drivers/tty/serial/pch_uart.c: add console support

Add console support to pch_uart.  To enable append e.g.
console=ttyPCH0,115200 to your kernel command line.

This is not expected work on CM-iTC boards due to their having a different
clock.

Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 5f479dada6f2b25a309b48c50d5b2dee0a35777d..956f2f02947b4e6a397a500c8ab34e06cb716e25 100644 (file)
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1575,6 +1575,15 @@ config SERIAL_PCH_UART
          ML7213/ML7223 is companion chip for Intel Atom E6xx series.
          ML7213/ML7223 is completely compatible for Intel EG20T PCH.
 
+config SERIAL_PCH_UART_CONSOLE
+       bool "Support for console on Intel EG20T PCH UART/OKI SEMICONDUCTOR ML7213 IOH"
+       depends on SERIAL_PCH_UART=y
+       select SERIAL_CORE_CONSOLE
+       help
+         Say Y here if you wish to use the PCH UART as the system console
+         (the system  console is the device which receives all kernel messages and
+         warnings and which allows logins in single user mode).
+
 config SERIAL_MSM_SMD
        bool "Enable tty device interface for some SMD ports"
        default n

diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c
index 21febef926aa7c31f09ef26dbbbfa34d78f76df1..b950d059a78141d90697a1a951c3f3401c75af6c 100644 (file)
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -25,6 +25,9 @@
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/dmi.h>
+#include <linux/console.h>
+#include <linux/nmi.h>
+#include <linux/delay.h>
 
 #include <linux/dmaengine.h>
 #include <linux/pch_dma.h>
@@ -198,6 +201,10 @@ enum {
 
 #define PCI_VENDOR_ID_ROHM             0x10DB
 
+#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
+
+#define DEFAULT_BAUD_RATE 1843200 /* 1.8432MHz */
+
 struct pch_uart_buffer {
        unsigned char *buf;
        int size;
@@ -272,6 +279,9 @@ static struct pch_uart_driver_data drv_dat[] = {
        [pch_ml7223_uart1] = {PCH_UART_2LINE, 1},
 };
 
+#ifdef CONFIG_SERIAL_PCH_UART_CONSOLE
+static struct eg20t_port *pch_uart_ports[PCH_UART_NR];
+#endif
 static unsigned int default_baud = 9600;
 static const int trigger_level_256[4] = { 1, 64, 128, 224 };
 static const int trigger_level_64[4] = { 1, 16, 32, 56 };
@@ -1380,6 +1390,143 @@ static struct uart_ops pch_uart_ops = {
        .verify_port = pch_uart_verify_port
 };
 
