net: wwan: t7xx: Device deep sleep lock/unlock

Introduce the mechanism to lock/unlock the device 'deep sleep' mode.
When the PCIe link state is L1.2 or L2, the host side still can keep
the device is in D0 state from the host side point of view. At the same
time, if the device's 'deep sleep' mode is unlocked, the device will
go to 'deep sleep' while it is still in D0 state on the host side.

Signed-off-by: Haijun Liu <[e-mail]>
Signed-off-by: Chandrashekar Devegowda <[e-mail]>
Co-developed-by: Ricardo Martinez <[e-mail]>
Signed-off-by: Ricardo Martinez <[e-mail]>
Reviewed-by: Ilpo Järvinen <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/wwan/t7xx/t7xx_hif_cldma.c

···
 	if (ret < 0 && ret != -EACCES)
 		return ret;
 
+	t7xx_pci_disable_sleep(md_ctrl->t7xx_dev);
 	queue = &md_ctrl->txq[qno];
 
 	spin_lock_irqsave(&md_ctrl->cldma_lock, flags);
···
 			queue->tx_next = list_next_entry_circular(tx_req, gpd_ring, entry);
 			spin_unlock_irqrestore(&queue->ring_lock, flags);
 
+			if (!t7xx_pci_sleep_disable_complete(md_ctrl->t7xx_dev)) {
+				ret = -ETIMEDOUT;
+				break;
+			}
+
 			/* Protect the access to the modem for queues operations (resume/start)
 			 * which access shared locations by all the queues.
 			 * cldma_lock is independent of ring_lock which is per queue.
···
 		}
 		spin_unlock_irqrestore(&queue->ring_lock, flags);
 
+		if (!t7xx_pci_sleep_disable_complete(md_ctrl->t7xx_dev)) {
+			ret = -ETIMEDOUT;
+			break;
+		}
+
 		if (!t7xx_cldma_hw_queue_status(&md_ctrl->hw_info, qno, MTK_TX)) {
 			spin_lock_irqsave(&md_ctrl->cldma_lock, flags);
 			t7xx_cldma_hw_resume_queue(&md_ctrl->hw_info, qno, MTK_TX);
···
 	} while (!ret);
 
 allow_sleep:
+	t7xx_pci_enable_sleep(md_ctrl->t7xx_dev);
 	pm_runtime_mark_last_busy(md_ctrl->dev);
 	pm_runtime_put_autosuspend(md_ctrl->dev);
 	return ret;

drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c

···
 	if (ret < 0 && ret != -EACCES)
 		return;
 
-	t7xx_dpmaif_do_rx(dpmaif_ctrl, rxq);
+	t7xx_pci_disable_sleep(dpmaif_ctrl->t7xx_dev);
+	if (t7xx_pci_sleep_disable_complete(dpmaif_ctrl->t7xx_dev))
+		t7xx_dpmaif_do_rx(dpmaif_ctrl, rxq);
 
+	t7xx_pci_enable_sleep(dpmaif_ctrl->t7xx_dev);
 	pm_runtime_mark_last_busy(dpmaif_ctrl->dev);
 	pm_runtime_put_autosuspend(dpmaif_ctrl->dev);
 	atomic_set(&rxq->rx_processing, 0);
···
 	if (ret < 0 && ret != -EACCES)
 		return;
 
+	t7xx_pci_disable_sleep(dpmaif_ctrl->t7xx_dev);
+
 	/* ALL RXQ use one BAT table, so choose DPF_RX_QNO_DFT */
 	rxq = &dpmaif_ctrl->rxq[DPF_RX_QNO_DFT];
-	t7xx_dpmaif_bat_release_and_add(rxq);
-	t7xx_dpmaif_frag_bat_release_and_add(rxq);
+	if (t7xx_pci_sleep_disable_complete(dpmaif_ctrl->t7xx_dev)) {
+		t7xx_dpmaif_bat_release_and_add(rxq);
+		t7xx_dpmaif_frag_bat_release_and_add(rxq);
+	}
 
