media: rc: ir-spi: constrain carrier frequency

Carrier frequency is currently unconstrained, allowing the SPI transfer
to be allocated and filled only for it to be later rejected by the SPI
controller since the frequency is too large.

Add a check to constrain the carrier frequency inside
ir_spi_set_tx_carrier().

Also, move the number of bits per pulse to a macro since it is not used
in multiple places.

Signed-off-by: Cosmin Tanislav <[e-mail]>
Signed-off-by: Sean Young <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>

drivers/media/rc/ir-spi.c

···
 #define IR_SPI_DRIVER_NAME		"ir-spi"
 
 #define IR_SPI_DEFAULT_FREQUENCY	38000
+#define IR_SPI_BITS_PER_PULSE		16
 
 struct ir_spi_data {
 	u32 freq;
···
 
 	memset(&xfer, 0, sizeof(xfer));
 
-	xfer.speed_hz = idata->freq * 16;
+	xfer.speed_hz = idata->freq * IR_SPI_BITS_PER_PULSE;
 	xfer.len = len * sizeof(*tx_buf);
 	xfer.tx_buf = tx_buf;
 
···
 	struct ir_spi_data *idata = dev->priv;
 
 	if (!carrier)
+		return -EINVAL;
+
+	if (carrier > idata->spi->max_speed_hz / IR_SPI_BITS_PER_PULSE)
 		return -EINVAL;
 
 	idata->freq = carrier;