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SubjectRe: [PATCH 2/2] ARM: aspeed: Add secure boot controller support
On Tue, Feb 01, 2022 at 03:35:01PM +1030, Joel Stanley wrote:
> This reads out the status of the secure boot controller and exposes it
> in sysfs using the bootinfo sysfs api.
>
> An example on a AST2600A3 QEMU model:
>
> # grep -r . /sys/firmware/bootinfo/*
> /sys/firmware/bootinfo/abr_image:0
> /sys/firmware/bootinfo/low_security_key:0
> /sys/firmware/bootinfo/otp_protected:0
> /sys/firmware/bootinfo/secure_boot:1
> /sys/firmware/bootinfo/uart_boot:0
>
> 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
>
> The initialisation is changed from early_initcall to subsys_initcall
> because we need the firmware_kobj to be initialised, and because there's
> no requirement to print this information early.
>
> Signed-off-by: Joel Stanley <joel@jms.id.au>
> Reviewed-by: Ryan Chen <ryan_chen@aspeedtech.com>
> ---
> drivers/soc/aspeed/aspeed-socinfo.c | 84 ++++++++++++++++++++++++++++-
> 1 file changed, 83 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/soc/aspeed/aspeed-socinfo.c b/drivers/soc/aspeed/aspeed-socinfo.c
> index 1ca140356a08..fe77b31e4d1d 100644
> --- a/drivers/soc/aspeed/aspeed-socinfo.c
> +++ b/drivers/soc/aspeed/aspeed-socinfo.c
> @@ -8,6 +8,9 @@
> #include <linux/platform_device.h>
> #include <linux/slab.h>
> #include <linux/sys_soc.h>
> +#include <linux/firmware_bootinfo.h>
> +
> +static u32 security_status;
>
> static struct {
> const char *name;
> @@ -74,6 +77,83 @@ 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)

Where do these bits come from?

> +
> +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));

sysfs_emit() here and everywhere else you use sprintf() please.

> +}
> +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_bootinfo_init(void)
> +{
> + struct device_node *np;
> + void __iomem *base;
> +
> + /* AST2600 only */
> + np = of_find_compatible_node(NULL, NULL, "aspeed,ast2600-sbc");
> + if (!of_device_is_available(np))
> + return -ENODEV;
> +
> + base = of_iomap(np, 0);
> + if (!base) {
> + of_node_put(np);
> + return -ENODEV;
> + }
> +
> + security_status = readl(base + SEC_STATUS);
> +
> + iounmap(base);
> + of_node_put(np);
> +
> + firmware_bootinfo_init(aspeed_groups[0]);
> +
> + pr_info("AST2600 secure boot %s\n",
> + (security_status & SECURE_BOOT) ? "enabled" : "disabled");

When all is good, no need to print anything out.

> +
> + return 0;
> +}
> +
> static int __init aspeed_socinfo_init(void)
> {
> struct soc_device_attribute *attrs;
> @@ -148,6 +228,8 @@ static int __init aspeed_socinfo_init(void)
> attrs->revision,
> attrs->soc_id);
>
> + aspeed_bootinfo_init();

Why does this function return a value and yet you ignore it?


thanks,

greg k-h

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