linux-kernel - Re: [PATCH] applesmc: add sysfs file to report OSK

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Date:	Mon, 10 Dec 2012 17:44:20 +0100
From:	Alexander Graf <agraf@...e.de>
To:	"Gabriel L. Somlo" <somlo@....edu>
Cc:	"rydberg@...omail.se" <rydberg@...omail.se>,
	"khali@...ux-fr.org" <khali@...ux-fr.org>,
	"linux@...ck-us.net" <linux@...ck-us.net>,
	"lm-sensors@...sensors.org" <lm-sensors@...sensors.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"rene@...ctcode.com" <rene@...ctcode.com>
Subject: Re: [PATCH] applesmc: add sysfs file to report OSK



On 10.12.2012, at 15:51, "Gabriel L. Somlo" <somlo@....edu> wrote:

> The AppleSMC contains two char[32] keys, OSK0 and OSK1, which are not
> reported in the key count and index by default. These keys are used by
> the OS X boot sequence, and normally don't matter when running Linux.
> 
> This patch creates a sysfs entry which reports the value of these keys
> as an ASCII string, to help emulators (such as QEMU) load OS X when
> running on genuine Apple hardware.
> 
> Signed-off-by: Gabriel L. Somlo <somlo@....edu>

Acked-by: Alexander Graf <agraf@...e.de>

Alex

> ---
> 
> For extra context: To boot OS X as a guest, QEMU must (among others)
> emulate the AppleSMC. To boot successfully, OS X insists on querying
> the (emulated) SMC for the value of OSK0 and OSK1. Currently, these
> values must be supplied on the QEMU command line as
> 
>  -device applesmc,osk="...concatenated values of OSK0 and OSK1..."
> 
> With the availability of /sys/devices/platform/applesmc.768/osk, the
> emulated QEMU AppleSMC could acquire this string directly from the
> (Apple-manufactured) host machine.
> 
> Thanks,
>  Gabriel
> 
> drivers/hwmon/applesmc.c |   18 ++++++++++++++++++
> 1 files changed, 18 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/hwmon/applesmc.c b/drivers/hwmon/applesmc.c
> index b41baff..0c7cc71 100644
> --- a/drivers/hwmon/applesmc.c
> +++ b/drivers/hwmon/applesmc.c
> @@ -1013,6 +1013,23 @@ static ssize_t applesmc_key_at_index_store(struct device *dev,
>    return count;
> }
> 
> +static ssize_t applesmc_osk_show(struct device *dev,
> +                struct device_attribute *attr, char *sysfsbuf)
> +{
> +    int fail;
> +
> +    mutex_lock(&smcreg.mutex);
> +    fail = read_smc(APPLESMC_READ_CMD, "OSK0", sysfsbuf, 32) ||
> +           read_smc(APPLESMC_READ_CMD, "OSK1", sysfsbuf + 32, 32);
> +    mutex_unlock(&smcreg.mutex);
> +    if (fail)
> +        return -1;
> +
> +    sysfsbuf[64] = '\n';
> +    sysfsbuf[65] = '\0';
> +    return 65;
> +}
> +
> static struct led_classdev applesmc_backlight = {
>    .name            = "smc::kbd_backlight",
>    .default_trigger    = "nand-disk",
> @@ -1027,6 +1044,7 @@ static struct applesmc_node_group info_group[] = {
>    { "key_at_index_type", applesmc_key_at_index_type_show },
>    { "key_at_index_data_length", applesmc_key_at_index_data_length_show },
>    { "key_at_index_data", applesmc_key_at_index_read_show },
> +    { "osk", applesmc_osk_show },
>    { }
> };
> 
> -- 
> 1.7.7.6
> 
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