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Message-Id: <20080229123512.f85f417c.akpm@linux-foundation.org>
Date: Fri, 29 Feb 2008 12:35:12 -0800
From: Andrew Morton <akpm@...ux-foundation.org>
To: Dirk Eibach <eibach@...ys.de>
Cc: linux-kernel@...r.kernel.org, greg@...ah.com, apw@...dowen.org,
linux-usb@...r.kernel.org
Subject: Re: [PATCH] usb: add sysfs configuration interface for CP2101
On Fri, 29 Feb 2008 13:31:11 +0100
Dirk Eibach <eibach@...ys.de> wrote:
> So here is a new try.
>
Please reissue the possibly-updated changelog and signed-off-by: with each
revision of a patch.
Please cc linux-usb on usb patches.
> diff -purN linux-2.6.24/drivers/usb/serial/cp2101.c linux-2.6.24-diff/drivers/usb/serial/cp2101.c
> --- linux-2.6.24/drivers/usb/serial/cp2101.c 2008-01-24 23:58:37.000000000 +0100
> +++ linux-2.6.24-diff/drivers/usb/serial/cp2101.c 2008-02-29 13:15:58.168233146 +0100
> @@ -18,6 +18,8 @@
> */
>
> #include <linux/kernel.h>
> +#include <linux/fs.h>
> +#include <linux/platform_device.h>
> #include <linux/errno.h>
> #include <linux/slab.h>
> #include <linux/tty.h>
> @@ -52,6 +54,8 @@ static void cp2101_shutdown(struct usb_s
>
> static int debug;
>
> +static int enable_config = false;
Should be either
static int enable_config;
or, if you're being very formal,
static bool enable_config = false;
or, if you're being less formal and want to avoid bloating the kernel image,
static bool enable_config;
> +static ssize_t write_reload(struct device *dev, struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + int result;
> + struct usb_device *usbdev = container_of(dev, struct usb_device, dev);
> +
> + /* writing "0" does not trigger */
> + if (!strict_strtoul(buf, NULL, 0))
> + return count;
> +
> + result = usb_control_msg(usbdev,
> + usb_sndctrlpipe(usbdev, 0),
> + CP2101_EEPROM, REQTYPE_HOST_TO_DEVICE, EEPROM_RELOAD,
> + 0, NULL, 0, 300);
> +
> + /* this request is expected to fail because cp210x reboots */
> +
> + return count;
> +}
The comment will suffice - there's no need to add the do-nothing `result'.
> +static DEVICE_ATTR(reload, S_IWUGO, NULL, write_reload);
> +
> +static ssize_t write_vendor_id(struct device *dev, struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + int result;
> + struct usb_device *usbdev = container_of(dev, struct usb_device, dev);
> +
> + unsigned long vendor_id = strict_strtoul(buf, NULL, 0);
> +
> + if (!vendor_id || vendor_id > 0xffff)
> + return -EINVAL;
> +
> + result = usb_control_msg(usbdev,
> + usb_sndctrlpipe(usbdev, 0),
> + CP2101_EEPROM, REQTYPE_HOST_TO_DEVICE, EEPROM_VENDOR_ID,
> + vendor_id, NULL, 0, 300);
> +
> + if (result)
> + return -EIO;
> +
> + return count;
> +}
usb_control_msg() already returns an errno - we should just propagate that
back to the caller rather than overwriting, say, -ENOMEM with -EIO.
> +static DEVICE_ATTR(vendor_id, S_IWUGO, NULL, write_vendor_id);
> +
> +static ssize_t write_product_id(struct device *dev, struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + int result;
> + struct usb_device *usbdev = container_of(dev, struct usb_device, dev);
> +
> + unsigned long product_id = strict_strtoul(buf, NULL, 0);
> +
> + if (!product_id || product_id > 0xffff)
> + return -EINVAL;
> +
> + result = usb_control_msg(usbdev,
> + usb_sndctrlpipe(usbdev, 0),
> + CP2101_EEPROM, REQTYPE_HOST_TO_DEVICE, EEPROM_PRODUCT_ID,
> + product_id, NULL, 0, 300);
> +
> + if (result)
> + return -EIO;
> +
> + return count;
> +}
ditto
> +static DEVICE_ATTR(product_id, S_IWUGO, NULL, write_product_id);
> +
> +static ssize_t write_serialnumber(struct device *dev,
> + struct device_attribute *attr, const char *buf, size_t count)
> +{
> + int result;
> + unsigned int k;
> + struct usb_device *usbdev = container_of(dev, struct usb_device, dev);
> + u8 serial_stringsize = 2 + 2*count;
> + char serial[2 + 2*SERIALNUMBER_MAX_CHARS];
128 bytes of stack is a little more than we'd like (the kernel is really
squeezy on stack space sometimes). kmalloc would be better...