+	t7xx_pci_enable_sleep(dpmaif_ctrl->t7xx_dev);
 	pm_runtime_mark_last_busy(dpmaif_ctrl->dev);
 	pm_runtime_put_autosuspend(dpmaif_ctrl->dev);
 }

drivers/net/wwan/t7xx/t7xx_hif_dpmaif_tx.c

···
 	if (ret < 0 && ret != -EACCES)
 		return;
 
-	hw_info = &dpmaif_ctrl->hw_info;
-	ret = t7xx_dpmaif_tx_release(dpmaif_ctrl, txq->index, txq->drb_size_cnt);
-	if (ret == -EAGAIN ||
-	    (t7xx_dpmaif_ul_clr_done(hw_info, txq->index) &&
-	     t7xx_dpmaif_drb_ring_not_empty(txq))) {
-		queue_work(dpmaif_ctrl->txq[txq->index].worker,
-			   &dpmaif_ctrl->txq[txq->index].dpmaif_tx_work);
-		/* Give the device time to enter the low power state */
-		t7xx_dpmaif_clr_ip_busy_sts(hw_info);
-	} else {
-		t7xx_dpmaif_clr_ip_busy_sts(hw_info);
-		t7xx_dpmaif_unmask_ulq_intr(hw_info, txq->index);
+	/* The device may be in low power state. Disable sleep if needed */
+	t7xx_pci_disable_sleep(dpmaif_ctrl->t7xx_dev);
+	if (t7xx_pci_sleep_disable_complete(dpmaif_ctrl->t7xx_dev)) {
+		hw_info = &dpmaif_ctrl->hw_info;
+		ret = t7xx_dpmaif_tx_release(dpmaif_ctrl, txq->index, txq->drb_size_cnt);
+		if (ret == -EAGAIN ||
+		    (t7xx_dpmaif_ul_clr_done(hw_info, txq->index) &&
+		     t7xx_dpmaif_drb_ring_not_empty(txq))) {
+			queue_work(dpmaif_ctrl->txq[txq->index].worker,
+				   &dpmaif_ctrl->txq[txq->index].dpmaif_tx_work);
+			/* Give the device time to enter the low power state */
+			t7xx_dpmaif_clr_ip_busy_sts(hw_info);
+		} else {
+			t7xx_dpmaif_clr_ip_busy_sts(hw_info);
+			t7xx_dpmaif_unmask_ulq_intr(hw_info, txq->index);
+		}
 	}
 
+	t7xx_pci_enable_sleep(dpmaif_ctrl->t7xx_dev);
 	pm_runtime_mark_last_busy(dpmaif_ctrl->dev);
 	pm_runtime_put_autosuspend(dpmaif_ctrl->dev);
 }
···
 
 static void t7xx_do_tx_hw_push(struct dpmaif_ctrl *dpmaif_ctrl)
 {
+	bool wait_disable_sleep = true;
+
 	do {
 		struct dpmaif_tx_queue *txq;
 		int drb_send_cnt;
···
 			usleep_range(10, 20);
 			cond_resched();
 			continue;
+		}
+
+		/* Wait for the PCIe resource to unlock */
+		if (wait_disable_sleep) {
+			if (!t7xx_pci_sleep_disable_complete(dpmaif_ctrl->t7xx_dev))
+				return;
+
+			wait_disable_sleep = false;
 		}
 
 		t7xx_dpmaif_ul_update_hw_drb_cnt(&dpmaif_ctrl->hw_info, txq->index,
···
 		if (ret < 0 && ret != -EACCES)
 			return ret;
 
+		t7xx_pci_disable_sleep(dpmaif_ctrl->t7xx_dev);
 		t7xx_do_tx_hw_push(dpmaif_ctrl);
+		t7xx_pci_enable_sleep(dpmaif_ctrl->t7xx_dev);
 		pm_runtime_mark_last_busy(dpmaif_ctrl->dev);
 		pm_runtime_put_autosuspend(dpmaif_ctrl->dev);
 	}

drivers/net/wwan/t7xx/t7xx_mhccif.c

···
 
 	t7xx_mhccif_clear_interrupts(t7xx_dev, int_status);
 
