[PATCH 4.1 83/86] pinctrl: baytrail: Use raw_spinlock for locking

Greg Kroah-Hartman
2015-11-06T19:39:35Z

From: Mika Westerberg <mika.westerberg@linux.intel.com>

commit 78e1c896932df5b8bcdff7bf5417d8e72a4d0d6b upstream.

The Intel Baytrail pinctrl driver implements irqchip callbacks which are
called with desc->lock raw_spinlock held. In mainline this is fine because
spinlock resolves to raw_spinlock. However, running the same code in -rt we
get:

BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:917
in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper/0
Preemption disabled at:[<ffffffff81092e9f>] cpu_startup_entry+0x17f/0x480

CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.1.5-rt5 #13
...
Call Trace:
<IRQ> [<ffffffff816283c6>] dump_stack+0x4a/0x61
[<ffffffff81077e17>] ___might_sleep+0xe7/0x170
[<ffffffff8162d6cf>] rt_spin_lock+0x1f/0x50
[<ffffffff812e3b88>] byt_gpio_clear_triggering+0x38/0x60
[<ffffffff812e3bc1>] byt_irq_mask+0x11/0x20
[<ffffffff810a7013>] handle_level_irq+0x83/0x150
[<ffffffff810a3457>] generic_handle_irq+0x27/0x40
[<ffffffff812e3a5f>] byt_gpio_irq_handler+0x7f/0xc0
[<ffffffff810050aa>] handle_irq+0xaa/0x190
...

This is because in -rt spinlocks are preemptible so taking the driver
private spinlock in irqchip callbacks causes might_sleep() to trigger.

In order to keep -rt happy but at the same time make sure that register
accesses get serialized, convert the driver to use raw_spinlock instead.

Also shorten the critical section a bit in few places.

Suggested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Cc: Lucas De Marchi <lucas.de.marchi@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/pinctrl/intel/pinctrl-baytrail.c | 50 +++++++++++++++----------------
1 file changed, 25 insertions(+), 25 deletions(-)

--- a/drivers/pinctrl/intel/pinctrl-baytrail.c
+++ b/drivers/pinctrl/intel/pinctrl-baytrail.c
@@ -146,7 +146,7 @@ struct byt_gpio_pin_context {
struct byt_gpio {
struct gpio_chip chip;
struct platform_device *pdev;
- spinlock_t lock;
+ raw_spinlock_t lock;
void __iomem *reg_base;
struct pinctrl_gpio_range *range;
struct byt_gpio_pin_context *saved_context;
@@ -174,11 +174,11 @@ static void byt_gpio_clear_triggering(st
unsigned long flags;
u32 value;

- spin_lock_irqsave(&vg->lock, flags);
+ raw_spin_lock_irqsave(&vg->lock, flags);
value = readl(reg);
value &= ~(BYT_TRIG_POS | BYT_TRIG_NEG | BYT_TRIG_LVL);
writel(value, reg);
- spin_unlock_irqrestore(&vg->lock, flags);
+ raw_spin_unlock_irqrestore(&vg->lock, flags);
}

static u32 byt_get_gpio_mux(struct byt_gpio *vg, unsigned offset)
@@ -203,7 +203,7 @@ static int byt_gpio_request(struct gpio_
u32 value, gpio_mux;
unsigned long flags;

- spin_lock_irqsave(&vg->lock, flags);
+ raw_spin_lock_irqsave(&vg->lock, flags);

/*
* In most cases, func pin mux 000 means GPIO function.
@@ -225,7 +225,7 @@ static int byt_gpio_request(struct gpio_
"pin %u forcibly re-configured as GPIO\n", offset);
}

- spin_unlock_irqrestore(&vg->lock, flags);
+ raw_spin_unlock_irqrestore(&vg->lock, flags);

pm_runtime_get(&vg->pdev->dev);

@@ -251,7 +251,7 @@ static int byt_irq_type(struct irq_data
if (offset >= vg->chip.ngpio)
return -EINVAL;

- spin_lock_irqsave(&vg->lock, flags);
+ raw_spin_lock_irqsave(&vg->lock, flags);
value = readl(reg);

WARN(value & BYT_DIRECT_IRQ_EN,
@@ -270,7 +270,7 @@ static int byt_irq_type(struct irq_data
else if (type & IRQ_TYPE_LEVEL_MASK)
__irq_set_handler_locked(d->irq, handle_level_irq);

- spin_unlock_irqrestore(&vg->lock, flags);
+ raw_spin_unlock_irqrestore(&vg->lock, flags);

return 0;
}
@@ -282,9 +282,9 @@ static int byt_gpio_get(struct gpio_chip
unsigned long flags;
u32 val;

