linux-kernel - [PATCH 07/15] staging: wfx: introduce a way to poll IRQ

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Date:   Tue,  5 May 2020 14:37:49 +0200
From:   Jerome Pouiller <Jerome.Pouiller@...abs.com>
To:     devel@...verdev.osuosl.org, linux-wireless@...r.kernel.org
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S . Miller" <davem@...emloft.net>,
        Jérôme Pouiller 
        <jerome.pouiller@...abs.com>
Subject: [PATCH 07/15] staging: wfx: introduce a way to poll IRQ

From: Jérôme Pouiller <jerome.pouiller@...abs.com>

It is possible to check if an IRQ is ending by polling the control
register. This function must used with care: if an IRQ fires while the
host reads control register, the IRQ can be lost. However, it could be
useful in some cases.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@...abs.com>
---
 drivers/staging/wfx/bh.c | 28 ++++++++++++++++++++++++++++
 drivers/staging/wfx/bh.h |  1 +
 2 files changed, 29 insertions(+)

diff --git a/drivers/staging/wfx/bh.c b/drivers/staging/wfx/bh.c
index ba7fa0a7cd9a..d3e7eed89c38 100644
--- a/drivers/staging/wfx/bh.c
+++ b/drivers/staging/wfx/bh.c
@@ -307,6 +307,34 @@ void wfx_bh_request_tx(struct wfx_dev *wdev)
 	queue_work(system_highpri_wq, &wdev->hif.bh);
 }
 
+/*
+ * If IRQ is not available, this function allow to manually poll the control
+ * register and simulate an IRQ ahen an event happened.
+ *
+ * Note that the device has a bug: If an IRQ raise while host read control
+ * register, the IRQ is lost. So, use this function carefully (only duing
+ * device initialisation).
+ */
+void wfx_bh_poll_irq(struct wfx_dev *wdev)
+{
+	ktime_t now, start;
+	u32 reg;
+
+	start = ktime_get();
+	for (;;) {
+		control_reg_read(wdev, &reg);
+		now = ktime_get();
+		if (reg & 0xFFF)
+			break;
+		if (ktime_after(now, ktime_add_ms(start, 1000))) {
+			dev_err(wdev->dev, "time out while polling control register\n");
+			return;
+		}
+		udelay(200);
+	}
+	wfx_bh_request_rx(wdev);
+}
+
 void wfx_bh_register(struct wfx_dev *wdev)
 {
 	INIT_WORK(&wdev->hif.bh, bh_work);
diff --git a/drivers/staging/wfx/bh.h b/drivers/staging/wfx/bh.h
index 93ca98424e0b..4b73437869e1 100644
--- a/drivers/staging/wfx/bh.h
+++ b/drivers/staging/wfx/bh.h
@@ -28,5 +28,6 @@ void wfx_bh_register(struct wfx_dev *wdev);
 void wfx_bh_unregister(struct wfx_dev *wdev);
 void wfx_bh_request_rx(struct wfx_dev *wdev);
 void wfx_bh_request_tx(struct wfx_dev *wdev);
+void wfx_bh_poll_irq(struct wfx_dev *wdev);
 
 #endif /* WFX_BH_H */
-- 
2.26.1