1 files changed, 58 insertions, 13 deletions

diff --git a/drivers/gpio/gpio-bcm-kona.c b/drivers/gpio/gpio-bcm-kona.c
index d329a143f5ec..0c97a8c95e06 100644
--- a/drivers/gpio/gpio-bcm-kona.c
+++ b/drivers/gpio/gpio-bcm-kona.c
@@ -76,6 +76,22 @@ struct bcm_kona_gpio {
 struct bcm_kona_gpio_bank {
 	int id;
 	int irq;
+	/*
+	 * Used to keep track of lock/unlock operations for each GPIO in the
+	 * bank.
+	 *
+	 * All GPIOs are locked by default (see bcm_kona_gpio_reset), and the
+	 * unlock count for all GPIOs is 0 by default. Each unlock increments
+	 * the counter, and each lock decrements the counter.
+	 *
+	 * The lock function only locks the GPIO once its unlock counter is
+	 * down to 0. This is necessary because the GPIO is unlocked in two
+	 * places in this driver: once for requested GPIOs, and once for
+	 * requested IRQs. Since it is possible for a GPIO to be requested
+	 * as both a GPIO and an IRQ, we need to ensure that we don't lock it
+	 * too early.
+	 */
+	u8 gpio_unlock_count[GPIO_PER_BANK];
 	/* Used in the interrupt handler */
 	struct bcm_kona_gpio *kona_gpio;
 };
@@ -93,14 +109,24 @@ static void bcm_kona_gpio_lock_gpio(struct bcm_kona_gpio *kona_gpio,
 	u32 val;
 	unsigned long flags;
 	int bank_id = GPIO_BANK(gpio);
+	int bit = GPIO_BIT(gpio);
+	struct bcm_kona_gpio_bank *bank = &kona_gpio->banks[bank_id];
 
-	raw_spin_lock_irqsave(&kona_gpio->lock, flags);
+	if (bank->gpio_unlock_count[bit] == 0) {
+		dev_err(kona_gpio->gpio_chip.parent,
+			"Unbalanced locks for GPIO %u\n", gpio);
+		return;
+	}
 
-	val = readl(kona_gpio->reg_base + GPIO_PWD_STATUS(bank_id));
-	val |= BIT(gpio);
-	bcm_kona_gpio_write_lock_regs(kona_gpio->reg_base, bank_id, val);
+	if (--bank->gpio_unlock_count[bit] == 0) {
+		raw_spin_lock_irqsave(&kona_gpio->lock, flags);
 
-	raw_spin_unlock_irqrestore(&kona_gpio->lock, flags);
+		val = readl(kona_gpio->reg_base + GPIO_PWD_STATUS(bank_id));
+		val |= BIT(bit);
+		bcm_kona_gpio_write_lock_regs(kona_gpio->reg_base, bank_id, val);
+
+		raw_spin_unlock_irqrestore(&kona_gpio->lock, flags);
+	}
 }
 
 static void bcm_kona_gpio_unlock_gpio(struct bcm_kona_gpio *kona_gpio,
@@ -109,14 +135,20 @@ static void bcm_kona_gpio_unlock_gpio(struct bcm_kona_gpio *kona_gpio,
 	u32 val;
 	unsigned long flags;
 	int bank_id = GPIO_BANK(gpio);
+	int bit = GPIO_BIT(gpio);
+	struct bcm_kona_gpio_bank *bank = &kona_gpio->banks[bank_id];
 
-	raw_spin_lock_irqsave(&kona_gpio->lock, flags);
+	if (bank->gpio_unlock_count[bit] == 0) {
+		raw_spin_lock_irqsave(&kona_gpio->lock, flags);
 
-	val = readl(kona_gpio->reg_base + GPIO_PWD_STATUS(bank_id));
-	val &= ~BIT(gpio);
-	bcm_kona_gpio_write_lock_regs(kona_gpio->reg_base, bank_id, val);
+		val = readl(kona_gpio->reg_base + GPIO_PWD_STATUS(bank_id));
+		val &= ~BIT(bit);
+		bcm_kona_gpio_write_lock_regs(kona_gpio->reg_base, bank_id, val);
 
-	raw_spin_unlock_irqrestore(&kona_gpio->lock, flags);
+		raw_spin_unlock_irqrestore(&kona_gpio->lock, flags);
+	}
+
+	++bank->gpio_unlock_count[bit];
 }
 
 static int bcm_kona_gpio_get_dir(struct gpio_chip *chip, unsigned gpio)
@@ -367,6 +399,7 @@ static void bcm_kona_gpio_irq_mask(struct irq_data *d)
 
 	kona_gpio = irq_data_get_irq_chip_data(d);
 	reg_base = kona_gpio->reg_base;
+
 	raw_spin_lock_irqsave(&kona_gpio->lock, flags);
 
 	val = readl(reg_base + GPIO_INT_MASK(bank_id));
@@ -389,6 +422,7 @@ static void bcm_kona_gpio_irq_unmask(struct irq_data *d)
 
 	kona_gpio = irq_data_get_irq_chip_data(d);
 	reg_base = kona_gpio->reg_base;
+
 	raw_spin_lock_irqsave(&kona_gpio->lock, flags);
 
 	val = readl(reg_base + GPIO_INT_MSKCLR(bank_id));
@@ -484,15 +518,26 @@ static void bcm_kona_gpio_irq_handler(struct irq_desc *desc)
 static int bcm_kona_gpio_irq_reqres(struct irq_data *d)
 {
 	struct bcm_kona_gpio *kona_gpio = irq_data_get_irq_chip_data(d);
+	unsigned int gpio = d->hwirq;
 
-	return gpiochip_reqres_irq(&kona_gpio->gpio_chip, d->hwirq);
+	/*
+	 * We need to unlock the GPIO before any other operations are performed
+	 * on the relevant GPIO configuration registers
+	 */
+	bcm_kona_gpio_unlock_gpio(kona_gpio, gpio);
+
+	return gpiochip_reqres_irq(&kona_gpio->gpio_chip, gpio);
 }
 
 static void bcm_kona_gpio_irq_relres(struct irq_data *d)
 {
 	struct bcm_kona_gpio *kona_gpio = irq_data_get_irq_chip_data(d);
+	unsigned int gpio = d->hwirq;
+
+	/* Once we no longer use it, lock the GPIO again */
+	bcm_kona_gpio_lock_gpio(kona_gpio, gpio);
 
-	gpiochip_relres_irq(&kona_gpio->gpio_chip, d->hwirq);
+	gpiochip_relres_irq(&kona_gpio->gpio_chip, gpio);
 }
 
 static struct irq_chip bcm_gpio_irq_chip = {
@@ -630,7 +675,7 @@ static int bcm_kona_gpio_probe(struct platform_device *pdev)
 		bank->irq = platform_get_irq(pdev, i);
 		bank->kona_gpio = kona_gpio;
 		if (bank->irq < 0) {
-			dev_err(dev, "Couldn't get IRQ for bank %d", i);
+			dev_err(dev, "Couldn't get IRQ for bank %d\n", i);
 			ret = -ENOENT;
 			goto err_irq_domain;
 		}