serial: support 16-bit register interface for console

Currently, 8-bit (MMIO) and 32-bit (MMIO32) register interfaces are
supported for the 8250 console, but the 16-bit (MMIO16) is not.
The 8250 UART device on my board is connected to a 16-bit bus and
my main motivation is to use earlycon with it.
(Refer to arch/arm/boot/dts/uniphier-support-card.dtsi)

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 742f69d..054e11d 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -721,16 +721,17 @@ 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_core.c b/drivers/tty/serial/8250/8250_core.c
index 3912646..c9720a9 100644 (file)
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -620,7 +620,7 @@ static int univ8250_console_setup(struct console *co, char *options)
  *     @options: ptr to option string from console command line
  *
  *     Only attempts to match console command lines of the form:
- *         console=uart[8250],io|mmio|mmio32,<addr>[,<options>]
+ *         console=uart[8250],io|mmio|mmio16|mmio32,<addr>[,<options>]
  *         console=uart[8250],0x<addr>[,<options>]
  *     This form is used to register an initial earlycon boot console and
  *     replace it with the serial8250_console at 8250 driver init.
@@ -650,8 +650,9 @@ static int univ8250_console_match(struct console *co, char *name, int idx,
 
                if (port->iotype != iotype)
                        continue;
-               if ((iotype == UPIO_MEM || iotype == UPIO_MEM32) &&
-                   (port->mapbase != addr))
+               if ((iotype == UPIO_MEM || iotype == UPIO_MEM16 ||
+                    iotype == UPIO_MEM32 || iotype == UPIO_MEM32BE)
+                   && (port->mapbase != addr))
                        continue;
                if (iotype == UPIO_PORT && port->iobase != addr)
                        continue;

diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
index ca16195..af62131 100644 (file)
--- a/drivers/tty/serial/8250/8250_early.c
+++ b/drivers/tty/serial/8250/8250_early.c
@@ -42,6 +42,8 @@ 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:
@@ -59,6 +61,9 @@ 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 52d82d2..8d262bc 100644 (file)
--- 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:
@@ -2462,6 +2480,7 @@ 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;
@@ -2499,6 +2518,7 @@ 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 (file)
--- 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/of_serial.c b/drivers/tty/serial/of_serial.c
index de50296..6d002ee 100644 (file)
--- a/drivers/tty/serial/of_serial.c
+++ b/drivers/tty/serial/of_serial.c
@@ -122,6 +122,9 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
                case 1:
                        port->iotype = UPIO_MEM;
                        break;
+               case 2:
+                       port->iotype = UPIO_MEM16;
+                       break;
                case 4:
                        port->iotype = of_device_is_big_endian(np) ?
                                       UPIO_MEM32BE : UPIO_MEM32;

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 22cfc32..b1f54ab 100644 (file)
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1818,8 +1818,8 @@ 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|mmio32native,<addr>,<options>
- *        console=<name>,io|mmio|mmio32|mmio32be|mmio32native,<addr>,<options>
+ *        earlycon=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
+ *        console=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
  *
  *     The optional form
  *        earlycon=<name>,0x<addr>,<options>
@@ -1834,6 +1834,9 @@ 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;
@@ -2186,6 +2189,7 @@ 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:
@@ -2831,6 +2835,7 @@ 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 (file)
--- 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 (file)
--- 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