[PATCH] wlcore/wl18xx: Add invert-irq OF property for physically inverted IRQ

[Eugeniu Rosca <erosca@de.adit-jv.com>]

The wl1837mod datasheet [1] says about the WL_IRQ pin:

 ---8<---
SDIO available, interrupt out. Active high. [..]
Set to rising edge (active high) on powerup.
 ---8<---

That's the reason of seeing the interrupt configured as:
 - IRQ_TYPE_EDGE_RISING on HiKey 960/970
 - IRQ_TYPE_LEVEL_HIGH on a number of i.MX6 platforms

We assert that all those platforms have the WL_IRQ pin connected
to the SoC _directly_ (confirmed on HiKey 970 [2]).

That's not the case for R-Car Kingfisher extension target, which carries
a WL1837MODGIMOCT IC. There is an SN74LV1T04DBVR inverter present
between the WLAN_IRQ pin of the WL18* chip and the SoC, effectively
reversing the requirement quoted from [1]. IOW, in Kingfisher DTS
configuration we would need to use IRQ_TYPE_EDGE_FALLING or
IRQ_TYPE_LEVEL_LOW.

Unfortunately, v4.2-rc1 commit bd763482c82ea2 ("wl18xx: wlan_irq:
support platform dependent interrupt types") made a special case out
of these interrupt types. After this commit, it is impossible to provide
an IRQ configuration via DTS which would describe an inverter present
between the WL18* chip and the SoC, generating the need for workarounds
like [3].

Create a boolean OF property, called "invert-irq" to specify that
the WLAN_IRQ pin of WL18* is connected to the SoC via an inverter.

This solution has been successfully tested on R-Car H3ULCB-KF-M06 using
the DTS configuration [4] combined with the "invert-irq" property.

[1] http://www.ti.com/lit/ds/symlink/wl1837mod.pdf
[2] https://www.96boards.org/documentation/consumer/hikey/hikey970/hardware-docs/
[3] https://github.com/CogentEmbedded/meta-rcar/blob/289fbd4f8354/meta-rcar-gen3-adas/recipes-kernel/linux/linux-renesas/0024-wl18xx-do-not-invert-IRQ-on-WLxxxx-side.patch
[4] https://patchwork.kernel.org/patch/10895879/
    ("arm64: dts: ulcb-kf: Add support for TI WL1837")

Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>
---
 drivers/net/wireless/ti/wl18xx/main.c     | 5 +++++
 drivers/net/wireless/ti/wlcore/sdio.c     | 2 ++
 drivers/net/wireless/ti/wlcore/wlcore_i.h | 4 ++++
 3 files changed, 11 insertions(+)

diff --git a/drivers/net/wireless/ti/wl18xx/main.c b/drivers/net/wireless/ti/wl18xx/main.c
index 496b9b63cea1..cea91d1aee98 100644
--- a/drivers/net/wireless/ti/wl18xx/main.c
+++ b/drivers/net/wireless/ti/wl18xx/main.c
@@ -877,6 +877,8 @@ static int wl18xx_pre_boot(struct wl1271 *wl)
 
 static int wl18xx_pre_upload(struct wl1271 *wl)
 {
+	struct platform_device *pdev = wl->pdev;
+	struct wlcore_platdev_data *pdata = dev_get_platdata(&pdev->dev);
 	u32 tmp;
 	int ret;
 	u16 irq_invert;
@@ -932,6 +934,9 @@ static int wl18xx_pre_upload(struct wl1271 *wl)
 	if (ret < 0)
 		goto out;
 
+	if (pdata->invert_irq)
+		goto out;
+
 	ret = irq_get_trigger_type(wl->irq);
 	if ((ret == IRQ_TYPE_LEVEL_LOW) || (ret == IRQ_TYPE_EDGE_FALLING)) {
 		wl1271_info("using inverted interrupt logic: %d", ret);
diff --git a/drivers/net/wireless/ti/wlcore/sdio.c b/drivers/net/wireless/ti/wlcore/sdio.c
index 4d4b07701149..581f56b0b6a2 100644
--- a/drivers/net/wireless/ti/wlcore/sdio.c
+++ b/drivers/net/wireless/ti/wlcore/sdio.c
@@ -266,6 +266,8 @@ static int wlcore_probe_of(struct device *dev, int *irq, int *wakeirq,
 	of_property_read_u32(np, "tcxo-clock-frequency",
 			     &pdev_data->tcxo_clock_freq);
 
+	pdev_data->invert_irq = of_property_read_bool(np, "invert-irq");
+
 	return 0;
 }
 #else
diff --git a/drivers/net/wireless/ti/wlcore/wlcore_i.h b/drivers/net/wireless/ti/wlcore/wlcore_i.h
index 32ec121ccac2..01679f9d7170 100644
--- a/drivers/net/wireless/ti/wlcore/wlcore_i.h
+++ b/drivers/net/wireless/ti/wlcore/wlcore_i.h
@@ -213,6 +213,10 @@ struct wlcore_platdev_data {
 	u32 ref_clock_freq;	/* in Hertz */
 	u32 tcxo_clock_freq;	/* in Hertz, tcxo is always XTAL */
 	bool pwr_in_suspend;
+	bool invert_irq;	/* specify if there is a physical IRQ inverter
+				 * between WL chip and SoC, like SN74LV1T04DBVR
+				 * in case of R-Car Kingfisher board
+				 */
 };
 
 #define MAX_NUM_KEYS 14
-- 
2.21.0