+#ifdef CONFIG_SERIAL_PCH_UART_CONSOLE
+
+/*
+ *     Wait for transmitter & holding register to empty
+ */
+static void wait_for_xmitr(struct eg20t_port *up, int bits)
+{
+       unsigned int status, tmout = 10000;
+
+       /* Wait up to 10ms for the character(s) to be sent. */
+       for (;;) {
+               status = ioread8(up->membase + UART_LSR);
+
+               if ((status & bits) == bits)
+                       break;
+               if (--tmout == 0)
+                       break;
+               udelay(1);
+       }
+
+       /* Wait up to 1s for flow control if necessary */
+       if (up->port.flags & UPF_CONS_FLOW) {
+               unsigned int tmout;
+               for (tmout = 1000000; tmout; tmout--) {
+                       unsigned int msr = ioread8(up->membase + UART_MSR);
+                       if (msr & UART_MSR_CTS)
+                               break;
+                       udelay(1);
+                       touch_nmi_watchdog();
+               }
+       }
+}
+
+static void pch_console_putchar(struct uart_port *port, int ch)
+{
+       struct eg20t_port *priv =
+               container_of(port, struct eg20t_port, port);
+
+       wait_for_xmitr(priv, UART_LSR_THRE);
+       iowrite8(ch, priv->membase + PCH_UART_THR);
+}
+
+/*
+ *     Print a string to the serial port trying not to disturb
+ *     any possible real use of the port...
+ *
+ *     The console_lock must be held when we get here.
+ */
+static void
+pch_console_write(struct console *co, const char *s, unsigned int count)
+{
+       struct eg20t_port *priv;
+
+       unsigned long flags;
+       u8 ier;
+       int locked = 1;
+
+       priv = pch_uart_ports[co->index];
+
+       touch_nmi_watchdog();
+
+       local_irq_save(flags);
+       if (priv->port.sysrq) {
+               /* serial8250_handle_port() already took the lock */
+               locked = 0;
+       } else if (oops_in_progress) {
+               locked = spin_trylock(&priv->port.lock);
+       } else
+               spin_lock(&priv->port.lock);
+
+       /*
+        *      First save the IER then disable the interrupts
+        */
+       ier = ioread8(priv->membase + UART_IER);
+
+       pch_uart_hal_disable_interrupt(priv, PCH_UART_HAL_ALL_INT);
+
+       uart_console_write(&priv->port, s, count, pch_console_putchar);
+
+       /*
+        *      Finally, wait for transmitter to become empty
+        *      and restore the IER
+        */
+       wait_for_xmitr(priv, BOTH_EMPTY);
+       iowrite8(ier, priv->membase + UART_IER);
+
+       if (locked)
+               spin_unlock(&priv->port.lock);
+       local_irq_restore(flags);
+}
+
+static int __init pch_console_setup(struct console *co, char *options)
+{
+       struct uart_port *port;
+       int baud = 9600;
+       int bits = 8;
+       int parity = 'n';
+       int flow = 'n';
+
+       /*
+        * Check whether an invalid uart number has been specified, and
+        * if so, search for the first available port that does have
+        * console support.
+        */
+       if (co->index >= PCH_UART_NR)
+               co->index = 0;
+       port = &pch_uart_ports[co->index]->port;
+
+       if (!port || (!port->iobase && !port->membase))
+               return -ENODEV;
+
+       /* setup uartclock */
+       port->uartclk = DEFAULT_BAUD_RATE;
+
+       if (options)
+               uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+       return uart_set_options(port, co, baud, parity, bits, flow);
+}
+
+static struct uart_driver pch_uart_driver;
+
+static struct console pch_console = {
+       .name           = PCH_UART_DRIVER_DEVICE,
+       .write          = pch_console_write,
+       .device         = uart_console_device,
+       .setup          = pch_console_setup,
+       .flags          = CON_PRINTBUFFER | CON_ANYTIME,
+       .index          = -1,
+       .data           = &pch_uart_driver,
+};
+
+#define PCH_CONSOLE    (&pch_console)
+#else
+#define PCH_CONSOLE    NULL
+#endif
+
 static struct uart_driver pch_uart_driver = {
        .owner = THIS_MODULE,
        .driver_name = KBUILD_MODNAME,
@@ -1387,6 +1534,7 @@ static struct uart_driver pch_uart_driver = {
        .major = 0,
        .minor = 0,
        .nr = PCH_UART_NR,
+       .cons = PCH_CONSOLE,
 };
 
 static struct eg20t_port *pch_uart_init_port(struct pci_dev *pdev,
@@ -1413,7 +1561,7 @@ static struct eg20t_port *pch_uart_init_port(struct pci_dev *pdev,
        if (!rxbuf)
                goto init_port_free_txbuf;
 
-       base_baud = 1843200; /* 1.8432MHz */
+       base_baud = DEFAULT_BAUD_RATE;
 
        /* quirk for CM-iTC board */
        board_name = dmi_get_system_info(DMI_BOARD_NAME);
@@ -1463,6 +1611,9 @@ static struct eg20t_port *pch_uart_init_port(struct pci_dev *pdev,
        pci_set_drvdata(pdev, priv);
        pch_uart_hal_request(pdev, fifosize, base_baud);
 
+#ifdef CONFIG_SERIAL_PCH_UART_CONSOLE
+       pch_uart_ports[board->line_no] = priv;
+#endif
        ret = uart_add_one_port(&pch_uart_driver, &priv->port);
        if (ret < 0)
                goto init_port_hal_free;
@@ -1470,6 +1621,9 @@ static struct eg20t_port *pch_uart_init_port(struct pci_dev *pdev,
        return priv;
 
 init_port_hal_free:
+#ifdef CONFIG_SERIAL_PCH_UART_CONSOLE
+       pch_uart_ports[board->line_no] = NULL;
+#endif
        free_page((unsigned long)rxbuf);
 init_port_free_txbuf:
        kfree(priv);
@@ -1492,6 +1646,10 @@ static void pch_uart_pci_remove(struct pci_dev *pdev)
        priv = (struct eg20t_port *)pci_get_drvdata(pdev);
 
        pci_disable_msi(pdev);
+
+#ifdef CONFIG_SERIAL_PCH_UART_CONSOLE
+       pch_uart_ports[priv->port.line] = NULL;
+#endif
        pch_uart_exit_port(priv);
        pci_disable_device(pdev);
        kfree(priv);