Currently, 8-bit (MMIO) and 32-bit (MMIO32) register strides are
supported for the 8250 console, but 16-bit (MMIO16) stride is not.
The 8250 UART device on my board is connected to a 16-bit bus
(reg-shift = <1>) and I am eager to use earlycon with it.
Refer to arch/arm/boot/dts/uniphier-support-card.dtsi:
serialsc: uart@000b0000 {
compatible = "ns16550a";
reg = <0x000b0000 0x20>;
clock-frequency = <12288000>;
reg-shift = <1>;
};
Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
---
Changes in v2:
- Do not change userspace-exported macros
Documentation/kernel-parameters.txt | 9 +++++----
drivers/tty/serial/8250/8250_early.c | 5 +++++
drivers/tty/serial/8250/8250_port.c | 20 ++++++++++++++++++++
drivers/tty/serial/earlycon.c | 15 +++++++++++----
drivers/tty/serial/serial_core.c | 9 +++++++--
include/linux/serial_core.h | 1 +
include/uapi/linux/serial.h | 1 +
7 files changed, 50 insertions(+), 10 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 22a4b68..761f08c 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -720,16 +720,17 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
uart[8250],io,<addr>[,options]
uart[8250],mmio,<addr>[,options]
+ uart[8250],mmio16,<addr>[,options]
uart[8250],mmio32,<addr>[,options]
uart[8250],0x<addr>[,options]
Start an early, polled-mode console on the 8250/16550
UART at the specified I/O port or MMIO address,
switching to the matching ttyS device later.
MMIO inter-register address stride is either 8-bit
- (mmio) or 32-bit (mmio32).
- If none of [io|mmio|mmio32], <addr> is assumed to be
- equivalent to 'mmio'. 'options' are specified in the
- same format described for ttyS above; if unspecified,
+ (mmio), 16-bit (mmio16), or 32-bit (mmio32).
+ If none of [io|mmio|mmio16|mmio32], <addr> is assumed
+ to be equivalent to 'mmio'. 'options' are specified in
+ the same format described for ttyS above; if unspecified,
the h/w is not re-initialized.
hvc<n> Use the hypervisor console device <n>. This is for
diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
index faed05f..7aff3d8 100644
--- a/drivers/tty/serial/8250/8250_early.c
+++ b/drivers/tty/serial/8250/8250_early.c
@@ -40,6 +40,8 @@ static unsigned int __init serial8250_early_in(struct uart_port *port, int offse
switch (port->iotype) {
case UPIO_MEM:
return readb(port->membase + offset);
+ case UPIO_MEM16:
+ return readw(port->membase + (offset << 1));
case UPIO_MEM32:
return readl(port->membase + (offset << 2));
case UPIO_MEM32BE:
@@ -57,6 +59,9 @@ static void __init serial8250_early_out(struct uart_port *port, int offset, int
case UPIO_MEM:
writeb(value, port->membase + offset);
break;
+ case UPIO_MEM16:
+ writew(value, port->membase + (offset << 1));
+ break;
case UPIO_MEM32:
writel(value, port->membase + (offset << 2));
break;
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 0bbf340..f976948 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -368,6 +368,18 @@ static void mem_serial_out(struct uart_port *p, int offset, int value)
writeb(value, p->membase + offset);
}
+static void mem16_serial_out(struct uart_port *p, int offset, int value)
+{
+ offset = offset << p->regshift;
+ writew(value, p->membase + offset);
+}
+
+static unsigned int mem16_serial_in(struct uart_port *p, int offset)
+{
+ offset = offset << p->regshift;
+ return readw(p->membase + offset);
+}
+
static void mem32_serial_out(struct uart_port *p, int offset, int value)
{
offset = offset << p->regshift;
@@ -425,6 +437,11 @@ static void set_io_from_upio(struct uart_port *p)
p->serial_out = mem_serial_out;
break;
+ case UPIO_MEM16:
+ p->serial_in = mem16_serial_in;
+ p->serial_out = mem16_serial_out;
+ break;
+
case UPIO_MEM32:
p->serial_in = mem32_serial_in;
p->serial_out = mem32_serial_out;
@@ -459,6 +476,7 @@ serial_port_out_sync(struct uart_port *p, int offset, int value)
{
switch (p->iotype) {
case UPIO_MEM:
+ case UPIO_MEM16:
case UPIO_MEM32:
