From: Jiri Slaby <jslaby@suse.cz>
To: Baruch Siach <baruch@tkos.co.il>
Cc: linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Indan Zupancic <indan@nul.nu>, Greg KH <greg@kroah.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Alex Gershgorin <agersh@rambler.ru>
Subject: Re: [PATCHv3] drivers/misc: Altera active serial implementation
Date: Mon, 15 Nov 2010 10:33:37 +0100 [thread overview]
Message-ID: <4CE0FE71.6000303@suse.cz> (raw)
In-Reply-To: <fa8a1cda966a356d4c0bfe6e285c01679bf6ef60.1289809182.git.baruch@tkos.co.il>
On 11/15/2010 09:23 AM, Baruch Siach wrote:
> --- /dev/null
> +++ b/drivers/misc/altera_as.c
> @@ -0,0 +1,349 @@
...
> +struct altera_as_device {
> + unsigned id;
> + struct device *dev;
> + struct miscdevice miscdev;
> + struct mutex open_lock;
> + struct gpio gpios[AS_GPIO_NUM];
> +};
> +
> +/*
> + * The only functions updating this array are .probe/.remove, which are
> + * serialized. Hence, no locking is needed here.
> + */
> +static struct {
> + int minor;
Why you need minor here? It's in drvdata->miscdev.minor.
> + struct altera_as_device *drvdata;
> +} altera_as_devs[AS_MAX_DEVS];
You don't need the struct at all.
static struct altera_as_device *drvdata[AS_MAX_DEVS];
should be enough.
> +static int altera_as_open(struct inode *inode, struct file *file)
> +{
> + int ret;
> + struct altera_as_device *drvdata = get_as_dev(iminor(inode));
> +
> + if (drvdata == NULL)
> + return -ENODEV;
> + file->private_data = drvdata;
> +
> + ret = mutex_trylock(&drvdata->open_lock);
> + if (ret == 0)
> + return -EBUSY;
> +
> + ret = gpio_request_array(drvdata->gpios, ARRAY_SIZE(drvdata->gpios));
> + if (ret < 0) {
> + mutex_unlock(&drvdata->open_lock);
> + return ret;
> + }
So leaving to userspace with mutex held. This is *wrong*. use
test_and_set_bit or alike instead.
> + return 0;
> +}
> +
> +static ssize_t altera_as_write(struct file *file, const char __user *buf,
> + size_t count, loff_t *ppos)
> +{
...
> + while ((count - written) > 0) {
> + err = copy_from_user(page_buf, buf+written, AS_PAGE_SIZE);
> + if (err < 0) {
> + err = -EFAULT;
> + goto out;
> + }
> +
> + xmit_cmd(drvdata->gpios, AS_WRITE_ENABLE);
> +
> + gpio_set_value(drvdata->gpios[ASIO_NCS].gpio, 0);
> + /* op code */
> + xmit_byte(drvdata->gpios, AS_PAGE_PROGRAM);
> + /* address */
> + xmit_byte(drvdata->gpios, (*ppos >> 16) & 0xff);
> + xmit_byte(drvdata->gpios, (*ppos >> 8) & 0xff);
> + xmit_byte(drvdata->gpios, *ppos & 0xff);
> + /* page data (LSB first) */
> + for (i = 0; i < AS_PAGE_SIZE; i++)
> + xmit_byte(drvdata->gpios, bitrev8(page_buf[i]));
> + gpio_set_value(drvdata->gpios[ASIO_NCS].gpio, 1);
> + mdelay(7);
So if I write 100 pages, I will _spin_ for 700 ms. You should rather
(m)sleep here.
> +
> + *ppos += AS_PAGE_SIZE;
> + written += AS_PAGE_SIZE;
> + }
> +
> +out:
> + kfree(page_buf);
> + return err ?: written;
> +}
...
> +static int __init altera_as_probe(struct platform_device *pdev)
> +{
...
> + drvdata->miscdev.minor = MISC_DYNAMIC_MINOR;
> + drvdata->miscdev.name = kasprintf(GFP_KERNEL, "altera_as%d",
> + pdata->id);
> + if (drvdata->miscdev.name == NULL)
> + return -ENOMEM;
> + drvdata->miscdev.fops = &altera_as_fops;
> + if (misc_register(&drvdata->miscdev) < 0) {
Hmm, how many devices can be in the system? This doesn't look like the
right way.
> + kfree(drvdata->miscdev.name);
> + return -ENODEV;
> + }
> + altera_as_devs[pdata->id].minor = drvdata->miscdev.minor;
> + altera_as_devs[pdata->id].drvdata = drvdata;
So now the device is usable without the mutex and gpios inited?
> + mutex_init(&drvdata->open_lock);
> +
> + drvdata->id = pdata->id;
> +
> + drvdata->gpios[ASIO_DATA].gpio = pdata->data;
> + drvdata->gpios[ASIO_DATA].flags = GPIOF_IN;
> + drvdata->gpios[ASIO_DATA].label = "as_data";
...
> + drvdata->gpios[ASIO_NCE].gpio = pdata->nce;
> + drvdata->gpios[ASIO_NCE].flags = GPIOF_OUT_INIT_HIGH;
> + drvdata->gpios[ASIO_NCE].label = "as_nce";
> +
> + dev_info(drvdata->dev, "Altera Cyclone Active Serial driver\n");
> +
> + return 0;
> +}
regards,
--
js
suse labs
next prev parent reply other threads:[~2010-11-15 9:33 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-15 8:23 [PATCHv3] drivers/misc: Altera active serial implementation Baruch Siach
2010-11-15 9:33 ` Jiri Slaby [this message]
2010-11-15 10:08 ` Baruch Siach
2010-11-15 10:28 ` Jiri Slaby
2010-11-15 13:40 ` Baruch Siach
2010-11-15 14:24 ` Jiri Slaby
2010-11-15 16:19 ` Greg KH
2010-11-16 0:47 ` Indan Zupancic
2010-11-16 5:56 ` Baruch Siach
2010-11-16 7:42 ` H. Peter Anvin
2010-11-16 11:04 ` Alan Cox
2010-11-16 13:09 ` Jiri Slaby
2010-11-17 5:32 ` Baruch Siach
2010-11-17 5:43 ` H. Peter Anvin
2010-11-17 5:48 ` Baruch Siach
2010-11-17 8:31 ` Jiri Slaby
2010-11-17 11:08 ` Alan Cox
2010-11-16 11:05 ` Alan Cox
2010-11-17 6:18 ` Thomas Chou
2010-11-17 13:28 ` Baruch Siach
[not found] ` <4CE42457.8090001@zytor.com>
2010-11-18 2:15 ` Thomas Chou
2010-11-18 2:15 ` H. Peter Anvin
2010-11-22 5:57 ` Baruch Siach
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