[RFC PATCH 0/3] ACPI based system device hotplug framework

This patch implements a default mechanism to detect and manage ACPI system
device hotplug slots based on standard ACPI interfaces.
1) Detech hotplug slot by checking existence of _EJ0 and _STA methods.
2) Power off a slot by excuting _EJ0 method.

It's the default hotplug slot enumerating mechanism, platform specifc drivers
may provide advanced implementation to override the default implementation.

Signed-off-by: Jiang Liu
Signed-off-by: Gaohuai Han
Signed-off-by: Jiang Liu

drivers/acpi/Kconfig | 10 +++
drivers/acpi/hotplug/Makefile | 1 +
drivers/acpi/hotplug/slot_enum.c | 3 +
drivers/acpi/hotplug/slot_enum_ej0.c | 113 ++++++++++++++++++++++++++++++++++
4 files changed, 127 insertions(+)
create mode 100644 drivers/acpi/hotplug/slot_enum_ej0.c

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 711e18e..c9f7918 100644
a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -344,6 +344,16 @@ config ACPI_HOTPLUG_ENUM
To compile this driver as a module, choose M here:
the module will be called acpihp_enum.

+config ACPI_HOTPLUG_ENUM_EJ0
+ bool "Detecting ACPI Hotplug Slot by Checking _EJ0 Method"
+ depends on ACPI_HOTPLUG_ENUM
+ default y
+ help
+ Enable detecting ACPI hotplug slots by checking ACPI _EJ0 method
+ under ACPI device objects.
+
+ It's the default method to detect ACPI hotplug slots.
+
config ACPI_CONTAINER
tristate "Container and Module Devices (EXPERIMENTAL)"
depends on EXPERIMENTAL
diff --git a/drivers/acpi/hotplug/Makefile b/drivers/acpi/hotplug/Makefile
index 41c0da9..23dfa93 100644
a/drivers/acpi/hotplug/Makefile
+++ b/drivers/acpi/hotplug/Makefile
@@ -7,3 +7,4 @@ acpihp-y = core.o

obj-$(CONFIG_ACPI_HOTPLUG_ENUM) += acpihp_enum.o
acpihp_enum-y = slot_enum.o
+acpihp_enum-y += slot_enum_ej0.o
diff --git a/drivers/acpi/hotplug/slot_enum.c b/drivers/acpi/hotplug/slot_enum.c
index 80396a3..a251ecf 100644
a/drivers/acpi/hotplug/slot_enum.c
+++ b/drivers/acpi/hotplug/slot_enum.c
@@ -40,11 +40,14 @@ struct acpihp_slot_id {

static struct acpihp_slot_ops *slot_ops_curr;

+extern struct acpihp_slot_ops acpihp_enum_ej0;
+
/*
* Array of platform specific enumeration methods.
* Entries in the array should be sorted by descending priority order.
*/
static struct acpihp_slot_ops *slot_ops_array[] = {
+ &acpihp_enum_ej0,
NULL
};

diff --git a/drivers/acpi/hotplug/slot_enum_ej0.c b/drivers/acpi/hotplug/slot_enum_ej0.c
new file mode 100644
index 0000000..2788860
/dev/null
+++ b/drivers/acpi/hotplug/slot_enum_ej0.c
@@ -0,0 +1,113 @@
+/*
+ * Copyright (C) 2011 Huawei Tech. Co., Ltd.
+ * Copyright (C) 2011 Gaohuai Han
+ * Copyright (C) 2011 Jiang Liu
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+
+#include <linux/acpi.h>
+#include <acpi/acpi.h>
+#include <acpi/acpi_hotplug.h>
+
+static acpi_status acpihp_enum_ej0_init(void)
+{
+ return AE_OK;
+}
+
+static void acpihp_enum_ej0_fini(void)
+{
+}
+
+static acpi_status acpihp_enum_ej0_check(acpi_handle handle)
+{
+ acpi_handle tmp;
+
+ /* Assume a device object with _EJ0 and _STA has a hotplug slot. */
+ if (ACPI_FAILURE(acpi_get_handle(handle, "_EJ0", &tmp)))
+ return AE_ERROR;
+ if (ACPI_FAILURE(acpi_get_handle(handle, METHOD_NAME__STA, &tmp)))
+ return AE_ERROR;
+
+ return AE_OK;
+}
+
+static acpi_status
+acpihp_enum_ej0_get_capabilities(acpi_handle handle, u32 *capability)
+{
+ /*
+ * Assume device objects with _EJ0 are capable of:
+ * ONLINE, OFFLINE, POWEROFF, HOTPLUG
+ */
+ *capability = ACPIHP_SLOT_CAP_ONLINE | ACPIHP_SLOT_CAP_OFFLINE |
+ ACPIHP_SLOT_CAP_POWEROFF | ACPIHP_SLOT_CAP_HOTPLUG;
+
+ return AE_OK;
+}
+
+static acpi_status acpihp_enum_ej0_poweron(acpi_handle handle)
+{
+ return AE_SUPPORT;
+}
+
+static acpi_status acpihp_enum_ej0_poweroff(acpi_handle handle)
+{
+ acpi_status status;
+ unsigned long long sta;
+ union acpi_object arg;
+ struct acpi_object_list arg_list;
+
+ if (!handle)
+ return AE_BAD_PARAMETER;
+
+ arg_list.count = 1;
+ arg_list.pointer = &arg;
+ arg.type = ACPI_TYPE_INTEGER;
+ arg.integer.value = 1;
+ status = acpi_evaluate_object(handle, "_EJ0", &arg_list, NULL);
+ if (ACPI_FAILURE(status)) {
+ ACPIHP_WARN("fails to power off object %p.", handle);
+ return status;
+ }
+
+ status = acpi_evaluate_integer(handle, METHOD_NAME__STA, NULL, &sta);
+ if (ACPI_FAILURE(status)) {
+ ACPIHP_WARN("fails to evaluate _STA method of object %p",
+ handle);
+ return status;
+ }
+
+ if (sta & (ACPI_STA_DEVICE_FUNCTIONING | ACPI_STA_DEVICE_ENABLED)) {
+ ACPIHP_WARN("object %p is still active after executing _EJ0.",
+ handle);
+ return AE_ERROR;
+ }
+
+ return AE_OK;
+}
+
+struct acpihp_slot_ops acpihp_enum_ej0 = {
+ .init = acpihp_enum_ej0_init,
+ .fini = acpihp_enum_ej0_fini,
+ .check = acpihp_enum_ej0_check,
+ .get_capabilities = acpihp_enum_ej0_get_capabilities,
+ .poweron = acpihp_enum_ej0_poweron,
+ .poweroff = acpihp_enum_ej0_poweroff,
+ .owner = THIS_MODULE,
+ .desc = "ACPI _EJ0 Based Hotplug Slot Enumerator"
+};
1.7.9.5

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