usb: dwc2: Add Interpacket Gap(IPG) feature support

Added GHWCFG4_IPG_ISOC_SUPPORTED and DCFG_IPG_ISOC_SUPPORDED
bits definitions to enable/disable IPG feature.

Added ipg_isoc_en core parameter which will indicate IPG support
enable/disable and initialize it.

Signed-off-by: Grigor Tovmasyan <tovmasya@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc2/core.h

@@ -380,6 +380,9 @@ enum dwc2_ep0_state {
  *                      is FS.
  *                       0 - No (default)
  *                       1 - Yes
+ * @ipg_isoc_en         Indicates the IPG supports is enabled or disabled.
+ *                       0 - Disable (default)
+ *                       1 - Enable
  * @ulpi_fs_ls:         Make ULPI phy operate in FS/LS mode only
  *                       0 - No (default)
  *                       1 - Yes
@@ -511,6 +514,7 @@ struct dwc2_core_params {
 	bool hird_threshold_en;
 	u8 hird_threshold;
 	bool activate_stm_fs_transceiver;
+	bool ipg_isoc_en;
 	u16 max_packet_count;
 	u32 max_transfer_size;
 	u32 ahbcfg;
@@ -560,6 +564,12 @@ struct dwc2_core_params {
  *                       0 - Slave only
  *                       1 - External DMA
  *                       2 - Internal DMA
+ * @ipg_isoc_en         This feature indicates that the controller supports
+ *                      the worst-case scenario of Rx followed by Rx
+ *                      Interpacket Gap (IPG) (32 bitTimes) as per the utmi
+ *                      specification for any token following ISOC OUT token.
+ *                       0 - Don't support
+ *                       1 - Support
  * @power_optimized     Are power optimizations enabled?
  * @num_dev_ep          Number of device endpoints available
  * @num_dev_in_eps      Number of device IN endpoints available
@@ -622,6 +632,7 @@ struct dwc2_hw_params {
 	unsigned hibernation:1;
 	unsigned utmi_phy_data_width:2;
 	unsigned lpm_mode:1;
+	unsigned ipg_isoc_en:1;
 	u32 snpsid;
 	u32 dev_ep_dirs;
 	u32 g_tx_fifo_size[MAX_EPS_CHANNELS];

drivers/usb/dwc2/debugfs.c

@@ -710,6 +710,7 @@ static int params_show(struct seq_file *seq, void *v)
 	print_param(seq, p, phy_ulpi_ddr);
 	print_param(seq, p, phy_ulpi_ext_vbus);
 	print_param(seq, p, i2c_enable);
+	print_param(seq, p, ipg_isoc_en);
 	print_param(seq, p, ulpi_fs_ls);
 	print_param(seq, p, host_support_fs_ls_low_power);
 	print_param(seq, p, host_ls_low_power_phy_clk);

drivers/usb/dwc2/gadget.c

@@ -3236,6 +3236,9 @@ void dwc2_hsotg_core_init_disconnected(struct dwc2_hsotg *hsotg,
 		dcfg |= DCFG_DEVSPD_HS;
 	}
 
+	if (hsotg->params.ipg_isoc_en)
+		dcfg |= DCFG_IPG_ISOC_SUPPORDED;
+
 	dwc2_writel(dcfg,  hsotg->regs + DCFG);
 
 	/* Clear any pending OTG interrupts */

drivers/usb/dwc2/hw.h

@@ -311,6 +311,7 @@
 #define GHWCFG4_UTMI_PHY_DATA_WIDTH_MASK	(0x3 << 14)
 #define GHWCFG4_UTMI_PHY_DATA_WIDTH_SHIFT	14
 #define GHWCFG4_ACG_SUPPORTED			BIT(12)
+#define GHWCFG4_IPG_ISOC_SUPPORTED		BIT(11)
 #define GHWCFG4_UTMI_PHY_DATA_WIDTH_8		0
 #define GHWCFG4_UTMI_PHY_DATA_WIDTH_16		1
 #define GHWCFG4_UTMI_PHY_DATA_WIDTH_8_OR_16	2
@@ -424,6 +425,7 @@
 #define DCFG_EPMISCNT_SHIFT		18
 #define DCFG_EPMISCNT_LIMIT		0x1f
 #define DCFG_EPMISCNT(_x)		((_x) << 18)
+#define DCFG_IPG_ISOC_SUPPORDED		BIT(17)
 #define DCFG_PERFRINT_MASK		(0x3 << 11)
 #define DCFG_PERFRINT_SHIFT		11
 #define DCFG_PERFRINT_LIMIT		0x3

drivers/usb/dwc2/params.c

@@ -298,6 +298,7 @@ static void dwc2_set_default_params(struct dwc2_hsotg *hsotg)
 	p->besl = true;
 	p->hird_threshold_en = true;
 	p->hird_threshold = 4;
+	p->ipg_isoc_en = false;
 	p->max_packet_count = hw->max_packet_count;
 	p->max_transfer_size = hw->max_transfer_size;
 	p->ahbcfg = GAHBCFG_HBSTLEN_INCR << GAHBCFG_HBSTLEN_SHIFT;
@@ -579,6 +580,7 @@ static void dwc2_check_params(struct dwc2_hsotg *hsotg)
 	CHECK_BOOL(enable_dynamic_fifo, hw->enable_dynamic_fifo);
 	CHECK_BOOL(en_multiple_tx_fifo, hw->en_multiple_tx_fifo);
 	CHECK_BOOL(i2c_enable, hw->i2c_enable);
+	CHECK_BOOL(ipg_isoc_en, hw->ipg_isoc_en);
 	CHECK_BOOL(acg_enable, hw->acg_enable);
 	CHECK_BOOL(reload_ctl, (hsotg->hw_params.snpsid > DWC2_CORE_REV_2_92a));
 	CHECK_BOOL(lpm, (hsotg->hw_params.snpsid >= DWC2_CORE_REV_2_80a));
@@ -772,6 +774,7 @@ int dwc2_get_hwparams(struct dwc2_hsotg *hsotg)
 	hw->utmi_phy_data_width = (hwcfg4 & GHWCFG4_UTMI_PHY_DATA_WIDTH_MASK) >>
 				  GHWCFG4_UTMI_PHY_DATA_WIDTH_SHIFT;
 	hw->acg_enable = !!(hwcfg4 & GHWCFG4_ACG_SUPPORTED);
+	hw->ipg_isoc_en = !!(hwcfg4 & GHWCFG4_IPG_ISOC_SUPPORTED);
 
 	/* fifo sizes */
 	hw->rx_fifo_size = (grxfsiz & GRXFSIZ_DEPTH_MASK) >>