From 7bee31883889018d4bfeae6654a725dd162b5826 Mon Sep 17 00:00:00 2001
From: Balaji Prakash J <bjagadee@codeaurora.org>
Date: Tue, 31 Aug 2021 08:57:30 +0300
Subject: [PATCH] usb: dwc3: reference clock period configuration
Git-commit: 7bee31883889018d4bfeae6654a725dd162b5826
References: jsc#PED-1817
Patch-mainline: v5.16-rc1
Set reference clock period when it differs from dwc3 default hardware
set.
We could calculate clock period based on reference clock frequency. But
this information is not always available. This is the case of PCI bus
attached USB host. For that reason we use a custom property.
Tested (USB2 only) on IPQ6010 SoC based board with 24 MHz reference
clock while hardware default is 19.2 MHz.
[ baruch: rewrite commit message; drop GFLADJ code; remove 'quirk-' from
property name; mention tested hardware ]
Acked-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Balaji Prakash J <bjagadee@codeaurora.org>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Nacked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/9f399bdf1ff752e31ab7497e3d5ce19bbb3ff247.1630389452.git.baruch@tkos.co.il
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
drivers/usb/dwc3/core.c | 29 +++++++++++++++++++++++++++++
drivers/usb/dwc3/core.h | 6 ++++++
2 files changed, 35 insertions(+)
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 01866dcb953b..ced366ff839b 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -26,6 +26,7 @@
#include <linux/acpi.h>
#include <linux/pinctrl/consumer.h>
#include <linux/reset.h>
+#include <linux/bitfield.h>
#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>
@@ -351,6 +352,29 @@ static void dwc3_frame_length_adjustment(struct dwc3 *dwc)
}
}
+/**
+ * dwc3_ref_clk_period - Reference clock period configuration
+ * Default reference clock period depends on hardware
+ * configuration. For systems with reference clock that differs
+ * from the default, this will set clock period in DWC3_GUCTL
+ * register.
+ * @dwc: Pointer to our controller context structure
+ * @ref_clk_per: reference clock period in ns
+ */
+static void dwc3_ref_clk_period(struct dwc3 *dwc)
+{
+ u32 reg;
+
+ if (dwc->ref_clk_per == 0)
+ return;
+
+ reg = dwc3_readl(dwc->regs, DWC3_GUCTL);
+ reg &= ~DWC3_GUCTL_REFCLKPER_MASK;
+ reg |= FIELD_PREP(DWC3_GUCTL_REFCLKPER_MASK, dwc->ref_clk_per);
+ dwc3_writel(dwc->regs, DWC3_GUCTL, reg);
+}
+
+
/**
* dwc3_free_one_event_buffer - Frees one event buffer
* @dwc: Pointer to our controller context structure
@@ -1011,6 +1035,9 @@ static int dwc3_core_init(struct dwc3 *dwc)
/* Adjust Frame Length */
dwc3_frame_length_adjustment(dwc);
+ /* Adjust Reference Clock Period */
+ dwc3_ref_clk_period(dwc);
+
dwc3_set_incr_burst_type(dwc);
usb_phy_set_suspend(dwc->usb2_phy, 0);
@@ -1393,6 +1420,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
&dwc->hsphy_interface);
device_property_read_u32(dev, "snps,quirk-frame-length-adjustment",
&dwc->fladj);
+ device_property_read_u32(dev, "snps,ref-clock-period-ns",
+ &dwc->ref_clk_per);
dwc->dis_metastability_quirk = device_property_read_bool(dev,
"snps,dis_metastability_quirk");
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 5612bfdf37da..324ca5f5e98d 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -387,6 +387,10 @@
#define DWC3_GFLADJ_30MHZ_SDBND_SEL BIT(7)
#define DWC3_GFLADJ_30MHZ_MASK 0x3f
+/* Global User Control Register*/
+#define DWC3_GUCTL_REFCLKPER_MASK 0xffc00000
+#define DWC3_GUCTL_REFCLKPER_SEL 22
+
/* Global User Control Register 2 */
#define DWC3_GUCTL2_RST_ACTBITLATER BIT(14)
@@ -970,6 +974,7 @@ struct dwc3_scratchpad_array {
* @regs: base address for our registers
* @regs_size: address space size
* @fladj: frame length adjustment
+ * @ref_clk_per: reference clock period configuration
* @irq_gadget: peripheral controller's IRQ number
* @otg_irq: IRQ number for OTG IRQs
* @current_otg_role: current role of operation while using the OTG block
@@ -1149,6 +1154,7 @@ struct dwc3 {
struct power_supply *usb_psy;
u32 fladj;
+ u32 ref_clk_per;
u32 irq_gadget;
u32 otg_irq;
u32 current_otg_role;
--
2.35.3