[PATCH 2/7] spmi: apple: Validate FIFO state

[Sasha Finkelstein <k@chaosmail.tech>]

From: Alba Mendez <me@alba.sh>

Check for data before reading the body of a reply, and check for
end of data afterwards.

Signed-off-by: Alba Mendez <me@alba.sh>
Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>
---
 drivers/spmi/spmi-apple-controller.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/spmi/spmi-apple-controller.c b/drivers/spmi/spmi-apple-controller.c
index 376cf682c43e..b4f442d0b4ad 100644
--- a/drivers/spmi/spmi-apple-controller.c
+++ b/drivers/spmi/spmi-apple-controller.c
@@ -78,6 +78,10 @@ static int spmi_read_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid,
 
 	/* Read SPMI data reply */
 	while (len_read < len) {
+		if (readl(spmi->regs + SPMI_STATUS_REG) & SPMI_RX_FIFO_EMPTY) {
+			dev_err(&ctrl->dev, "FIFO lacks reply data, controller stuck?\n");
+			return -EIO;
+		}
 		rsp = readl(spmi->regs + SPMI_RSP_REG);
 		i = 0;
 		while ((len_read < len) && (i < 4)) {
@@ -86,6 +90,9 @@ static int spmi_read_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");
+
 	return 0;
 }
 
@@ -115,6 +122,9 @@ static int spmi_write_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid,
 	/* Discard */
 	readl(spmi->regs + SPMI_RSP_REG);
 
+	if (!(readl(spmi->regs + SPMI_STATUS_REG) & SPMI_RX_FIFO_EMPTY))
+		dev_warn(&ctrl->dev, "FIFO has extra data\n");
+
 	return 0;
 }
 

-- 
2.55.0