+	if (int_status & D2H_INT_DS_LOCK_ACK)
+		complete_all(&t7xx_dev->sleep_lock_acquire);
+
 	if (int_status & D2H_INT_SR_ACK)
 		complete(&t7xx_dev->pm_sr_ack);
 

drivers/net/wwan/t7xx/t7xx_pci.c

···
 #include <linux/pm.h>
 #include <linux/pm_runtime.h>
 #include <linux/pm_wakeup.h>
+#include <linux/spinlock.h>
 
 #include "t7xx_mhccif.h"
 #include "t7xx_modem_ops.h"
···
 #define T7XX_PCI_IREG_BASE		0
 #define T7XX_PCI_EREG_BASE		2
 
+#define PM_SLEEP_DIS_TIMEOUT_MS		20
 #define PM_ACK_TIMEOUT_MS		1500
 #define PM_AUTOSUSPEND_MS		20000
 #define PM_RESOURCE_POLL_TIMEOUT_US	10000
···
 	MTK_PM_SUSPENDED,
 	MTK_PM_RESUMED,
 };
+
+static void t7xx_dev_set_sleep_capability(struct t7xx_pci_dev *t7xx_dev, bool enable)
+{
+	void __iomem *ctrl_reg = IREG_BASE(t7xx_dev) + T7XX_PCIE_MISC_CTRL;
+	u32 value;
+
+	value = ioread32(ctrl_reg);
+
+	if (enable)
+		value &= ~T7XX_PCIE_MISC_MAC_SLEEP_DIS;
+	else
+		value |= T7XX_PCIE_MISC_MAC_SLEEP_DIS;
+
+	iowrite32(value, ctrl_reg);
+}
 
 static int t7xx_wait_pm_config(struct t7xx_pci_dev *t7xx_dev)
 {
···
 
 	INIT_LIST_HEAD(&t7xx_dev->md_pm_entities);
 	mutex_init(&t7xx_dev->md_pm_entity_mtx);
+	spin_lock_init(&t7xx_dev->md_pm_lock);
+	init_completion(&t7xx_dev->sleep_lock_acquire);
 	init_completion(&t7xx_dev->pm_sr_ack);
 	atomic_set(&t7xx_dev->md_pm_state, MTK_PM_INIT);
 
···
 {
 	/* Enable the PCIe resource lock only after MD deep sleep is done */
 	t7xx_mhccif_mask_clr(t7xx_dev,
+			     D2H_INT_DS_LOCK_ACK |
 			     D2H_INT_SUSPEND_ACK |
 			     D2H_INT_RESUME_ACK |
 			     D2H_INT_SUSPEND_ACK_AP |
···
 	mutex_unlock(&t7xx_dev->md_pm_entity_mtx);
 
