From 63d47233f18ab6bb880cc4005a373a55c8364e0b Mon Sep 17 00:00:00 2001
From: Ran Wang <ran.wang_1@nxp.com>
Date: Fri, 22 Nov 2019 14:17:32 +0800
Subject: [PATCH] usb: dwc3: Add cache type configuration support

This feature is telling how to configure cache type on 4 different
transfer types: Data Read, Desc Read, Data Write and Desc write. For each
transfer type, controller has a 4-bit register field to enable different
cache type. Quoted from DWC3 data book Table 6-5 Cache Type Bit Assignments:
----------------------------------------------------------------
MBUS_TYPE| bit[3]       |bit[2]       |bit[1]     |bit[0]
----------------------------------------------------------------
AHB      |Cacheable     |Bufferable   |Privilegge |Data
AXI3     |Write Allocate|Read Allocate|Cacheable  |Bufferable
AXI4     |Allocate Other|Allocate     |Modifiable |Bufferable
AXI4     |Other Allocate|Allocate     |Modifiable |Bufferable
Native   |Same as AXI   |Same as AXI  |Same as AXI|Same as AXI
----------------------------------------------------------------
Note: The AHB, AXI3, AXI4, and PCIe busses use different names for certain
signals, which have the same meaning:
  Bufferable = Posted
  Cacheable = Modifiable = Snoop (negation of No Snoop)

In most cases, driver support is not required unless the default values of
registers are not correct *and* DWC3 node has enabled dma-coherent. So far we
have observed USB device detect failure on some Layerscape platforms if this
programming was not applied.

Related struct:
struct dwc3_cache_type {
	u8 transfer_type_datard;
	u8 transfer_type_descrd;
	u8 transfer_type_datawr;
	u8 transfer_type_descwr;
};

Signed-off-by: Ran Wang <ran.wang_1@nxp.com>
Reviewed-by: Jun Li <jun.li@nxp.com>
---
 drivers/usb/dwc3/core.c | 61 ++++++++++++++++++++++++++++++++++++++++++++-----
 drivers/usb/dwc3/core.h | 15 ++++++++++++
 2 files changed, 70 insertions(+), 6 deletions(-)

--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -919,6 +919,54 @@ static void dwc3_set_power_down_clk_scal
 	dwc3_writel(dwc->regs, DWC3_GCTL, reg);
 }
 
+#ifdef CONFIG_OF
+struct dwc3_cache_type {
+	u8 transfer_type_datard;
+	u8 transfer_type_descrd;
+	u8 transfer_type_datawr;
+	u8 transfer_type_descwr;
+};
+
+static const struct dwc3_cache_type layerscape_dwc3_cache_type = {
+	.transfer_type_datard = 2,
+	.transfer_type_descrd = 2,
+	.transfer_type_datawr = 2,
+	.transfer_type_descwr = 2,
+};
+
+/**
+ * dwc3_set_cache_type - Configure cache type registers
+ * @dwc: Pointer to our controller context structure
+ */
+static void dwc3_set_cache_type(struct dwc3 *dwc)
+{
+	u32 tmp, reg;
+	const struct dwc3_cache_type *cache_type =
+		device_get_match_data(dwc->dev);
+
+	if (cache_type) {
+		reg = dwc3_readl(dwc->regs,  DWC3_GSBUSCFG0);
+		tmp = reg;
+
+		reg &= ~DWC3_GSBUSCFG0_DATARD(~0);
+		reg |= DWC3_GSBUSCFG0_DATARD(cache_type->transfer_type_datard);
+
+		reg &= ~DWC3_GSBUSCFG0_DESCRD(~0);
+		reg |= DWC3_GSBUSCFG0_DESCRD(cache_type->transfer_type_descrd);
+
+		reg &= ~DWC3_GSBUSCFG0_DATAWR(~0);
+		reg |= DWC3_GSBUSCFG0_DATAWR(cache_type->transfer_type_datawr);
+
+		reg &= ~DWC3_GSBUSCFG0_DESCWR(~0);
+		reg |= DWC3_GSBUSCFG0_DESCWR(cache_type->transfer_type_descwr);
+
+		if (tmp != reg)
+			dwc3_writel(dwc->regs, DWC3_GSBUSCFG0, reg);
+	}
+}
+#endif
+
+
 /**
  * dwc3_core_init - Low-level initialization of DWC3 Core
  * @dwc: Pointer to our controller context structure
@@ -979,6 +1027,10 @@ static int dwc3_core_init(struct dwc3 *d
 
 	dwc3_set_incr_burst_type(dwc);
 
+#ifdef CONFIG_OF
+	dwc3_set_cache_type(dwc);
+#endif
+
 	usb_phy_set_suspend(dwc->usb2_phy, 0);
 	usb_phy_set_suspend(dwc->usb3_phy, 0);
 	ret = phy_power_on(dwc->usb2_generic_phy);
@@ -1932,12 +1984,9 @@ static const struct dev_pm_ops dwc3_dev_
 
 #ifdef CONFIG_OF
 static const struct of_device_id of_dwc3_match[] = {
-	{
-		.compatible = "snps,dwc3"
-	},
-	{
-		.compatible = "synopsys,dwc3"
-	},
+	{ .compatible = "fsl,layerscape-dwc3", .data = &layerscape_dwc3_cache_type, },
+	{ .compatible = "snps,dwc3" },
+	{ .compatible = "synopsys,dwc3"	},
 	{ },
 };
 MODULE_DEVICE_TABLE(of, of_dwc3_match);
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -167,6 +167,21 @@
 /* Bit fields */
 
 /* Global SoC Bus Configuration INCRx Register 0 */
+#ifdef CONFIG_OF
+#define DWC3_GSBUSCFG0_DATARD_SHIFT	28
+#define DWC3_GSBUSCFG0_DATARD(n)	(((n) & 0xf)		\
+			<< DWC3_GSBUSCFG0_DATARD_SHIFT)
+#define DWC3_GSBUSCFG0_DESCRD_SHIFT	24
+#define DWC3_GSBUSCFG0_DESCRD(n)	(((n) & 0xf)		\
+			<< DWC3_GSBUSCFG0_DESCRD_SHIFT)
+#define DWC3_GSBUSCFG0_DATAWR_SHIFT	20
+#define DWC3_GSBUSCFG0_DATAWR(n)	(((n) & 0xf)		\
+			<< DWC3_GSBUSCFG0_DATAWR_SHIFT)
+#define DWC3_GSBUSCFG0_DESCWR_SHIFT	16
+#define DWC3_GSBUSCFG0_DESCWR(n)	(((n) & 0xf)		\
+			<< DWC3_GSBUSCFG0_DESCWR_SHIFT)
+#endif
+
 #define DWC3_GSBUSCFG0_INCR256BRSTENA	(1 << 7) /* INCR256 burst */
 #define DWC3_GSBUSCFG0_INCR128BRSTENA	(1 << 6) /* INCR128 burst */
 #define DWC3_GSBUSCFG0_INCR64BRSTENA	(1 << 5) /* INCR64 burst */
