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linux/drivers/usb/dwc2/drd.c
Tomas Marek 2c6b6afa59 usb: dwc2: drd: fix clock gating on USB role switch 
The dwc2_handle_usb_suspend_intr() function disables gadget clocks in USB
peripheral mode when no other power-down mode is available (introduced by
commit 0112b7ce68 ("usb: dwc2: Update dwc2_handle_usb_suspend_intr function.")).
However, the dwc2_drd_role_sw_set() USB role update handler attempts to
read DWC2 registers if the USB role has changed while the USB is in suspend
mode (when the clocks are gated). This causes the system to hang.

Release the gadget clocks before handling the USB role update.

Fixes: 0112b7ce68 ("usb: dwc2: Update dwc2_handle_usb_suspend_intr function.")
Cc: stable@vger.kernel.org
Signed-off-by: Tomas Marek <tomas.marek@elrest.cz>
Link: https://lore.kernel.org/r/20240906055025.25057-1-tomas.marek@elrest.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-09-11 15:35:33 +02:00

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// SPDX-License-Identifier: GPL-2.0
/*
* drd.c - DesignWare USB2 DRD Controller Dual-role support
*
* Copyright (C) 2020 STMicroelectronics
*
* Author(s): Amelie Delaunay <amelie.delaunay@st.com>
*/
#include <linux/clk.h>
#include <linux/iopoll.h>
#include <linux/platform_device.h>
#include <linux/usb/role.h>
#include "core.h"
#define dwc2_ovr_gotgctl(gotgctl) \
((gotgctl) |= GOTGCTL_BVALOEN | GOTGCTL_AVALOEN | GOTGCTL_VBVALOEN | \
GOTGCTL_DBNCE_FLTR_BYPASS)
static void dwc2_ovr_init(struct dwc2_hsotg *hsotg)
{
unsigned long flags;
u32 gotgctl;
spin_lock_irqsave(&hsotg->lock, flags);
gotgctl = dwc2_readl(hsotg, GOTGCTL);
dwc2_ovr_gotgctl(gotgctl);
gotgctl &= ~(GOTGCTL_BVALOVAL | GOTGCTL_AVALOVAL | GOTGCTL_VBVALOVAL);
if (hsotg->role_sw_default_mode == USB_DR_MODE_HOST)
gotgctl |= GOTGCTL_AVALOVAL | GOTGCTL_VBVALOVAL;
else if (hsotg->role_sw_default_mode == USB_DR_MODE_PERIPHERAL)
gotgctl |= GOTGCTL_BVALOVAL | GOTGCTL_VBVALOVAL;
dwc2_writel(hsotg, gotgctl, GOTGCTL);
spin_unlock_irqrestore(&hsotg->lock, flags);
dwc2_force_mode(hsotg, (hsotg->dr_mode == USB_DR_MODE_HOST) ||
(hsotg->role_sw_default_mode == USB_DR_MODE_HOST));
}
static int dwc2_ovr_avalid(struct dwc2_hsotg *hsotg, bool valid)
{
u32 gotgctl = dwc2_readl(hsotg, GOTGCTL);
/* Check if A-Session is already in the right state */
if ((valid && (gotgctl & GOTGCTL_ASESVLD)) ||
(!valid && !(gotgctl & GOTGCTL_ASESVLD)))
return -EALREADY;
/* Always enable overrides to handle the resume case */
dwc2_ovr_gotgctl(gotgctl);
gotgctl &= ~GOTGCTL_BVALOVAL;
if (valid)
gotgctl |= GOTGCTL_AVALOVAL | GOTGCTL_VBVALOVAL;
else
gotgctl &= ~(GOTGCTL_AVALOVAL | GOTGCTL_VBVALOVAL);
