Hi Arnd,
On Wed, 17 Nov 2021 at 03:51, Joel Stanley <joel@xxxxxxxxx> wrote:
>
> This reads out the status of the secure boot controller and exposes it
> in sysfs.
>
> An example on a AST2600A3 QEMU model:
>
> # grep . /sys/bus/soc/devices/soc0/*
> /sys/bus/soc/devices/soc0/abr_image:0
> /sys/bus/soc/devices/soc0/family:AST2600
> /sys/bus/soc/devices/soc0/low_security_key:0
> /sys/bus/soc/devices/soc0/machine:Rainier 2U
> /sys/bus/soc/devices/soc0/otp_protected:0
> /sys/bus/soc/devices/soc0/revision:A3
> /sys/bus/soc/devices/soc0/secure_boot:1
> /sys/bus/soc/devices/soc0/serial_number:888844441234abcd
> /sys/bus/soc/devices/soc0/soc_id:05030303
> /sys/bus/soc/devices/soc0/uart_boot:1
Quoting from your response to my pull request:
> - I actually want to avoid custom attributes on soc device instances as much
> as possible. I have not looked in detail at what you add here, but the
> number of custom attributes means we should discuss this properly.
Can you explain the reasoning here?
I am a bit surprised given we have this nice feature in struct
soc_device_attribute:
struct soc_device_attribute {
...
const struct attribute_group *custom_attr_group;
};
Cheers,
Joel
>
> On boot the state of the system according to the secure boot controller
> will be printed:
>
> [ 0.037634] AST2600 secure boot enabled
>
> or
>
> [ 0.037935] AST2600 secure boot disabled
>
> Signed-off-by: Joel Stanley <joel@xxxxxxxxx>
> Reviewed-by: Ryan Chen <ryan_chen@xxxxxxxxxxxxxx>
> ---
> drivers/soc/aspeed/aspeed-socinfo.c | 73 +++++++++++++++++++++++++++++
> 1 file changed, 73 insertions(+)
>
> diff --git a/drivers/soc/aspeed/aspeed-socinfo.c b/drivers/soc/aspeed/aspeed-socinfo.c
> index 1ca140356a08..6faf2c199c90 100644
> --- a/drivers/soc/aspeed/aspeed-socinfo.c
> +++ b/drivers/soc/aspeed/aspeed-socinfo.c
> @@ -9,6 +9,8 @@
> #include <linux/slab.h>
> #include <linux/sys_soc.h>
>
> +static u32 security_status;
> +
> static struct {
> const char *name;
> const u32 id;
> @@ -74,6 +76,54 @@ static const char *siliconid_to_rev(u32 siliconid)
> return "??";
> }
>
> +#define SEC_STATUS 0x14
> +#define ABR_IMAGE_SOURCE BIT(13)
> +#define OTP_PROTECTED BIT(8)
> +#define LOW_SEC_KEY BIT(7)
> +#define SECURE_BOOT BIT(6)
> +#define UART_BOOT BIT(5)
> +
> +static ssize_t abr_image_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> + return sprintf(buf, "%d\n", !!(security_status & ABR_IMAGE_SOURCE));
> +}
> +static DEVICE_ATTR_RO(abr_image);
> +
> +static ssize_t low_security_key_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> + return sprintf(buf, "%d\n", !!(security_status & LOW_SEC_KEY));
> +}
> +static DEVICE_ATTR_RO(low_security_key);
> +
> +static ssize_t otp_protected_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> + return sprintf(buf, "%d\n", !!(security_status & OTP_PROTECTED));
> +}
> +static DEVICE_ATTR_RO(otp_protected);
> +
> +static ssize_t secure_boot_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> + return sprintf(buf, "%d\n", !!(security_status & SECURE_BOOT));
> +}
> +static DEVICE_ATTR_RO(secure_boot);
> +
> +static ssize_t uart_boot_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> + /* Invert the bit, as 1 is boot from SPI/eMMC */
> + return sprintf(buf, "%d\n", !(security_status & UART_BOOT));
> +}
> +static DEVICE_ATTR_RO(uart_boot);
> +
> +static struct attribute *aspeed_attrs[] = {
> + &dev_attr_abr_image.attr,
> + &dev_attr_low_security_key.attr,
> + &dev_attr_otp_protected.attr,
> + &dev_attr_secure_boot.attr,
> + &dev_attr_uart_boot.attr,
> + NULL,
> +};
> +ATTRIBUTE_GROUPS(aspeed);
> +
> static int __init aspeed_socinfo_init(void)
> {
> struct soc_device_attribute *attrs;
> @@ -81,6 +131,7 @@ static int __init aspeed_socinfo_init(void)
> struct device_node *np;
> void __iomem *reg;
> bool has_chipid = false;
> + bool has_sbe = false;
> u32 siliconid;
> u32 chipid[2];
> const char *machine = NULL;
> @@ -109,6 +160,20 @@ static int __init aspeed_socinfo_init(void)
> }
> of_node_put(np);
>
> + /* AST2600 only */
> + np = of_find_compatible_node(NULL, NULL, "aspeed,ast2600-sbc");
> + if (of_device_is_available(np)) {
> + void *base = of_iomap(np, 0);
> + if (!base) {
> + of_node_put(np);
> + return -ENODEV;
> + }
> + security_status = readl(base + SEC_STATUS);
> + has_sbe = true;
> + iounmap(base);
> + of_node_put(np);
> + }
> +
> attrs = kzalloc(sizeof(*attrs), GFP_KERNEL);
> if (!attrs)
> return -ENODEV;
> @@ -135,6 +200,9 @@ static int __init aspeed_socinfo_init(void)
> attrs->serial_number = kasprintf(GFP_KERNEL, "%08x%08x",
> chipid[1], chipid[0]);
>
> + if (has_sbe)
> + attrs->custom_attr_group = aspeed_groups[0];
> +
> soc_dev = soc_device_register(attrs);
> if (IS_ERR(soc_dev)) {
> kfree(attrs->soc_id);
> @@ -148,6 +216,11 @@ static int __init aspeed_socinfo_init(void)
> attrs->revision,
> attrs->soc_id);
>
> + if (has_sbe) {
> + pr_info("AST2600 secure boot %s\n",
> + (security_status & SECURE_BOOT) ? "enabled" : "disabled");
> + }
> +
> return 0;
> }
> early_initcall(aspeed_socinfo_init);
> --
> 2.33.0
>
