spi: aspeed: Workaround AST2500 limitations

It is not possible to configure a full 128MB window for a chip of the
same size on the AST2500 SPI controller. For this case, the maximum
window size is restricted to 120MB for CE0.

Reviewed-by: Joel Stanley <joel@jms.id.au>
Tested-by: Joel Stanley <joel@jms.id.au>
Tested-by: Tao Ren <rentao.bupt@gmail.com>
Tested-by: Jae Hyun Yoo <quic_jaehyoo@quicinc.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Link: https://lore.kernel.org/r/20220509175616.1089346-7-clg@kaod.org
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: legoater

drivers/spi/spi-aspeed-smc.c

@@ -451,6 +451,8 @@ static int aspeed_spi_set_window(struct aspeed_spi *aspi,
  * - ioremap each window, not strictly necessary since the overall window
  *   is correct.
  */
+static const struct aspeed_spi_data ast2500_spi_data;
+
 static int aspeed_spi_chip_adjust_window(struct aspeed_spi_chip *chip,
 					 u32 local_offset, u32 size)
 {
@@ -459,6 +461,16 @@ static int aspeed_spi_chip_adjust_window(struct aspeed_spi_chip *chip,
 	struct aspeed_spi_window *win = &windows[chip->cs];
 	int ret;
 
+	/*
+	 * Due to an HW issue on the AST2500 SPI controller, the CE0
+	 * window size should be smaller than the maximum 128MB.
+	 */
+	if (aspi->data == &ast2500_spi_data && chip->cs == 0 && size == SZ_128M) {
+		size = 120 << 20;
+		dev_info(aspi->dev, "CE%d window resized to %dMB (AST2500 HW quirk)",
+			 chip->cs, size >> 20);
+	}
+
 	aspeed_spi_get_windows(aspi, windows);
 
 	/* Adjust this chip window */