From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Oliver Schinagl <oliver+list@schinagl.nl>
Cc: maxime.ripard@free-electrons.com, Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
Oliver Schinagl <oliver@schinagl.nl>
Subject: Re: [PATCH 1/2] Initial support for Allwinner's Security ID fuses
Date: Thu, 6 Jun 2013 22:16:56 +0300 [thread overview]
Message-ID: <CAHp75Vdqc9xiPBvQUB3Hfb4EBFUsoVxyuH8MK=9spJ4+rieoDQ@mail.gmail.com> (raw)
In-Reply-To: <1370185130-15332-2-git-send-email-oliver+list@schinagl.nl>
On Sun, Jun 2, 2013 at 5:58 PM, Oliver Schinagl <oliver+list@schinagl.nl> wrote:
> From: Oliver Schinagl <oliver@schinagl.nl>
>
> Allwinner has electric fuses (efuse) on their line of chips. This driver
> reads those fuses, seeds the kernel entropy and exports them as a sysfs node.
>
> These fuses are most likly to be programmed at the factory, encoding
> things like Chip ID, some sort of serial number etc and appear to be
> reasonable unique.
> While in theory, these should be writeable by the user, it will probably
> be inconvinient to do so. Allwinner recommends that a certain input pin,
> labeled 'efuse_vddq', be connected to GND. From the name however it is
> highly likly that this name is the programming voltage, required to
> write these fuses.
> Even so, they can still be used to generate a board-unique mac from, board
> unique RSA key and seed the kernel RNG.
>
> Currently supported are the following known chips:
> Allwinner sun4i (A10)
> Allwinner sun5i (A13)
Few commets below.
> +++ b/drivers/misc/eeprom/sunxi_sid.c
> @@ -0,0 +1,172 @@
> +#define DRV_NAME "sunxi-sid"
> +#define DRV_VERSION "1.0"
> +static void __iomem *p_sid_reg_base;
So, why it's global?
> +/* We read the entire key, but only return the requested byte. This is of
> + * course slower then it could be and uses 4 times more reads as needed but
> + * keeps code a simpler.
> + */
> +u8 sunxi_sid_read_byte(const int offset)
> +{
> + u32 sid_key;
> + u8 ret;
> +
> + ret = 0;
ret is redundant variable in this function.
> + if (likely((SID_SIZE))) {
Extra braces.
Use antipattern here.
> + sid_key = ioread32be(p_sid_reg_base + round_down(offset, 4));
> + sid_key >>= (offset % 4) * 8;
> + ret = sid_key & 0xff;
No need to do & 0xff, since return type is byte.
> +static ssize_t sid_read(struct file *fd, struct kobject *kobj,
> + struct bin_attribute *attr, char *buf,
> + loff_t pos, size_t size)
> +{
> + ssize_t ret;
> + int i;
> +
> + ret = -EPERM;
When will it happen?
Moreover, ret is redundant.
> +
> + if ((likely(size > 0)) && ((size + pos) <= SID_SIZE)) {
Extra braces in second part of condition.
Use antipattern.
> +static int __init sunxi_sid_probe(struct platform_device *pdev)
> +{
> + int entropy[SID_SIZE], i, ret;
Usually ret variable is located at the end of definition block.
Moreover, there is no relationship between those three. It means one
line per variable.
> + struct device *dev;
> + struct resource *res;
> + void __iomem *sid_reg_base;
> +
> + dev = &pdev->dev;
Please, be consistent, somewhere you still use &pdev->dev.
I recomend to use &pdev->dev everywhere in probe(), since we don't
know if the device will be probed successfully.
> + if (unlikely(!pdev->dev.of_node)) {
> + dev_err(dev, "No devicetree data available\n");
> + ret = -EFAULT;
> + goto exit;
Plain return here and in entire function where it applies.
> + }
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + sid_reg_base = devm_ioremap_resource(&pdev->dev, res);
> + if (IS_ERR(sid_reg_base)) {
> + dev_err(dev, "Unable to obtain resource\n");
Redundant message. You have not to duplicate this.
> + ret = PTR_ERR(sid_reg_base);
> + goto exit;
> + }
> + platform_set_drvdata(pdev, sid_reg_base);
> + p_sid_reg_base = sid_reg_base;
> +
> + ret = device_create_bin_file(dev, &sid_bin_attr);
> + if (unlikely(ret)) {
Any benifit of (un)likely in probe()?
> +
> +
> +exit:
> + return ret;
Remove those two and empty lines.
