Date:   Sun, 30 Aug 2020 18:54:36 +0000
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Wesley Cheng <wcheng@...eaurora.org>
Cc:     sboyd@...nel.org, heikki.krogerus@...ux.intel.com,
        agross@...nel.org, robh+dt@...nel.org, gregkh@...uxfoundation.org,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH v8 1/4] usb: typec: Add QCOM PMIC typec detection driver

On Wed 12 Aug 07:19 UTC 2020, Wesley Cheng wrote:

> The QCOM SPMI typec driver handles the role and orientation detection, and
> notifies client drivers using the USB role switch framework.   It registers
> as a typec port, so orientation can be communicated using the typec switch
> APIs.  The driver also attains a handle to the VBUS output regulator, so it
> can enable/disable the VBUS source when acting as a host/device.
> 
> Signed-off-by: Wesley Cheng <wcheng@...eaurora.org>
> Acked-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> Reviewed-by: Stephen Boyd <sboyd@...nel.org>
> ---
>  drivers/usb/typec/Kconfig           |  12 ++
>  drivers/usb/typec/Makefile          |   1 +
>  drivers/usb/typec/qcom-pmic-typec.c | 271 ++++++++++++++++++++++++++++
>  3 files changed, 284 insertions(+)
>  create mode 100644 drivers/usb/typec/qcom-pmic-typec.c
> 
> diff --git a/drivers/usb/typec/Kconfig b/drivers/usb/typec/Kconfig
> index 559dd06117e7..63789cf88fce 100644
> --- a/drivers/usb/typec/Kconfig
> +++ b/drivers/usb/typec/Kconfig
> @@ -73,6 +73,18 @@ config TYPEC_TPS6598X
>  	  If you choose to build this driver as a dynamically linked module, the
>  	  module will be called tps6598x.ko.
>  
> +config TYPEC_QCOM_PMIC
> +	tristate "Qualcomm PMIC USB Type-C driver"
> +	depends on ARCH_QCOM || COMPILE_TEST
> +	help
> +	  Driver for supporting role switch over the Qualcomm PMIC.  This will
> +	  handle the USB Type-C role and orientation detection reported by the
> +	  QCOM PMIC if the PMIC has the capability to handle USB Type-C
> +	  detection.
> +
> +	  It will also enable the VBUS output to connected devices when a
> +	  DFP connection is made.
> +
>  source "drivers/usb/typec/mux/Kconfig"
>  
>  source "drivers/usb/typec/altmodes/Kconfig"
> diff --git a/drivers/usb/typec/Makefile b/drivers/usb/typec/Makefile
> index 7753a5c3cd46..cceffd987643 100644
> --- a/drivers/usb/typec/Makefile
> +++ b/drivers/usb/typec/Makefile
> @@ -6,4 +6,5 @@ obj-$(CONFIG_TYPEC_TCPM)	+= tcpm/
>  obj-$(CONFIG_TYPEC_UCSI)	+= ucsi/
>  obj-$(CONFIG_TYPEC_HD3SS3220)	+= hd3ss3220.o
>  obj-$(CONFIG_TYPEC_TPS6598X)	+= tps6598x.o
> +obj-$(CONFIG_TYPEC_QCOM_PMIC)	+= qcom-pmic-typec.o
>  obj-$(CONFIG_TYPEC)		+= mux/
> diff --git a/drivers/usb/typec/qcom-pmic-typec.c b/drivers/usb/typec/qcom-pmic-typec.c
> new file mode 100644
> index 000000000000..20b2b6502cb3
> --- /dev/null
> +++ b/drivers/usb/typec/qcom-pmic-typec.c
> @@ -0,0 +1,271 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2020, The Linux Foundation. All rights reserved.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/regmap.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/interrupt.h>
> +#include <linux/platform_device.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/usb/role.h>
> +#include <linux/usb/typec_mux.h>
> +#include <linux/regulator/consumer.h>

Please sort these alphabetically.

