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Date: Sun, 19 Aug 2012 20:34:45 +0200
From: Tomas Hlavacek <tmshlvck@...il.com>
To: gregkh@...uxfoundation.org, alan@...ux.intel.com,
linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: marek.vasut@...il.com, Tomas Hlavacek <tmshlvck@...il.com>
Subject: [PATCHv4 1/1] [RFC] uartclk from serial_core exposed to sysfs
Added file /sys/devices/.../tty/ttySX/uartclk to allow reading
uartclk value in struct uart_port in serial_core via sysfs.
It simplifies initialization verification of no-name cards that
have non-standard oscillator speed while having no distinguishing
PCI IDs to allow autodetection.
tty_register_device() has been generalized and refactored in order
to add support for setting drvdata and attribute_group to the device.
Signed-off-by: Tomas Hlavacek <tmshlvck@...il.com>
---
Documentation/ABI/testing/sysfs-tty | 9 +++++
drivers/tty/serial/serial_core.c | 37 +++++++++++++++++++-
drivers/tty/tty_io.c | 63 ++++++++++++++++++++++++++++++++---
include/linux/tty.h | 4 +++
4 files changed, 108 insertions(+), 5 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-tty b/Documentation/ABI/testing/sysfs-tty
index b138b66..b93a174 100644
--- a/Documentation/ABI/testing/sysfs-tty
+++ b/Documentation/ABI/testing/sysfs-tty
@@ -17,3 +17,12 @@ Description:
device, like 'tty1'.
The file supports poll() to detect virtual
console switches.
+
+What: /sys/class/tty/ttyS0/uartclk
+Date: Aug 2012
+Contact: Tomas Hlavacek <tmshlvck@...il.com>
+Description:
+ Shows the current uartclk value associated with the
+ UART port in serial_core, that is bound to TTY like ttyS0.
+ uartclk = 16 * baud_base
+
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index a21dc8e..e0c11da 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2293,6 +2293,38 @@ struct tty_driver *uart_console_device(struct console *co, int *index)
return p->tty_driver;
}
+static ssize_t uart_get_attr_uartclk(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ int ret;
+
+ struct tty_port *port = dev_get_drvdata(dev);
+ struct uart_state *state = container_of(port, struct uart_state, port);
+
+ mutex_lock(&state->port.mutex);
+ ret = snprintf(buf, PAGE_SIZE, "%d\n", state->uart_port->uartclk);
+ mutex_unlock(&state->port.mutex);
+
+ return ret;
+}
+
+static DEVICE_ATTR(uartclk, S_IRUSR | S_IRGRP, uart_get_attr_uartclk,
+ NULL);
+
+static struct attribute *tty_dev_attrs[] = {
+ &dev_attr_uartclk.attr,
+ NULL,
+};
+
+static struct attribute_group tty_dev_attr_group = {
+ .attrs = tty_dev_attrs,
+};
+
+static struct attribute_group *tty_dev_attr_groups[] = {
+ &tty_dev_attr_group,
+ NULL
+};
+
/**
* uart_add_one_port - attach a driver-defined port structure
* @drv: pointer to the uart low level driver structure for this port
@@ -2345,8 +2377,11 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
/*
* Register the port whether it's detected or not. This allows
* setserial to be used to alter this ports parameters.
+ * Use driverdata of the tty device for referencing the UART port.
+ * Set default device attributes to the new device.
*/
- tty_dev = tty_register_device(drv->tty_driver, uport->line, uport->dev);
+ tty_dev = tty_register_device_attr(drv->tty_driver, uport->line,
+ uport->dev, port, tty_dev_attr_groups);
if (likely(!IS_ERR(tty_dev))) {
device_set_wakeup_capable(tty_dev, 1);
} else {
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index b425c79..1c9d5b5 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -3009,12 +3009,42 @@ struct class *tty_class;
*
* Locking: ??
*/
-
struct device *tty_register_device(struct tty_driver *driver, unsigned index,
struct device *device)
{
+ return tty_register_device_attr(driver, index, device, NULL, NULL);
+}
+EXPORT_SYMBOL(tty_register_device);
+
+/**
+ * tty_register_device_attr - register a tty device
+ * @driver: the tty driver that describes the tty device
+ * @index: the index in the tty driver for this tty device
+ * @device: a struct device that is associated with this tty device.
+ * This field is optional, if there is no known struct device
+ * for this tty device it can be set to NULL safely.
+ * @drvdata: Driver data to be set to device (NULL = do not touch).
+ * @attr_grp: Attribute group to be set on device (NULL = do not touch).
+ *
+ * Returns a pointer to the struct device for this tty device
+ * (or ERR_PTR(-EFOO) on error).
+ *
+ * This call is required to be made to register an individual tty device
+ * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
+ * that bit is not set, this function should not be called by a tty
+ * driver.
+ *
+ * Locking: ??
+ */
+struct device *tty_register_device_attr(struct tty_driver *driver,
+ unsigned index, struct device *device,
+ void *drvdata,
+ struct attribute_group **attr_grp)
+{
char name[64];
- dev_t dev = MKDEV(driver->major, driver->minor_start) + index;
+ struct device *dev = NULL;
+ int retval = -ENODEV;
+ dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
if (index >= driver->num) {
printk(KERN_ERR "Attempt to register invalid tty line number "
@@ -3027,9 +3057,34 @@ struct device *tty_register_device(struct tty_driver *driver, unsigned index,
else
tty_line_name(driver, index, name);
- return device_create(tty_class, device, dev, NULL, name);
+
+ dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+ if (!dev) {
+ retval = -ENOMEM;
+ goto error;
+ }
+
+ dev->devt = devt;
+ dev->class = tty_class;
+ dev->parent = device;
+ dev_set_name(dev, "%s", name);
+ if (attr_grp)
+ dev->groups = attr_grp;
+ if (drvdata)
+ dev_set_drvdata(dev, drvdata);
+
+ retval = device_register(dev);
+ if (retval)
+ goto error;
+
+ return dev;
+
+error:
+ put_device(dev);
+ return ERR_PTR(retval);
+
}
-EXPORT_SYMBOL(tty_register_device);
+EXPORT_SYMBOL_GPL(tty_register_device_attr);
/**
* tty_unregister_device - unregister a tty device
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 9f47ab5..424777a 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -410,6 +410,10 @@ extern int tty_register_driver(struct tty_driver *driver);
extern int tty_unregister_driver(struct tty_driver *driver);
extern struct device *tty_register_device(struct tty_driver *driver,
unsigned index, struct device *dev);
+struct device *tty_register_device_attr(struct tty_driver *driver,
+ unsigned index, struct device *device,
+ void *drvdata,
+ struct attribute_group **attr_grp);
extern void tty_unregister_device(struct tty_driver *driver, unsigned index);
extern int tty_read_raw_data(struct tty_struct *tty, unsigned char *bufp,
int buflen);
--
1.7.10.4
--
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