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From:   Andrew Jeffery <andrew@aj.id.au>
To:     openipmi-developer@lists.sourceforge.net, openbmc@lists.ozlabs.org,
        minyard@acm.org
Cc:     joel@jms.id.au, ryan_chen@aspeedtech.com,
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        linus.walleij@linaro.org, linux-kernel@vger.kernel.org,
        tali.perry1@gmail.com, robh+dt@kernel.org, lee.jones@linaro.org,
        chiawei_wang@aspeedtech.com, linux-arm-kernel@lists.infradead.org,
        benjaminfair@google.com
Subject: [PATCH v2 13/21] ipmi: kcs_bmc: Decouple the IPMI chardev from the core
Date:   Fri, 19 Mar 2021 16:57:44 +1030
Message-Id: <20210319062752.145730-13-andrew@aj.id.au>
In-Reply-To: <20210319062752.145730-1-andrew@aj.id.au>
References: <20210319062752.145730-1-andrew@aj.id.au>
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Now that we have untangled the data-structures, split the userspace
interface out into its own module. Userspace interfaces and drivers are
registered to the KCS BMC core to support arbitrary binding of either.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
---
 drivers/char/ipmi/Kconfig             | 13 +++++
 drivers/char/ipmi/Makefile            |  3 +-
 drivers/char/ipmi/kcs_bmc.c           | 78 ++++++++++++++++++++++++++-
 drivers/char/ipmi/kcs_bmc.h           |  4 --
 drivers/char/ipmi/kcs_bmc_cdev_ipmi.c | 33 +++++++++---
 drivers/char/ipmi/kcs_bmc_client.h    | 14 +++++
 6 files changed, 132 insertions(+), 13 deletions(-)

diff --git a/drivers/char/ipmi/Kconfig b/drivers/char/ipmi/Kconfig
index 07847d9a459a..bc5f81899b62 100644
--- a/drivers/char/ipmi/Kconfig
+++ b/drivers/char/ipmi/Kconfig
@@ -124,6 +124,19 @@ config NPCM7XX_KCS_IPMI_BMC
 	  This support is also available as a module.  If so, the module
 	  will be called kcs_bmc_npcm7xx.
 
+config IPMI_KCS_BMC_CDEV_IPMI
+	depends on IPMI_KCS_BMC
+	tristate "IPMI character device interface for BMC KCS devices"
+	help
+	  Provides a BMC-side character device implementing IPMI
+	  semantics for KCS IPMI devices.
+
+	  Say YES if you wish to expose KCS devices on the BMC for IPMI
+	  purposes.
+
+	  This support is also available as a module. The module will be
+	  called kcs_bmc_cdev_ipmi.
+
 config ASPEED_BT_IPMI_BMC
 	depends on ARCH_ASPEED || COMPILE_TEST
 	depends on REGMAP && REGMAP_MMIO && MFD_SYSCON
diff --git a/drivers/char/ipmi/Makefile b/drivers/char/ipmi/Makefile
index a302bc865370..fcfa676afddb 100644
--- a/drivers/char/ipmi/Makefile
+++ b/drivers/char/ipmi/Makefile
@@ -22,7 +22,8 @@ obj-$(CONFIG_IPMI_SSIF) += ipmi_ssif.o
 obj-$(CONFIG_IPMI_POWERNV) += ipmi_powernv.o
 obj-$(CONFIG_IPMI_WATCHDOG) += ipmi_watchdog.o
 obj-$(CONFIG_IPMI_POWEROFF) += ipmi_poweroff.o
-obj-$(CONFIG_IPMI_KCS_BMC) += kcs_bmc.o kcs_bmc_cdev_ipmi.o
+obj-$(CONFIG_IPMI_KCS_BMC) += kcs_bmc.o
+obj-$(CONFIG_IPMI_KCS_BMC_CDEV_IPMI) += kcs_bmc_cdev_ipmi.o
 obj-$(CONFIG_ASPEED_BT_IPMI_BMC) += bt-bmc.o
 obj-$(CONFIG_ASPEED_KCS_IPMI_BMC) += kcs_bmc_aspeed.o
 obj-$(CONFIG_NPCM7XX_KCS_IPMI_BMC) += kcs_bmc_npcm7xx.o
diff --git a/drivers/char/ipmi/kcs_bmc.c b/drivers/char/ipmi/kcs_bmc.c
index 266ebec71d6f..694db6ee2a92 100644
--- a/drivers/char/ipmi/kcs_bmc.c
+++ b/drivers/char/ipmi/kcs_bmc.c
@@ -5,7 +5,9 @@
  */
 
