[PATCH] usb: dwc3: Enable the USB snooping

[Ran Wang <ran.wang_1@nxp.com>]

Add support for USB3 snooping by asserting bits
in register DWC3_GSBUSCFG0 for data and descriptor.

Signed-off-by: Changming Huang <jerry.huang@nxp.com>
Signed-off-by: Rajesh Bhagat <rajesh.bhagat@nxp.com>
Signed-off-by: Ran Wang <ran.wang_1@nxp.com>
---
 drivers/usb/dwc3/core.c | 24 ++++++++++++++++++++++++
 drivers/usb/dwc3/core.h | 10 ++++++++++
 2 files changed, 34 insertions(+)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 07832509584f..ffc078ab4a1c 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -236,6 +236,26 @@ static int dwc3_core_soft_reset(struct dwc3 *dwc)
 	return -ETIMEDOUT;
 }
 
+/*
+ * dwc3_enable_snooping - Enable snooping feature
+ * @dwc3: Pointer to our controller context structure
+ */
+static void dwc3_enable_snooping(struct dwc3 *dwc)
+{
+	u32 cfg;
+
+	cfg = dwc3_readl(dwc->regs, DWC3_GSBUSCFG0);
+	if (dwc->dma_coherent) {
+		cfg &= ~DWC3_GSBUSCFG0_SNP_MASK;
+		cfg |= (AXI3_CACHE_TYPE_SNP << DWC3_GSBUSCFG0_DATARD_SHIFT) |
+			(AXI3_CACHE_TYPE_SNP << DWC3_GSBUSCFG0_DESCRD_SHIFT) |
+			(AXI3_CACHE_TYPE_SNP << DWC3_GSBUSCFG0_DATAWR_SHIFT) |
+			(AXI3_CACHE_TYPE_SNP << DWC3_GSBUSCFG0_DESCWR_SHIFT);
+	}
+
+	dwc3_writel(dwc->regs, DWC3_GSBUSCFG0, cfg);
+}
+
 /*
  * dwc3_frame_length_adjustment - Adjusts frame length if required
  * @dwc3: Pointer to our controller context structure
@@ -776,6 +796,8 @@ static int dwc3_core_init(struct dwc3 *dwc)
 	/* Adjust Frame Length */
 	dwc3_frame_length_adjustment(dwc);
 
+	dwc3_enable_snooping(dwc);
+
 	usb_phy_set_suspend(dwc->usb2_phy, 0);
 	usb_phy_set_suspend(dwc->usb3_phy, 0);
 	ret = phy_power_on(dwc->usb2_generic_phy);
@@ -1021,6 +1043,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
 				&hird_threshold);
 	dwc->usb3_lpm_capable = device_property_read_bool(dev,
 				"snps,usb3_lpm_capable");
+	dwc->dma_coherent = device_property_read_bool(dev,
+				"dma-coherent");
 
 	dwc->disable_scramble_quirk = device_property_read_bool(dev,
 				"snps,disable_scramble_quirk");
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 4a4a4c98508c..6e6a66650e53 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -153,6 +153,14 @@
 
 /* Bit fields */
 
+/* Global SoC Bus Configuration Register 0 */
+#define AXI3_CACHE_TYPE_SNP		0x2 /* cacheable */
+#define DWC3_GSBUSCFG0_DATARD_SHIFT	28
+#define DWC3_GSBUSCFG0_DESCRD_SHIFT	24
+#define DWC3_GSBUSCFG0_DATAWR_SHIFT	20
+#define DWC3_GSBUSCFG0_DESCWR_SHIFT	16
+#define DWC3_GSBUSCFG0_SNP_MASK		0xffff0000
+
 /* Global Debug Queue/FIFO Space Available Register */
 #define DWC3_GDBGFIFOSPACE_NUM(n)	((n) & 0x1f)
 #define DWC3_GDBGFIFOSPACE_TYPE(n)	(((n) << 5) & 0x1e0)
@@ -859,6 +867,7 @@ struct dwc3_scratchpad_array {
  * 	3	- Reserved
  * @imod_interval: set the interrupt moderation interval in 250ns
  *                 increments or 0 to disable.
+ * @dma_coherent: set if enable dma-coherent.
  */
 struct dwc3 {
 	struct work_struct	drd_work;
@@ -990,6 +999,7 @@ struct dwc3 {
 	unsigned		setup_packet_pending:1;
 	unsigned		three_stage_setup:1;
 	unsigned		usb3_lpm_capable:1;
+	unsigned		dma_coherent:1;
 
 	unsigned		disable_scramble_quirk:1;
 	unsigned		u2exit_lfps_quirk:1;
-- 
2.14.1