Re: [PATCH V0 4/7] usb: common: eud: Added the driver support for Embedded USB Debugger(EUD)

schowdhu
2021-10-05T12:54:15Z

On 2021-10-04 17:01, Greg KH wrote:
> On Mon, Oct 04, 2021 at 04:46:22PM +0530, Souradeep Chowdhury wrote:
>> Add support for control peripheral of EUD (Embedded USB Debugger) to
>> listen to events such as USB attach/detach, pet EUD to indicate
>> software
>> is functional.Reusing the platform device kobj, sysfs entry 'enable'
>> is
>> created to enable or disable EUD.
>>
>> To enable the eud the following needs to be done
>> echo 1 > /sys/bus/platform/.../enable
>>
>> To disable eud, following is the command
>> echo 0 > /sys/bus/platform/.../enable
>>
>> Signed-off-by: Souradeep Chowdhury <schowdhu@codeaurora.org>
>> ---
>> Documentation/ABI/testing/sysfs-driver-eud | 7 +
>> drivers/usb/common/Kconfig | 9 +
>> drivers/usb/common/Makefile | 1 +
>> drivers/usb/common/qcom_eud.c | 256
>> +++++++++++++++++++++++++++++
>> 4 files changed, 273 insertions(+)
>> create mode 100644 Documentation/ABI/testing/sysfs-driver-eud
>> create mode 100644 drivers/usb/common/qcom_eud.c
>>
>> diff --git a/Documentation/ABI/testing/sysfs-driver-eud
>> b/Documentation/ABI/testing/sysfs-driver-eud
>> new file mode 100644
>> index 0000000..14a02da
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/sysfs-driver-eud
>> @@ -0,0 +1,7 @@
>> +What: /sys/bus/platform/.../enable
>
> Um, that's a _very_ generic regex, you just matched with any platform
> device that might have a "enable" sysfs entry :(
>
> Please use the dwc's name in here to help out with figuring this out.

Ack

>
>> +Date: October 2021
>> +Contact: Souradeep Chowdhury <schowdhu@codeaurora.org>
>
> No tabs?
>
>> +Description:
>> + The Enable/Disable sysfs interface for Embedded
>> + USB Debugger(EUD).This enables and disables the
>> + EUD based on a 1 or a 0 value.
>
> What does enabling or disabling actually do?
>
> And please use a ' ' after a '.'.

Ack. On enabling, the debug mode is set for EUD. EUD is a mux, that sits
between the connector and the
controller, routing UTMI signals to an internal USB hub, which in-turn
has debug functions attached to
the hub. On disabling, this routing stops as EUD gets disabled.

>
>> diff --git a/drivers/usb/common/Kconfig b/drivers/usb/common/Kconfig
>> index 5e8a04e..669b3fe 100644
>> --- a/drivers/usb/common/Kconfig
>> +++ b/drivers/usb/common/Kconfig
>> @@ -50,3 +50,12 @@ config USB_CONN_GPIO
>>
>> To compile the driver as a module, choose M here: the module will
>> be called usb-conn-gpio.ko
>> +
>> +config USB_QCOM_EUD
>> + tristate "USB EUD Driver"
>> + select USB_ROLE_SWITCH
>> + help
>> + This module enables support for Qualcomm Technologies, Inc.
>> + Embedded USB Debugger (EUD). The EUD is a control peripheral
>> + which reports VBUS attach/detach events and has USB-based
>> + debug and trace capabilities.
>
> What is the module name if this is built?

Ack. The module name for this is same as the driver name qcom_eud.ko,
will update the same here.

>
>> diff --git a/drivers/usb/common/Makefile b/drivers/usb/common/Makefile
>> index 8ac4d21..eb66045 100644
>> --- a/drivers/usb/common/Makefile
>> +++ b/drivers/usb/common/Makefile
>> @@ -11,3 +11,4 @@ usb-common-$(CONFIG_USB_LED_TRIG) += led.o
>> obj-$(CONFIG_USB_CONN_GPIO) += usb-conn-gpio.o
>> obj-$(CONFIG_USB_OTG_FSM) += usb-otg-fsm.o
>> obj-$(CONFIG_USB_ULPI_BUS) += ulpi.o
>> +obj-$(CONFIG_USB_QCOM_EUD) += qcom_eud.o
>> diff --git a/drivers/usb/common/qcom_eud.c
>> b/drivers/usb/common/qcom_eud.c
>> new file mode 100644
>> index 0000000..7a92fff
>> --- /dev/null
>> +++ b/drivers/usb/common/qcom_eud.c
>> @@ -0,0 +1,256 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Copyright (c) 2015-2021, The Linux Foundation. All rights
>> reserved.
>> + */
>> +
>> +#include <linux/bitops.h>
>> +#include <linux/delay.h>
>> +#include <linux/err.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/io.h>
>> +#include <linux/iopoll.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/slab.h>
>> +#include <linux/sysfs.h>
>> +#include <linux/usb/role.h>
>> +
>> +#define EUD_REG_INT1_EN_MASK 0x0024
>> +#define EUD_REG_INT_STATUS_1 0x0044
>> +#define EUD_REG_CTL_OUT_1 0x0074
>> +#define EUD_REG_VBUS_INT_CLR 0x0080
>> +#define EUD_REG_CSR_EUD_EN 0x1014
>> +#define EUD_REG_SW_ATTACH_DET 0x1018
>> +#define EUD_REG_EUD_EN2 0x0000
>> +
>> +#define EUD_ENABLE BIT(0)
>> +#define EUD_INT_PET_EUD BIT(0)
>> +#define EUD_INT_VBUS BIT(2)
>> +#define EUD_INT_SAFE_MODE BIT(4)
>> +#define EUD_INT_ALL (EUD_INT_VBUS|EUD_INT_SAFE_MODE)
>> +
>> +struct eud_chip {
>> + struct device *dev;
>> + struct usb_role_switch *role_sw;
>> + void __iomem *eud_reg_base;
>> + void __iomem *eud_mode_mgr2_phys_base;
>> + unsigned int int_status;
>> + int enable;
>
> bool?

