From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Oliver Schinagl <oliver+list@schinagl.nl>
Cc: Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"maxime.ripard" <maxime.ripard@free-electrons.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
Russell King <linux@arm.linux.org.uk>,
Linus Walleij <linus.walleij@linaro.org>,
Oliver Schinagl <oliver@schinagl.nl>
Subject: Re: [PATCH 1/2] Initial support for Allwinner's Security ID fuses
Date: Sat, 15 Jun 2013 05:14:49 +0300 [thread overview]
Message-ID: <CAHp75VdOrSA8EomPruMKzMgnSaVdtEEV0uB9bRpRGv7LiBsRPA@mail.gmail.com> (raw)
In-Reply-To: <1371251781-17167-2-git-send-email-oliver+list@schinagl.nl>
On Sat, Jun 15, 2013 at 2:16 AM, 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. To write these fuses, 2.5 V
> needs to be applied to this pin.
>
> 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 (A10s, A13)
Few comments below.
> +++ b/drivers/misc/eeprom/sunxi_sid.c
> +#include <linux/compiler.h>
Are you sure this has to be explicitly mentioned?
> +#define SID_SIZE (SID_KEYS * 4)
> +
> +
Extra line.
> +/* 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 simpler.
May be better to rewrite this logic and save CPU and I/O resources?
> + */
> +static u8 sunxi_sid_read_byte(const void __iomem *sid_reg_base,
> + const unsigned int offset)
> +{
> + u32 sid_key = 0;
> +
> + if (offset >= SID_SIZE)
> + goto exit;
Just return here.
> + sid_key = ioread32be(sid_reg_base + round_down(offset, 4));
> + sid_key >>= (offset % 4) * 8;
> + sid_key &= 0xff;
Redundant 0xff.
> + /* fall through */
> +
> +exit:
> + return (u8)sid_key;
No need to have explicit casting here.
> + pdev = (struct platform_device *)to_platform_device(kobj_to_dev(kobj));
Ditto.
> + sid_reg_base = (void __iomem *)platform_get_drvdata(pdev);
Ditto.
> +static int sunxi_sid_remove(struct platform_device *pdev)
> +{
> + device_remove_bin_file(&pdev->dev, &sid_bin_attr);
> + dev_info(&pdev->dev, "sunxi SID driver unloaded\n");
Often this is useless message. In what case this is crucial?
> +static int __init sunxi_sid_probe(struct platform_device *pdev)
> +{
> + int entropy[SID_SIZE], i;
> + struct resource *res;
> + void __iomem *sid_reg_base;
> + int ret;
> +
> + if (!pdev->dev.of_node) {
> + dev_err(&pdev->dev, "No devicetree data available\n");
> + ret = -ENXIO;
> + goto exit;
You have only return, use it. It's common practice in the .probe() function.
> + if (IS_ERR(sid_reg_base)) {
> + ret = PTR_ERR(sid_reg_base);
> + goto exit;
Ditto.
> + ret = device_create_bin_file(&pdev->dev, &sid_bin_attr);
> + if (ret) {
> + dev_err(&pdev->dev, "Unable to create sysfs bin entry\n");
> + goto exit;
Ditto.
> + dev_info(&pdev->dev, "sunxi SID ver %s loaded\n", DRV_VERSION);
> + ret = 0;
> + /* fall through */
Ditto.
> +
> +exit:
> + return ret;
Useless lines.
> +module_platform_driver(sunxi_sid_driver);
> +
> +
Extra line.
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2013-06-15 2:14 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
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 [this message]
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
2013-06-14 23:16 ` [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
2013-06-02 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
2013-06-10 21:43 ` Oliver Schinagl
2013-06-11 10:51 ` Andy Shevchenko
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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