 #include <linux/device.h>
+#include <linux/list.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 
 #include "kcs_bmc.h"
 
@@ -13,6 +15,11 @@
 #include "kcs_bmc_device.h"
 #include "kcs_bmc_client.h"
 
+/* Record probed devices and cdevs */
+static DEFINE_MUTEX(kcs_bmc_lock);
+static LIST_HEAD(kcs_bmc_devices);
+static LIST_HEAD(kcs_bmc_cdevs);
+
 /* Consumer data access */
 
 u8 kcs_bmc_read_data(struct kcs_bmc_device *kcs_bmc)
@@ -100,16 +107,83 @@ EXPORT_SYMBOL(kcs_bmc_disable_device);
 
 int kcs_bmc_add_device(struct kcs_bmc_device *kcs_bmc)
 {
-	return kcs_bmc_ipmi_attach_cdev(kcs_bmc);
+	struct kcs_bmc_cdev *cdev;
+	int rc;
+
+	spin_lock_init(&kcs_bmc->lock);
+	kcs_bmc->client = NULL;
+
+	mutex_lock(&kcs_bmc_lock);
+	list_add(&kcs_bmc->entry, &kcs_bmc_devices);
+	list_for_each_entry(cdev, &kcs_bmc_cdevs, entry) {
+		rc = cdev->ops->add_device(kcs_bmc);
+		if (rc)
+			dev_err(kcs_bmc->dev, "Failed to add chardev for KCS channel %d: %d",
+				kcs_bmc->channel, rc);
+	}
+	mutex_unlock(&kcs_bmc_lock);
+
+	return 0;
 }
 EXPORT_SYMBOL(kcs_bmc_add_device);
 
 int kcs_bmc_remove_device(struct kcs_bmc_device *kcs_bmc)
 {
-	return kcs_bmc_ipmi_detach_cdev(kcs_bmc);
+	struct kcs_bmc_cdev *cdev;
+	int rc;
+
+	mutex_lock(&kcs_bmc_lock);
+	list_del(&kcs_bmc->entry);
+	list_for_each_entry(cdev, &kcs_bmc_cdevs, entry) {
+		rc = cdev->ops->remove_device(kcs_bmc);
+		if (rc)
+			dev_err(kcs_bmc->dev, "Failed to remove chardev for KCS channel %d: %d",
+				kcs_bmc->channel, rc);
+	}
+	mutex_unlock(&kcs_bmc_lock);
+
+	return 0;
 }
 EXPORT_SYMBOL(kcs_bmc_remove_device);
 
+int kcs_bmc_register_cdev(struct kcs_bmc_cdev *cdev)
+{
+	struct kcs_bmc_device *kcs_bmc;
+	int rc;
+
+	mutex_lock(&kcs_bmc_lock);
+	list_add(&cdev->entry, &kcs_bmc_cdevs);
+	list_for_each_entry(kcs_bmc, &kcs_bmc_devices, entry) {
+		rc = cdev->ops->add_device(kcs_bmc);
+		if (rc)
+			dev_err(kcs_bmc->dev, "Failed to add chardev for KCS channel %d: %d",
+				kcs_bmc->channel, rc);
+	}
+	mutex_unlock(&kcs_bmc_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL(kcs_bmc_register_cdev);
+
+int kcs_bmc_unregister_cdev(struct kcs_bmc_cdev *cdev)
+{
+	struct kcs_bmc_device *kcs_bmc;
+	int rc;
+
+	mutex_lock(&kcs_bmc_lock);
+	list_del(&cdev->entry);
+	list_for_each_entry(kcs_bmc, &kcs_bmc_devices, entry) {
+		rc = cdev->ops->remove_device(kcs_bmc);
+		if (rc)
+			dev_err(kcs_bmc->dev, "Failed to add chardev for KCS channel %d: %d",
+				kcs_bmc->channel, rc);
+	}
+	mutex_unlock(&kcs_bmc_lock);
+
+	return rc;
+}
+EXPORT_SYMBOL(kcs_bmc_unregister_cdev);
+
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Haiyue Wang <haiyue.wang@linux.intel.com>");
 MODULE_AUTHOR("Andrew Jeffery <andrew@aj.id.au>");
diff --git a/drivers/char/ipmi/kcs_bmc.h b/drivers/char/ipmi/kcs_bmc.h
index 3f266740c759..5deb9a0b8e60 100644
--- a/drivers/char/ipmi/kcs_bmc.h
+++ b/drivers/char/ipmi/kcs_bmc.h
@@ -42,8 +42,4 @@ struct kcs_bmc_device {
 	spinlock_t lock;
 	struct kcs_bmc_client *client;
 };
-
-/* Temporary exports while refactoring */
-int kcs_bmc_ipmi_attach_cdev(struct kcs_bmc_device *kcs_bmc);
-int kcs_bmc_ipmi_detach_cdev(struct kcs_bmc_device *kcs_bmc);
 #endif /* __KCS_BMC_H__ */
diff --git a/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c b/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
index 58c42e76483d..df83d67851ac 100644
--- a/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
+++ b/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
@@ -469,8 +469,7 @@ static const struct file_operations kcs_bmc_ipmi_fops = {
 static DEFINE_SPINLOCK(kcs_bmc_ipmi_instances_lock);
 static LIST_HEAD(kcs_bmc_ipmi_instances);
 