case UPIO_MEM32BE:
case UPIO_AU:
@@ -2447,6 +2465,7 @@ static int serial8250_request_std_resource(struct uart_8250_port *up)
case UPIO_TSI:
case UPIO_MEM32:
case UPIO_MEM32BE:
+ case UPIO_MEM16:
case UPIO_MEM:
if (!port->mapbase)
break;
@@ -2484,6 +2503,7 @@ static void serial8250_release_std_resource(struct uart_8250_port *up)
case UPIO_TSI:
case UPIO_MEM32:
case UPIO_MEM32BE:
+ case UPIO_MEM16:
case UPIO_MEM:
if (!port->mapbase)
break;
diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
index f096360..07f7393 100644
--- a/drivers/tty/serial/earlycon.c
+++ b/drivers/tty/serial/earlycon.c
@@ -71,10 +71,16 @@ static int __init parse_options(struct earlycon_device *device, char *options)
return -EINVAL;
switch (port->iotype) {
+ case UPIO_MEM:
+ port->mapbase = addr;
+ break;
+ case UPIO_MEM16:
+ port->regshift = 1;
+ port->mapbase = addr;
+ break;
case UPIO_MEM32:
case UPIO_MEM32BE:
- port->regshift = 2; /* fall-through */
- case UPIO_MEM:
+ port->regshift = 2;
port->mapbase = addr;
break;
case UPIO_PORT:
@@ -91,10 +97,11 @@ static int __init parse_options(struct earlycon_device *device, char *options)
strlcpy(device->options, options, length);
}
- if (port->iotype == UPIO_MEM || port->iotype == UPIO_MEM32 ||
- port->iotype == UPIO_MEM32BE)
+ if (port->iotype == UPIO_MEM || port->iotype == UPIO_MEM16 ||
+ port->iotype == UPIO_MEM32 || port->iotype == UPIO_MEM32BE)
pr_info("Early serial console at MMIO%s 0x%llx (options '%s')\n",
(port->iotype == UPIO_MEM) ? "" :
+ (port->iotype == UPIO_MEM16) ? "16" :
(port->iotype == UPIO_MEM32) ? "32" : "32be",
(unsigned long long)port->mapbase,
device->options);
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 603d2cc..325acce 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1819,8 +1819,8 @@ uart_get_console(struct uart_port *ports, int nr, struct console *co)
* @options: ptr for <options> field; NULL if not present (out)
*
* Decodes earlycon kernel command line parameters of the form
- * earlycon=<name>,io|mmio|mmio32|mmio32be,<addr>,<options>
- * console=<name>,io|mmio|mmio32|mmio32be,<addr>,<options>
+ * earlycon=<name>,io|mmio|mmio16|mmio32|mmio32be,<addr>,<options>
+ * console=<name>,io|mmio|mmio16|mmio32|mmio32be,<addr>,<options>
*
* The optional form
* earlycon=<name>,0x<addr>,<options>
@@ -1835,6 +1835,9 @@ int uart_parse_earlycon(char *p, unsigned char *iotype, unsigned long *addr,
if (strncmp(p, "mmio,", 5) == 0) {
*iotype = UPIO_MEM;
p += 5;
+ } else if (strncmp(p, "mmio16,", 7) == 0) {
+ *iotype = UPIO_MEM16;
+ p += 7;
} else if (strncmp(p, "mmio32,", 7) == 0) {
*iotype = UPIO_MEM32;
p += 7;
@@ -2183,6 +2186,7 @@ uart_report_port(struct uart_driver *drv, struct uart_port *port)
"I/O 0x%lx offset 0x%x", port->iobase, port->hub6);
break;
case UPIO_MEM:
+ case UPIO_MEM16:
case UPIO_MEM32:
case UPIO_MEM32BE:
case UPIO_AU:
@@ -2828,6 +2832,7 @@ int uart_match_port(struct uart_port *port1, struct uart_port *port2)
return (port1->iobase == port2->iobase) &&
(port1->hub6 == port2->hub6);
case UPIO_MEM:
+ case UPIO_MEM16:
case UPIO_MEM32:
case UPIO_MEM32BE:
case UPIO_AU:
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 297d4fa..35aa87b 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -150,6 +150,7 @@ struct uart_port {
#define UPIO_AU (SERIAL_IO_AU) /* Au1x00 and RT288x type IO */
#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 */
unsigned int read_status_mask; /* driver specific */
unsigned int ignore_status_mask; /* driver specific */
diff --git a/include/uapi/linux/serial.h b/include/uapi/linux/serial.h
index 25331f9..5d59c3e 100644
--- a/include/uapi/linux/serial.h
+++ b/include/uapi/linux/serial.h
@@ -69,6 +69,7 @@ struct serial_struct {
#define SERIAL_IO_AU 4
#define SERIAL_IO_TSI 5
#define SERIAL_IO_MEM32BE 6
+#define SERIAL_IO_MEM16 7
#define UART_CLEAR_FIFO 0x01
#define UART_USE_FIFO 0x02
--
1.9.1
--
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