From: Marek Vasut <marek.vasut@gmail.com>
To: Tomas Hlavacek <tmshlvck@gmail.com>
Cc: gregkh@linuxfoundation.org, alan@linux.intel.com,
linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] [RFC] uartclk from serial_core exposed to sysfs
Date: Tue, 14 Aug 2012 14:50:23 +0200 [thread overview]
Message-ID: <201208141450.23453.marek.vasut@gmail.com> (raw)
In-Reply-To: <1344929718-22736-1-git-send-email-tmshlvck@gmail.com>
Dear Tomas Hlavacek,
> 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@gmail.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));
You don't need this cast here.
> + mutex_lock(&state->port.mutex);
> + ret = snprintf(buf, PAGE_SIZE, "%d\n", state->uart_port->uartclk);
Do you really need such a large buffer (PAGE_SIZE) ?
> + 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;
This magic value here would use some documentation.
> + 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);
next prev parent reply other threads:[~2012-08-14 12:50 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAEB7QLAJXkK6NDPVDi36n_U_X_DGh5niHJhH6FpqBUZFmXQ2Xg@mail.gmail.com>
2012-08-14 7:35 ` [PATCH 1/1] [RFC] uartclk from serial_core exposed to sysfs Tomas Hlavacek
2012-08-14 12:50 ` Marek Vasut [this message]
2012-08-15 17:09 ` Tomas Hlavacek
2012-08-15 17:12 ` [PATCHv2 " Tomas Hlavacek
2012-08-16 10:31 ` [PATCH " Alan Cox
2012-08-17 14:43 ` [PATCHv3 " Tomas Hlavacek
2012-08-17 15:06 ` Greg KH
2012-08-17 16:30 ` Tomas Hlavacek
2012-08-17 16:54 ` Greg KH
2012-08-17 18:44 ` Marek Vasut
2012-08-17 19:01 ` Greg KH
2012-08-17 20:25 ` Tomas Hlavacek
2012-08-19 18:34 ` [PATCHv4 " Tomas Hlavacek
2012-08-21 13:24 ` Tomas Hlavacek
2012-08-21 13:44 ` Alan Cox
2012-09-05 20:36 ` Greg KH
2012-09-05 23:16 ` [PATCHv5 1/1] uartclk value " Tomas Hlavacek
2012-09-05 23:42 ` Greg KH
2012-09-06 1:01 ` Tomas Hlavacek
2012-09-06 1:17 ` [PATCH v6] " Tomas Hlavacek
2012-09-06 16:23 ` [PATCH v6] tty: " Greg KH
2012-09-06 17:54 ` [PATCH v6] " Jiri Slaby
2012-09-06 18:39 ` Tomas Hlavacek
2012-09-06 18:54 ` Jiri Slaby
2012-09-06 19:41 ` Tomas Hlavacek
2012-09-06 19:47 ` Jiri Slaby
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