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Subject[PATCH v6] uartclk value from serial_core exposed to sysfs
Date
Added file /sys/devices/.../tty/ttySX/uartclk to allow reading
uartclk value in struct uart_port in serial_core via sysfs.

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@gmail.com>
---
Documentation/ABI/testing/sysfs-tty | 9 +++++
drivers/tty/serial/serial_core.c | 34 ++++++++++++++++-
drivers/tty/tty_io.c | 69 ++++++++++++++++++++++++++++++-----
include/linux/tty.h | 4 ++
4 files changed, 104 insertions(+), 12 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-tty b/Documentation/ABI/testing/sysfs-tty
index b138b66..0c43015 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: Sep 2012
+Contact: Tomas Hlavacek <tmshlvck@gmail.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 137b25c..5d212f8 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2309,6 +2309,36 @@ 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 const 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
@@ -2362,8 +2392,8 @@ 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.
*/
- tty_dev = tty_port_register_device(port, 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 d3bf91a..dcb30d5 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -3041,9 +3041,39 @@ static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
struct device *tty_register_device(struct tty_driver *driver, unsigned index,
struct device *device)
{
- struct device *ret;
+ 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.
+ * @attr_grp: Attribute group to be set on device.
+ *
+ * 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,
+ const struct attribute_group **attr_grp)
+{
char name[64];
- dev_t dev = MKDEV(driver->major, driver->minor_start) + index;
+ dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
+ struct device *dev = NULL;
+ int retval = -ENODEV;
bool cdev = false;

if (index >= driver->num) {
@@ -3058,19 +3088,38 @@ struct device *tty_register_device(struct tty_driver *driver, unsigned index,
tty_line_name(driver, index, name);

if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
- int error = tty_cdev_add(driver, dev, index, 1);
- if (error)
- return ERR_PTR(error);
+ retval = tty_cdev_add(driver, devt, index, 1);
+ if (retval)
+ goto error;
cdev = true;
}

- ret = device_create(tty_class, device, dev, NULL, name);
- if (IS_ERR(ret) && cdev)
- cdev_del(&driver->cdevs[index]);
+ dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+ if (!dev) {
+ retval = -ENOMEM;
+ goto error;
+ }

- return ret;
+ dev->devt = devt;
+ dev->class = tty_class;
+ dev->parent = device;
+ dev_set_name(dev, "%s", name);
+ dev->groups = attr_grp;
+ dev_set_drvdata(dev, drvdata);
+
+ retval = device_register(dev);
+ if (retval)
+ goto error;
+
+ return dev;
+
+error:
+ put_device(dev);
+ if (cdev)
+ cdev_del(&driver->cdevs[index]);
+ 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 9892121..599d603 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -412,6 +412,10 @@ 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);
+extern struct device *tty_register_device_attr(struct tty_driver *driver,
+ unsigned index, struct device *device,
+ void *drvdata,
+ const 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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