[PATCH 5/7] spmi: apple: lock around FIFOs

[Sasha Finkelstein <k@chaosmail.tech>]

From: Alba Mendez <me@alba.sh>

The driver was missing locking around register interactions

Signed-off-by: Alba Mendez <me@alba.sh>
Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>
---
 drivers/spmi/spmi-apple-controller.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/spmi/spmi-apple-controller.c b/drivers/spmi/spmi-apple-controller.c
index d69d16665ce8..d8509f027df6 100644
--- a/drivers/spmi/spmi-apple-controller.c
+++ b/drivers/spmi/spmi-apple-controller.c
@@ -14,6 +14,7 @@
 #include <linux/io.h>
 #include <linux/iopoll.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/platform_device.h>
 #include <linux/spmi.h>
 
@@ -35,6 +36,7 @@
 
 struct apple_spmi {
 	void __iomem *regs;
+	struct mutex fifo_lock;
 };
 
 #define poll_reg(spmi, reg, val, cond) \
@@ -73,6 +75,10 @@ static int spmi_raw_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid,
 	size_t i = 0, j;
 	int ret;
 
+	ret = mutex_lock_interruptible(&spmi->fifo_lock);
+	if (ret)
+		return ret;
+
 	writel(spmi_cmd, spmi->regs + SPMI_CMD_REG);
 
 	while (i < len) {
@@ -86,7 +92,7 @@ static int spmi_raw_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid,
 
 	ret = apple_spmi_wait_rx_not_empty(ctrl);
 	if (ret)
-		return ret;
+		goto out;
 
 	reply = readl(spmi->regs + SPMI_RSP_REG);
 
@@ -94,7 +100,8 @@ static int spmi_raw_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid,
 	while (len_read < ilen) {
 		if (readl(spmi->regs + SPMI_STATUS_REG) & SPMI_RX_FIFO_EMPTY) {
 			dev_err(&ctrl->dev, "FIFO lacks reply data, controller stuck?\n");
-			return -EIO;
+			ret = -EIO;
+			goto out;
 		}
 		rsp = readl(spmi->regs + SPMI_RSP_REG);
 		i = 0;
@@ -107,6 +114,8 @@ static int spmi_raw_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid,
 	if (!(readl(spmi->regs + SPMI_STATUS_REG) & SPMI_RX_FIFO_EMPTY))
 		dev_warn(&ctrl->dev, "FIFO has extra data\n");
 
+	mutex_unlock(&spmi->fifo_lock);
+
 	if (!ilen && !(reply & SPMI_REPLY_ACK)) {
 		dev_err(&ctrl->dev, "command not acknowledged\n");
 		return -EIO;
@@ -116,6 +125,10 @@ static int spmi_raw_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid,
 		return -EIO;
 	}
 	return 0;
+
+out:
+	mutex_unlock(&spmi->fifo_lock);
+	return ret;
 }
 
 /* Send a raw command with 1..16 input data frames */
@@ -181,6 +194,7 @@ static int apple_spmi_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	spmi = spmi_controller_get_drvdata(ctrl);
+	mutex_init(&spmi->fifo_lock);
 
 	spmi->regs = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(spmi->regs))

-- 
2.55.0