mfd: twl6030-irq: Migrate to IRQ threaded handler

1) Removed request_irq() and replaced it with request_threaded_irq().

2) Removed generic_handle_irq() and replaced it with
handle_nested_irq().
  Handling of these interrupts is nested, as we are handling an
interrupt (for e.g rtc, mmc1) when we are still servicing TWL irq.

3) Removed I2C read-retry logic for the case when twl_i2c_read() is
failed inside IRQ handler - there is no sense to do that, so just report
an error and return.

4) Each nested IRQ is configured with corresponding parent_irq,
which need to be retriggered in case if nested IRQ is marked
as IRQS_PENDING.

Signed-off-by: Naga Venkata Srikanth V <vnv.srikanth@samsung.com>
Signed-off-by: Oleg_Kosheliev <oleg.kosheliev@ti.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: Graeme Gregory <gg@slimlogic.co.uk>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 50 insertions, 100 deletions

diff --git a/drivers/mfd/twl6030-irq.c b/drivers/mfd/twl6030-irq.c
index 277a8dba42d5..1606cedbbff4 100644
--- a/drivers/mfd/twl6030-irq.c
+++ b/drivers/mfd/twl6030-irq.c
@@ -90,7 +90,6 @@ static unsigned twl6030_irq_base;
 static int twl_irq;
 static bool twl_irq_wake_enabled;
 
-static struct completion irq_event;
 static atomic_t twl6030_wakeirqs = ATOMIC_INIT(0);
 
 static int twl6030_irq_pm_notifier(struct notifier_block *notifier,
@@ -131,95 +130,57 @@ static struct notifier_block twl6030_irq_pm_notifier_block = {
 };
 
 /*
- * This thread processes interrupts reported by the Primary Interrupt Handler.
- */
-static int twl6030_irq_thread(void *data)
+* Threaded irq handler for the twl6030 interrupt.
+* We query the interrupt controller in the twl6030 to determine
+* which module is generating the interrupt request and call
+* handle_nested_irq for that module.
+*/
+static irqreturn_t twl6030_irq_thread(int irq, void *data)
 {
-        long irq = (long)data;
-        static unsigned i2c_errors;
-        static const unsigned max_i2c_errors = 100;
-        int ret;
-
-        while (!kthread_should_stop()) {
-                int i;
-                union {
+        int i, ret;
+        union {
                 u8 bytes[4];
                 u32 int_sts;
-                } sts;
-
-                /* Wait for IRQ, then read PIH irq status (also blocking) */
-                wait_for_completion_interruptible(&irq_event);
-
-                /* read INT_STS_A, B and C in one shot using a burst read */
-                ret = twl_i2c_read(TWL_MODULE_PIH, sts.bytes,
-                                REG_INT_STS_A, 3);
-                if (ret) {
-                        pr_warning("twl6030: I2C error %d reading PIH ISR\n",
-                                        ret);
-                        if (++i2c_errors >= max_i2c_errors) {
-                                printk(KERN_ERR "Maximum I2C error count"
-                                                " exceeded.  Terminating %s.\n",
-                                                __func__);
-                                break;
-                        }
-                        complete(&irq_event);
-                        continue;
-                }
-
+        } sts;
 
+        /* read INT_STS_A, B and C in one shot using a burst read */
+        ret = twl_i2c_read(TWL_MODULE_PIH, sts.bytes, REG_INT_STS_A, 3);
+        if (ret) {
+                pr_warn("twl6030_irq: I2C error %d reading PIH ISR\n", ret);
+                return IRQ_HANDLED;
+        }
 
-                sts.bytes[3] = 0; /* Only 24 bits are valid*/
+        sts.bytes[3] = 0; /* Only 24 bits are valid*/
 
-                /*
-                 * Since VBUS status bit is not reliable for VBUS disconnect
-                 * use CHARGER VBUS detection status bit instead.
-                 */
-                if (sts.bytes[2] & 0x10)
-                        sts.bytes[2] |= 0x08;
+        /*
+         * Since VBUS status bit is not reliable for VBUS disconnect
+         * use CHARGER VBUS detection status bit instead.
+         */
+        if (sts.bytes[2] & 0x10)
+                sts.bytes[2] |= 0x08;
 
-                for (i = 0; sts.int_sts; sts.int_sts >>= 1, i++) {
-                        local_irq_disable();
-                        if (sts.int_sts & 0x1) {
-                                int module_irq = twl6030_irq_base +
+        for (i = 0; sts.int_sts; sts.int_sts >>= 1, i++)
+                if (sts.int_sts & 0x1) {
+                        int module_irq = twl6030_irq_base +
                                         twl6030_interrupt_mapping[i];
-                                generic_handle_irq(module_irq);
-
-                        }
-                local_irq_enable();
+                        handle_nested_irq(module_irq);
+                        pr_debug("twl6030_irq: PIH ISR %u, virq%u\n",
+                                 i, module_irq);
                 }
 
