u-boot/arch/arm/mach-imx/mx7/snvs.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright 2018 Linaro
 */

#include <asm/io.h>
#include <asm/arch/imx-regs.h>
#include <linux/bitops.h>

#define SNVS_HPCOMR		0x04
#define SNVS_HPCOMR_NPSWA_EN	BIT(31)

void init_snvs(void)
{
	u32 val;

	/* Ensure SNVS HPCOMR sets NPSWA_EN to allow unpriv access to SNVS LP */
	val = readl(SNVS_BASE_ADDR + SNVS_HPCOMR);
	val |= SNVS_HPCOMR_NPSWA_EN;
	writel(val, SNVS_BASE_ADDR + SNVS_HPCOMR);
}
SPDX: Convert all of our single license tags to Linux Kernel style When U-Boot started using SPDX tags we were among the early adopters and there weren't a lot of other examples to borrow from. So we picked the area of the file that usually had a full license text and replaced it with an appropriate SPDX-License-Identifier: entry. Since then, the Linux Kernel has adopted SPDX tags and they place it as the very first line in a file (except where shebangs are used, then it's second line) and with slightly different comment styles than us. In part due to community overlap, in part due to better tag visibility and in part for other minor reasons, switch over to that style. This commit changes all instances where we have a single declared license in the tag as both the before and after are identical in tag contents. There's also a few places where I found we did not have a tag and have introduced one. Signed-off-by: Tom Rini <trini@konsulko.com> 2018-05-06 21:58:06 +00:00			`// SPDX-License-Identifier: GPL-2.0+`
imx: mx7: snvs: Add an SNVS init routine Working with HAB on the i.MX7 we've encountered a case where a board that successfully authenticates u-boot when booting Linux via OPTEE subsequently fails to properly bring up the RTC. The RTC registers live in the low-power block of the Secure Non-Volatile Storage (SNVS) block. The root cause of the error has been traced to the HAB handing off the SNVS-RTC in a state where HPCOMR::NPSWA_EN = 0 in other words where the Non-Privileged Software Access Enable bit is zero. In ordinary circumstances this is OK since we typically do not run in TZ mode, however when we boot via HAB and enablng TrustZone, it is required to set HPCOMR::NPSWA_EN = 1 in order for the upstream Linux driver to have sufficient permissions to manipulate the SNVS-LP block. On our reference board it is the difference between Linux doing this: root@imx7s-warp-mbl:~# dmesg \| grep rtc snvs_rtc_enable read 0x00000000 from SNVS_LPLR @ 0x00000034 snvs_rtc_enable read 0x00000021 from SNVS_LPCR @ 0x00000038 snvs_rtc_enable read 0x00000000 from SNVS_HPLR @ 0x00000000 snvs_rtc_enable read 0x80002100 from SNVS_HPCOMR @ 0x00000004 snvs_rtc 30370000.snvs:snvs-rtc-lp: rtc core: registered 30370000.snvs:snvs-rtc-lp as rtc0 snvs_rtc 30370000.snvs:snvs-rtc-lp: setting system clock to2018-04-01 00:51:04 UTC (1522543864) and doing this: root@imx7s-warp-mbl:~# dmesg \| grep rtc snvs_rtc_enable read 0x00000000 from SNVS_LPLR @ 0x00000034 snvs_rtc_enable read 0x00000020 from SNVS_LPCR @ 0x00000038 snvs_rtc_enable read 0x00000001 from SNVS_HPLR @ 0x00000000 snvs_rtc_enable read 0x00002020 from SNVS_HPCOMR @ 0x00000004 snvs_rtc 30370000.snvs:snvs-rtc-lp: failed to enable rtc -110 snvs_rtc: probe of 30370000.snvs:snvs-rtc-lp failed with error -110 hctosys: unable to open rtc device (rtc0) Note bit 1 of LPCR is not set in the second case and is set in the first case and that bit 31 of HPCOMR is set in the second case but not in the first. Setting NPSWA_EN in HPCOMR allows us to boot through enabling TrustZone and continue onto the kernel. The kernel then has the necessary permissions to set LPCR::SRTC_ENV (RTC enable in the LP command register) whereas in contrast - in the failing case the non-privileged kernel cannot do so. This patch adds a simple init_snvs() call which sets the permission-bit called from soc.c for the i.MX7. It may be possible, safe and desirable to perform this on other i.MX processors but for now this is only tested on i.MX7 as working. Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org> 2018-04-05 18:46:06 +00:00			`/*`
			`* Copyright 2018 Linaro`
			`*/`

			`#include <asm/io.h>`
			`#include <asm/arch/imx-regs.h>`
			`#include <linux/bitops.h>`

			`#define SNVS_HPCOMR 0x04`
			`#define SNVS_HPCOMR_NPSWA_EN BIT(31)`

			`void init_snvs(void)`
			`{`
			`u32 val;`

			`/* Ensure SNVS HPCOMR sets NPSWA_EN to allow unpriv access to SNVS LP */`
			`val = readl(SNVS_BASE_ADDR + SNVS_HPCOMR);`
			`val \|= SNVS_HPCOMR_NPSWA_EN;`
			`writel(val, SNVS_BASE_ADDR + SNVS_HPCOMR);`
			`}`