dwc2_writel(hsotg, gotgctl, GOTGCTL);
return 0;
}
static int dwc2_ovr_bvalid(struct dwc2_hsotg *hsotg, bool valid)
{
u32 gotgctl = dwc2_readl(hsotg, GOTGCTL);
/* Check if B-Session is already in the right state */
if ((valid && (gotgctl & GOTGCTL_BSESVLD)) ||
(!valid && !(gotgctl & GOTGCTL_BSESVLD)))
return -EALREADY;
/* Always enable overrides to handle the resume case */
dwc2_ovr_gotgctl(gotgctl);
gotgctl &= ~GOTGCTL_AVALOVAL;
if (valid)
gotgctl |= GOTGCTL_BVALOVAL | GOTGCTL_VBVALOVAL;
else
gotgctl &= ~(GOTGCTL_BVALOVAL | GOTGCTL_VBVALOVAL);
dwc2_writel(hsotg, gotgctl, GOTGCTL);
return 0;
}
static int dwc2_drd_role_sw_set(struct usb_role_switch *sw, enum usb_role role)
{
struct dwc2_hsotg *hsotg = usb_role_switch_get_drvdata(sw);
unsigned long flags;
int already = 0;
/* Skip session not in line with dr_mode */
if ((role == USB_ROLE_DEVICE && hsotg->dr_mode == USB_DR_MODE_HOST) ||
(role == USB_ROLE_HOST && hsotg->dr_mode == USB_DR_MODE_PERIPHERAL))
return -EINVAL;
#if IS_ENABLED(CONFIG_USB_DWC2_PERIPHERAL) || \
IS_ENABLED(CONFIG_USB_DWC2_DUAL_ROLE)
/* Skip session if core is in test mode */
if (role == USB_ROLE_NONE && hsotg->test_mode) {
dev_dbg(hsotg->dev, "Core is in test mode\n");
return -EBUSY;
}
#endif
/*
* In case of USB_DR_MODE_PERIPHERAL, clock is disabled at the end of
* the probe and enabled on udc_start.
* If role-switch set is called before the udc_start, we need to enable
* the clock to read/write GOTGCTL and GUSBCFG registers to override
* mode and sessions. It is the case if cable is plugged at boot.
*/
if (!hsotg->ll_hw_enabled && hsotg->clk) {
int ret = clk_prepare_enable(hsotg->clk);
if (ret)
return ret;
}
spin_lock_irqsave(&hsotg->lock, flags);
if (role == USB_ROLE_NONE) {
/* default operation mode when usb role is USB_ROLE_NONE */
if (hsotg->role_sw_default_mode == USB_DR_MODE_HOST)
role = USB_ROLE_HOST;
else if (hsotg->role_sw_default_mode == USB_DR_MODE_PERIPHERAL)
role = USB_ROLE_DEVICE;
}
if ((IS_ENABLED(CONFIG_USB_DWC2_PERIPHERAL) ||
IS_ENABLED(CONFIG_USB_DWC2_DUAL_ROLE)) &&
dwc2_is_device_mode(hsotg) &&
hsotg->lx_state == DWC2_L2 &&
hsotg->params.power_down == DWC2_POWER_DOWN_PARAM_NONE &&
hsotg->bus_suspended &&
!hsotg->params.no_clock_gating)
dwc2_gadget_exit_clock_gating(hsotg, 0);
if (role == USB_ROLE_HOST) {
already = dwc2_ovr_avalid(hsotg, true);
} else if (role == USB_ROLE_DEVICE) {
already = dwc2_ovr_bvalid(hsotg, true);
if (dwc2_is_device_enabled(hsotg)) {
/* This clear DCTL.SFTDISCON bit */
dwc2_hsotg_core_connect(hsotg);
}
} else {
if (dwc2_is_device_mode(hsotg)) {
if (!dwc2_ovr_bvalid(hsotg, false))
/* This set DCTL.SFTDISCON bit */
dwc2_hsotg_core_disconnect(hsotg);
} else {
dwc2_ovr_avalid(hsotg, false);
}
}
