gpio: Report errors when GPIOs cannot be read

Some controllers do not allow the output value to be read. Detect this and
report the error in that case.

Signed-off-by: Simon Glass <sjg@chromium.org>

diff --git a/cmd/gpio.c b/cmd/gpio.c
index 693998e8bd5d14822504aa5806c8f9ad0f7f1010..ecdc453918f48e1e9390b20f21a8010530315f97 100644 (file)
--- a/cmd/gpio.c
+++ b/cmd/gpio.c
@@ -119,7 +119,7 @@ static int do_gpio(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
        unsigned int gpio;
        enum gpio_cmd sub_cmd;
-       ulong value;
+       int value;
        const char *str_cmd, *str_gpio = NULL;
        int ret;
 #ifdef CONFIG_DM_GPIO
@@ -197,15 +197,35 @@ static int do_gpio(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
                value = gpio_get_value(gpio);
        } else {
                switch (sub_cmd) {
-                       case GPIO_SET:    value = 1; break;
-                       case GPIO_CLEAR:  value = 0; break;
-                       case GPIO_TOGGLE: value = !gpio_get_value(gpio); break;
-                       default:          goto show_usage;
+               case GPIO_SET:
+                       value = 1;
+                       break;
+               case GPIO_CLEAR:
+                       value = 0;
+                       break;
+               case GPIO_TOGGLE:
+                       value = gpio_get_value(gpio);
+                       if (!IS_ERR_VALUE(value))
+                               value = !value;
+                       break;
+               default:
+                       goto show_usage;
                }
                gpio_direction_output(gpio, value);
        }
-       printf("gpio: pin %s (gpio %i) value is %lu\n",
-               str_gpio, gpio, value);
+       printf("gpio: pin %s (gpio %i) value is ", str_gpio, gpio);
+       if (IS_ERR_VALUE(value))
+               printf("unknown (ret=%d)\n", value);
+       else
+               printf("%d\n", value);
+       if (sub_cmd != GPIO_INPUT && !IS_ERR_VALUE(value)) {
+               int nval = gpio_get_value(gpio);
+
+               if (IS_ERR_VALUE(nval))
+                       printf("   Warning: no access to GPIO output value\n");
+               else if (nval != value)
+                       printf("   Warning: value of pin is still %d\n", nval);
+       }
 
        if (ret != -EBUSY)
                gpio_free(gpio);