staging: dwc2: add driver parameter to set AHB config register value

The dwc2 driver sets the value of the DWC2 GAHBCFG register to 0x6,
which is GAHBCFG_HBSTLEN_INCR4. But different platforms may require
different values. In particular, the Broadcom 2835 SOC used in the
Raspberry Pi needs a value of 0x10, otherwise the DWC2 controller
stops working after a short period of heavy USB traffic.

So this patch adds another driver parameter named 'ahbcfg'. The
default value is 0x6. Any platform needing a different value should
add a DT attribute to set it.

This patch also removes the 'ahb_single' driver parameter, since
that bit can now be set using 'ahbcfg'.

This patch does not add DT support to platform.c, I will leave that
to whoever owns the first platform that needs a non-default value.
(Stephen?)
Signed-off-by: Paul Zimmerman <paulz@synopsys.com>
Tested-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Matthijs Kooijman <matthijs@stdin.nl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/dwc2/core.c

@@ -277,7 +277,7 @@ static void dwc2_phy_init(struct dwc2_hsotg *hsotg, bool select_phy)
 
 static int dwc2_gahbcfg_init(struct dwc2_hsotg *hsotg)
 {
-	u32 ahbcfg = 0;
+	u32 ahbcfg = readl(hsotg->regs + GAHBCFG);
 
 	switch (hsotg->hwcfg2 & GHWCFG2_ARCHITECTURE_MASK) {
 	case GHWCFG2_EXT_DMA_ARCH:
@@ -286,11 +286,11 @@ static int dwc2_gahbcfg_init(struct dwc2_hsotg *hsotg)
 
 	case GHWCFG2_INT_DMA_ARCH:
 		dev_dbg(hsotg->dev, "Internal DMA Mode\n");
-		/*
-		 * Old value was GAHBCFG_HBSTLEN_INCR - done for
-		 * Host mode ISOC in issue fix - vahrama
-		 */
-		ahbcfg |= GAHBCFG_HBSTLEN_INCR4;
+		if (hsotg->core_params->ahbcfg != -1) {
+			ahbcfg &= GAHBCFG_CTRL_MASK;
+			ahbcfg |= hsotg->core_params->ahbcfg &
+				  ~GAHBCFG_CTRL_MASK;
+		}
 		break;
 
 	case GHWCFG2_SLAVE_ONLY_ARCH:
@@ -313,9 +313,6 @@ static int dwc2_gahbcfg_init(struct dwc2_hsotg *hsotg)
 		hsotg->core_params->dma_desc_enable = 0;
 	}
 
-	if (hsotg->core_params->ahb_single > 0)
-		ahbcfg |= GAHBCFG_AHB_SINGLE;
-
 	if (hsotg->core_params->dma_enable > 0)
 		ahbcfg |= GAHBCFG_DMA_EN;
 
@@ -2586,35 +2583,13 @@ int dwc2_set_param_reload_ctl(struct dwc2_hsotg *hsotg, int val)
 	return retval;
 }
 
-int dwc2_set_param_ahb_single(struct dwc2_hsotg *hsotg, int val)
+int dwc2_set_param_ahbcfg(struct dwc2_hsotg *hsotg, int val)
 {
-	int valid = 1;
-	int retval = 0;
-
-	if (DWC2_PARAM_TEST(val, 0, 1)) {
-		if (val >= 0) {
-			dev_err(hsotg->dev,
-				"'%d' invalid for parameter ahb_single\n", val);
-			dev_err(hsotg->dev, "ahb_single must be 0 or 1\n");
-		}
-		valid = 0;
-	}
-
-	if (val > 0 && hsotg->snpsid < DWC2_CORE_REV_2_94a)
-		valid = 0;
-
-	if (!valid) {
-		if (val >= 0)
-			dev_err(hsotg->dev,
-				"%d invalid for parameter ahb_single. Check HW configuration.\n",
-				val);
-		val = 0;
-		dev_dbg(hsotg->dev, "Setting ahb_single to %d\n", val);
-		retval = -EINVAL;
-	}
-
-	hsotg->core_params->ahb_single = val;
-	return retval;
+	if (val != -1)
+		hsotg->core_params->ahbcfg = val;
+	else
+		hsotg->core_params->ahbcfg = GAHBCFG_HBSTLEN_INCR4;
+	return 0;
 }
 
