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tty: serial: 21285: stop using the unused[] variable from struct uart_port 

Much like the samsung_tty driver (now I know where they copied the idea
from), the 21285 uart driver uses 2 bytes from the "unused" array of
struct uart_port to keep tx/rx enabled/disabled state.  Those fields are
going away (they were never really needed in the first place), so fix up
the 21285 driver by another horrible hack.

Instead of creating a whole structure for just 2 bytes, just use two
bits from the private_data pointer instead, as that pointer is never
used.  The two bits reflect if tx/rx is now enabled/disabled.

Astute readers will note that once rx is disabled, nothing ever seems to
turn it back on, making one wonder if anyone has ever done this.

Reported-by: kbuild test robot <lkp@intel.com>
Cc: Dmitry Safonov <dima@arista.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Link: https://lore.kernel.org/r/20191219145109.GA1962496@kroah.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Greg Kroah-Hartman 2019-12-19 15:51:09 +01:00
parent 82cfd2e62b
commit 293f899594
1 changed files with 45 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

55
drivers/tty/serial/21285.c
View File

@ -41,8 +41,43 @@
static const char serial21285_name[] = "Footbridge UART";
#define tx_enabled(port) ((port)->unused[0])
#define rx_enabled(port) ((port)->unused[1])
/*
* We only need 2 bits of data, so instead of creating a whole structure for
* this, use bits of the private_data pointer of the uart port structure.
*/
#define tx_enabled_bit 0
#define rx_enabled_bit 1
static bool is_enabled(struct uart_port *port, int bit)
{
unsigned long private_data = (unsigned long)port->private_data;
if (test_bit(bit, &private_data))
return true;
return false;
}
static void enable(struct uart_port *port, int bit)
{
unsigned long private_data = (unsigned long)port->private_data;
set_bit(bit, &private_data);
}
static void disable(struct uart_port *port, int bit)
{
unsigned long private_data = (unsigned long)port->private_data;
clear_bit(bit, &private_data);
}
#define is_tx_enabled(port) is_enabled(port, tx_enabled_bit)
#define tx_enable(port) enable(port, tx_enabled_bit)
#define tx_disable(port) disable(port, tx_enabled_bit)
#define is_rx_enabled(port) is_enabled(port, rx_enabled_bit)
#define rx_enable(port) enable(port, rx_enabled_bit)
#define rx_disable(port) disable(port, rx_enabled_bit)
/*
* The documented expression for selecting the divisor is:
@ -57,25 +92,25 @@ static const char serial21285_name[] = "Footbridge UART";
static void serial21285_stop_tx(struct uart_port *port)
{
if (tx_enabled(port)) {
if (is_tx_enabled(port)) {
disable_irq_nosync(IRQ_CONTX);
tx_enabled(port) = 0;
tx_disable(port);
}
}
static void serial21285_start_tx(struct uart_port *port)
{
if (!tx_enabled(port)) {
if (!is_tx_enabled(port)) {
enable_irq(IRQ_CONTX);
tx_enabled(port) = 1;
tx_enable(port);
}
}
static void serial21285_stop_rx(struct uart_port *port)
{
if (rx_enabled(port)) {
if (is_rx_enabled(port)) {
disable_irq_nosync(IRQ_CONRX);
rx_enabled(port) = 0;
rx_disable(port);
}
}
@ -185,8 +220,8 @@ static int serial21285_startup(struct uart_port *port)
{
int ret;
tx_enabled(port) = 1;
rx_enabled(port) = 1;
tx_enable(port);
rx_enable(port);
ret = request_irq(IRQ_CONRX, serial21285_rx_chars, 0,
serial21285_name, port);