> + if (count > SERIALNUMBER_MAX_CHARS)
> + return -EINVAL;
> +
> + serial[0] = serial_stringsize;
> + serial[1] = USB_DT_STRING;
> +
> + /* convert to utf-16 */
> + printk("#Max index: %d\n", serial_stringsize - 1);
checkpatch...
> + for (k = 0; k < count; ++k) {
> + printk("Address index %d and %d\n", 2+2*k, 2+2*k+1);
> + serial[2+2*k] = buf[k];
> + serial[2+2*k+1] = 0;
> + }
> +
> + result = usb_control_msg(usbdev,
> + usb_sndctrlpipe(usbdev, 0),
> + CP2101_EEPROM, REQTYPE_HOST_TO_DEVICE, EEPROM_SERIALNUMBER,
> + 0, serial, serial_stringsize, 300);
> +
> + if (result != serial_stringsize)
> + return -EIO;
> +
> + return count;
> +}
>
> ...
>
> +static ssize_t write_lock_forever(struct device *dev,
> + struct device_attribute *attr, const char *buf, size_t count)
> +{
> + int result;
> + struct usb_device *usbdev = container_of(dev, struct usb_device, dev);
> +
> + unsigned long lock = strict_strtoul(buf, NULL, 0);
> +
> + /* be really, really sure to know what you are doing here */
> + if (lock != 0xabadbabe)
> + return -EINVAL;
this is incomprehehsible without docs
> + result = usb_control_msg(usbdev,
> + usb_sndctrlpipe(usbdev, 0),
> + CP2101_EEPROM, REQTYPE_HOST_TO_DEVICE, EEPROM_LOCK,
> + 0x00f0, NULL, 0, 300);
> +
> + if (result)
> + return -EIO;
> +
> + return count;
> +}
> +
> +static DEVICE_ATTR(lock_forever, S_IWUGO, NULL, write_lock_forever);
> +
> +static struct attribute *cp2101_attributes[] = {
> + &dev_attr_reload.attr,
> + &dev_attr_vendor_id.attr,
> + &dev_attr_product_id.attr,
> + &dev_attr_productstring.attr,
> + &dev_attr_serialnumber.attr,
> + &dev_attr_self_powered.attr,
> + &dev_attr_max_power.attr,
> + &dev_attr_release_version.attr,
> + &dev_attr_lock_forever.attr,
> + NULL
> +};
> +
> +static const struct attribute_group cp2101_group = {
> + .attrs = cp2101_attributes,
> +};
> +
> static int cp2101_startup (struct usb_serial *serial)
> {
> + int err;
> +
> /* CP2101 buffers behave strangely unless device is reset */
> usb_reset_device(serial->dev);
> - return 0;
> +
> + if (!enable_config)
> + return 0;
> +
> + err = sysfs_create_group(&serial->dev->dev.kobj, &cp2101_group);
> +
> + return err;
> }
>
> static void cp2101_shutdown (struct usb_serial *serial)
> @@ -721,6 +1015,11 @@ static void cp2101_shutdown (struct usb_
> for (i=0; i < serial->num_ports; ++i) {
> cp2101_cleanup(serial->port[i]);
> }
> +
> + if (!enable_config)
> + return;
> +
> + sysfs_remove_group(&serial->dev->dev.kobj, &cp2101_group);
> }
>
> static int __init cp2101_init (void)
> @@ -758,3 +1057,6 @@ MODULE_LICENSE("GPL");
>
> module_param(debug, bool, S_IRUGO | S_IWUSR);
> MODULE_PARM_DESC(debug, "Enable verbose debugging messages");
> +
> +module_param(enable_config, bool, S_IRUGO | S_IWUSR);
> +MODULE_PARM_DESC(enable_config, "Enable sysfs access to configuration eeprom.");
>
--
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