linux-kernel - [PATCH v3 4/5] fpga manager: xilinx-spi: add error checking after gpiod_get

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Message-Id: <20200828195808.27975-4-luca@lucaceresoli.net>
Date:   Fri, 28 Aug 2020 21:58:07 +0200
From:   Luca Ceresoli <luca@...aceresoli.net>
To:     linux-fpga@...r.kernel.org
Cc:     Luca Ceresoli <luca@...aceresoli.net>,
        Moritz Fischer <mdf@...nel.org>, Tom Rix <trix@...hat.com>,
        Michal Simek <michal.simek@...inx.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Anatolij Gustschin <agust@...x.de>
Subject: [PATCH v3 4/5] fpga manager: xilinx-spi: add error checking after gpiod_get_value()

Current code calls gpiod_get_value() without error checking. Should the
GPIO controller fail, execution would continue without any error message.

Fix by checking for negative error values.

Reported-by: Tom Rix <trix@...hat.com>
Signed-off-by: Luca Ceresoli <luca@...aceresoli.net>

---

Changes in v3:
 - rebase on previous patches

This patch is new in v2
---
 drivers/fpga/xilinx-spi.c | 35 +++++++++++++++++++++++++++--------
 1 file changed, 27 insertions(+), 8 deletions(-)

diff --git a/drivers/fpga/xilinx-spi.c b/drivers/fpga/xilinx-spi.c
index a7b919eb0b2a..9488c8fbaefd 100644
--- a/drivers/fpga/xilinx-spi.c
+++ b/drivers/fpga/xilinx-spi.c
@@ -27,11 +27,22 @@ struct xilinx_spi_conf {
 	struct gpio_desc *done;
 };
 
-static enum fpga_mgr_states xilinx_spi_state(struct fpga_manager *mgr)
+static int get_done_gpio(struct fpga_manager *mgr)
 {
 	struct xilinx_spi_conf *conf = mgr->priv;
+	int ret;
+
+	ret = gpiod_get_value(conf->done);
+
+	if (ret < 0)
+		dev_err(&mgr->dev, "Error reading DONE (%d)\n", ret);
 
-	if (!gpiod_get_value(conf->done))
+	return ret;
+}
+
+static enum fpga_mgr_states xilinx_spi_state(struct fpga_manager *mgr)
+{
+	if (!get_done_gpio(mgr))
 		return FPGA_MGR_STATE_RESET;
 
 	return FPGA_MGR_STATE_UNKNOWN;
@@ -57,10 +68,21 @@ static int wait_for_init_b(struct fpga_manager *mgr, int value,
 
 	if (conf->init_b) {
 		while (time_before(jiffies, timeout)) {
-			if (gpiod_get_value(conf->init_b) == value)
+			int ret = gpiod_get_value(conf->init_b);
+
+			if (ret == value)
 				return 0;
+
+			if (ret < 0) {
+				dev_err(&mgr->dev, "Error reading INIT_B (%d)\n", ret);
+				return ret;
+			}
+
 			usleep_range(100, 400);
 		}
+
+		dev_err(&mgr->dev, "Timeout waiting for INIT_B to %s\n",
+			value ? "assert" : "deassert");
 		return -ETIMEDOUT;
 	}
 
@@ -85,7 +107,6 @@ static int xilinx_spi_write_init(struct fpga_manager *mgr,
 
 	err = wait_for_init_b(mgr, 1, 1); /* min is 500 ns */
 	if (err) {
-		dev_err(&mgr->dev, "INIT_B pin did not go low\n");
 		gpiod_set_value(conf->prog_b, 0);
 		return err;
 	}
@@ -93,12 +114,10 @@ static int xilinx_spi_write_init(struct fpga_manager *mgr,
 	gpiod_set_value(conf->prog_b, 0);
 
 	err = wait_for_init_b(mgr, 0, 0);
-	if (err) {
-		dev_err(&mgr->dev, "INIT_B pin did not go high\n");
+	if (err)
 		return err;
-	}
 
-	if (gpiod_get_value(conf->done)) {
+	if (get_done_gpio(mgr)) {
 		dev_err(&mgr->dev, "Unexpected DONE pin state...\n");
 		return -EIO;
 	}
-- 
2.28.0