irqchip/imx-irqsteer: Handle runtime power management correctly

The power domain is automatically activated from clk_prepare(). However, on
certain platforms like i.MX8QM and i.MX8QXP, the power-on handling invokes
sleeping functions, which triggers the 'scheduling while atomic' bug in the
context switch path during device probing:

 BUG: scheduling while atomic: kworker/u13:1/48/0x00000002
 Call trace:
  __schedule_bug+0x54/0x6c
  __schedule+0x7f0/0xa94
  schedule+0x5c/0xc4
  schedule_preempt_disabled+0x24/0x40
  __mutex_lock.constprop.0+0x2c0/0x540
  __mutex_lock_slowpath+0x14/0x20
  mutex_lock+0x48/0x54
  clk_prepare_lock+0x44/0xa0
  clk_prepare+0x20/0x44
  imx_irqsteer_resume+0x28/0xe0
  pm_generic_runtime_resume+0x2c/0x44
  __genpd_runtime_resume+0x30/0x80
  genpd_runtime_resume+0xc8/0x2c0
  __rpm_callback+0x48/0x1d8
  rpm_callback+0x6c/0x78
  rpm_resume+0x490/0x6b4
  __pm_runtime_resume+0x50/0x94
  irq_chip_pm_get+0x2c/0xa0
  __irq_do_set_handler+0x178/0x24c
  irq_set_chained_handler_and_data+0x60/0xa4
  mxc_gpio_probe+0x160/0x4b0

Cure this by implementing the irq_bus_lock/sync_unlock() interrupt chip
callbacks and handle power management in them as they are invoked from
non-atomic context.

[ tglx: Rewrote change log, added Fixes tag ]

Fixes: 0136afa ("irqchip: Add driver for imx-irqsteer controller")
Signed-off-by: Shenwei Wang <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]

Author: Shenwei Wang

drivers/irqchip/irq-imx-irqsteer.c

@@ -36,6 +36,7 @@ struct irqsteer_data {
 	int			channel;
 	struct irq_domain	*domain;
 	u32			*saved_reg;
+	struct device		*dev;
 };
 
 static int imx_irqsteer_get_reg_index(struct irqsteer_data *data,
@@ -72,10 +73,26 @@ static void imx_irqsteer_irq_mask(struct irq_data *d)
 	raw_spin_unlock_irqrestore(&data->lock, flags);
 }
 
+static void imx_irqsteer_irq_bus_lock(struct irq_data *d)
+{
+	struct irqsteer_data *data = d->chip_data;
+
+	pm_runtime_get_sync(data->dev);
+}
+
+static void imx_irqsteer_irq_bus_sync_unlock(struct irq_data *d)
+{
+	struct irqsteer_data *data = d->chip_data;
+
+	pm_runtime_put_autosuspend(data->dev);
+}
+
 static const struct irq_chip imx_irqsteer_irq_chip = {
-	.name		= "irqsteer",
-	.irq_mask	= imx_irqsteer_irq_mask,
-	.irq_unmask	= imx_irqsteer_irq_unmask,
+	.name			= "irqsteer",
+	.irq_mask		= imx_irqsteer_irq_mask,
+	.irq_unmask		= imx_irqsteer_irq_unmask,
+	.irq_bus_lock		= imx_irqsteer_irq_bus_lock,
+	.irq_bus_sync_unlock	= imx_irqsteer_irq_bus_sync_unlock,
 };
 
 static int imx_irqsteer_irq_map(struct irq_domain *h, unsigned int irq,
@@ -150,6 +167,7 @@ static int imx_irqsteer_probe(struct platform_device *pdev)
 	if (!data)
 		return -ENOMEM;
 
+	data->dev = &pdev->dev;
 	data->regs = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(data->regs)) {
 		dev_err(&pdev->dev, "failed to initialize reg\n");