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--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -833,6 +833,7 @@ static int serial8250_probe(struct platf
uart.port.get_mctrl = p->get_mctrl;
uart.port.pm = p->pm;
uart.port.dev = &dev->dev;
+ uart.port.rw_delay = p->rw_delay;
uart.port.irqflags |= irqflag;
ret = serial8250_register_8250_port(&uart);
if (ret < 0) {
@@ -989,6 +990,7 @@ int serial8250_register_8250_port(struct
uart->bugs = up->bugs;
uart->port.mapbase = up->port.mapbase;
uart->port.mapsize = up->port.mapsize;
+ uart->port.rw_delay = up->port.rw_delay;
uart->port.private_data = up->port.private_data;
uart->tx_loadsz = up->tx_loadsz;
uart->capabilities = up->capabilities;
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2229,6 +2229,7 @@ uart_report_port(struct uart_driver *drv
snprintf(address, sizeof(address),
"I/O 0x%lx offset 0x%x", port->iobase, port->hub6);
break;
+ case UPIO_MEM_DELAY:
case UPIO_MEM:
case UPIO_MEM16:
case UPIO_MEM32:
@@ -2893,6 +2894,7 @@ int uart_match_port(struct uart_port *po
case UPIO_HUB6:
return (port1->iobase == port2->iobase) &&
(port1->hub6 == port2->hub6);
+ case UPIO_MEM_DELAY:
case UPIO_MEM:
case UPIO_MEM16:
case UPIO_MEM32:
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -28,6 +28,7 @@ struct plat_serial8250_port {
void *private_data;
unsigned char regshift; /* register shift */
unsigned char iotype; /* UPIO_* */
+ unsigned int rw_delay; /* udelay for slower busses IXP4XX Expansion Bus */
unsigned char hub6;
upf_t flags; /* UPF_* flags */
unsigned int type; /* If UPF_FIXED_TYPE */
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -152,6 +152,7 @@ struct uart_port {
#define UPIO_TSI (SERIAL_IO_TSI) /* Tsi108/109 type IO */
#define UPIO_MEM32BE (SERIAL_IO_MEM32BE) /* 32b big endian */
#define UPIO_MEM16 (SERIAL_IO_MEM16) /* 16b little endian */
+#define UPIO_MEM_DELAY (SERIAL_IO_MEM_DELAY)
unsigned int read_status_mask; /* driver specific */
unsigned int ignore_status_mask; /* driver specific */
@@ -233,6 +234,7 @@ struct uart_port {
int hw_stopped; /* sw-assisted CTS flow state */
unsigned int mctrl; /* current modem ctrl settings */
unsigned int timeout; /* character-based timeout */
+ unsigned int rw_delay; /* udelay for slow busses, IXP4XX Expansion Bus */
unsigned int type; /* port type */
const struct uart_ops *ops;
unsigned int custom_divisor;
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -384,6 +384,20 @@ static unsigned int mem16_serial_in(stru
return readw(p->membase + offset);
}
+static unsigned int memdelay_serial_in(struct uart_port *p, int offset)
+{
+ struct uart_8250_port *up = (struct uart_8250_port *)p;
+ udelay(up->port.rw_delay);
+ return mem_serial_in(p, offset);
+}
+
+static void memdelay_serial_out(struct uart_port *p, int offset, int value)
+{
+ struct uart_8250_port *up = (struct uart_8250_port *)p;
+ udelay(up->port.rw_delay);
+ mem_serial_out(p, offset, value);
+}
+
static void mem32_serial_out(struct uart_port *p, int offset, int value)
{
offset = offset << p->regshift;
@@ -456,6 +470,11 @@ static void set_io_from_upio(struct uart
p->serial_out = mem32be_serial_out;
break;
+ case UPIO_MEM_DELAY:
+ p->serial_in = memdelay_serial_in;
+ p->serial_out = memdelay_serial_out;
+ break;
+
#ifdef CONFIG_SERIAL_8250_RT288X
case UPIO_AU:
p->serial_in = au_serial_in;
@@ -483,6 +502,7 @@ serial_port_out_sync(struct uart_port *p
case UPIO_MEM16:
case UPIO_MEM32:
case UPIO_MEM32BE:
+ case UPIO_MEM_DELAY:
case UPIO_AU:
p->serial_out(p, offset, value);
p->serial_in(p, UART_LCR); /* safe, no side-effects */
@@ -2759,6 +2779,7 @@ static int serial8250_request_std_resour
case UPIO_MEM32BE:
case UPIO_MEM16:
case UPIO_MEM:
+ case UPIO_MEM_DELAY:
if (!port->mapbase)
break;
@@ -2797,6 +2818,7 @@ static void serial8250_release_std_resou
case UPIO_MEM32BE:
case UPIO_MEM16:
case UPIO_MEM:
+ case UPIO_MEM_DELAY:
if (!port->mapbase)
break;
--- a/include/uapi/linux/serial.h
+++ b/include/uapi/linux/serial.h
@@ -70,6 +70,7 @@ struct serial_struct {
#define SERIAL_IO_TSI 5
#define SERIAL_IO_MEM32BE 6
#define SERIAL_IO_MEM16 7
+#define SERIAL_IO_MEM_DELAY 10
#define UART_CLEAR_FIFO 0x01
#define UART_USE_FIFO 0x02
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