serial: sc16is7xx: fix broken port 0 uart init

commit 2861ed4d6e6d1a2c9de9bf5b0abd996c2dc673d0 upstream.

The sc16is7xx_config_rs485() function is called only for the second
port (index 1, channel B), causing initialization problems for the
first port.

For the sc16is7xx driver, port->membase and port->mapbase are not set,
and their default values are 0. And we set port->iobase to the device
index. This means that when the first device is registered using the
uart_add_one_port() function, the following values will be in the port
structure:
    port->membase = 0
    port->mapbase = 0
    port->iobase  = 0

Therefore, the function uart_configure_port() in serial_core.c will
exit early because of the following check:
	/*
	 * If there isn't a port here, don't do anything further.
	 */
	if (!port->iobase && !port->mapbase && !port->membase)
		return;

Typically, I2C and SPI drivers do not set port->membase and
port->mapbase.

The max310x driver sets port->membase to ~0 (all ones). By
implementing the same change in this driver, uart_configure_port() is
now correctly executed for all ports.

Fixes: dfeae619d781 ("serial: sc16is7xx")
Cc: stable@vger.kernel.org
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Lech Perczak <lech.perczak@camlingroup.com>
Tested-by: Lech Perczak <lech.perczak@camlingroup.com>
Link: https://lore.kernel.org/r/20230807214556.540627-2-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 93cf5f7..58b565a 100644 (file)
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -1439,6 +1439,12 @@ static int sc16is7xx_probe(struct device *dev,
                s->p[i].port.fifosize   = SC16IS7XX_FIFO_SIZE;
                s->p[i].port.flags      = UPF_FIXED_TYPE | UPF_LOW_LATENCY;
                s->p[i].port.iobase     = i;
+               /*
+                * Use all ones as membase to make sure uart_configure_port() in
+                * serial_core.c does not abort for SPI/I2C devices where the
+                * membase address is not applicable.
+                */
+               s->p[i].port.membase    = (void __iomem *)~0;
                s->p[i].port.iotype     = UPIO_PORT;
                s->p[i].port.uartclk    = freq;
                s->p[i].port.rs485_config = sc16is7xx_config_rs485;