Apple's earlier SoCs, like A7-A11, requires 32-bit writes for the serial
port. Otherwise, a SError happens when writing to UTXH (+0x20). This only
manifested in earlycon as reg-io-width in the device tree is consulted
for normal serial writes.
Change the iotype of the port to UPIO_MEM32, to allow the serial port to
function on A7-A11 SoCs. This change does not appear to affect Apple M1 and
above.
Signed-off-by: Nick Chan <towinchenmi@xxxxxxxxx>
---
drivers/tty/serial/samsung_tty.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
index c4f2ac9518aa..27b8a50bd3e7 100644
--- a/drivers/tty/serial/samsung_tty.c
+++ b/drivers/tty/serial/samsung_tty.c
@@ -2536,7 +2536,7 @@ static const struct s3c24xx_serial_drv_data s5l_serial_drv_data = {
.name = "Apple S5L UART",
.type = TYPE_APPLE_S5L,
.port_type = PORT_8250,
- .iotype = UPIO_MEM,
+ .iotype = UPIO_MEM32,
.fifosize = 16,
.rx_fifomask = S3C2410_UFSTAT_RXMASK,
.rx_fifoshift = S3C2410_UFSTAT_RXSHIFT,
@@ -2825,8 +2825,10 @@ static int __init apple_s5l_early_console_setup(struct earlycon_device *device,
/* Close enough to S3C2410 for earlycon... */
device->port.private_data = &s3c2410_early_console_data;
+ /* ... however, we need to change the port iotype */
+ device->port.iotype = UPIO_MEM32;
#ifdef CONFIG_ARM64
- /* ... but we need to override the existing fixmap entry as nGnRnE */
+ /* ... and also override the existing fixmap entry as nGnRnE */
__set_fixmap(FIX_EARLYCON_MEM_BASE, device->port.mapbase,
__pgprot(PROT_DEVICE_nGnRnE));
#endif
--
2.46.0
