[PATCH v2] ipmi:si: Add async init to ipmi_si

[Michal Clapinski <mclapinski@google.com>]

Added a new config option to allow offloading individual calls to
try_smi_init(). Saves 100ms on my system.

Signed-off-by: Michal Clapinski <mclapinski@google.com>
---
v2:
- instead of offloading the whole init function, offload just the
  individual calls to try_smi_init()

I didn't implement the periodic retry feature that was talked about
under v1 due to my lack of expertise. LMK if this is a deal-breaker.
---
 drivers/char/ipmi/Kconfig        |  9 +++++++++
 drivers/char/ipmi/ipmi_si_intf.c | 32 ++++++++++++++++++++++++++++----
 2 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/drivers/char/ipmi/Kconfig b/drivers/char/ipmi/Kconfig
index 669f76000197..c8fa445c1c17 100644
--- a/drivers/char/ipmi/Kconfig
+++ b/drivers/char/ipmi/Kconfig
@@ -67,6 +67,15 @@ config IPMI_SI
 	  Currently, only KCS and SMIC are supported.  If
 	  you are using IPMI, you should probably say "y" here.
 
+config IPMI_SI_ASYNC_INIT
+	bool 'Asynchronous initialization of IPMI System Interface'
+	depends on IPMI_SI
+	default n
+	help
+	  Offloads invidual SMI inits. It speeds up the boot time.
+	  It also introduces a very small risk that something else might fail
+	  if it depends on synchronous IPMI init.
+
 config IPMI_SSIF
 	tristate 'IPMI SMBus handler (SSIF)'
 	depends on I2C
diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
index 9a9d12be9bf7..504d5b8636ba 100644
--- a/drivers/char/ipmi/ipmi_si_intf.c
+++ b/drivers/char/ipmi/ipmi_si_intf.c
@@ -39,6 +39,7 @@
 #include <linux/rcupdate.h>
 #include <linux/ipmi.h>
 #include <linux/ipmi_smi.h>
+#include <linux/async.h>
 #include "ipmi_si.h"
 #include "ipmi_si_sm.h"
 #include <linux/string.h>
@@ -2174,6 +2175,17 @@ static bool __init ipmi_smi_info_same(struct smi_info *e1, struct smi_info *e2)
 		e1->io.addr_data == e2->io.addr_data);
 }
 
+static ASYNC_DOMAIN_EXCLUSIVE(ipmi_si_async_domain);
+
+static void __init async_try_smi_init(void *data, async_cookie_t cookie)
+{
+	struct smi_info *smi = data;
+
+	mutex_lock(&smi_infos_lock);
+	try_smi_init(smi);
+	mutex_unlock(&smi_infos_lock);
+}
+
 static int __init init_ipmi_si(void)
 {
 	struct smi_info *e, *e2;
@@ -2219,8 +2231,13 @@ static int __init init_ipmi_si(void)
 				break;
 			}
 		}
-		if (!dup)
-			try_smi_init(e);
+		if (!dup) {
+			if (IS_ENABLED(CONFIG_IPMI_SI_ASYNC_INIT))
+				async_schedule_domain(async_try_smi_init, e,
+						      &ipmi_si_async_domain);
+			else
+				try_smi_init(e);
+		}
 	}
 
 	/*
@@ -2253,8 +2270,13 @@ static int __init init_ipmi_si(void)
 				break;
 			}
 		}
-		if (!dup)
-			try_smi_init(e);
+		if (!dup) {
+			if (IS_ENABLED(CONFIG_IPMI_SI_ASYNC_INIT))
+				async_schedule_domain(async_try_smi_init, e,
+						      &ipmi_si_async_domain);
+			else
+				try_smi_init(e);
+		}
 	}
 
 	initialized = true;
@@ -2401,6 +2423,8 @@ static void cleanup_ipmi_si(void)
 	if (!initialized)
 		return;
 
+	async_synchronize_full_domain(&ipmi_si_async_domain);
+
 	ipmi_si_pci_shutdown();
 
 	ipmi_si_ls2k_shutdown();
-- 
2.55.0.795.g602f6c329a-goog