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Message-Id: <1307631547-31884-1-git-send-email-alexander.stein@systec-electronic.com>
Date: Thu, 9 Jun 2011 16:59:07 +0200
From: Alexander Stein <alexander.stein@...tec-electronic.com>
To: Alan Cox <alan@...ux.intel.com>
Cc: linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
Tomoya MORINAGA <tomoya-linux@....okisemi.com>,
Alexander Stein <alexander.stein@...tec-electronic.com>
Subject: [PATCH RFC] pch_uart: Add console support
This patch add console support to pch_uart. To enable append e.g.
console=ttyPCH0,115200 to your kernel command line.
Expected issues:
* Should not work on CM-iTC boards due to different clock.
Signed-off-by: Alexander Stein <alexander.stein@...tec-electronic.com>
---
drivers/tty/serial/Kconfig | 9 +++
drivers/tty/serial/pch_uart.c | 159 ++++++++++++++++++++++++++++++++++++++++-
2 files changed, 167 insertions(+), 1 deletions(-)
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 636144c..69115fe 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1600,6 +1600,15 @@ 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 e3e6d6b..a3d0c9e 100644
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -22,6 +22,9 @@
#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>
@@ -197,6 +200,10 @@ 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;
@@ -271,6 +278,9 @@ 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 };
@@ -1378,6 +1388,143 @@ 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,
@@ -1385,6 +1532,7 @@ 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,
@@ -1411,7 +1559,7 @@ 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);
@@ -1459,6 +1607,9 @@ 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;
@@ -1466,6 +1617,9 @@ 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);
@@ -1486,6 +1640,9 @@ static void pch_uart_pci_remove(struct pci_dev *pdev)
struct eg20t_port *priv;
priv = (struct eg20t_port *)pci_get_drvdata(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);
--
1.7.3.4
--
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