linux-kernel - [PATCH v4 1/1] pinctrl: baytrail: Warn if direct IRQ GPIO set to output

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Date:	Thu, 12 Jun 2014 11:06:20 -0700
From:	eric.ernst@...ux.intel.com
To:	linus.walleij@...aro.org, linux-kernel@...r.kernel.org,
	mark.gross@...el.com, mika.westerberg@...ux.intel.com
Cc:	eric.ernst@...ux.intel.com
Subject: [PATCH v4 1/1] pinctrl: baytrail: Warn if direct IRQ GPIO set to output

From: Eric Ernst <eric.ernst@...ux.intel.com>

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@...ux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
---
 drivers/pinctrl/pinctrl-baytrail.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/pinctrl/pinctrl-baytrail.c b/drivers/pinctrl/pinctrl-baytrail.c
index 975572e2f260..c34add934216 100644
--- a/drivers/pinctrl/pinctrl-baytrail.c
+++ b/drivers/pinctrl/pinctrl-baytrail.c
@@ -303,12 +303,22 @@ 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;
 
-- 
1.7.9.5

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