soc: aspeed: snoop: Add clock control logic

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>

1 files 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;
 }