[PATCH v2 5/9] mfd: t7l66xb: make use of raw_spinlock variants

Julia Cartwright
2017-03-21T23:32:01Z

The t7l66xb mfd driver currently implements an irq_chip for handling
interrupts; due to how irq_chip handling is done, it's necessary for the
irq_chip methods to be invoked from hardirq context, even on a a
real-time kernel. Because the spinlock_t type becomes a "sleeping"
spinlock w/ RT kernels, it is not suitable to be used with irq_chips.

A quick audit of the operations under the lock reveal that they do only
minimal, bounded work, and are therefore safe to do under a raw spinlock.

Acked-for-MFD-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Julia Cartwright <julia@ni.com>
---
v1 -> v2:
- No functional change. Added Lee's ack.

drivers/mfd/t7l66xb.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/mfd/t7l66xb.c b/drivers/mfd/t7l66xb.c
index 94bd89cb1f06..22c811396edc 100644
--- a/drivers/mfd/t7l66xb.c
+++ b/drivers/mfd/t7l66xb.c
@@ -69,7 +69,7 @@ static const struct resource t7l66xb_mmc_resources[] = {
struct t7l66xb {
void __iomem *scr;
/* Lock to protect registers requiring read/modify/write ops. */
- spinlock_t lock;
+ raw_spinlock_t lock;

struct resource rscr;
struct clk *clk48m;
@@ -89,13 +89,13 @@ static int t7l66xb_mmc_enable(struct platform_device *mmc)

clk_prepare_enable(t7l66xb->clk32k);

- spin_lock_irqsave(&t7l66xb->lock, flags);
+ raw_spin_lock_irqsave(&t7l66xb->lock, flags);

dev_ctl = tmio_ioread8(t7l66xb->scr + SCR_DEV_CTL);
dev_ctl |= SCR_DEV_CTL_MMC;
tmio_iowrite8(dev_ctl, t7l66xb->scr + SCR_DEV_CTL);

- spin_unlock_irqrestore(&t7l66xb->lock, flags);
+ raw_spin_unlock_irqrestore(&t7l66xb->lock, flags);

tmio_core_mmc_enable(t7l66xb->scr + 0x200, 0,
t7l66xb_mmc_resources[0].start & 0xfffe);
@@ -110,13 +110,13 @@ static int t7l66xb_mmc_disable(struct platform_device *mmc)
unsigned long flags;
u8 dev_ctl;

- spin_lock_irqsave(&t7l66xb->lock, flags);
+ raw_spin_lock_irqsave(&t7l66xb->lock, flags);

dev_ctl = tmio_ioread8(t7l66xb->scr + SCR_DEV_CTL);
dev_ctl &= ~SCR_DEV_CTL_MMC;
tmio_iowrite8(dev_ctl, t7l66xb->scr + SCR_DEV_CTL);

- spin_unlock_irqrestore(&t7l66xb->lock, flags);
+ raw_spin_unlock_irqrestore(&t7l66xb->lock, flags);

clk_disable_unprepare(t7l66xb->clk32k);

@@ -206,11 +206,11 @@ static void t7l66xb_irq_mask(struct irq_data *data)
unsigned long flags;
u8 imr;

- spin_lock_irqsave(&t7l66xb->lock, flags);
+ raw_spin_lock_irqsave(&t7l66xb->lock, flags);
imr = tmio_ioread8(t7l66xb->scr + SCR_IMR);
imr |= 1 << (data->irq - t7l66xb->irq_base);
tmio_iowrite8(imr, t7l66xb->scr + SCR_IMR);
- spin_unlock_irqrestore(&t7l66xb->lock, flags);
+ raw_spin_unlock_irqrestore(&t7l66xb->lock, flags);
}

static void t7l66xb_irq_unmask(struct irq_data *data)
@@ -219,11 +219,11 @@ static void t7l66xb_irq_unmask(struct irq_data *data)
unsigned long flags;
u8 imr;

- spin_lock_irqsave(&t7l66xb->lock, flags);
+ raw_spin_lock_irqsave(&t7l66xb->lock, flags);
imr = tmio_ioread8(t7l66xb->scr + SCR_IMR);
imr &= ~(1 << (data->irq - t7l66xb->irq_base));
tmio_iowrite8(imr, t7l66xb->scr + SCR_IMR);
- spin_unlock_irqrestore(&t7l66xb->lock, flags);
+ raw_spin_unlock_irqrestore(&t7l66xb->lock, flags);
}

static struct irq_chip t7l66xb_chip = {
@@ -321,7 +321,7 @@ static int t7l66xb_probe(struct platform_device *dev)
if (!t7l66xb)
return -ENOMEM;

- spin_lock_init(&t7l66xb->lock);
+ raw_spin_lock_init(&t7l66xb->lock);

platform_set_drvdata(dev, t7l66xb);

--
2.12.0