[PATCH 3/7] spmi: apple: check transaction status

[Sasha Finkelstein <k@chaosmail.tech>]

From: Alba Mendez <me@alba.sh>

Check for parity errors and missing command ACKs

Signed-off-by: Alba Mendez <me@alba.sh>
Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>
---
 drivers/spmi/spmi-apple-controller.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/spmi/spmi-apple-controller.c b/drivers/spmi/spmi-apple-controller.c
index b4f442d0b4ad..4678a9e5270a 100644
--- a/drivers/spmi/spmi-apple-controller.c
+++ b/drivers/spmi/spmi-apple-controller.c
@@ -22,6 +22,12 @@
 #define SPMI_CMD_REG 0x4
 #define SPMI_RSP_REG 0x8
 
+/* SPMI_RSP_REG reply word */
+#define SPMI_REPLY_FRAME_PARITY_OFFSET 16
+#define SPMI_REPLY_ACK BIT(15)
+#define SPMI_REPLY_SLAVE_ID GENMASK(14, 8)
+#define SPMI_REPLY_CMD GENMASK(7, 0)
+
 #define SPMI_RX_FIFO_EMPTY BIT(24)
 
 #define REG_POLL_INTERVAL_US 10000
@@ -62,7 +68,7 @@ static int spmi_read_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid,
 {
 	struct apple_spmi *spmi = spmi_controller_get_drvdata(ctrl);
 	u32 spmi_cmd = apple_spmi_pack_cmd(opc, sid, saddr, len);
-	u32 rsp;
+	u32 reply, rsp;
 	size_t len_read = 0;
 	u8 i;
 	int ret;
@@ -73,8 +79,7 @@ static int spmi_read_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid,
 	if (ret)
 		return ret;
 
-	/* Discard SPMI reply status */
-	readl(spmi->regs + SPMI_RSP_REG);
+	reply = readl(spmi->regs + SPMI_RSP_REG);
 
 	/* Read SPMI data reply */
 	while (len_read < len) {
@@ -93,6 +98,10 @@ 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");
 
+	if ((~reply >> SPMI_REPLY_FRAME_PARITY_OFFSET) & ((1 << len) - 1)) {
+		dev_err(&ctrl->dev, "some frames failed parity check\n");
+		return -EIO;
+	}
 	return 0;
 }
 
@@ -101,6 +110,7 @@ static int spmi_write_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid,
 {
 	struct apple_spmi *spmi = spmi_controller_get_drvdata(ctrl);
 	u32 spmi_cmd = apple_spmi_pack_cmd(opc, sid, saddr, len);
+	u32 reply;
 	size_t i = 0, j;
 	int ret;
 
@@ -119,12 +129,15 @@ static int spmi_write_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid,
 	if (ret)
 		return ret;
 
-	/* Discard */
-	readl(spmi->regs + SPMI_RSP_REG);
+	reply = 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");
 
+	if (!(reply & SPMI_REPLY_ACK)) {
+		dev_err(&ctrl->dev, "command not acknowledged\n");
+		return -EIO;
+	}
 	return 0;
 }
 

-- 
2.55.0