[PATCH v3 4/5] fpga manager: xilinx-spi: add error checking after gpiod_get_value()

[Luca Ceresoli]

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 <t...@redhat.com>
Signed-off-by: Luca Ceresoli <l...@lucaceresoli.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