linux-kernel - [PATCH 4.14 124/124] gpio: brcmstb: release the bgpio lock during irq handlers

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Message-Id: <20181119162634.317442434@linuxfoundation.org>
Date:   Mon, 19 Nov 2018 17:29:38 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Doug Berger <opendmb@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Gregory Fong <gregory.0xf0@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Sudip Mukherjee <sudipm.mukherjee@...il.com>
Subject: [PATCH 4.14 124/124] gpio: brcmstb: release the bgpio lock during irq handlers

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Doug Berger <opendmb@...il.com>

commit 142c168e0e50164e67c9399c28dedd65a307cfe5 upstream.

The basic memory-mapped GPIO controller lock must be released
before calling the registered GPIO interrupt handlers to allow
the interrupt handlers to access the hardware.

Examples of why a GPIO interrupt handler might want to access
the GPIO hardware include an interrupt that is configured to
trigger on rising and falling edges that needs to read the
current level of the input to know how to respond, or an
interrupt that causes a change in a GPIO output in the same
bank. If the lock is not released before enterring the handler
the hardware accesses will deadlock when they attempt to grab
the lock.

Since the lock is only needed to protect the calculation of
unmasked pending interrupts create a dedicated function to
perform this and hide the complexity.

Fixes: 19a7b6940b78 ("gpio: brcmstb: Add interrupt and wakeup source support")
Signed-off-by: Doug Berger <opendmb@...il.com>
Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
Acked-by: Gregory Fong <gregory.0xf0@...il.com>
Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpio/gpio-brcmstb.c |   21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

--- a/drivers/gpio/gpio-brcmstb.c
+++ b/drivers/gpio/gpio-brcmstb.c
@@ -63,6 +63,21 @@ brcmstb_gpio_gc_to_priv(struct gpio_chip
 	return bank->parent_priv;
 }
 
+static unsigned long
+brcmstb_gpio_get_active_irqs(struct brcmstb_gpio_bank *bank)
+{
+	void __iomem *reg_base = bank->parent_priv->reg_base;
+	unsigned long status;
+	unsigned long flags;
+
+	spin_lock_irqsave(&bank->gc.bgpio_lock, flags);
+	status = bank->gc.read_reg(reg_base + GIO_STAT(bank->id)) &
+		 bank->gc.read_reg(reg_base + GIO_MASK(bank->id));
+	spin_unlock_irqrestore(&bank->gc.bgpio_lock, flags);
+
+	return status;
+}
+
 static void brcmstb_gpio_set_imask(struct brcmstb_gpio_bank *bank,
 		unsigned int offset, bool enable)
 {
@@ -205,11 +220,8 @@ static void brcmstb_gpio_irq_bank_handle
 	struct irq_domain *irq_domain = bank->gc.irqdomain;
 	void __iomem *reg_base = priv->reg_base;
 	unsigned long status;
-	unsigned long flags;
 
-	spin_lock_irqsave(&bank->gc.bgpio_lock, flags);
-	while ((status = bank->gc.read_reg(reg_base + GIO_STAT(bank->id)) &
-			 bank->gc.read_reg(reg_base + GIO_MASK(bank->id)))) {
+	while ((status = brcmstb_gpio_get_active_irqs(bank))) {
 		int bit;
 
 		for_each_set_bit(bit, &status, 32) {
@@ -224,7 +236,6 @@ static void brcmstb_gpio_irq_bank_handle
 			generic_handle_irq(irq_find_mapping(irq_domain, bit));
 		}
 	}
-	spin_unlock_irqrestore(&bank->gc.bgpio_lock, flags);
 }
 
 /* Each UPG GIO block has one IRQ for all banks */