[PATCH v2 1/2] misc: Add clock control logic into Aspeed LPC SNOOP driver

From: John Wang <wangzhiqiang.bj@bytedance.com>
To: xuxiaohan@bytedance.com, yulei.sh@bytedance.com
Cc: Jae Hyun Yoo <jae.hyun.yoo@intel.com>,
	Vernon Mauery <vernon.mauery@linux.intel.com>,
	Joel Stanley <joel@jms.id.au>, Andrew Jeffery <andrew@aj.id.au>,
	Patrick Venture <venture@google.com>,
	Robert Lippert <rlippert@google.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Benjamin Fair <benjaminfair@google.com>,
	linux-arm-kernel@lists.infradead.org (moderated list:ARM/ASPEED
	MACHINE SUPPORT),
	linux-aspeed@lists.ozlabs.org (moderated list:ARM/ASPEED MACHINE
	SUPPORT), linux-kernel@vger.kernel.org (open list)
Subject: [PATCH v2 1/2] misc: Add clock control logic into Aspeed LPC SNOOP driver
Date: Tue,  8 Dec 2020 17:17:47 +0800	[thread overview]
Message-ID: <20201208091748.1920-1-wangzhiqiang.bj@bytedance.com> (raw)

From: Jae Hyun Yoo <jae.hyun.yoo@intel.com>

If LPC SNOOP driver is registered ahead of lpc-ctrl module, LPC
SNOOP block will be enabled without heart beating of LCLK until
lpc-ctrl enables the LCLK. This issue causes improper handling on
host interrupts when the host sends interrupt in that time frame.
Then kernel eventually forcibly disables the interrupt with
dumping stack and printing a 'nobody cared this irq' message out.

To prevent this issue, all LPC sub-nodes should enable LCLK
individually so this patch adds clock control logic into the LPC
SNOOP driver.

Fixes: 3772e5da4454 ("drivers/misc: Aspeed LPC snoop output using misc
chardev")

Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@intel.com>
Signed-off-by: Vernon Mauery <vernon.mauery@linux.intel.com>
Signed-off-by: John Wang <wangzhiqiang.bj@bytedance.com>
---
v2:
  reword: Add fixes line
---
 drivers/soc/aspeed/aspeed-lpc-snoop.c | 30 ++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/drivers/soc/aspeed/aspeed-lpc-snoop.c b/drivers/soc/aspeed/aspeed-lpc-snoop.c
index 682ba0eb4eba..20acac6342ef 100644
--- a/drivers/soc/aspeed/aspeed-lpc-snoop.c
+++ b/drivers/soc/aspeed/aspeed-lpc-snoop.c
@@ -11,6 +11,7 @@
  */
 
 #include <linux/bitops.h>
+#include <linux/clk.h>
 #include <linux/interrupt.h>
 #include <linux/fs.h>
 #include <linux/kfifo.h>
@@ -67,6 +68,7 @@ struct aspeed_lpc_snoop_channel {
 struct aspeed_lpc_snoop {
 	struct regmap		*regmap;
 	int			irq;
+	struct clk		*clk;
 	struct aspeed_lpc_snoop_channel chan[NUM_SNOOP_CHANNELS];
 };
 
@@ -282,22 +284,42 @@ static int aspeed_lpc_snoop_probe(struct platform_device *pdev)
 		return -ENODEV;
 	}
 
+	lpc_snoop->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(lpc_snoop->clk)) {
+		rc = PTR_ERR(lpc_snoop->clk);
+		if (rc != -EPROBE_DEFER)
+			dev_err(dev, "couldn't get clock\n");
+		return rc;
+	}
+	rc = clk_prepare_enable(lpc_snoop->clk);
+	if (rc) {
+		dev_err(dev, "couldn't enable clock\n");
+		return rc;
+	}
+
 	rc = aspeed_lpc_snoop_config_irq(lpc_snoop, pdev);
 	if (rc)
-		return rc;
+		goto err;
 
 	rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, 0, port);
 	if (rc)
-		return rc;
+		goto err;
 
 	/* Configuration of 2nd snoop channel port is optional */
 	if (of_property_read_u32_index(dev->of_node, "snoop-ports",
 				       1, &port) == 0) {
 		rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, 1, port);
-		if (rc)
+		if (rc) {
 			aspeed_lpc_disable_snoop(lpc_snoop, 0);
+			goto err;
+		}
 	}
 
+	return 0;
+
+err:
+	clk_disable_unprepare(lpc_snoop->clk);
+
 	return rc;
 }
 
@@ -309,6 +331,8 @@ static int aspeed_lpc_snoop_remove(struct platform_device *pdev)
 	aspeed_lpc_disable_snoop(lpc_snoop, 0);
 	aspeed_lpc_disable_snoop(lpc_snoop, 1);
 
+	clk_disable_unprepare(lpc_snoop->clk);
+
 	return 0;
 }
 
-- 
2.25.1

