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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jae Hyun Yoo <jae.hyun.yoo@intel.com>,
        Vernon Mauery <vernon.mauery@linux.intel.com>,
        John Wang <wangzhiqiang.bj@bytedance.com>,
        Joel Stanley <joel@jms.id.au>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 055/247] soc: aspeed: snoop: Add clock control logic
Date:   Mon,  1 Mar 2021 17:11:15 +0100
Message-Id: <20210301161034.369309830@linuxfoundation.org>
In-Reply-To: <20210301161031.684018251@linuxfoundation.org>
References: <20210301161031.684018251@linuxfoundation.org>
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From: Jae Hyun Yoo <jae.hyun.yoo@intel.com>

[ Upstream commit 3f94cf15583be554df7aaa651b8ff8e1b68fbe51 ]

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>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20201208091748.1920-1-wangzhiqiang.bj@bytedance.com
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/misc/aspeed-lpc-snoop.c | 30 +++++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/drivers/misc/aspeed-lpc-snoop.c b/drivers/misc/aspeed-lpc-snoop.c
index c10be21a1663d..b4a776bf44bc5 100644
--- a/drivers/misc/aspeed-lpc-snoop.c
+++ b/drivers/misc/aspeed-lpc-snoop.c
@@ -15,6 +15,7 @@
  */
 
 #include <linux/bitops.h>
+#include <linux/clk.h>
 #include <linux/interrupt.h>
 #include <linux/fs.h>
 #include <linux/kfifo.h>
@@ -71,6 +72,7 @@ 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];
 };
 
@@ -286,22 +288,42 @@ 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;
 }
 
@@ -313,6 +335,8 @@ 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;
 }
 
-- 
2.27.0