[PATCH v2 6/9] mfd: tc6393xb: make use of raw_spinlock variants

Julia Cartwright
2017-03-21T22:54:44Z

The tc6393xb 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/tc6393xb.c | 52 +++++++++++++++++++++++++-------------------------
1 file changed, 26 insertions(+), 26 deletions(-)

diff --git a/drivers/mfd/tc6393xb.c b/drivers/mfd/tc6393xb.c
index d42d322ac7ca..d16e71bd9482 100644
--- a/drivers/mfd/tc6393xb.c
+++ b/drivers/mfd/tc6393xb.c
@@ -95,7 +95,7 @@ struct tc6393xb {

struct clk *clk; /* 3,6 Mhz */

- spinlock_t lock; /* protects RMW cycles */
+ raw_spinlock_t lock; /* protects RMW cycles */

struct {
u8 fer;
@@ -126,13 +126,13 @@ static int tc6393xb_nand_enable(struct platform_device *nand)
struct tc6393xb *tc6393xb = platform_get_drvdata(dev);
unsigned long flags;

- spin_lock_irqsave(&tc6393xb->lock, flags);
+ raw_spin_lock_irqsave(&tc6393xb->lock, flags);

/* SMD buffer on */
dev_dbg(&dev->dev, "SMD buffer on\n");
tmio_iowrite8(0xff, tc6393xb->scr + SCR_GPI_BCR(1));

- spin_unlock_irqrestore(&tc6393xb->lock, flags);
+ raw_spin_unlock_irqrestore(&tc6393xb->lock, flags);

return 0;
}
@@ -226,7 +226,7 @@ static int tc6393xb_ohci_enable(struct platform_device *dev)
u16 ccr;
u8 fer;

- spin_lock_irqsave(&tc6393xb->lock, flags);
+ raw_spin_lock_irqsave(&tc6393xb->lock, flags);

ccr = tmio_ioread16(tc6393xb->scr + SCR_CCR);
ccr |= SCR_CCR_USBCK;
@@ -236,7 +236,7 @@ static int tc6393xb_ohci_enable(struct platform_device *dev)
fer |= SCR_FER_USBEN;
tmio_iowrite8(fer, tc6393xb->scr + SCR_FER);

- spin_unlock_irqrestore(&tc6393xb->lock, flags);
+ raw_spin_unlock_irqrestore(&tc6393xb->lock, flags);

return 0;
}
@@ -248,7 +248,7 @@ static int tc6393xb_ohci_disable(struct platform_device *dev)
u16 ccr;
u8 fer;

- spin_lock_irqsave(&tc6393xb->lock, flags);
+ raw_spin_lock_irqsave(&tc6393xb->lock, flags);

fer = tmio_ioread8(tc6393xb->scr + SCR_FER);
fer &= ~SCR_FER_USBEN;
@@ -258,7 +258,7 @@ static int tc6393xb_ohci_disable(struct platform_device *dev)
ccr &= ~SCR_CCR_USBCK;
tmio_iowrite16(ccr, tc6393xb->scr + SCR_CCR);

- spin_unlock_irqrestore(&tc6393xb->lock, flags);
+ raw_spin_unlock_irqrestore(&tc6393xb->lock, flags);

return 0;
}
@@ -280,14 +280,14 @@ static int tc6393xb_fb_enable(struct platform_device *dev)
unsigned long flags;
u16 ccr;

- spin_lock_irqsave(&tc6393xb->lock, flags);
+ raw_spin_lock_irqsave(&tc6393xb->lock, flags);

ccr = tmio_ioread16(tc6393xb->scr + SCR_CCR);
ccr &= ~SCR_CCR_MCLK_MASK;
ccr |= SCR_CCR_MCLK_48;
tmio_iowrite16(ccr, tc6393xb->scr + SCR_CCR);

- spin_unlock_irqrestore(&tc6393xb->lock, flags);
+ raw_spin_unlock_irqrestore(&tc6393xb->lock, flags);

return 0;
}
@@ -298,14 +298,14 @@ static int tc6393xb_fb_disable(struct platform_device *dev)
unsigned long flags;
u16 ccr;

- spin_lock_irqsave(&tc6393xb->lock, flags);
+ raw_spin_lock_irqsave(&tc6393xb->lock, flags);

ccr = tmio_ioread16(tc6393xb->scr + SCR_CCR);
ccr &= ~SCR_CCR_MCLK_MASK;
ccr |= SCR_CCR_MCLK_OFF;
tmio_iowrite16(ccr, tc6393xb->scr + SCR_CCR);

- spin_unlock_irqrestore(&tc6393xb->lock, flags);
+ raw_spin_unlock_irqrestore(&tc6393xb->lock, flags);

return 0;
}
@@ -317,7 +317,7 @@ int tc6393xb_lcd_set_power(struct platform_device *fb, bool on)
u8 fer;
unsigned long flags;

- spin_lock_irqsave(&tc6393xb->lock, flags);
+ raw_spin_lock_irqsave(&tc6393xb->lock, flags);

fer = ioread8(tc6393xb->scr + SCR_FER);
if (on)
@@ -326,7 +326,7 @@ int tc6393xb_lcd_set_power(struct platform_device *fb, bool on)
fer &= ~SCR_FER_SLCDEN;
iowrite8(fer, tc6393xb->scr + SCR_FER);

