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mlxbf-bootctl: Support sysfs entries for RTC battery status

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This patch extends the mlxbf-bootctl driver's sysfs entries
to support read access for the board's RTC battery status.
A successful read from this attribute returns the status of
the board's RTC battery. The RTC battery status register is
also cleared upon successful read operation.

Signed-off-by: Xiangrong Li <xiangrongl@nvidia.com>
Reviewed-by: David Thompson <davthompson@nvidia.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20250124144655.48564-1-xiangrongl@nvidia.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
This commit is contained in:
Xiangrong Li 2025-01-24 14:46:55 +00:00 committed by Ilpo Järvinen
parent 2014c95afe
commit 5d40a85775
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GPG Key ID: 59AC4F6153E5CE31
3 changed files with 35 additions and 0 deletions
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10
Documentation/ABI/testing/sysfs-platform-mellanox-bootctl
View File

@ -150,3 +150,13 @@ Description:
The "mfg_lock" sysfs attribute is write-only.
A successful write to this attribute will latch the
board-level attributes into EEPROM, making them read-only.
What: /sys/bus/platform/devices/MLNXBF04:00/rtc_battery
Date: June 2025
KernelVersion: 6.15
Contact: "Xiangrong Li <xiangrongl@nvidia.com>"
Description:
The "rtc_battery" sysfs attribute is read-only.
A successful read from this attribute returns the status of
the board's RTC battery. The RTC battery status register is
also cleared upon successful read operation.

20
drivers/platform/mellanox/mlxbf-bootctl.c
View File

@ -91,6 +91,7 @@ static const char * const mlxbf_rsh_log_level[] = {
static DEFINE_MUTEX(icm_ops_lock);
static DEFINE_MUTEX(os_up_lock);
static DEFINE_MUTEX(mfg_ops_lock);
static DEFINE_MUTEX(rtc_ops_lock);
/*
* Objects are stored within the MFG partition per type.
@ -489,6 +490,23 @@ static ssize_t large_icm_store(struct device *dev,
return res.a0 ? -EPERM : count;
}
static ssize_t rtc_battery_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
struct arm_smccc_res res;
mutex_lock(&rtc_ops_lock);
arm_smccc_smc(MLNX_HANDLE_GET_RTC_LOW_BATT, 0, 0, 0, 0,
0, 0, 0, &res);
mutex_unlock(&rtc_ops_lock);
if (res.a0)
return -EPERM;
return sysfs_emit(buf, "0x%lx\n", res.a1);
}
static ssize_t os_up_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
@ -906,6 +924,7 @@ static DEVICE_ATTR_RW(sn);
static DEVICE_ATTR_RW(uuid);
static DEVICE_ATTR_RW(rev);
static DEVICE_ATTR_WO(mfg_lock);
static DEVICE_ATTR_RO(rtc_battery);
static struct attribute *mlxbf_bootctl_attrs[] = {
&dev_attr_post_reset_wdog.attr,
@ -925,6 +944,7 @@ static struct attribute *mlxbf_bootctl_attrs[] = {
&dev_attr_uuid.attr,
&dev_attr_rev.attr,
&dev_attr_mfg_lock.attr,
&dev_attr_rtc_battery.attr,
NULL
};

5
drivers/platform/mellanox/mlxbf-bootctl.h
View File

@ -103,6 +103,11 @@
*/
#define MLNX_HANDLE_OS_UP 0x82000014
/*
* SMC function ID to get and clear the RTC low voltage bit
*/
#define MLNX_HANDLE_GET_RTC_LOW_BATT 0x82000023
/* SMC function IDs for SiP Service queries */
#define MLXBF_BOOTCTL_SIP_SVC_CALL_COUNT 0x8200ff00
#define MLXBF_BOOTCTL_SIP_SVC_UID 0x8200ff01