Re: [PATCH V3 4/7] soc: qcom: eud: Add driver support for Embedded USB Debugger(EUD)

Souradeep Chowdhury
2022-01-17T04:59:24Z

On 1/7/2022 6:49 AM, Bjorn Andersson wrote:
> On Tue 04 Jan 03:58 PST 2022, 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 <quic_schowdhu@quicinc.com>
>> ---
>> Documentation/ABI/testing/sysfs-driver-eud | 9 +
>> drivers/soc/qcom/Kconfig | 10 ++
>> drivers/soc/qcom/Makefile | 1 +
>> drivers/soc/qcom/qcom_eud.c | 260 +++++++++++++++++++++++++++++
>> 4 files changed, 280 insertions(+)
>> create mode 100644 Documentation/ABI/testing/sysfs-driver-eud
>> create mode 100644 drivers/soc/qcom/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..2381552
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/sysfs-driver-eud
>> @@ -0,0 +1,9 @@
>> +What: /sys/bus/platform/drivers/eud/.../enable
>> +Date: January 2022
>> +Contact: Souradeep Chowdhury <schowdhu@codeaurora.org>
>> +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. By enabling EUD,
>> + the user is able to activate the mini-usb hub of
>> + EUD for debug and trace capabilities.
>> diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
>> index 79b568f..a4db41b 100644
>> --- a/drivers/soc/qcom/Kconfig
>> +++ b/drivers/soc/qcom/Kconfig
>> @@ -42,6 +42,16 @@ config QCOM_CPR
>> To compile this driver as a module, choose M here: the module will
>> be called qcom-cpr
>>
>> +config QCOM_EUD
>> + tristate "QCOM Embedded USB Debugger(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. On selecting m, the module name
>> + that is built is qcom_eud.ko
>> +
>> config QCOM_GENI_SE
>> tristate "QCOM GENI Serial Engine Driver"
>> depends on ARCH_QCOM || COMPILE_TEST
>> diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
>> index ad675a6..3331a40 100644
>> --- a/drivers/soc/qcom/Makefile
>> +++ b/drivers/soc/qcom/Makefile
>> @@ -4,6 +4,7 @@ obj-$(CONFIG_QCOM_AOSS_QMP) += qcom_aoss.o
>> obj-$(CONFIG_QCOM_GENI_SE) += qcom-geni-se.o
>> obj-$(CONFIG_QCOM_COMMAND_DB) += cmd-db.o
>> obj-$(CONFIG_QCOM_CPR) += cpr.o
>> +obj-$(CONFIG_QCOM_EUD) += qcom_eud.o
>> obj-$(CONFIG_QCOM_GSBI) += qcom_gsbi.o
>> obj-$(CONFIG_QCOM_MDT_LOADER) += mdt_loader.o
>> obj-$(CONFIG_QCOM_OCMEM) += ocmem.o
>> diff --git a/drivers/soc/qcom/qcom_eud.c b/drivers/soc/qcom/qcom_eud.c
>> new file mode 100644
>> index 0000000..7c4cc7d
>> --- /dev/null
>> +++ b/drivers/soc/qcom/qcom_eud.c
>> @@ -0,0 +1,260 @@
>> +// 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>
> Is this needed?
Ack.
>
>> +#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;
> This is unnecessarily long, "base" or "eud" seems sufficient.
Ack
>
>> + void __iomem *eud_mode_mgr2_phys_base;
> "mode_mgr"
Ack
>
>> + unsigned int int_status;
>> + int eud_irq;
> "irq"
Ack
>
>> + bool enable;
> "enable" is an action, but you use it to track if the state of the EUD,
> i.e if it's "enabled".
Ack
>
>> + bool usb_attach;
> "attach" vs "attached"
Ack
>
>> +
> Empty 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);
> When this fails, don't you want to disable the EUD again?
Ack
>
>> +}
>> +
>> +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 sysfs_emit(buf, "%d\n", chip->enable);
>> +}
>> +
>> +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);
>> + bool enable;
>> + int ret;
>> +
>> + if (kstrtobool(buf, &enable))
>> + return -EINVAL;
>> +
>> + if (enable) {
>> + ret = enable_eud(chip);
>> + if (!ret)
>> + chip->enable = enable;
>> + } else {
>> + disable_eud(chip);
>> + }
>> +
>> + return count;
>> +}
>> +
>> +static DEVICE_ATTR_RW(enable);
>> +
>> +static struct attribute *eud_attrs[] = {
>> + &dev_attr_enable.attr,
>> + NULL,
>> +};
>> +ATTRIBUTE_GROUPS(eud);
>> +
>> +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;
> chip->usb_attach = reg & EUD_INT_SAFE_MODE;
Ack
>> +
>> + /* 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);
> How come you do this before waking up the threaded handler?
Ack
>
>> +}
>> +
>> +static void pet_eud(struct eud_chip *chip)
>> +{
>> + u32 reg;
>> + int ret;
>> +
>> + /* read sw_attach_det[0] to find attach/detach event */
> Please instead describe what this means, like:
>
> /*
> * When the EUD_INT_PET_EUD in SW_ATTACH_DET is set, the cable has been
> * disconnected and we need to detach the something because something.
> */
Ack
>
>> + reg = readl(chip->eud_reg_base + EUD_REG_SW_ATTACH_DET);
> Please drop the double space.
Ack
>
>> + 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);
> Can you please help me see what differs between this and the write in
> the else statement?