spin_unlock_irqrestore(&hsotg->lock, flags);
if (!already && hsotg->dr_mode == USB_DR_MODE_OTG)
/* This will raise a Connector ID Status Change Interrupt */
dwc2_force_mode(hsotg, role == USB_ROLE_HOST);
if (!hsotg->ll_hw_enabled && hsotg->clk)
clk_disable_unprepare(hsotg->clk);
dev_dbg(hsotg->dev, "%s-session valid\n",
role == USB_ROLE_NONE ? "No" :
role == USB_ROLE_HOST ? "A" : "B");
return 0;
}
int dwc2_drd_init(struct dwc2_hsotg *hsotg)
{
struct usb_role_switch_desc role_sw_desc = {0};
struct usb_role_switch *role_sw;
int ret;
if (!device_property_read_bool(hsotg->dev, "usb-role-switch"))
return 0;
hsotg->role_sw_default_mode = usb_get_role_switch_default_mode(hsotg->dev);
role_sw_desc.driver_data = hsotg;
role_sw_desc.fwnode = dev_fwnode(hsotg->dev);
role_sw_desc.set = dwc2_drd_role_sw_set;
role_sw_desc.allow_userspace_control = true;
role_sw = usb_role_switch_register(hsotg->dev, &role_sw_desc);
if (IS_ERR(role_sw)) {
ret = PTR_ERR(role_sw);
dev_err(hsotg->dev,
"failed to register role switch: %d\n", ret);
return ret;
}
hsotg->role_sw = role_sw;
/* Enable override and initialize values */
dwc2_ovr_init(hsotg);
return 0;
}
void dwc2_drd_suspend(struct dwc2_hsotg *hsotg)
{
u32 gintsts, gintmsk;
if (hsotg->role_sw && !hsotg->params.external_id_pin_ctl) {
gintmsk = dwc2_readl(hsotg, GINTMSK);
gintmsk &= ~GINTSTS_CONIDSTSCHNG;
dwc2_writel(hsotg, gintmsk, GINTMSK);
gintsts = dwc2_readl(hsotg, GINTSTS);
dwc2_writel(hsotg, gintsts | GINTSTS_CONIDSTSCHNG, GINTSTS);
}
}
void dwc2_drd_resume(struct dwc2_hsotg *hsotg)
{
u32 gintsts, gintmsk;
enum usb_role role;
if (hsotg->role_sw) {
/* get last known role (as the get ops isn't implemented by this driver) */
role = usb_role_switch_get_role(hsotg->role_sw);
if (role == USB_ROLE_NONE) {
if (hsotg->role_sw_default_mode == USB_DR_MODE_HOST)
role = USB_ROLE_HOST;
else if (hsotg->role_sw_default_mode == USB_DR_MODE_PERIPHERAL)
role = USB_ROLE_DEVICE;
}
/* restore last role that may have been lost */
if (role == USB_ROLE_HOST)
dwc2_ovr_avalid(hsotg, true);
else if (role == USB_ROLE_DEVICE)
dwc2_ovr_bvalid(hsotg, true);
dwc2_force_mode(hsotg, role == USB_ROLE_HOST);
dev_dbg(hsotg->dev, "resuming %s-session valid\n",
role == USB_ROLE_NONE ? "No" :
role == USB_ROLE_HOST ? "A" : "B");
}
if (hsotg->role_sw && !hsotg->params.external_id_pin_ctl) {
gintsts = dwc2_readl(hsotg, GINTSTS);
dwc2_writel(hsotg, gintsts | GINTSTS_CONIDSTSCHNG, GINTSTS);
gintmsk = dwc2_readl(hsotg, GINTMSK);
gintmsk |= GINTSTS_CONIDSTSCHNG;
dwc2_writel(hsotg, gintmsk, GINTMSK);
}
}
void dwc2_drd_exit(struct dwc2_hsotg *hsotg)
{
if (hsotg->role_sw)
usb_role_switch_unregister(hsotg->role_sw);
}
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