Ack.

>
>> + int eud_irq;
>> + bool usb_attach;
>> +
>
> No need for a blank line.

Ack

>
>> +};
>> +
>> +static int enable_eud(struct eud_chip *priv)
>> +{
>> + writel(EUD_ENABLE, priv->eud_reg_base + EUD_REG_CSR_EUD_EN);
>> + writel(EUD_INT_VBUS | EUD_INT_SAFE_MODE,
>> + priv->eud_reg_base + EUD_REG_INT1_EN_MASK);
>> + writel(1, priv->eud_mode_mgr2_phys_base + EUD_REG_EUD_EN2);
>> +
>> + return usb_role_switch_set_role(priv->role_sw, USB_ROLE_DEVICE);
>> +}
>> +
>> +static void disable_eud(struct eud_chip *priv)
>> +{
>> + writel(0, priv->eud_reg_base + EUD_REG_CSR_EUD_EN);
>> + writel(0, priv->eud_mode_mgr2_phys_base + EUD_REG_EUD_EN2);
>> +}
>> +
>> +static ssize_t enable_show(struct device *dev,
>> + struct device_attribute *attr, char *buf)
>> +{
>> + struct eud_chip *chip = dev_get_drvdata(dev);
>> +
>> + return sprintf(buf, "%d", chip->enable);
>
> sysfs_emit() please.

Ack

>
>> +}
>> +
>> +static ssize_t enable_store(struct device *dev,
>> + struct device_attribute *attr,
>> + const char *buf, size_t count)
>> +{
>> + struct eud_chip *chip = dev_get_drvdata(dev);
>> + unsigned long enable;
>> + int ret;
>> +
>> + if (kstrtoul(buf, 16, &enable))
>> + return -EINVAL;
>
> Use the default sysfs function to parse 0/1/y/n/Y/N please.

Ack

>
>> +
>> + if (enable == 1) {
>> + ret = enable_eud(chip);
>> + if (!ret)
>> + chip->enable = enable;
>> + } else if (enable == 0) {
>> + disable_eud(chip);
>> + } else {
>> + return -EINVAL;
>> + }
>> +
>> + return count;
>> +}
>> +
>> +static DEVICE_ATTR_RW(enable);
>> +
>> +static const struct device_attribute *eud_attrs[] = {
>> + &dev_attr_enable,
>> + NULL,
>> +};
>
> You create a list of attributes and then never use it?
>
> Who reviewed this thing?
>
> You were so close in getting this right, see below...

