Unverified Commit 5d40a857 authored by Xiangrong Li's avatar Xiangrong Li Committed by Ilpo Järvinen
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mlxbf-bootctl: Support sysfs entries for RTC battery status 



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: default avatarXiangrong Li <xiangrongl@nvidia.com>
Reviewed-by: default avatarDavid Thompson <davthompson@nvidia.com>
Reviewed-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20250124144655.48564-1-xiangrongl@nvidia.com


Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
parent 2014c95a

Documentation/ABI/testing/sysfs-platform-mellanox-bootctl

+10 −0
Original line number Diff line number Diff line
@@ -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.

drivers/platform/mellanox/mlxbf-bootctl.c

+20 −0
Original line number Diff line number Diff line
@@ -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

};

drivers/platform/mellanox/mlxbf-bootctl.h

+5 −0
Original line number Diff line number Diff line
@@ -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