-int kcs_bmc_ipmi_attach_cdev(struct kcs_bmc_device *kcs_bmc);
-int kcs_bmc_ipmi_attach_cdev(struct kcs_bmc_device *kcs_bmc)
+static int kcs_bmc_ipmi_attach_cdev(struct kcs_bmc_device *kcs_bmc)
 {
 	struct kcs_bmc_ipmi *priv;
 	int rc;
@@ -512,10 +511,8 @@ int kcs_bmc_ipmi_attach_cdev(struct kcs_bmc_device *kcs_bmc)
 
 	return 0;
 }
-EXPORT_SYMBOL(kcs_bmc_ipmi_attach_cdev);
 
-int kcs_bmc_ipmi_detach_cdev(struct kcs_bmc_device *kcs_bmc);
-int kcs_bmc_ipmi_detach_cdev(struct kcs_bmc_device *kcs_bmc)
+static int kcs_bmc_ipmi_detach_cdev(struct kcs_bmc_device *kcs_bmc)
 {
 	struct kcs_bmc_ipmi *priv = NULL, *pos;
 
@@ -541,7 +538,31 @@ int kcs_bmc_ipmi_detach_cdev(struct kcs_bmc_device *kcs_bmc)
 
 	return 0;
 }
-EXPORT_SYMBOL(kcs_bmc_ipmi_detach_cdev);
+
+static const struct kcs_bmc_cdev_ops kcs_bmc_ipmi_cdev_ops = {
+	.add_device = kcs_bmc_ipmi_attach_cdev,
+	.remove_device = kcs_bmc_ipmi_detach_cdev,
+};
+
+static struct kcs_bmc_cdev kcs_bmc_ipmi_cdev = {
+	.ops = &kcs_bmc_ipmi_cdev_ops,
+};
+
+static int kcs_bmc_ipmi_init(void)
+{
+	return kcs_bmc_register_cdev(&kcs_bmc_ipmi_cdev);
+}
+module_init(kcs_bmc_ipmi_init);
+
+static void kcs_bmc_ipmi_exit(void)
+{
+	int rc;
+
+	rc = kcs_bmc_unregister_cdev(&kcs_bmc_ipmi_cdev);
+	if (rc)
+		pr_warn("Failed to remove KCS BMC client: %d", rc);
+}
+module_exit(kcs_bmc_ipmi_exit);
 
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Haiyue Wang <haiyue.wang@linux.intel.com>");
diff --git a/drivers/char/ipmi/kcs_bmc_client.h b/drivers/char/ipmi/kcs_bmc_client.h
index 2dd710f4b4aa..d0a7404ff584 100644
--- a/drivers/char/ipmi/kcs_bmc_client.h
+++ b/drivers/char/ipmi/kcs_bmc_client.h
@@ -10,6 +10,17 @@
 
 #include "kcs_bmc.h"
 
+struct kcs_bmc_cdev_ops {
+	int (*add_device)(struct kcs_bmc_device *kcs_bmc);
+	int (*remove_device)(struct kcs_bmc_device *kcs_bmc);
+};
+
+struct kcs_bmc_cdev {
+	struct list_head entry;
+
+	const struct kcs_bmc_cdev_ops *ops;
+};
+
 struct kcs_bmc_client_ops {
 	int (*event)(struct kcs_bmc_client *client);
 };
@@ -20,6 +31,9 @@ struct kcs_bmc_client {
 	struct kcs_bmc_device *dev;
 };
 
+int kcs_bmc_register_cdev(struct kcs_bmc_cdev *cdev);
+int kcs_bmc_unregister_cdev(struct kcs_bmc_cdev *cdev);
+
 int kcs_bmc_enable_device(struct kcs_bmc_device *kcs_bmc, struct kcs_bmc_client *client);
 void kcs_bmc_disable_device(struct kcs_bmc_device *kcs_bmc, struct kcs_bmc_client *client);
 
-- 
2.27.0