Coreboot tables provide information about the CMOS-RAM checksum. Add a command which can check and update this.
With this it is possible to adjust CMOS-RAM settings and tidy up the checksum afterwards.
Signed-off-by: Simon Glass sjg@chromium.org ---
cmd/Kconfig | 11 +++ cmd/x86/Makefile | 1 + cmd/x86/cbcmos.c | 141 +++++++++++++++++++++++++++++++++++++++ doc/usage/cmd/cbcmos.rst | 42 ++++++++++++ doc/usage/index.rst | 1 + test/cmd/coreboot.c | 42 ++++++++++++ 6 files changed, 238 insertions(+) create mode 100644 cmd/x86/cbcmos.c create mode 100644 doc/usage/cmd/cbcmos.rst
diff --git a/cmd/Kconfig b/cmd/Kconfig index 987f7d8cf623..e6977dc91bb2 100644 --- a/cmd/Kconfig +++ b/cmd/Kconfig @@ -2742,6 +2742,17 @@ config CMD_CBSYSINFO memory by coreboot before jumping to U-Boot. It can be useful for debugging the beaaviour of coreboot or U-Boot.
+config CMD_CBCMOS + bool "cbcmos" + depends on X86 + default y if SYS_COREBOOT + help + This provides information options to check the CMOS RAM checksum, + if present, as well as to update it. + + It is useful when coreboot CMOS-RAM settings must be examined or + updated. + config CMD_CYCLIC bool "cyclic - Show information about cyclic functions" depends on CYCLIC diff --git a/cmd/x86/Makefile b/cmd/x86/Makefile index 5f82204c87e6..565e20776755 100644 --- a/cmd/x86/Makefile +++ b/cmd/x86/Makefile @@ -1,6 +1,7 @@ # SPDX-License-Identifier: GPL-2.0+
obj-$(CONFIG_CMD_CBSYSINFO) += cbsysinfo.o +obj-$(CONFIG_CMD_CBCMOS) += cbcmos.o obj-y += mtrr.o obj-$(CONFIG_CMD_EXCEPTION) += exception.o obj-$(CONFIG_USE_HOB) += hob.o diff --git a/cmd/x86/cbcmos.c b/cmd/x86/cbcmos.c new file mode 100644 index 000000000000..8d2f85fd0ec6 --- /dev/null +++ b/cmd/x86/cbcmos.c @@ -0,0 +1,141 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Support for booting from coreboot + * + * Copyright 2021 Google LLC + */ + +#define LOG_CATEGORY UCLASS_RTC + +#include <common.h> +#include <command.h> +#include <dm.h> +#include <rtc.h> +#include <asm/cb_sysinfo.h> +#include <asm/global_data.h> + +DECLARE_GLOBAL_DATA_PTR; + +const struct sysinfo_t *get_table(void) +{ + if (!gd->arch.coreboot_table) { + printf("No coreboot sysinfo table found\n"); + return NULL; + } + + return &lib_sysinfo; +} + +static int calc_sum(struct udevice *dev, uint start_bit, uint bit_count) +{ + uint start_byte = start_bit / 8; + uint byte_count = bit_count / 8; + int ret, i; + uint sum; + + log_debug("Calc sum from %x: %x bytes\n", start_byte, byte_count); + sum = 0; + for (i = 0; i < bit_count / 8; i++) { + ret = rtc_read8(dev, start_bit / 8 + i); + if (ret < 0) + return ret; + sum += ret; + } + + return (sum & 0xff) << 8 | (sum & 0xff00) >> 8; +} + +/** + * prep_cbcmos() - Prepare for a CMOS-RAM command + * + * @tab: coreboot table + * @devnum: RTC device name to use, or NULL for the first one + * @dep: Returns RTC device on success + * Return: calculated checksum for CMOS RAM or -ve on error + */ +static int prep_cbcmos(const struct sysinfo_t *tab, const char *devname, + struct udevice **devp) +{ + struct udevice *dev; + int ret; + + if (!tab) + return CMD_RET_FAILURE; + if (devname) + ret = uclass_get_device_by_name(UCLASS_RTC, devname, &dev); + else + ret = uclass_first_device_err(UCLASS_RTC, &dev); + if (ret) { + printf("Failed to get RTC device: %dE\n", ret); + return ret; + } + + ret = calc_sum(dev, tab->cmos_range_start, + tab->cmos_range_end + 1 - tab->cmos_range_start); + if (ret < 0) { + printf("Failed to read RTC device: %dE\n", ret); + return ret; + } + *devp = dev; + + return ret; +} + +static int do_cbcmos_check(struct cmd_tbl *cmdtp, int flag, int argc, + char *const argv[]) +{ + const struct sysinfo_t *tab = get_table(); + struct udevice *dev; + u16 cur, sum; + int ret; + + ret = prep_cbcmos(tab, argv[1], &dev); + if (ret < 0) + return CMD_RET_FAILURE; + sum = ret; + + ret = rtc_read16(dev, tab->cmos_checksum_location / 8, &cur); + if (ret < 0) { + printf("Failed to read RTC