net: wwan: t7xx: Ensure init is completed before system sleep

When the system attempts to sleep while mtk_t7xx is not ready, the driver
cannot put the device to sleep:
[ 12.472918] mtk_t7xx 0000:57:00.0: [PM] Exiting suspend, modem in invalid state
[ 12.472936] mtk_t7xx 0000:57:00.0: PM: pci_pm_suspend(): t7xx_pci_pm_suspend+0x0/0x20 [mtk_t7xx] returns -14
[ 12.473678] mtk_t7xx 0000:57:00.0: PM: dpm_run_callback(): pci_pm_suspend+0x0/0x1b0 returns -14
[ 12.473711] mtk_t7xx 0000:57:00.0: PM: failed to suspend async: error -14
[ 12.764776] PM: Some devices failed to suspend, or early wake event detected

Mediatek confirmed the device can take a rather long time to complete
its initialization, so wait for up to 20 seconds until init is done.

Signed-off-by: Kai-Heng Feng <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/wwan/t7xx/t7xx_pci.c

···
 #define T7XX_PCI_IREG_BASE		0
 #define T7XX_PCI_EREG_BASE		2
 
+#define T7XX_INIT_TIMEOUT		20
 #define PM_SLEEP_DIS_TIMEOUT_MS		20
 #define PM_ACK_TIMEOUT_MS		1500
 #define PM_AUTOSUSPEND_MS		20000
···
 	spin_lock_init(&t7xx_dev->md_pm_lock);
 	init_completion(&t7xx_dev->sleep_lock_acquire);
 	init_completion(&t7xx_dev->pm_sr_ack);
+	init_completion(&t7xx_dev->init_done);
 	atomic_set(&t7xx_dev->md_pm_state, MTK_PM_INIT);
 
 	device_init_wakeup(&pdev->dev, true);
···
 	pm_runtime_mark_last_busy(&t7xx_dev->pdev->dev);
 	pm_runtime_allow(&t7xx_dev->pdev->dev);
 	pm_runtime_put_noidle(&t7xx_dev->pdev->dev);
+	complete_all(&t7xx_dev->init_done);
 }
 
 static int t7xx_pci_pm_reinit(struct t7xx_pci_dev *t7xx_dev)
···
 	__t7xx_pci_pm_suspend(pdev);
 }
 
+static int t7xx_pci_pm_prepare(struct device *dev)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct t7xx_pci_dev *t7xx_dev;
+
+	t7xx_dev = pci_get_drvdata(pdev);
+	if (!wait_for_completion_timeout(&t7xx_dev->init_done, T7XX_INIT_TIMEOUT * HZ)) {
+		dev_warn(dev, "Not ready for system sleep.\n");
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
 static int t7xx_pci_pm_suspend(struct device *dev)
 {
 	return __t7xx_pci_pm_suspend(to_pci_dev(dev));
···
 }
 
 static const struct dev_pm_ops t7xx_pci_pm_ops = {
+	.prepare = t7xx_pci_pm_prepare,
 	.suspend = t7xx_pci_pm_suspend,
 	.resume = t7xx_pci_pm_resume,
 	.resume_noirq = t7xx_pci_pm_resume_noirq,

drivers/net/wwan/t7xx/t7xx_pci.h

···
 	struct t7xx_modem	*md;
 	struct t7xx_ccmni_ctrl	*ccmni_ctlb;
 	bool			rgu_pci_irq_en;
+	struct completion	init_done;
 
 	/* Low Power Items */
 	struct list_head	md_pm_entities;