powerpc/pseries: Add ibm,get-dynamic-sensor-state RTAS call support

JIRA: https://issues.redhat.com/browse/RHEL-101838

commit 496c752
Author: Haren Myneni <haren@linux.ibm.com>
Date:   Wed Apr 16 15:57:40 2025 -0700

    powerpc/pseries: Add ibm,get-dynamic-sensor-state RTAS call support

    The RTAS call ibm,get-dynamic-sensor-state is used to get the
    sensor state identified by the location code and the sensor
    token. The librtas library provides an API
    rtas_get_dynamic_sensor() which uses /dev/mem access for work
    area allocation but is restricted under system lockdown.

    This patch provides an interface with new ioctl
     PAPR_DYNAMIC_SENSOR_IOC_GET to the papr-indices character
    driver which executes this HCALL and copies the sensor state
    in the user specified ioctl buffer.

    Refer PAPR 7.3.19 ibm,get-dynamic-sensor-state for more
    information on this RTAS call.
    - User input parameters to the RTAS call: location code string
      and the sensor token

    Expose these interfaces to user space with a /dev/papr-indices
    character device using the following programming model:
     int fd = open("/dev/papr-indices", O_RDWR);
     int ret = ioctl(fd, PAPR_DYNAMIC_SENSOR_IOC_GET,
                    struct papr_indices_io_block)
      - The user space specifies input parameters in
        papr_indices_io_block struct
      - Returned state for the specified sensor is copied to
        papr_indices_io_block.dynamic_param.state

    Signed-off-by: Haren Myneni <haren@linux.ibm.com>
    Tested-by: Sathvika Vasireddy <sv@linux.ibm.com>
    Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
    Link: https://patch.msgid.link/20250416225743.596462-6-haren@linux.ibm.com

Signed-off-by: Mamatha Inamdar <minamdar@redhat.com>

Author: Mamatha Inamdar

arch/powerpc/include/asm/rtas.h

@@ -339,6 +339,7 @@ extern unsigned long rtas_rmo_buf;
 extern struct mutex rtas_ibm_get_vpd_lock;
 extern struct mutex rtas_ibm_get_indices_lock;
 extern struct mutex rtas_ibm_set_dynamic_indicator_lock;
+extern struct mutex rtas_ibm_get_dynamic_sensor_state_lock;
 
 #define GLOBAL_INTERRUPT_QUEUE 9005
 

arch/powerpc/kernel/rtas.c

@@ -79,6 +79,7 @@ EXPORT_SYMBOL(rtas_flash_term_hook);
 DEFINE_MUTEX(rtas_ibm_get_vpd_lock);
 DEFINE_MUTEX(rtas_ibm_get_indices_lock);
 DEFINE_MUTEX(rtas_ibm_set_dynamic_indicator_lock);
+DEFINE_MUTEX(rtas_ibm_get_dynamic_sensor_state_lock);
 
 /* RTAS use home made raw locking instead of spin_lock_irqsave
  * because those can be called from within really nasty contexts
@@ -1126,6 +1127,9 @@ static struct mutex *find_rtas_mutex(int token)
 	if (token == rtas_token("ibm,set-dynamic-indicator"))
 		return &rtas_ibm_set_dynamic_indicator_lock;
 
+	if (token == rtas_token("ibm,get-dynamic-sensor-state"))
+		return &rtas_ibm_get_dynamic_sensor_state_lock;
+
 	return NULL;
 }
 

arch/powerpc/platforms/pseries/papr-indices.c

@@ -371,6 +371,67 @@ static long papr_dynamic_indicator_ioc_set(struct papr_indices_io_block __user *
 	return ret;
 }
 
+/**
+ * papr_dynamic_sensor_ioc_get - ibm,get-dynamic-sensor-state RTAS Call
+ * PAPR 2.13 7.3.19
+ *
+ * @ubuf: Input parameters to RTAS call such as sensor token
+ *        Copies the state in user space buffer.
+ *
+ *
+ * Returns success or -errno.
+ */
+
+static long papr_dynamic_sensor_ioc_get(struct papr_indices_io_block __user *ubuf)
+{
+	struct papr_indices_io_block kbuf;
+	struct rtas_work_area *work_area;
+	s32 fwrc, token, ret;
+	u32 rets;
+
+	token = rtas_token("ibm,get-dynamic-sensor-state");
+	if (token == RTAS_UNKNOWN_SERVICE)
+		return -ENOENT;
+
+	mutex_lock(&rtas_ibm_get_dynamic_sensor_state_lock);
+	work_area = papr_dynamic_indice_buf_from_user(ubuf, &kbuf);
+	if (IS_ERR(work_area)) {
+		ret = PTR_ERR(work_area);
+		goto out;
+	}
+
+	do {
+		fwrc = rtas_call(token, 2, 2, &rets,
+				kbuf.dynamic_param.token,
+				rtas_work_area_phys(work_area));
+	} while (rtas_busy_delay(fwrc));
+
+	rtas_work_area_free(work_area);
+
+	switch (fwrc) {
+	case 0:		/* Success */
+		if (put_user(rets, &ubuf->dynamic_param.state))
+			ret = -EFAULT;
+		else
+			ret = 0;
+		break;
+	case RTAS_IBM_DYNAMIC_INDICE_NO_INDICATOR:	/* No such indicator */
+		ret = -EOPNOTSUPP;
+		break;
+	default:
+		pr_err("unexpected ibm,get-dynamic-sensor result %d\n",
+				fwrc);
+		fallthrough;
+	case RTAS_HARDWARE_ERROR:	/* Hardware/platform error */
+		ret = -EIO;
+		break;
+	}
+
+out:
+	mutex_unlock(&rtas_ibm_get_dynamic_sensor_state_lock);
+	return ret;
+}
+
 /*
  * Top-level ioctl handler for /dev/papr-indices.
  */
@@ -384,6 +445,9 @@ static long papr_indices_dev_ioctl(struct file *filp, unsigned int ioctl,
 	case PAPR_INDICES_IOC_GET:
 		ret = papr_indices_create_handle(argp);
 		break;
+	case PAPR_DYNAMIC_SENSOR_IOC_GET:
+		ret = papr_dynamic_sensor_ioc_get(argp);
+		break;
 	case PAPR_DYNAMIC_INDICATOR_IOC_SET:
 		if (filp->f_mode & FMODE_WRITE)
 			ret = papr_dynamic_indicator_ioc_set(argp);
@@ -416,6 +480,9 @@ static __init int papr_indices_init(void)
 	if (!rtas_service_present("ibm,set-dynamic-indicator"))
 		return -ENODEV;
 
+	if (!rtas_service_present("ibm,get-dynamic-sensor-state"))
+		return -ENODEV;
+
 	return misc_register(&papr_indices_dev);
 }
 machine_device_initcall(pseries, papr_indices_init);