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Subject[patch 3/3] platform-drivers: x86: pmic: Use irq_chip buslock mechanism
The set_type function of the pmic irq chip is a horrible hack. It
schedules work because it cannot access the scu chip from the set_type
function. That breaks the assumption, that the type is set after
set_type has returned.

irq_chips provide buslock functions to avoid the above. Convert the
driver to use the proper model.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Feng Tang <feng.tang@intel.com>
Cc: Matthew Garrett <mjg@redhat.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Alek Du <alek.du@intel.com>
---
drivers/platform/x86/intel_pmic_gpio.c | 80 +++++++++++++--------------------
1 file changed, 32 insertions(+), 48 deletions(-)

Index: linux-2.6/drivers/platform/x86/intel_pmic_gpio.c
===================================================================
--- linux-2.6.orig/drivers/platform/x86/intel_pmic_gpio.c
+++ linux-2.6/drivers/platform/x86/intel_pmic_gpio.c
@@ -60,23 +60,18 @@ enum pmic_gpio_register {
#define GPOSW_DOU 0x08
#define GPOSW_RDRV 0x30

+#define GPIO_UPDATE_TYPE 0x80000000

#define NUM_GPIO 24

-struct pmic_gpio_irq {
- spinlock_t lock;
- u32 trigger[NUM_GPIO];
- u32 dirty;
- struct work_struct work;
-};
-
-
struct pmic_gpio {
+ struct mutex buslock;
struct gpio_chip chip;
- struct pmic_gpio_irq irqtypes;
void *gpiointr;
int irq;
unsigned irq_base;
+ unsigned int update_type;
+ u32 trigger_type;
};

static void pmic_program_irqtype(int gpio, int type)
@@ -92,37 +87,6 @@ static void pmic_program_irqtype(int gpi
intel_scu_ipc_update_register(GPIO0 + gpio, 0x00, 0x10);
};

-static void pmic_irqtype_work(struct work_struct *work)
-{
- struct pmic_gpio_irq *t =
- container_of(work, struct pmic_gpio_irq, work);
- unsigned long flags;
- int i;
- u16 type;
-
- spin_lock_irqsave(&t->lock, flags);
- /* As we drop the lock, we may need multiple scans if we race the
- pmic_irq_type function */
- while (t->dirty) {
- /*
- * For each pin that has the dirty bit set send an IPC
- * message to configure the hardware via the PMIC
- */
- for (i = 0; i < NUM_GPIO; i++) {
- if (!(t->dirty & (1 << i)))
- continue;
- t->dirty &= ~(1 << i);
- /* We can't trust the array entry or dirty
- once the lock is dropped */
- type = t->trigger[i];
- spin_unlock_irqrestore(&t->lock, flags);
- pmic_program_irqtype(i, type);
- spin_lock_irqsave(&t->lock, flags);
- }
- }
- spin_unlock_irqrestore(&t->lock, flags);
-}
-
static int pmic_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
{
if (offset > 8) {
@@ -190,20 +154,21 @@ static void pmic_gpio_set(struct gpio_ch
1 << (offset - 16));
}

+/*
+ * This is called from genirq with pg->buslock locked and
+ * irq_desc->lock held. We can not access the scu bus here, so we
+ * store the change and update in the bus_sync_unlock() function below
+ */
static int pmic_irq_type(struct irq_data *data, unsigned type)
{
struct pmic_gpio *pg = irq_data_get_irq_chip_data(data);
u32 gpio = data->irq - pg->irq_base;
- unsigned long flags;

if (gpio >= pg->chip.ngpio)
return -EINVAL;

- spin_lock_irqsave(&pg->irqtypes.lock, flags);
- pg->irqtypes.trigger[gpio] = type;
- pg->irqtypes.dirty |= (1 << gpio);
- spin_unlock_irqrestore(&pg->irqtypes.lock, flags);
- schedule_work(&pg->irqtypes.work);
+ pg->trigger_type = type;
+ pg->update_type = gpio | GPIO_UPDATE_TYPE;
return 0;
}

@@ -214,6 +179,26 @@ static int pmic_gpio_to_irq(struct gpio_
return pg->irq_base + offset;
}

+static void pmic_bus_lock(struct irq_data *data)
+{
+ struct pmic_gpio *pg = irq_data_get_irq_chip_data(data);
+
+ mutex_lock(&pg->buslock);
+}
+
+static void pmic_bus_sync_unlock(struct irq_data *data)
+{
+ struct pmic_gpio *pg = irq_data_get_irq_chip_data(data);
+
+ if (pg->update_type) {
+ unsigned int gpio = pg->update_type & ~GPIO_UPDATE_TYPE;
+
+ pmic_program_irqtype(gpio, pg->trigger_type);
+ pg->update_type = 0;
+ }
+ mutex_unlock(&pg->buslock);
+}
+
/* the gpiointr register is read-clear, so just do nothing. */
static void pmic_irq_unmask(struct irq_data *data) { }

@@ -287,8 +272,7 @@ static int __devinit platform_pmic_gpio_
pg->chip.can_sleep = 1;
pg->chip.dev = dev;

- INIT_WORK(&pg->irqtypes.work, pmic_irqtype_work);
- spin_lock_init(&pg->irqtypes.lock);
+ mutex_init(&pg->buslock);

pg->chip.dev = dev;
retval = gpiochip_add(&pg->chip);



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