@ enum dspi_trans_mode {
 
 struct fsl_dspi_devtype_data {
 	enum dspi_trans_mode trans_mode;
+	u8 max_clock_factor;
 };
 
 static const struct fsl_dspi_devtype_data vf610_data = {
 	.trans_mode = DSPI_EOQ_MODE,
+	.max_clock_factor = 2,
 };
 
 static const struct fsl_dspi_devtype_data ls1021a_v1_data = {
 	.trans_mode = DSPI_TCFQ_MODE,
+	.max_clock_factor = 8,
 };
 
 static const struct fsl_dspi_devtype_data ls2085a_data = {
 	.trans_mode = DSPI_TCFQ_MODE,
+	.max_clock_factor = 8,
 };
 
 struct fsl_dspi {
@@ -726,6 +730,9 @@ static int dspi_probe(struct platform_device *pdev)
 	}
 	clk_prepare_enable(dspi->clk);
 
+	master->max_speed_hz =
+		clk_get_rate(dspi->clk) / dspi->devtype_data->max_clock_factor;
+
 	init_waitqueue_head(&dspi->waitq);
 	platform_set_drvdata(pdev, master);