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// SPDX-License-Identifier: GPL-2.0+
/*
* Support for booting from coreboot
*
* Copyright 2021 Google LLC
*/
#define LOG_CATEGORY UCLASS_RTC
#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;
}
U_BOOT_LONGHELP(cbcmos,
"check - check CMOS RAM\n"
"cbcmos update - Update CMOS-RAM checksum";
);
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));
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