> +
> +#define TYPEC_MISC_STATUS		0xb
> +#define CC_ATTACHED			BIT(0)
> +#define CC_ORIENTATION			BIT(1)
> +#define SNK_SRC_MODE			BIT(6)
> +#define TYPEC_MODE_CFG			0x44
> +#define TYPEC_DISABLE_CMD		BIT(0)
> +#define EN_SNK_ONLY			BIT(1)
> +#define EN_SRC_ONLY			BIT(2)
> +#define TYPEC_VCONN_CONTROL		0x46
> +#define VCONN_EN_SRC			BIT(0)
> +#define VCONN_EN_VAL			BIT(1)
> +#define TYPEC_EXIT_STATE_CFG		0x50
> +#define SEL_SRC_UPPER_REF		BIT(2)
> +#define TYPEC_INTR_EN_CFG_1		0x5e
> +#define TYPEC_INTR_EN_CFG_1_MASK	GENMASK(7, 0)
> +
> +struct qcom_pmic_typec {
> +	struct device		*dev;
> +	struct fwnode_handle	*fwnode;
> +	struct regmap		*regmap;
> +	u32			base;
> +
> +	struct typec_capability *cap;
> +	struct typec_port	*port;
> +	struct usb_role_switch *role_sw;
> +
> +	struct regulator	*vbus_reg;
> +	bool			vbus_enabled;
> +};
> +
> +static void qcom_pmic_typec_enable_vbus_regulator(struct qcom_pmic_typec
> +							*qcom_usb, bool enable)
> +{
> +	int ret;
> +
> +	if (enable == qcom_usb->vbus_enabled)
> +		return;
> +
> +	if (!qcom_usb->vbus_reg) {

I don't think this does what you intend it to.

You call this function during probe, which will attempt to look up the
dcdc. In the subsequent patches you don't specify usb_vbus-supply, so
this will successfully return a valid (dummy) regulator and we won't
enter here again.

If on the other hand you specify usb_vbus-supply in the DT and this
driver has not yet probed you will set vbus_reg to NULL and hence retry
the next time, but you will continue to report the new role regardless.

So afaict, it's possible to be in host role with vbus disabled (or vice
versa depending on boot state) until some event would cause this logic
to trigger again. Which I assume would mean that the user would have to
disconnect/reconnect the cable.

So, rather than acquiring usb_vbus lazily here I think you want to do
this directly in probe and propagate any errors (such as -EPROBE_DEFER)
to ensure that the DCDC is registered before evaluating check_connection().

> +		qcom_usb->vbus_reg = devm_regulator_get(qcom_usb->dev,
> +							"usb_vbus");
> +		if (IS_ERR(qcom_usb->vbus_reg)) {
> +			qcom_usb->vbus_reg = NULL;
> +			return;
> +		}
> +	}
> +
> +	if (enable) {
> +		ret = regulator_enable(qcom_usb->vbus_reg);
> +		if (ret)
> +			return;
> +	} else {
> +		ret = regulator_disable(qcom_usb->vbus_reg);
> +		if (ret)
> +			return;
> +	}
> +	qcom_usb->vbus_enabled = enable;
> +}
> +
> +static void qcom_pmic_typec_check_connection(struct qcom_pmic_typec *qcom_usb)
> +{
> +	enum typec_orientation orientation;
> +	enum usb_role role;
> +	unsigned int stat;
> +	bool enable_vbus;
> +
> +	regmap_read(qcom_usb->regmap, qcom_usb->base + TYPEC_MISC_STATUS,
> +		    &stat);
> +
> +	if (stat & CC_ATTACHED) {
> +		orientation = (stat & CC_ORIENTATION) ?
> +				TYPEC_ORIENTATION_REVERSE :
> +				TYPEC_ORIENTATION_NORMAL;
> +		typec_set_orientation(qcom_usb->port, orientation);
> +
> +		role = (stat & SNK_SRC_MODE) ? USB_ROLE_HOST : USB_ROLE_DEVICE;
> +		if (role == USB_ROLE_HOST)
> +			enable_vbus = true;
> +		else
> +			enable_vbus = false;
> +	} else {
> +		role = USB_ROLE_NONE;
> +		enable_vbus = false;
> +	}
> +
> +	qcom_pmic_typec_enable_vbus_regulator(qcom_usb, enable_vbus);
> +	usb_role_switch_set_role(qcom_usb->role_sw, role);
> +}
> +
> +static irqreturn_t qcom_pmic_typec_interrupt(int irq, void *_qcom_usb)
> +{
> +	struct qcom_pmic_typec *qcom_usb = _qcom_usb;
> +
> +	qcom_pmic_typec_check_connection(qcom_usb);
> +	return IRQ_HANDLED;
> +}
> +
> +static void qcom_pmic_typec_typec_hw_init(struct qcom_pmic_typec *qcom_usb)
> +{
> +	u8 mode = 0;
> +
> +	regmap_update_bits(qcom_usb->regmap,
> +			   qcom_usb->base + TYPEC_INTR_EN_CFG_1,
> +			   TYPEC_INTR_EN_CFG_1_MASK, 0);
> +
> +	if (qcom_usb->cap->type != TYPEC_PORT_DRP)
> +		mode = (qcom_usb->cap->type == TYPEC_PORT_SNK) ?