 	return -ENXIO;
+}
+
+int t7xx_pci_sleep_disable_complete(struct t7xx_pci_dev *t7xx_dev)
+{
+	struct device *dev = &t7xx_dev->pdev->dev;
+	int ret;
+
+	ret = wait_for_completion_timeout(&t7xx_dev->sleep_lock_acquire,
+					  msecs_to_jiffies(PM_SLEEP_DIS_TIMEOUT_MS));
+	if (!ret)
+		dev_err_ratelimited(dev, "Resource wait complete timed out\n");
+
+	return ret;
+}
+
+/**
+ * t7xx_pci_disable_sleep() - Disable deep sleep capability.
+ * @t7xx_dev: MTK device.
+ *
+ * Lock the deep sleep capability, note that the device can still go into deep sleep
+ * state while device is in D0 state, from the host's point-of-view.
+ *
+ * If device is in deep sleep state, wake up the device and disable deep sleep capability.
+ */
+void t7xx_pci_disable_sleep(struct t7xx_pci_dev *t7xx_dev)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&t7xx_dev->md_pm_lock, flags);
+	t7xx_dev->sleep_disable_count++;
+	if (atomic_read(&t7xx_dev->md_pm_state) < MTK_PM_RESUMED)
+		goto unlock_and_complete;
+
+	if (t7xx_dev->sleep_disable_count == 1) {
+		u32 status;
+
+		reinit_completion(&t7xx_dev->sleep_lock_acquire);
+		t7xx_dev_set_sleep_capability(t7xx_dev, false);
+
+		status = ioread32(IREG_BASE(t7xx_dev) + T7XX_PCIE_RESOURCE_STATUS);
+		if (status & T7XX_PCIE_RESOURCE_STS_MSK)
+			goto unlock_and_complete;
+
+		t7xx_mhccif_h2d_swint_trigger(t7xx_dev, H2D_CH_DS_LOCK);
+	}
+	spin_unlock_irqrestore(&t7xx_dev->md_pm_lock, flags);
+	return;
+
+unlock_and_complete:
+	spin_unlock_irqrestore(&t7xx_dev->md_pm_lock, flags);
+	complete_all(&t7xx_dev->sleep_lock_acquire);
+}
+
+/**
+ * t7xx_pci_enable_sleep() - Enable deep sleep capability.
+ * @t7xx_dev: MTK device.
+ *
+ * After enabling deep sleep, device can enter into deep sleep state.
+ */
+void t7xx_pci_enable_sleep(struct t7xx_pci_dev *t7xx_dev)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&t7xx_dev->md_pm_lock, flags);
+	t7xx_dev->sleep_disable_count--;
+	if (atomic_read(&t7xx_dev->md_pm_state) < MTK_PM_RESUMED)
+		goto unlock;
+
+	if (t7xx_dev->sleep_disable_count == 0)
+		t7xx_dev_set_sleep_capability(t7xx_dev, true);
+
+unlock:
+	spin_unlock_irqrestore(&t7xx_dev->md_pm_lock, flags);
 }
 
 static int t7xx_send_pm_request(struct t7xx_pci_dev *t7xx_dev, u32 request)

drivers/net/wwan/t7xx/t7xx_pci.h

···
 #include <linux/irqreturn.h>
 #include <linux/mutex.h>
 #include <linux/pci.h>
+#include <linux/spinlock.h>
 #include <linux/types.h>
 
 #include "t7xx_reg.h"
···
  * @md_pm_entity_mtx: protects md_pm_entities list
  * @pm_sr_ack: ack from the device when went to sleep or woke up
  * @md_pm_state: state for resume/suspend
+ * @md_pm_lock: protects PCIe sleep lock
+ * @sleep_disable_count: PCIe L1.2 lock counter
+ * @sleep_lock_acquire: indicates that sleep has been disabled
  */
 struct t7xx_pci_dev {
 	t7xx_intr_callback	intr_handler[EXT_INT_NUM];
···
 	struct mutex		md_pm_entity_mtx;	/* Protects MD PM entities list */
 	struct completion	pm_sr_ack;
 	atomic_t		md_pm_state;
+	spinlock_t		md_pm_lock;		/* Protects PCI resource lock */
+	unsigned int		sleep_disable_count;
+	struct completion	sleep_lock_acquire;
 };
 
 enum t7xx_pm_id {
···
 	void			*entity_param;
 };
 
+void t7xx_pci_disable_sleep(struct t7xx_pci_dev *t7xx_dev);
+void t7xx_pci_enable_sleep(struct t7xx_pci_dev *t7xx_dev);
+int t7xx_pci_sleep_disable_complete(struct t7xx_pci_dev *t7xx_dev);
 int t7xx_pci_pm_entity_register(struct t7xx_pci_dev *t7xx_dev, struct md_pm_entity *pm_entity);
 int t7xx_pci_pm_entity_unregister(struct t7xx_pci_dev *t7xx_dev, struct md_pm_entity *pm_entity);
 void t7xx_pci_pm_init_late(struct t7xx_pci_dev *t7xx_dev);