ipmi: kcs_bmc: Decouple the IPMI chardev from the core

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>
Message-Id: <20210608104757.582199-9-andrew@aj.id.au>
Reviewed-by: Zev Weiss <zweiss@equinix.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>

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

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

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 registered devices and drivers */
+static DEFINE_MUTEX(kcs_bmc_lock);
+static LIST_HEAD(kcs_bmc_devices);
+static LIST_HEAD(kcs_bmc_drivers);
+
 /* Consumer data access */
 
 u8 kcs_bmc_read_data(struct kcs_bmc_device *kcs_bmc)
@@ -98,22 +105,83 @@ void kcs_bmc_disable_device(struct kcs_bmc_device *kcs_bmc, struct kcs_bmc_clien
 }
 EXPORT_SYMBOL(kcs_bmc_disable_device);
 
-int kcs_bmc_ipmi_add_device(struct kcs_bmc_device *kcs_bmc);
 int kcs_bmc_add_device(struct kcs_bmc_device *kcs_bmc)
 {
-	return kcs_bmc_ipmi_add_device(kcs_bmc);
+	struct kcs_bmc_driver *drv;
+	int error = 0;
+	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(drv, &kcs_bmc_drivers, entry) {
+		rc = drv->ops->add_device(kcs_bmc);
+		if (!rc)
+			continue;
+
+		dev_err(kcs_bmc->dev, "Failed to add chardev for KCS channel %d: %d",
+			kcs_bmc->channel, rc);
+		error = rc;
+	}
+	mutex_unlock(&kcs_bmc_lock);
+
+	return error;
 }
 EXPORT_SYMBOL(kcs_bmc_add_device);
 
-int kcs_bmc_ipmi_remove_device(struct kcs_bmc_device *kcs_bmc);
 void kcs_bmc_remove_device(struct kcs_bmc_device *kcs_bmc)
 {
-	if (kcs_bmc_ipmi_remove_device(kcs_bmc))
-		pr_warn("Failed to remove device for KCS channel %d\n",
-			kcs_bmc->channel);
+	struct kcs_bmc_driver *drv;
+	int rc;
+
+	mutex_lock(&kcs_bmc_lock);
+	list_del(&kcs_bmc->entry);
+	list_for_each_entry(drv, &kcs_bmc_drivers, entry) {
+		rc = drv->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);
 }
 EXPORT_SYMBOL(kcs_bmc_remove_device);
 
+void kcs_bmc_register_driver(struct kcs_bmc_driver *drv)
+{
+	struct kcs_bmc_device *kcs_bmc;
+	int rc;
+
+	mutex_lock(&kcs_bmc_lock);
+	list_add(&drv->entry, &kcs_bmc_drivers);
+	list_for_each_entry(kcs_bmc, &kcs_bmc_devices, entry) {
+		rc = drv->ops->add_device(kcs_bmc);
+		if (rc)
+			dev_err(kcs_bmc->dev, "Failed to add driver for KCS channel %d: %d",
+				kcs_bmc->channel, rc);
+	}
+	mutex_unlock(&kcs_bmc_lock);
+}
+EXPORT_SYMBOL(kcs_bmc_register_driver);
+
+void kcs_bmc_unregister_driver(struct kcs_bmc_driver *drv)
+{
+	struct kcs_bmc_device *kcs_bmc;
+	int rc;
+
+	mutex_lock(&kcs_bmc_lock);
+	list_del(&drv->entry);
+	list_for_each_entry(kcs_bmc, &kcs_bmc_devices, entry) {
+		rc = drv->ops->remove_device(kcs_bmc);
+		if (rc)
+			dev_err(kcs_bmc->dev, "Failed to remove driver for KCS channel %d: %d",
+				kcs_bmc->channel, rc);
+	}
+	mutex_unlock(&kcs_bmc_lock);
+}
+EXPORT_SYMBOL(kcs_bmc_unregister_driver);
+
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Haiyue Wang <haiyue.wang@linux.intel.com>");
 MODULE_AUTHOR("Andrew Jeffery <andrew@aj.id.au>");

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_add_device(struct kcs_bmc_device *kcs_bmc);
-int kcs_bmc_ipmi_add_device(struct kcs_bmc_device *kcs_bmc)
+static int kcs_bmc_ipmi_add_device(struct kcs_bmc_device *kcs_bmc)
 {
 	struct kcs_bmc_ipmi *priv;
 	int rc;
@@ -512,10 +511,8 @@ int kcs_bmc_ipmi_add_device(struct kcs_bmc_device *kcs_bmc)
 
 	return 0;
 }
-EXPORT_SYMBOL(kcs_bmc_ipmi_add_device);
 
-int kcs_bmc_ipmi_remove_device(struct kcs_bmc_device *kcs_bmc);
-int kcs_bmc_ipmi_remove_device(struct kcs_bmc_device *kcs_bmc)
+static int kcs_bmc_ipmi_remove_device(struct kcs_bmc_device *kcs_bmc)
 {
 	struct kcs_bmc_ipmi *priv = NULL, *pos;
 
@@ -541,7 +538,29 @@ int kcs_bmc_ipmi_remove_device(struct kcs_bmc_device *kcs_bmc)
 
 	return 0;
 }
-EXPORT_SYMBOL(kcs_bmc_ipmi_remove_device);
+
+static const struct kcs_bmc_driver_ops kcs_bmc_ipmi_driver_ops = {
+	.add_device = kcs_bmc_ipmi_add_device,
+	.remove_device = kcs_bmc_ipmi_remove_device,
+};
+
+static struct kcs_bmc_driver kcs_bmc_ipmi_driver = {
+	.ops = &kcs_bmc_ipmi_driver_ops,
+};
+
+static int kcs_bmc_ipmi_init(void)
+{
+	kcs_bmc_register_driver(&kcs_bmc_ipmi_driver);
+
+	return 0;
+}
+module_init(kcs_bmc_ipmi_init);
+
+static void kcs_bmc_ipmi_exit(void)
+{
+	kcs_bmc_unregister_driver(&kcs_bmc_ipmi_driver);
+}
+module_exit(kcs_bmc_ipmi_exit);
 
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Haiyue Wang <haiyue.wang@linux.intel.com>");

drivers/char/ipmi/kcs_bmc_client.h

@@ -8,6 +8,17 @@
 
 #include "kcs_bmc.h"
 
+struct kcs_bmc_driver_ops {
+	int (*add_device)(struct kcs_bmc_device *kcs_bmc);
+	int (*remove_device)(struct kcs_bmc_device *kcs_bmc);
+};
+
+struct kcs_bmc_driver {
+	struct list_head entry;
+
+	const struct kcs_bmc_driver_ops *ops;
+};
+
 struct kcs_bmc_client_ops {
 	irqreturn_t (*event)(struct kcs_bmc_client *client);
 };
@@ -18,6 +29,9 @@ struct kcs_bmc_client {
 	struct kcs_bmc_device *dev;
 };
 
+void kcs_bmc_register_driver(struct kcs_bmc_driver *drv);
+void kcs_bmc_unregister_driver(struct kcs_bmc_driver *drv);
+
 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);