-                /*
-                 * NOTE:
-                 * Simulation confirms that documentation is wrong w.r.t the
-                 * interrupt status clear operation. A single *byte* write to
-                 * any one of STS_A to STS_C register results in all three
-                 * STS registers being reset. Since it does not matter which
-                 * value is written, all three registers are cleared on a
-                 * single byte write, so we just use 0x0 to clear.
-                 */
-                ret = twl_i2c_write_u8(TWL_MODULE_PIH, 0x00, REG_INT_STS_A);
-                if (ret)
-                        pr_warning("twl6030: I2C error in clearing PIH ISR\n");
-
-                enable_irq(irq);
-        }
-
-        return 0;
-}
+        /*
+         * NOTE:
+         * Simulation confirms that documentation is wrong w.r.t the
+         * interrupt status clear operation. A single *byte* write to
+         * any one of STS_A to STS_C register results in all three
+         * STS registers being reset. Since it does not matter which
+         * value is written, all three registers are cleared on a
+         * single byte write, so we just use 0x0 to clear.
+         */
+        ret = twl_i2c_write_u8(TWL_MODULE_PIH, 0x00, REG_INT_STS_A);
+        if (ret)
+                pr_warn("twl6030_irq: I2C error in clearing PIH ISR\n");
 
-/*
- * handle_twl6030_int() is the desc->handle method for the twl6030 interrupt.
- * This is a chained interrupt, so there is no desc->action method for it.
- * Now we need to query the interrupt controller in the twl6030 to determine
- * which module is generating the interrupt request.  However, we can't do i2c
- * transactions in interrupt context, so we must defer that work to a kernel
- * thread.  All we do here is acknowledge and mask the interrupt and wakeup
- * the kernel thread.
- */
-static irqreturn_t handle_twl6030_pih(int irq, void *devid)
-{
-        disable_irq_nosync(irq);
-        complete(devid);
         return IRQ_HANDLED;
 }
 
@@ -351,7 +312,6 @@ int twl6030_init_irq(struct device *dev, int irq_num)
 {
         struct                  device_node *node = dev->of_node;
         int                     nr_irqs, irq_base, irq_end;
-        struct task_struct      *task;
         static struct irq_chip  twl6030_irq_chip;
         int                     status = 0;
         int                     i;
@@ -396,36 +356,26 @@ int twl6030_init_irq(struct device *dev, int irq_num)
                 irq_set_chip_and_handler(i, &twl6030_irq_chip,
                                          handle_simple_irq);
                 irq_set_chip_data(i, (void *)irq_num);
+                irq_set_nested_thread(i, true);
+                irq_set_parent(i, irq_num);
                 activate_irq(i);
         }
 
-        dev_info(dev, "PIH (irq %d) chaining IRQs %d..%d\n",
-                        irq_num, irq_base, irq_end);
+        dev_info(dev, "PIH (irq %d) nested IRQs %d..%d\n",
+                 irq_num, irq_base, irq_end);
 
         /* install an irq handler to demultiplex the TWL6030 interrupt */
-        init_completion(&irq_event);
-
-        status = request_irq(irq_num, handle_twl6030_pih, 0, "TWL6030-PIH",
-                             &irq_event);
+        status = request_threaded_irq(irq_num, NULL, twl6030_irq_thread,
+                                      IRQF_ONESHOT, "TWL6030-PIH", NULL);
         if (status < 0) {
                 dev_err(dev, "could not claim irq %d: %d\n", irq_num, status);
                 goto fail_irq;
         }
 
-        task = kthread_run(twl6030_irq_thread, (void *)irq_num, "twl6030-irq");
-        if (IS_ERR(task)) {
-                dev_err(dev, "could not create irq %d thread!\n", irq_num);
-                status = PTR_ERR(task);
-                goto fail_kthread;
-        }
-
         twl_irq = irq_num;
         register_pm_notifier(&twl6030_irq_pm_notifier_block);
         return irq_base;
 
-fail_kthread:
-        free_irq(irq_num, &irq_event);
-
 fail_irq:
         for (i = irq_base; i < irq_end; i++)
                 irq_set_chip_and_handler(i, NULL, NULL);
@@ -435,12 +385,12 @@ fail_irq:
 
 int twl6030_exit_irq(void)
 {
-        unregister_pm_notifier(&twl6030_irq_pm_notifier_block);
 
-        if (twl6030_irq_base) {
-                pr_err("twl6030: can't yet clean up IRQs?\n");
-                return -ENOSYS;
+        if (twl_irq) {
+                unregister_pm_notifier(&twl6030_irq_pm_notifier_block);
+                free_irq(twl_irq, NULL);
         }
+
         return 0;
 }