Ack. Will move this out of the if else statement.

>
>> + } 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 */
> That's what the next line says as well, please drop this comment.
Ack
>
>> + reg = readl(chip->eud_reg_base + EUD_REG_INT_STATUS_1);
> Please drop the double space.
Ack
>
>> + switch (reg & EUD_INT_ALL) {
> What if both of these bits are set? Won't you just end up with an
> interrupt storm until someone disables the EUD again?
So EUD can either be in safe mode or vbus mode ,  both bits will not be
set together.
>
>> + 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;
> This is the only case where you break to return IRQ_HANDLED. Please be
> consistent.
Ack
>
>> + 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) {
> I presume you have this here to signal that EUD_INT_VBUS was set in
> EUD_REG_INT_STATUS_1 in handle_eud_irq().
>
> But 1) unless this was true you wouldn't have woken up the threaded
> handler and 2) you never clear int_status, so once you've received the
> EUD_INT_VBUS it seems to forever be true.
Ack. Will be clearing the int bits once this is done.
>
>> + 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;
>> + struct fwnode_handle *fwnode = pdev->dev.fwnode, *ep, *connector;
>> + int ret;
>> +
>> + chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
>> + if (!chip)
>> + return -ENOMEM;
>> +
>> + chip->dev = &pdev->dev;
>> +
>> + ep = fwnode_graph_get_next_endpoint(fwnode, NULL);
>> + if (!ep)
>> + return -ENODEV;
>> +
>> + connector = fwnode_graph_get_remote_port_parent(ep);
>> + fwnode_handle_put(ep);
>> + if (!connector)
>> + return -ENODEV;
>> +
>> + chip->role_sw = fwnode_usb_role_switch_get(connector);
> Can't you just call usb_role_switch_get(&pdev->dev) to find the
> "usb-role-switch", without having to traverse the fwnode_graph manually?

"usb_role_switch_get" finds the role_switch from the current or the
parent node, however

in this case the usb-role-switch property is present at the parent of
the connector node

which is attached to the eud node via port end point.

>
>> + if (IS_ERR(chip->role_sw)) {
>> + return dev_err_probe(chip->dev, PTR_ERR(chip->role_sw),
>> + "failed to get role switch\n");
>> + }
> Note that from now on you must usb_role_switch_put(chip->role_sw);
Ack
>
>> +
>> + 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 dev_err_probe(chip->dev, ret, "failed to allocate irq\n");
>> +
>> + enable_irq_wake(chip->eud_irq);
>> +
>> + platform_set_drvdata(pdev, chip);
>> +
>> + return 0;
>> +}
>> +
>> +static int eud_remove(struct platform_device *pdev)
>> +{
>> + struct eud_chip *chip = platform_get_drvdata(pdev);
>> +
>> + if (chip->enable)
>> + disable_eud(chip);
>> +
>> + device_init_wakeup(&pdev->dev, false);
>> + disable_irq_wake(chip->eud_irq);
>> +
>> + return 0;
>> +}
>> +
>> +static const struct of_device_id eud_dt_match[] = {
>> + { .compatible = "qcom,sc7280-eud" },
>> + { }
>> +};
>> +MODULE_DEVICE_TABLE(of, eud_dt_match);
>> +
>> +static struct platform_driver eud_driver = {
>> + .probe = eud_probe,
> I would prefer if you didn't indent the assignments.
Ack
>
>> + .remove = eud_remove,
>> + .driver = {
>> + .name = "eud",
> "qcom_eud" please.
Ack
>
> Regards,
> Bjorn
>
>> + .dev_groups = eud_groups,
>> + .of_match_table = eud_dt_match,
>> + },
>> +};
>> +module_platform_driver(eud_driver);
>> +
>> +MODULE_DESCRIPTION("QTI EUD driver");
>> +MODULE_LICENSE("GPL v2");
>> --
>> 2.7.4
>>