[RFC][PATCH v2 2/5] usb: dwc3: Execute GCTL Core Soft Reset while switch mdoe for Hisilicon Kirin Soc

[John Stultz <john.stultz@linaro.org>]

From: Yu Chen <chenyu56@huawei.com>

A GCTL soft reset should be executed when switch mode for dwc3 core
of Hisilicon Kirin Soc.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Yu Chen <chenyu56@huawei.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Chunfeng Yun <chunfeng.yun@mediatek.com>
Cc: linux-usb@vger.kernel.org
Cc: devicetree@vger.kernel.org
Signed-off-by: Yu Chen <chenyu56@huawei.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
 drivers/usb/dwc3/core.c | 20 ++++++++++++++++++++
 drivers/usb/dwc3/core.h |  3 +++
 2 files changed, 23 insertions(+)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 999ce5e84d3c..440261432421 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -112,6 +112,19 @@ void dwc3_set_prtcap(struct dwc3 *dwc, u32 mode)
 	dwc->current_dr_role = mode;
 }
 
+static void dwc3_gctl_core_soft_reset(struct dwc3 *dwc)
+{
+	u32 reg;
+
+	reg = dwc3_readl(dwc->regs, DWC3_GCTL);
+	reg |= DWC3_GCTL_CORESOFTRESET;
+	dwc3_writel(dwc->regs, DWC3_GCTL, reg);
+
+	reg = dwc3_readl(dwc->regs, DWC3_GCTL);
+	reg &= ~DWC3_GCTL_CORESOFTRESET;
+	dwc3_writel(dwc->regs, DWC3_GCTL, reg);
+}
+
 static void __dwc3_set_mode(struct work_struct *work)
 {
 	struct dwc3 *dwc = work_to_dwc(work);
@@ -156,6 +169,10 @@ static void __dwc3_set_mode(struct work_struct *work)
 
 	dwc3_set_prtcap(dwc, dwc->desired_dr_role);
 
+	/* Execute a GCTL Core Soft Reset when switch mode */
+	if (dwc->gctl_reset_quirk)
+		dwc3_gctl_core_soft_reset(dwc);
+
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
 	switch (dwc->desired_dr_role) {
@@ -1316,6 +1333,9 @@ static void dwc3_get_properties(struct dwc3 *dwc)
 	dwc->dis_metastability_quirk = device_property_read_bool(dev,
 				"snps,dis_metastability_quirk");
 
+	dwc->gctl_reset_quirk = device_property_read_bool(dev,
+				"snps,gctl-reset-quirk");
+
 	dwc->lpm_nyet_threshold = lpm_nyet_threshold;
 	dwc->tx_de_emphasis = tx_de_emphasis;
 
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 1c8b349379af..b3cb6eec3f8f 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -1029,6 +1029,7 @@ struct dwc3_scratchpad_array {
  * 	2	- No de-emphasis
  * 	3	- Reserved
  * @dis_metastability_quirk: set to disable metastability quirk.
+ * @gctl_reset_quirk: set to do a gctl soft-reset while switch operation mode.
  * @imod_interval: set the interrupt moderation interval in 250ns
  *                 increments or 0 to disable.
  */
@@ -1219,6 +1220,8 @@ struct dwc3 {
 
 	unsigned		dis_metastability_quirk:1;
 
+	unsigned		gctl_reset_quirk:1;
+
 	u16			imod_interval;
 };
 
-- 
2.17.1