 int dwc2_set_param_otg_ver(struct dwc2_hsotg *hsotg, int val)
@@ -2681,7 +2656,7 @@ int dwc2_set_parameters(struct dwc2_hsotg *hsotg,
 	retval |= dwc2_set_param_en_multiple_tx_fifo(hsotg,
 			params->en_multiple_tx_fifo);
 	retval |= dwc2_set_param_reload_ctl(hsotg, params->reload_ctl);
-	retval |= dwc2_set_param_ahb_single(hsotg, params->ahb_single);
+	retval |= dwc2_set_param_ahbcfg(hsotg, params->ahbcfg);
 	retval |= dwc2_set_param_otg_ver(hsotg, params->otg_ver);
 
 	return retval;

drivers/staging/dwc2/core.h

@@ -150,10 +150,11 @@ enum dwc2_lx_state {
  *                      are enabled
  * @reload_ctl:         True to allow dynamic reloading of HFIR register during
  *                      runtime
- * @ahb_single:         This bit enables SINGLE transfers for remainder data in
- *                      a transfer for DMA mode of operation.
- *                       0 - remainder data will be sent using INCR burst size
- *                       1 - remainder data will be sent using SINGLE burst size
+ * @ahbcfg:             This field allows the default value of the GAHBCFG
+ *                      register to be overridden
+ *                       -1         - GAHBCFG value will not be overridden
+ *                       all others - GAHBCFG value will be overridden with
+ *                                    this value
  * @otg_ver:            OTG version supported
  *                       0 - 1.3
  *                       1 - 2.0
@@ -189,7 +190,7 @@ struct dwc2_core_params {
 	int host_ls_low_power_phy_clk;
 	int ts_dline;
 	int reload_ctl;
-	int ahb_single;
+	int ahbcfg;
 };
 
 /**
@@ -643,7 +644,7 @@ extern int dwc2_set_param_en_multiple_tx_fifo(struct dwc2_hsotg *hsotg,
 
 extern int dwc2_set_param_reload_ctl(struct dwc2_hsotg *hsotg, int val);
 
-extern int dwc2_set_param_ahb_single(struct dwc2_hsotg *hsotg, int val);
+extern int dwc2_set_param_ahbcfg(struct dwc2_hsotg *hsotg, int val);
 
 extern int dwc2_set_param_otg_ver(struct dwc2_hsotg *hsotg, int val);
 

drivers/staging/dwc2/hw.h

@@ -78,6 +78,10 @@
 #define GAHBCFG_HBSTLEN_INCR8			(5 << 1)
 #define GAHBCFG_HBSTLEN_INCR16			(7 << 1)
 #define GAHBCFG_GLBL_INTR_EN		(1 << 0)
+#define GAHBCFG_CTRL_MASK		(GAHBCFG_P_TXF_EMP_LVL | \
+					 GAHBCFG_NP_TXF_EMP_LVL | \
+					 GAHBCFG_DMA_EN | \
+					 GAHBCFG_GLBL_INTR_EN)
 
 #define GUSBCFG				HSOTG_REG(0x00C)
 #define GUSBCFG_FORCEDEVMODE		(1 << 30)

drivers/staging/dwc2/pci.c

@@ -83,7 +83,7 @@ static const struct dwc2_core_params dwc2_module_params = {
 	.host_ls_low_power_phy_clk	= -1,
 	.ts_dline			= -1,
 	.reload_ctl			= -1,
-	.ahb_single			= -1,
+	.ahbcfg				= -1,
 };
 
 /**