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2013-06-06 19:17 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-02 14:58 [PATCH 0/2] v2 Driver for Allwinner sunxi Security ID Oliver Schinagl
2013-06-02 14:58 ` [PATCH 1/2] Initial support for Allwinner's Security ID fuses Oliver Schinagl
2013-06-02 15:09 ` Russell King - ARM Linux
2013-06-02 15:21 ` Oliver Schinagl
2013-06-06 19:16 ` Andy Shevchenko [this message]
2013-06-10 21:43 ` Oliver Schinagl
2013-06-11 10:51 ` Andy Shevchenko
2013-06-11 17:44 ` [PATCH 1/2] Initial support for Allwinner's Security ID fuses; Unanswered comments Oliver Schinagl
2013-06-02 14:58 ` [PATCH 2/2] Add sunxi-sid to dts for sun4i and sun5i Oliver Schinagl
-- strict thread matches above, loose matches on Subject: below --
2013-08-27 14:13 [PATCHv5 0/2] Driver for Allwinner sunxi Security ID oliver+list
2013-08-27 14:13 ` [PATCH 1/2] Initial support for Allwinner's Security ID fuses oliver+list
2013-08-27 15:42 ` Maxime Ripard
2013-06-17 20:59 [PATCH 0/2] v4 Driver for Allwinner sunxi Security ID Oliver Schinagl
2013-06-17 20:59 ` [PATCH 1/2] Initial support for Allwinner's Security ID fuses Oliver Schinagl
2013-06-17 21:06 ` Tomasz Figa
2013-06-17 22:58 ` Greg KH
2013-06-24 9:29 ` Maxime Ripard
2013-06-24 16:04 ` Greg KH
2013-06-24 17:11 ` Oliver Schinagl
2013-06-24 18:15 ` Greg KH
2013-06-24 21:21 ` Oliver Schinagl
2013-06-24 21:46 ` Greg KH
2013-06-26 8:32 ` Oliver Schinagl
2013-06-26 17:51 ` Greg KH
2013-07-05 7:24 ` Oliver Schinagl
2013-07-06 19:36 ` Greg KH
2013-07-07 0:17 ` Greg KH
2013-06-26 9:10 ` Russell King - ARM Linux
2013-06-26 17:51 ` Greg KH
2013-06-24 21:04 ` Maxime Ripard
2013-06-26 9:22 ` Geert Uytterhoeven
2013-06-26 17:49 ` Greg KH
2013-06-18 5:41 ` Andy Shevchenko
2013-06-14 23:16 [PATCH 0/2] v3 Driver for Allwinner sunxi Security ID Oliver Schinagl
2013-06-14 23:16 ` [PATCH 1/2] Initial support for Allwinner's Security ID fuses Oliver Schinagl
2013-06-15 2:14 ` Andy Shevchenko
2013-06-15 9:34 ` Oliver Schinagl
2013-06-15 10:28 ` Tomasz Figa
2013-06-17 10:36 ` Oliver Schinagl
2013-06-17 11:25 ` Russell King - ARM Linux
2013-06-17 11:32 ` Oliver Schinagl
2013-06-17 11:51 ` Maxime Ripard
2013-06-17 12:04 ` Oliver Schinagl
2013-06-17 12:51 ` Tomasz Figa
2013-06-17 13:10 ` Oliver Schinagl
2013-06-17 13:23 ` Tomasz Figa
2013-06-17 13:47 ` Oliver Schinagl
2013-05-17 13:35 [PATCH 0/2] Driver for Allwinner sunxi Security ID Oliver Schinagl
2013-05-17 13:35 ` [PATCH 1/2] Initial support for Allwinner's Security ID fuses Oliver Schinagl
2013-05-17 13:45 ` Arnd Bergmann
2013-05-17 18:54 ` Oliver Schinagl
2013-05-17 21:18 ` Maxime Ripard
2013-05-18 17:19 ` Oliver Schinagl
2013-05-19 15:22 ` Maxime Ripard
2013-05-24 21:50 ` Oliver Schinagl
2013-05-25 12:22 ` Maxime Ripard
2013-05-25 19:25 ` Oliver Schinagl
2013-05-26 9:35 ` Maxime Ripard
2013-05-23 7:56 ` Linus Walleij
2013-05-23 8:10 ` Oliver Schinagl
2013-05-23 8:20 ` Linus Walleij
2013-05-23 14:58 ` Maxime Ripard
2013-05-23 15:05 ` Oliver Schinagl
2013-05-23 15:27 ` Maxime Ripard
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