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mfd: ezx-pcap: Replace mutex_lock with spin_lock
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As mutex_lock might sleep. Function pcap_adc_irq is an interrupt handler.
The use of mutex_lock in pcap_adc_irq may cause sleep in IRQ context.
Replace mutex_lock with spin_lock to avoid this.

Signed-off-by: Fuqian Huang <[email protected]>
Signed-off-by: Lee Jones <[email protected]>
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@Yellow-Pay
Yellow-Pay authored and Lee Jones committed Sep 2, 2019
1 parent 5cd690a commit b65dc4f
Showing 1 changed file with 30 additions and 23 deletions.
53 changes: 30 additions & 23 deletions drivers/mfd/ezx-pcap.c
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Original file line number Diff line number Diff line change
Expand Up @@ -35,7 +35,7 @@ struct pcap_chip {

/* IO */
u32 buf;
struct mutex io_mutex;
spinlock_t io_lock;

/* IRQ */
unsigned int irq_base;
Expand All @@ -48,7 +48,7 @@ struct pcap_chip {
struct pcap_adc_request *adc_queue[PCAP_ADC_MAXQ];
u8 adc_head;
u8 adc_tail;
struct mutex adc_mutex;
spinlock_t adc_lock;
};

/* IO */
Expand Down Expand Up @@ -76,41 +76,44 @@ static int ezx_pcap_putget(struct pcap_chip *pcap, u32 *data)

int ezx_pcap_write(struct pcap_chip *pcap, u8 reg_num, u32 value)
{
unsigned long flags;
int ret;

mutex_lock(&pcap->io_mutex);
spin_lock_irqsave(&pcap->io_lock, flags);
value &= PCAP_REGISTER_VALUE_MASK;
value |= PCAP_REGISTER_WRITE_OP_BIT
| (reg_num << PCAP_REGISTER_ADDRESS_SHIFT);
ret = ezx_pcap_putget(pcap, &value);
mutex_unlock(&pcap->io_mutex);
spin_unlock_irqrestore(&pcap->io_lock, flags);

return ret;
}
EXPORT_SYMBOL_GPL(ezx_pcap_write);

int ezx_pcap_read(struct pcap_chip *pcap, u8 reg_num, u32 *value)
{
unsigned long flags;
int ret;

mutex_lock(&pcap->io_mutex);
spin_lock_irqsave(&pcap->io_lock, flags);
*value = PCAP_REGISTER_READ_OP_BIT
| (reg_num << PCAP_REGISTER_ADDRESS_SHIFT);

ret = ezx_pcap_putget(pcap, value);
mutex_unlock(&pcap->io_mutex);
spin_unlock_irqrestore(&pcap->io_lock, flags);

return ret;
}
EXPORT_SYMBOL_GPL(ezx_pcap_read);

int ezx_pcap_set_bits(struct pcap_chip *pcap, u8 reg_num, u32 mask, u32 val)
{
unsigned long flags;
int ret;
u32 tmp = PCAP_REGISTER_READ_OP_BIT |
(reg_num << PCAP_REGISTER_ADDRESS_SHIFT);

mutex_lock(&pcap->io_mutex);
spin_lock_irqsave(&pcap->io_lock, flags);
ret = ezx_pcap_putget(pcap, &tmp);
if (ret)
goto out_unlock;
Expand All @@ -121,7 +124,7 @@ int ezx_pcap_set_bits(struct pcap_chip *pcap, u8 reg_num, u32 mask, u32 val)

ret = ezx_pcap_putget(pcap, &tmp);
out_unlock:
mutex_unlock(&pcap->io_mutex);
spin_unlock_irqrestore(&pcap->io_lock, flags);

return ret;
}
Expand Down Expand Up @@ -212,14 +215,15 @@ static void pcap_irq_handler(struct irq_desc *desc)
/* ADC */
void pcap_set_ts_bits(struct pcap_chip *pcap, u32 bits)
{
unsigned long flags;
u32 tmp;

mutex_lock(&pcap->adc_mutex);
spin_lock_irqsave(&pcap->adc_lock, flags);
ezx_pcap_read(pcap, PCAP_REG_ADC, &tmp);
tmp &= ~(PCAP_ADC_TS_M_MASK | PCAP_ADC_TS_REF_LOWPWR);
tmp |= bits & (PCAP_ADC_TS_M_MASK | PCAP_ADC_TS_REF_LOWPWR);
ezx_pcap_write(pcap, PCAP_REG_ADC, tmp);
mutex_unlock(&pcap->adc_mutex);
spin_unlock_irqrestore(&pcap->adc_lock, flags);
}
EXPORT_SYMBOL_GPL(pcap_set_ts_bits);

