pinctrl: baytrail: Warn if direct IRQ GPIO set to output

For Baytrail, you should never set a GPIO set to direct_irq
to output mode.  When direct_irq_en is set for a GPIO, it is
tied directly to an APIC internally, and making the pad output
does not make any sense. Assert a WARN() in the event this happens.

Signed-off-by: Eric Ernst <eric.ernst@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/pinctrl/pinctrl-baytrail.c b/drivers/pinctrl/pinctrl-baytrail.c
index 975572e..701a646 100644 (file)
--- a/drivers/pinctrl/pinctrl-baytrail.c
+++ b/drivers/pinctrl/pinctrl-baytrail.c
@@ -44,6 +44,7 @@
 
 /* BYT_CONF0_REG register bits */
 #define BYT_IODEN              BIT(31)
+#define BYT_DIRECT_IRQ_EN      BIT(27)
 #define BYT_TRIG_NEG           BIT(26)
 #define BYT_TRIG_POS           BIT(25)
 #define BYT_TRIG_LVL           BIT(24)
@@ -303,12 +304,22 @@ static int byt_gpio_direction_output(struct gpio_chip *chip,
                                     unsigned gpio, int value)
 {
        struct byt_gpio *vg = to_byt_gpio(chip);
+       void __iomem *conf_reg = byt_gpio_reg(chip, gpio, BYT_CONF0_REG);
        void __iomem *reg = byt_gpio_reg(chip, gpio, BYT_VAL_REG);
        unsigned long flags;
        u32 reg_val;
 
        spin_lock_irqsave(&vg->lock, flags);
 
+       /*
+        * Before making any direction modifications, do a check if gpio
+        * is set for direct IRQ.  On baytrail, setting GPIO to output does
+        * not make sense, so let's at least warn the caller before they shoot
+        * themselves in the foot.
+        */
+       WARN(readl(conf_reg) & BYT_DIRECT_IRQ_EN,
+               "Potential Error: Setting GPIO with direct_irq_en to output");
+
        reg_val = readl(reg) | BYT_DIR_MASK;
        reg_val &= ~BYT_OUTPUT_EN;