device: %dE\n", ret); + return CMD_RET_FAILURE; + } + if (sum != cur) { + printf("Checksum %04x error: calculated %04x\n", cur, sum); + return CMD_RET_FAILURE; + } + + return 0; +} + +static int do_cbcmos_update(struct cmd_tbl *cmdtp, int flag, int argc, + char *const argv[]) +{ + const struct sysinfo_t *tab = get_table(); + struct udevice *dev; + u16 sum; + int ret; + + ret = prep_cbcmos(tab, argv[1], &dev); + if (ret < 0) + return CMD_RET_FAILURE; + sum = ret; + + ret = rtc_write16(dev, tab->cmos_checksum_location / 8, sum); + if (ret < 0) { + printf("Failed to read RTC device: %dE\n", ret); + return CMD_RET_FAILURE; + } + printf("Checksum %04x written\n", sum); + + return 0; +} + +#ifdef CONFIG_SYS_LONGHELP +static char cbcmos_help_text[] = + "check - check CMOS RAM\n" + "cbcmos update - Update CMOS-RAM checksum"; +#endif /* CONFIG_SYS_LONGHELP */ + +U_BOOT_CMD_WITH_SUBCMDS(cbcmos, "coreboot CMOS RAM", cbcmos_help_text, + U_BOOT_SUBCMD_MKENT(check, 2, 1, do_cbcmos_check), + U_BOOT_SUBCMD_MKENT(update, 2, 1, do_cbcmos_update)); diff --git a/doc/usage/cmd/cbcmos.rst b/doc/usage/cmd/cbcmos.rst new file mode 100644 index 000000000000..156521dd02b9 --- /dev/null +++ b/doc/usage/cmd/cbcmos.rst @@ -0,0 +1,42 @@ +.. SPDX-License-Identifier: GPL-2.0+ + +cbcmos +====== + +Synopis +------- + +:: + + cbcmos check [<dev>] + cbcmos update [<dev>] + + +Description +----------- + +This checks or updates the CMOS-RAM checksum value against the CMOS-RAM +contents. It is used with coreboot, which provides information about where to +find the checksum and what part of the CMOS RAM it covers. + +If `<dev>` is provided then the named real-time clock (RTC) device is used. +Otherwise the default RTC is used. + +Example +------- + +This shows checking and updating a checksum across bytes 38 and 39 of the +CMOS RAM:: + + => rtc read 38 2 + 00000038: 71 00 q. + => cbc check + => rtc write 38 66 + => rtc read 38 2 + 00000038: 66 00 f. + => cbc check + Checksum 7100 error: calculated 6600 + => cbc update + Checksum 6600 written + => cbc check + => diff --git a/doc/usage/index.rst b/doc/usage/index.rst index 98b4719c4088..ae908e92327a 100644 --- a/doc/usage/index.rst +++ b/doc/usage/index.rst @@ -40,6 +40,7 @@ Shell commands cmd/button cmd/bootz cmd/cat + cmd/cbcmos cmd/cbsysinfo cmd/cedit cmd/cls diff --git a/test/cmd/coreboot.c b/test/cmd/coreboot.c index eb3d8905986d..0c49aca9f58a 100644 --- a/test/cmd/coreboot.c +++ b/test/cmd/coreboot.c @@ -8,10 +8,16 @@
#include <common.h> #include <command.h> +#include <dm.h> +#include <rtc.h> #include <test/cmd.h> #include <test/test.h> #include <test/ut.h>
+enum { + CSUM_LOC = 0x3f0 / 8, +}; + /** * test_cmd_cbsysinfo() - test the cbsysinfo command produces expected output * @@ -42,3 +48,39 @@ static int test_cmd_cbsysinfo(struct unit_test_state *uts) return 0; } CMD_TEST(test_cmd_cbsysinfo, UT_TESTF_CONSOLE_REC); + +/* test cbcmos command */ +static int test_cmd_cbcmos(struct unit_test_state *uts) +{ + u16 old_csum, new_csum; + struct udevice *dev; + + /* initially the checksum should be correct */ + ut_assertok(run_command("cbcmos check", 0)); + ut_assert_console_end(); + + /* make a change to the checksum */ + ut_assertok(uclass_first_device_err(UCLASS_RTC, &dev)); + ut_assertok(rtc_read16(dev, CSUM_LOC, &old_csum)); + ut_assertok(rtc_write16(dev, CSUM_LOC, old_csum + 1)); + + /* now the command should fail */ + ut_asserteq(1, run_command("cbcmos check", 0)); + ut_assert_nextline("Checksum %04x error: calculated %04x", + old_csum + 1, old_csum); + ut_assert_console_end(); + + /* now get it to fix the checksum */ + ut_assertok(run_command("cbcmos update", 0)); + ut_assert_nextline("Checksum %04x written", old_csum); + ut_assert_console_end(); + + /* check the RTC looks right */ + ut_assertok(rtc_read16(dev, CSUM_LOC, &new_csum)); + ut_asserteq(old_csum, new_csum); + ut_assert_console_end(); + + return 0; +} +CMD_TEST(test_cmd_cbcmos, UT_TESTF_CONSOLE_REC); +