Expand All @@ -234,15 +238,16 @@ static void pcap_disable_adc(struct pcap_chip *pcap)

static void pcap_adc_trigger(struct pcap_chip *pcap)
{
unsigned long flags;
u32 tmp;
u8 head;

mutex_lock(&pcap->adc_mutex);
spin_lock_irqsave(&pcap->adc_lock, flags);
head = pcap->adc_head;
if (!pcap->adc_queue[head]) {
/* queue is empty, save power */
pcap_disable_adc(pcap);
mutex_unlock(&pcap->adc_mutex);
spin_unlock_irqrestore(&pcap->adc_lock, flags);
return;
}
/* start conversion on requested bank, save TS_M bits */
Expand All @@ -254,7 +259,7 @@ static void pcap_adc_trigger(struct pcap_chip *pcap)
tmp |= PCAP_ADC_AD_SEL1;

ezx_pcap_write(pcap, PCAP_REG_ADC, tmp);
mutex_unlock(&pcap->adc_mutex);
spin_unlock_irqrestore(&pcap->adc_lock, flags);
ezx_pcap_write(pcap, PCAP_REG_ADR, PCAP_ADR_ASC);
}

Expand All @@ -265,11 +270,11 @@ static irqreturn_t pcap_adc_irq(int irq, void *_pcap)
u16 res[2];
u32 tmp;

mutex_lock(&pcap->adc_mutex);
spin_lock(&pcap->adc_lock);
req = pcap->adc_queue[pcap->adc_head];

if (WARN(!req, "adc irq without pending request\n")) {
mutex_unlock(&pcap->adc_mutex);
spin_unlock(&pcap->adc_lock);
return IRQ_HANDLED;
}

Expand All @@ -285,7 +290,7 @@ static irqreturn_t pcap_adc_irq(int irq, void *_pcap)

pcap->adc_queue[pcap->adc_head] = NULL;
pcap->adc_head = (pcap->adc_head + 1) & (PCAP_ADC_MAXQ - 1);
mutex_unlock(&pcap->adc_mutex);
spin_unlock(&pcap->adc_lock);

/* pass the results and release memory */
req->callback(req->data, res);
Expand All @@ -301,6 +306,7 @@ int pcap_adc_async(struct pcap_chip *pcap, u8 bank, u32 flags, u8 ch[],
void *callback, void *data)
{
struct pcap_adc_request *req;
unsigned long irq_flags;

/* This will be freed after we have a result */
req = kmalloc(sizeof(struct pcap_adc_request), GFP_KERNEL);
Expand All @@ -314,15 +320,15 @@ int pcap_adc_async(struct pcap_chip *pcap, u8 bank, u32 flags, u8 ch[],
req->callback = callback;
req->data = data;

mutex_lock(&pcap->adc_mutex);
spin_lock_irqsave(&pcap->adc_lock, irq_flags);
if (pcap->adc_queue[pcap->adc_tail]) {
mutex_unlock(&pcap->adc_mutex);
spin_unlock_irqrestore(&pcap->adc_lock, irq_flags);
kfree(req);
return -EBUSY;
}
pcap->adc_queue[pcap->adc_tail] = req;
pcap->adc_tail = (pcap->adc_tail + 1) & (PCAP_ADC_MAXQ - 1);
mutex_unlock(&pcap->adc_mutex);
spin_unlock_irqrestore(&pcap->adc_lock, irq_flags);

/* start conversion */
pcap_adc_trigger(pcap);
Expand Down Expand Up @@ -389,16 +395,17 @@ static int pcap_add_subdev(struct pcap_chip *pcap,
static int ezx_pcap_remove(struct spi_device *spi)
{
struct pcap_chip *pcap = spi_get_drvdata(spi);
unsigned long flags;
int i;

/* remove all registered subdevs */
device_for_each_child(&spi->dev, NULL, pcap_remove_subdev);

/* cleanup ADC */
mutex_lock(&pcap->adc_mutex);
spin_lock_irqsave(&pcap->adc_lock, flags);
for (i = 0; i < PCAP_ADC_MAXQ; i++)
kfree(pcap->adc_queue[i]);
mutex_unlock(&pcap->adc_mutex);
spin_unlock_irqrestore(&pcap->adc_lock, flags);

/* cleanup irqchip */
for (i = pcap->irq_base; i < (pcap->irq_base + PCAP_NIRQS); i++)
Expand Down Expand Up @@ -426,8 +433,8 @@ static int ezx_pcap_probe(struct spi_device *spi)
goto ret;
}

mutex_init(&pcap->io_mutex);
mutex_init(&pcap->adc_mutex);
spin_lock_init(&pcap->io_lock);
spin_lock_init(&pcap->adc_lock);
INIT_WORK(&pcap->isr_work, pcap_isr_work);
INIT_WORK(&pcap->msr_work, pcap_msr_work);
spi_set_drvdata(spi, pcap);
Expand Down

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