- spin_lock_irqsave(&vg->lock, flags);
+ raw_spin_lock_irqsave(&vg->lock, flags);
val = readl(reg);
- spin_unlock_irqrestore(&vg->lock, flags);
+ raw_spin_unlock_irqrestore(&vg->lock, flags);

return val & BYT_LEVEL;
}
@@ -296,7 +296,7 @@ static void byt_gpio_set(struct gpio_chi
unsigned long flags;
u32 old_val;

- spin_lock_irqsave(&vg->lock, flags);
+ raw_spin_lock_irqsave(&vg->lock, flags);

old_val = readl(reg);

@@ -305,7 +305,7 @@ static void byt_gpio_set(struct gpio_chi
else
writel(old_val & ~BYT_LEVEL, reg);

- spin_unlock_irqrestore(&vg->lock, flags);
+ raw_spin_unlock_irqrestore(&vg->lock, flags);
}

static int byt_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
@@ -315,13 +315,13 @@ static int byt_gpio_direction_input(stru
unsigned long flags;
u32 value;

- spin_lock_irqsave(&vg->lock, flags);
+ raw_spin_lock_irqsave(&vg->lock, flags);

value = readl(reg) | BYT_DIR_MASK;
value &= ~BYT_INPUT_EN; /* active low */
writel(value, reg);

- spin_unlock_irqrestore(&vg->lock, flags);
+ raw_spin_unlock_irqrestore(&vg->lock, flags);

return 0;
}
@@ -335,7 +335,7 @@ static int byt_gpio_direction_output(str
unsigned long flags;
u32 reg_val;

- spin_lock_irqsave(&vg->lock, flags);
+ raw_spin_lock_irqsave(&vg->lock, flags);

/*
* Before making any direction modifications, do a check if gpio
@@ -354,7 +354,7 @@ static int byt_gpio_direction_output(str
else
writel(reg_val & ~BYT_LEVEL, reg);

- spin_unlock_irqrestore(&vg->lock, flags);
+ raw_spin_unlock_irqrestore(&vg->lock, flags);

return 0;
}
@@ -363,18 +363,19 @@ static void byt_gpio_dbg_show(struct seq
{
struct byt_gpio *vg = to_byt_gpio(chip);
int i;
- unsigned long flags;
u32 conf0, val, offs;

- spin_lock_irqsave(&vg->lock, flags);
-
for (i = 0; i < vg->chip.ngpio; i++) {
const char *pull_str = NULL;
const char *pull = NULL;
+ unsigned long flags;
const char *label;
offs = vg->range->pins[i] * 16;
+
+ raw_spin_lock_irqsave(&vg->lock, flags);
conf0 = readl(vg->reg_base + offs + BYT_CONF0_REG);
val = readl(vg->reg_base + offs + BYT_VAL_REG);
+ raw_spin_unlock_irqrestore(&vg->lock, flags);

label = gpiochip_is_requested(chip, i);
if (!label)
@@ -427,7 +428,6 @@ static void byt_gpio_dbg_show(struct seq

seq_puts(s, "\n");
}
- spin_unlock_irqrestore(&vg->lock, flags);
}

static void byt_gpio_irq_handler(unsigned irq, struct irq_desc *desc)
@@ -459,10 +459,10 @@ static void byt_irq_ack(struct irq_data
unsigned offset = irqd_to_hwirq(d);
void __iomem *reg;

- spin_lock(&vg->lock);
+ raw_spin_lock(&vg->lock);
reg = byt_gpio_reg(&vg->chip, offset, BYT_INT_STAT_REG);
writel(BIT(offset % 32), reg);
- spin_unlock(&vg->lock);
+ raw_spin_unlock(&vg->lock);
}

static void byt_irq_unmask(struct irq_data *d)
@@ -474,9 +474,9 @@ static void byt_irq_unmask(struct irq_da
void __iomem *reg;
u32 value;

- spin_lock_irqsave(&vg->lock, flags);
-
reg = byt_gpio_reg(&vg->chip, offset, BYT_CONF0_REG);
+
+ raw_spin_lock_irqsave(&vg->lock, flags);
value = readl(reg);

switch (irqd_get_trigger_type(d)) {
@@ -497,7 +497,7 @@ static void byt_irq_unmask(struct irq_da

writel(value, reg);

- spin_unlock_irqrestore(&vg->lock, flags);
+ raw_spin_unlock_irqrestore(&vg->lock, flags);
}

static void byt_irq_mask(struct irq_data *d)
@@ -589,7 +589,7 @@ static int byt_gpio_probe(struct platfor
if (IS_ERR(vg->reg_base))
return PTR_ERR(vg->reg_base);

- spin_lock_init(&vg->lock);
+ raw_spin_lock_init(&vg->lock);

gc = &vg->chip;
gc->label = dev_name(&pdev->dev);