Afaict cap->type can have the values DRP, SNK and SRC. So I think it
would be cleaner just to do:

	if (type == SRC)
		mode = EN_SRC_ONLY;
	else if (type == SNK)
		mode = EN_SNK_ONLY;

I also think you should pass "type" as a parameter to this function,
rather than digging it out of qcom_usb->cap (which serves no other
purpose).

> +					EN_SNK_ONLY : EN_SRC_ONLY;
> +	regmap_update_bits(qcom_usb->regmap, qcom_usb->base + TYPEC_MODE_CFG,
> +			   EN_SNK_ONLY | EN_SRC_ONLY, mode);
> +
> +	regmap_update_bits(qcom_usb->regmap,
> +			   qcom_usb->base + TYPEC_VCONN_CONTROL,
> +			   VCONN_EN_SRC | VCONN_EN_VAL, VCONN_EN_SRC);
> +	regmap_update_bits(qcom_usb->regmap,
> +			   qcom_usb->base + TYPEC_EXIT_STATE_CFG,
> +			   SEL_SRC_UPPER_REF, SEL_SRC_UPPER_REF);
> +}
> +
> +static int qcom_pmic_typec_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct qcom_pmic_typec *qcom_usb;
> +	struct typec_capability *cap;
> +	const char *buf;
> +	int ret, irq, role;
> +	u32 reg;
> +
> +	ret = device_property_read_u32(dev, "reg", &reg);
> +	if (ret < 0) {
> +		dev_err(dev, "missing base address\n");
> +		return ret;
> +	}
> +
> +	qcom_usb = devm_kzalloc(dev, sizeof(*qcom_usb), GFP_KERNEL);
> +	if (!qcom_usb)
> +		return -ENOMEM;
> +
> +	qcom_usb->dev = dev;
> +	qcom_usb->base = reg;
> +
> +	qcom_usb->regmap = dev_get_regmap(dev->parent, NULL);
> +	if (!qcom_usb->regmap) {
> +		dev_err(dev, "Failed to get regmap\n");
> +		return -EINVAL;
> +	}
> +
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0)
> +		return -EINVAL;
> +
> +	ret = devm_request_threaded_irq(qcom_usb->dev, irq, NULL,
> +					qcom_pmic_typec_interrupt, IRQF_ONESHOT,
> +					"qcom-pmic-typec", qcom_usb);

qcom_usb->port and qcom_usb->role_sw are both dereferenced in the irq
handler, but not created until later in this function. You need to
reorder these to make sure the qcom_usb is fully initialized before you
register the isr.

> +	if (ret) {
> +		dev_err(&pdev->dev, "Could not request IRQ\n");
> +		return ret;
> +	}
> +
> +	qcom_usb->fwnode = device_get_named_child_node(dev, "connector");

I don't see that you need to carry fwnode (and a reference to it) past
probe. So just keep it on the stack and release it after acquiring the
two string and the role switcher.

