[v3,04/12] tty: serial: samsung: prepare for different IO types

GS101's Connectivity Peripheral blocks (peric0/1 blocks) which
include the I3C and USI (I2C, SPI, UART) only allow 32-bit
register accesses. If using 8-bit register accesses, a SError
Interrupt is raised causing the system unusable.

Instead of specifying the reg-io-width = 4 everywhere, for each node,
the requirement should be deduced from the compatible.

Prepare the samsung tty driver to allow IO types different than
UPIO_MEM. ``struct uart_port::iotype`` is an unsigned char where all
its 8 bits are exposed to uapi. We can't make NULL checks on it to
verify if it's set, thus always set it from the driver's data.
Use u8 for the ``iotype`` member of ``struct s3c24xx_uart_info`` to
emphasize that the iotype is an 8 bit mask.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
---
v3:
- reposition the ``iotype`` member of ``struct s3c24xx_uart_info`` so
  that we reduce the struct's memory footprint.
- change ``iotype`` to u8 to emphasize that it's a 8 bit mask and update
  the commit message explaining why.
v2: new patch

 drivers/tty/serial/samsung_tty.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

On Tue, Jan 9, 2024 at 6:59 AM Tudor Ambarus <tudor.ambarus@linaro.org> wrote:
>
> GS101's Connectivity Peripheral blocks (peric0/1 blocks) which
> include the I3C and USI (I2C, SPI, UART) only allow 32-bit
> register accesses. If using 8-bit register accesses, a SError
> Interrupt is raised causing the system unusable.
>
> Instead of specifying the reg-io-width = 4 everywhere, for each node,
> the requirement should be deduced from the compatible.
>
> Prepare the samsung tty driver to allow IO types different than
> UPIO_MEM. ``struct uart_port::iotype`` is an unsigned char where all
> its 8 bits are exposed to uapi. We can't make NULL checks on it to
> verify if it's set, thus always set it from the driver's data.
> Use u8 for the ``iotype`` member of ``struct s3c24xx_uart_info`` to
> emphasize that the iotype is an 8 bit mask.
>
> Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
> ---

Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>

> v3:
> - reposition the ``iotype`` member of ``struct s3c24xx_uart_info`` so
>   that we reduce the struct's memory footprint.
> - change ``iotype`` to u8 to emphasize that it's a 8 bit mask and update
>   the commit message explaining why.
> v2: new patch
>
>  drivers/tty/serial/samsung_tty.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
> index 66bd6c090ace..ff646cddd3f8 100644
> --- a/drivers/tty/serial/samsung_tty.c
> +++ b/drivers/tty/serial/samsung_tty.c
> @@ -84,6 +84,7 @@ struct s3c24xx_uart_info {
>         unsigned long           clksel_mask;
>         unsigned long           clksel_shift;
>         unsigned long           ucon_mask;
> +       u8                      iotype;
>
>         /* uart port features */
>
> @@ -1742,7 +1743,6 @@ static void s3c24xx_serial_init_port_default(int index) {
>
>         spin_lock_init(&port->lock);
>
> -       port->iotype = UPIO_MEM;
>         port->uartclk = 0;
>         port->fifosize = 16;
>         port->flags = UPF_BOOT_AUTOCONF;
> @@ -1989,6 +1989,8 @@ static int s3c24xx_serial_probe(struct platform_device *pdev)
>                 break;
>         }
>
> +       ourport->port.iotype = ourport->info->iotype;
> +
>         if (np) {
>                 of_property_read_u32(np,
>                         "samsung,uart-fifosize", &ourport->port.fifosize);
> @@ -2401,6 +2403,7 @@ static const struct s3c24xx_serial_drv_data s3c6400_serial_drv_data = {
>                 .name           = "Samsung S3C6400 UART",
>                 .type           = TYPE_S3C6400,
>                 .port_type      = PORT_S3C6400,
> +               .iotype         = UPIO_MEM,
>                 .fifosize       = 64,
>                 .has_divslot    = 1,
>                 .rx_fifomask    = S3C2440_UFSTAT_RXMASK,
> @@ -2430,6 +2433,7 @@ static const struct s3c24xx_serial_drv_data s5pv210_serial_drv_data = {
>                 .name           = "Samsung S5PV210 UART",
>                 .type           = TYPE_S3C6400,
>                 .port_type      = PORT_S3C6400,
> +               .iotype         = UPIO_MEM,
>                 .has_divslot    = 1,
>                 .rx_fifomask    = S5PV210_UFSTAT_RXMASK,
>                 .rx_fifoshift   = S5PV210_UFSTAT_RXSHIFT,
> @@ -2459,6 +2463,7 @@ static const struct s3c24xx_serial_drv_data s5pv210_serial_drv_data = {
>                 .name           = "Samsung Exynos UART",        \
>                 .type           = TYPE_S3C6400,                 \
>                 .port_type      = PORT_S3C6400,                 \
> +               .iotype         = UPIO_MEM,                     \
>                 .has_divslot    = 1,                            \
>                 .rx_fifomask    = S5PV210_UFSTAT_RXMASK,        \
>                 .rx_fifoshift   = S5PV210_UFSTAT_RXSHIFT,       \
> @@ -2519,6 +2524,7 @@ 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,
>                 .fifosize       = 16,
>                 .rx_fifomask    = S3C2410_UFSTAT_RXMASK,
>                 .rx_fifoshift   = S3C2410_UFSTAT_RXSHIFT,
> @@ -2548,6 +2554,7 @@ static const struct s3c24xx_serial_drv_data artpec8_serial_drv_data = {
>                 .name           = "Axis ARTPEC-8 UART",
>                 .type           = TYPE_S3C6400,
>                 .port_type      = PORT_S3C6400,
> +               .iotype         = UPIO_MEM,
>                 .fifosize       = 64,
>                 .has_divslot    = 1,
>                 .rx_fifomask    = S5PV210_UFSTAT_RXMASK,
> --
> 2.43.0.472.g3155946c3a-goog
>
>