Ack

>
>> +
>> +static void usb_attach_detach(struct eud_chip *chip)
>> +{
>> + u32 reg;
>> +
>> + /* read ctl_out_1[4] to find USB attach or detach event */
>> + reg = readl(chip->eud_reg_base + EUD_REG_CTL_OUT_1);
>> + if (reg & EUD_INT_SAFE_MODE)
>> + chip->usb_attach = true;
>> + else
>> + chip->usb_attach = false;
>> +
>> + /* set and clear vbus_int_clr[0] to clear interrupt */
>> + writel(BIT(0), chip->eud_reg_base + EUD_REG_VBUS_INT_CLR);
>> + writel(0, chip->eud_reg_base + EUD_REG_VBUS_INT_CLR);
>> +}
>> +
>> +static void pet_eud(struct eud_chip *chip)
>> +{
>> + u32 reg;
>> + int ret;
>> +
>> + /* read sw_attach_det[0] to find attach/detach event */
>> + reg = readl(chip->eud_reg_base + EUD_REG_SW_ATTACH_DET);
>> + if (reg & EUD_INT_PET_EUD) {
>> + /* Detach & Attach pet for EUD */
>> + writel(0, chip->eud_reg_base + EUD_REG_SW_ATTACH_DET);
>> + /* Delay to make sure detach pet is done before attach pet */
>> + ret = readl_poll_timeout(chip->eud_reg_base +
>> EUD_REG_SW_ATTACH_DET,
>> + reg, (reg == 0), 1, 100);
>> + if (ret) {
>> + dev_err(chip->dev, "Detach pet failed\n");
>> + return;
>> + }
>> +
>> + writel(EUD_INT_PET_EUD, chip->eud_reg_base +
>> + EUD_REG_SW_ATTACH_DET);
>> + } else {
>> + /* Attach pet for EUD */
>> + writel(EUD_INT_PET_EUD, chip->eud_reg_base +
>> + EUD_REG_SW_ATTACH_DET);
>> + }
>> +}
>> +
>> +static irqreturn_t handle_eud_irq(int irq, void *data)
>> +{
>> + struct eud_chip *chip = data;
>> + u32 reg;
>> +
>> + /* read status register and find out which interrupt triggered */
>> + reg = readl(chip->eud_reg_base + EUD_REG_INT_STATUS_1);
>> + switch (reg & EUD_INT_ALL) {
>> + case EUD_INT_VBUS:
>> + chip->int_status = EUD_INT_VBUS;
>> + usb_attach_detach(chip);
>> + return IRQ_WAKE_THREAD;
>> + case EUD_INT_SAFE_MODE:
>> + pet_eud(chip);
>> + break;
>> + default:
>> + return IRQ_NONE;
>> + }
>> + return IRQ_HANDLED;
>> +}
>> +
>> +static irqreturn_t handle_eud_irq_thread(int irq, void *data)
>> +{
>> + struct eud_chip *chip = data;
>> + int ret;
>> +
>> + if (chip->int_status == EUD_INT_VBUS) {
>> + if (chip->usb_attach)
>> + ret = usb_role_switch_set_role(chip->role_sw, USB_ROLE_DEVICE);
>> + else
>> + ret = usb_role_switch_set_role(chip->role_sw, USB_ROLE_HOST);
>> + if (ret)
>> + dev_err(chip->dev, "failed to set role switch\n");
>> + }
>> +
>> + return IRQ_HANDLED;
>> +}
>> +
>> +static int eud_probe(struct platform_device *pdev)
>> +{
>> + struct eud_chip *chip;
>> + int ret;
>> +
>> + chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
>> + if (!chip)
>> + return -ENOMEM;
>> +
>> + chip->dev = &pdev->dev;
>> +
>> + chip->role_sw = usb_role_switch_get(chip->dev);
>> + if (IS_ERR(chip->role_sw)) {
>> + if (PTR_ERR(chip->role_sw) != -EPROBE_DEFER)
>> + dev_err(chip->dev, "failed to get role switch\n");
>> +
>> + return PTR_ERR(chip->role_sw);
>> + }
>> +
>> + chip->eud_reg_base = devm_platform_ioremap_resource(pdev, 0);
>> + if (IS_ERR(chip->eud_reg_base))
>> + return PTR_ERR(chip->eud_reg_base);
>> +
>> + chip->eud_mode_mgr2_phys_base = devm_platform_ioremap_resource(pdev,
>> 1);
>> + if (IS_ERR(chip->eud_mode_mgr2_phys_base))
>> + return PTR_ERR(chip->eud_mode_mgr2_phys_base);
>> +
>> + chip->eud_irq = platform_get_irq(pdev, 0);
>> + ret = devm_request_threaded_irq(&pdev->dev, chip->eud_irq,
>> handle_eud_irq,
>> + handle_eud_irq_thread, IRQF_ONESHOT, NULL, chip);
>> + if (ret)
>> + return ret;
>> +
>> + device_init_wakeup(&pdev->dev, true);
>> + enable_irq_wake(chip->eud_irq);
>> +
>> + platform_set_drvdata(pdev, chip);
>> +
>> + ret = device_create_file(&pdev->dev, eud_attrs[0]);
>
> You raced with userspace and lost :(
>
> Please properly attach the sysfs file to the platform driver to have
> the
> driver core register this correctly.

Ok.

>
>> +
>> + return ret;
>> +}
>> +
>> +static int eud_remove(struct platform_device *pdev)
>> +{
>> + struct eud_chip *chip = platform_get_drvdata(pdev);
>> +
>> + if (chip->enable)
>> + disable_eud(chip);
>> +
>> + device_remove_file(&pdev->dev, eud_attrs[0]);
>
> No need for this if you do the above correctly.

Ack.

>
>> + device_init_wakeup(&pdev->dev, false);
>
> Why is this needed?

This is already handled in device_unregister() path so will remove this.

>
> thanks,
>
> greg k-h