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Message-Id: <1344929718-22736-1-git-send-email-tmshlvck@gmail.com>
Date: Tue, 14 Aug 2012 09:35:18 +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: [PATCH 1/1] [RFC] uartclk from serial_core exposed to sysfs
Support for read/modify of uartclk via sysfs added.
It may prove useful with some no-name cards that
has different oscillator speeds and no distinguishing
PCI IDs to allow autodetection. It allows better integration
with udev and/or init scripts.
Signed-off-by: Tomas Hlavacek <tmshlvck@...il.com>
---
drivers/tty/serial/serial_core.c | 54 ++++++++++++++++++++++++++++++++++++++
drivers/tty/tty_io.c | 17 ++++++++++++
include/linux/tty.h | 2 ++
3 files changed, 73 insertions(+)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index a21dc8e..059b438 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2293,6 +2293,46 @@ struct tty_driver *uart_console_device(struct console *co, int *index)
return p->tty_driver;
}
+static ssize_t get_attr_uartclk(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ int ret;
+
+ struct uart_state *state = (struct uart_state *)(dev_get_drvdata(dev));
+ mutex_lock(&state->port.mutex);
+ ret = snprintf(buf, PAGE_SIZE, "%d\n", state->uart_port->uartclk);
+ mutex_unlock(&state->port.mutex);
+ return ret;
+}
+
+static ssize_t set_attr_uartclk(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t count)
+{
+ struct uart_state *state = (struct uart_state *)(dev_get_drvdata(dev));
+ unsigned int val;
+ int ret;
+
+ ret = kstrtouint(buf, 10, &val);
+ if (ret)
+ return ret;
+
+ mutex_lock(&state->port.mutex);
+
+ /*
+ * Check value: baud_base has to be more than 9600
+ * and uartclock = baud_base * 16 .
+ */
+ if (val >= 153600)
+ state->uart_port->uartclk = val;
+
+ mutex_unlock(&state->port.mutex);
+
+ return count;
+}
+
+static DEVICE_ATTR(uartclk, S_IRUGO | S_IWUSR, get_attr_uartclk,
+ set_attr_uartclk);
+
/**
* uart_add_one_port - attach a driver-defined port structure
* @drv: pointer to the uart low level driver structure for this port
@@ -2355,6 +2395,14 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
}
/*
+ * Expose uartclk in sysfs. Use driverdata of the tty device for
+ * referencing the UART port.
+ */
+ dev_set_drvdata(tty_dev, state);
+ if (device_create_file(tty_dev, &dev_attr_uartclk) < 0)
+ dev_err(tty_dev, "Failed to add uartclk attr\n");
+
+ /*
* Ensure UPF_DEAD is not set.
*/
uport->flags &= ~UPF_DEAD;
@@ -2397,6 +2445,12 @@ int uart_remove_one_port(struct uart_driver *drv, struct uart_port *uport)
mutex_unlock(&port->mutex);
/*
+ * Remove uartclk file from sysfs.
+ */
+ device_remove_file(tty_lookup_device(drv->tty_driver, uport->line),
+ &dev_attr_uartclk);
+
+ /*
* Remove the devices from the tty layer
*/
tty_unregister_device(drv->tty_driver, uport->line);
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index b425c79..8ea8622 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -3049,6 +3049,23 @@ void tty_unregister_device(struct tty_driver *driver, unsigned index)
}
EXPORT_SYMBOL(tty_unregister_device);
+/*
+ * tty_lookup_device - lookup a tty device
+ * @driver: the tty driver that describes the tty device
+ * @index: the index in the tty driver for this tty device
+ *
+ * This function returns a struct device pointer when device has
+ * been found and NULL otherwise.
+ *
+ * Locking: ??
+ */
+struct device *tty_lookup_device(struct tty_driver *driver, unsigned index)
+{
+ dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
+ return class_find_device(tty_class, NULL, &devt, dev_match_devt);
+}
+EXPORT_SYMBOL(tty_lookup_device);
+
struct tty_driver *__alloc_tty_driver(int lines, struct module *owner)
{
struct tty_driver *driver;
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 9f47ab5..5d408a1 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -410,6 +410,8 @@ 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_lookup_device(struct tty_driver *driver,
+ unsigned index);
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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