tty: serial: samsung: Fix A7-A11 serial earlycon SError

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.

Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Neal Gompa <neal@gompa.dev>
Tested-by: Janne Grunau <j@jannau.net>
Signed-off-by: Nick Chan <towinchenmi@gmail.com>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20240911050741.14477-3-towinchenmi@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
index c4f2ac9518aa2a7e4298b8578a7e92c43793bd5a..3fdec06322acdb00dcb717371c1c2fcda03214dc 100644 (file)
--- 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,
@@ -2822,6 +2822,9 @@ OF_EARLYCON_DECLARE(gs101, "google,gs101-uart", gs101_early_console_setup);
 static int __init apple_s5l_early_console_setup(struct earlycon_device *device,
                                                const char *opt)
 {
+       /* Apple A7-A11 requires MMIO32 register accesses. */
+       device->port.iotype = UPIO_MEM32;
+
        /* Close enough to S3C2410 for earlycon... */
        device->port.private_data = &s3c2410_early_console_data;