[Patch v5 7/7] acpi_memhotplug.c: auto bind the memory device which is hotplugged before the driver is loaded

[Wen Congyang]

If the memory device is hotplugged before the driver is loaded, the user
cannot see this device under the directory /sys/bus/acpi/devices/, and the
user cannot bind it by hand after the driver is loaded.  This patch
introduces a new feature to bind such device when the driver is being
loaded.

CC: David Rientjes <rient...@google.com>
CC: Jiang Liu <liu...@gmail.com>
CC: Len Brown <len.br...@intel.com>
CC: Benjamin Herrenschmidt <b...@kernel.crashing.org>
CC: Paul Mackerras <pau...@samba.org>
CC: Christoph Lameter <c...@linux.com>
Cc: Minchan Kim <minchan....@gmail.com>
CC: Andrew Morton <a...@linux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motoh...@jp.fujitsu.com>
CC: Yasuaki Ishimatsu <isimatu.yasu...@jp.fujitsu.com>
CC: Rafael J. Wysocki <r...@sisk.pl>
CC: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
Signed-off-by: Wen Congyang <we...@cn.fujitsu.com>
---
 drivers/acpi/acpi_memhotplug.c | 37 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index e0f7425..9f1d107 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -52,6 +52,9 @@ MODULE_LICENSE("GPL");
 #define MEMORY_POWER_ON_STATE  1
 #define MEMORY_POWER_OFF_STATE 2
 
+static bool auto_probe;
+module_param(auto_probe, bool, S_IRUGO | S_IWUSR);
+
 static int acpi_memory_device_add(struct acpi_device *device);
 static int acpi_memory_device_remove(struct acpi_device *device, int type);
 
@@ -494,12 +497,44 @@ acpi_memory_register_notify_handler(acpi_handle handle,
                                    u32 level, void *ctxt, void **retv)
 {
        acpi_status status;
-
+       struct acpi_memory_device *mem_device = NULL;
+       unsigned long long current_status;
 
        status = is_memory_device(handle);
        if (ACPI_FAILURE(status))
                return AE_OK;   /* continue */
 
+       if (auto_probe) {
+               /* Get device present/absent information from the _STA */
+               status = acpi_evaluate_integer(handle, "_STA", NULL,
+                                              &current_status);
+               if (ACPI_FAILURE(status))
+                       goto install;
+
+               /*
+                * Check for device status. Device should be
+                * present/enabled/functioning.
+                */
+               if (!(current_status &
+                     (ACPI_STA_DEVICE_PRESENT | ACPI_STA_DEVICE_ENABLED |
+                      ACPI_STA_DEVICE_FUNCTIONING)))
+                       goto install;
+
+               if (acpi_memory_get_device(handle, &mem_device))
+                       goto install;
+
+               /* We have bound this device while we register the driver */
+               if (mem_device->state == MEMORY_POWER_ON_STATE)
+                       goto install;
+
+               ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+                                 "\nauto probe memory device\n"));
+
+               if (acpi_memory_enable_device(mem_device))
+                       pr_err(PREFIX "Cannot enable memory device\n");
+       }
+
+install:
        status = acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
                                             acpi_memory_device_notify, NULL);
        /* continue */
-- 
1.8.0

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