> +	if (!qcom_usb->fwnode)
> +		return -EINVAL;
> +
> +	cap = devm_kzalloc(dev, sizeof(*cap), GFP_KERNEL);
> +	if (!cap) {
> +		ret = -ENOMEM;
> +		goto err_put_node;
> +	}
> +
> +	ret = fwnode_property_read_string(qcom_usb->fwnode, "power-role", &buf);
> +	if (!ret) {
> +		role = typec_find_port_power_role(buf);
> +		if (role < 0)
> +			role = TYPEC_PORT_SNK;
> +	} else {
> +		role = TYPEC_PORT_SNK;
> +	}
> +	cap->type = role;
> +
> +	ret = fwnode_property_read_string(qcom_usb->fwnode, "data-role", &buf);
> +	if (!ret) {
> +		role = typec_find_port_data_role(buf);
> +		if (role < 0)
> +			role = TYPEC_PORT_UFP;
> +	} else {
> +		role = TYPEC_PORT_UFP;
> +	}
> +	cap->data = role;
> +
> +	cap->prefer_role = TYPEC_NO_PREFERRED_ROLE;
> +	cap->fwnode = qcom_usb->fwnode;
> +	qcom_usb->port = typec_register_port(dev, cap);

cap is cloned in typec_register_port(), which implies that it doesn't
have to live beyond this function call. So rather than allocating cap on
the heap I think you should just carry it on the stack.

> +	if (IS_ERR(qcom_usb->port)) {
> +		ret = PTR_ERR(qcom_usb->port);
> +		dev_err(dev, "Failed to register type c port %d\n", ret);
> +		goto err_put_node;
> +	}
> +
> +	qcom_usb->cap = cap;

As stated above this seems to only serve the purpose of passing
cap->type into hw_init() called below, so I don't think you should stash
it in qcom_usb.

Regards,
Bjorn

> +
> +	qcom_usb->role_sw = fwnode_usb_role_switch_get(qcom_usb->fwnode);
> +	if (IS_ERR(qcom_usb->role_sw)) {
> +		if (PTR_ERR(qcom_usb->role_sw) != -EPROBE_DEFER)
> +			dev_err(dev, "failed to get role switch\n");
> +		ret = PTR_ERR(qcom_usb->role_sw);
> +		goto err_typec_port;
> +	}
> +
> +	platform_set_drvdata(pdev, qcom_usb);
> +	qcom_pmic_typec_typec_hw_init(qcom_usb);
> +	qcom_pmic_typec_check_connection(qcom_usb);
> +
> +	return 0;
> +
> +err_typec_port:
> +	typec_unregister_port(qcom_usb->port);
> +err_put_node:
> +	fwnode_handle_put(qcom_usb->fwnode);
> +
> +	return ret;
> +}
> +
> +static int qcom_pmic_typec_remove(struct platform_device *pdev)
> +{
> +	struct qcom_pmic_typec *qcom_usb = platform_get_drvdata(pdev);
> +
> +	usb_role_switch_set_role(qcom_usb->role_sw, USB_ROLE_NONE);
> +	qcom_pmic_typec_enable_vbus_regulator(qcom_usb, 0);
> +
> +	typec_unregister_port(qcom_usb->port);
> +	usb_role_switch_put(qcom_usb->role_sw);
> +	fwnode_handle_put(qcom_usb->fwnode);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id qcom_pmic_typec_table[] = {
> +	{ .compatible = "qcom,pm8150b-usb-typec" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, qcom_pmic_typec_table);
> +
> +static struct platform_driver qcom_pmic_typec = {
> +	.driver = {
> +		.name = "qcom,pmic-typec",
> +		.of_match_table = qcom_pmic_typec_table,
> +	},
> +	.probe = qcom_pmic_typec_probe,
> +	.remove = qcom_pmic_typec_remove,
> +};
> +module_platform_driver(qcom_pmic_typec);
> +
> +MODULE_DESCRIPTION("QCOM PMIC USB type C driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
> 

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