- spin_unlock_irqrestore(&tc6393xb->lock, flags);
+ raw_spin_unlock_irqrestore(&tc6393xb->lock, flags);

return 0;
}
@@ -338,12 +338,12 @@ int tc6393xb_lcd_mode(struct platform_device *fb,
struct tc6393xb *tc6393xb = platform_get_drvdata(dev);
unsigned long flags;

- spin_lock_irqsave(&tc6393xb->lock, flags);
+ raw_spin_lock_irqsave(&tc6393xb->lock, flags);

iowrite16(mode->pixclock, tc6393xb->scr + SCR_PLL1CR + 0);
iowrite16(mode->pixclock >> 16, tc6393xb->scr + SCR_PLL1CR + 2);

- spin_unlock_irqrestore(&tc6393xb->lock, flags);
+ raw_spin_unlock_irqrestore(&tc6393xb->lock, flags);

return 0;
}
@@ -462,11 +462,11 @@ static void tc6393xb_gpio_set(struct gpio_chip *chip,
struct tc6393xb *tc6393xb = gpiochip_get_data(chip);
unsigned long flags;

- spin_lock_irqsave(&tc6393xb->lock, flags);
+ raw_spin_lock_irqsave(&tc6393xb->lock, flags);

__tc6393xb_gpio_set(chip, offset, value);

- spin_unlock_irqrestore(&tc6393xb->lock, flags);
+ raw_spin_unlock_irqrestore(&tc6393xb->lock, flags);
}

static int tc6393xb_gpio_direction_input(struct gpio_chip *chip,
@@ -476,13 +476,13 @@ static int tc6393xb_gpio_direction_input(struct gpio_chip *chip,
unsigned long flags;
u8 doecr;

- spin_lock_irqsave(&tc6393xb->lock, flags);
+ raw_spin_lock_irqsave(&tc6393xb->lock, flags);

doecr = tmio_ioread8(tc6393xb->scr + SCR_GPO_DOECR(offset / 8));
doecr &= ~TC_GPIO_BIT(offset);
tmio_iowrite8(doecr, tc6393xb->scr + SCR_GPO_DOECR(offset / 8));

- spin_unlock_irqrestore(&tc6393xb->lock, flags);
+ raw_spin_unlock_irqrestore(&tc6393xb->lock, flags);

return 0;
}
@@ -494,7 +494,7 @@ static int tc6393xb_gpio_direction_output(struct gpio_chip *chip,
unsigned long flags;
u8 doecr;

- spin_lock_irqsave(&tc6393xb->lock, flags);
+ raw_spin_lock_irqsave(&tc6393xb->lock, flags);

__tc6393xb_gpio_set(chip, offset, value);

@@ -502,7 +502,7 @@ static int tc6393xb_gpio_direction_output(struct gpio_chip *chip,
doecr |= TC_GPIO_BIT(offset);
tmio_iowrite8(doecr, tc6393xb->scr + SCR_GPO_DOECR(offset / 8));

- spin_unlock_irqrestore(&tc6393xb->lock, flags);
+ raw_spin_unlock_irqrestore(&tc6393xb->lock, flags);

return 0;
}
@@ -548,11 +548,11 @@ static void tc6393xb_irq_mask(struct irq_data *data)
unsigned long flags;
u8 imr;

- spin_lock_irqsave(&tc6393xb->lock, flags);
+ raw_spin_lock_irqsave(&tc6393xb->lock, flags);
imr = tmio_ioread8(tc6393xb->scr + SCR_IMR);
imr |= 1 << (data->irq - tc6393xb->irq_base);
tmio_iowrite8(imr, tc6393xb->scr + SCR_IMR);
- spin_unlock_irqrestore(&tc6393xb->lock, flags);
+ raw_spin_unlock_irqrestore(&tc6393xb->lock, flags);
}

static void tc6393xb_irq_unmask(struct irq_data *data)
@@ -561,11 +561,11 @@ static void tc6393xb_irq_unmask(struct irq_data *data)
unsigned long flags;
u8 imr;

- spin_lock_irqsave(&tc6393xb->lock, flags);
+ raw_spin_lock_irqsave(&tc6393xb->lock, flags);
imr = tmio_ioread8(tc6393xb->scr + SCR_IMR);
imr &= ~(1 << (data->irq - tc6393xb->irq_base));
tmio_iowrite8(imr, tc6393xb->scr + SCR_IMR);
- spin_unlock_irqrestore(&tc6393xb->lock, flags);
+ raw_spin_unlock_irqrestore(&tc6393xb->lock, flags);
}

static struct irq_chip tc6393xb_chip = {
@@ -628,7 +628,7 @@ static int tc6393xb_probe(struct platform_device *dev)
goto err_kzalloc;
}

- spin_lock_init(&tc6393xb->lock);
+ raw_spin_lock_init(&tc6393xb->lock);

platform_set_drvdata(dev, tc6393xb);

--
2.12.0