[v8,2/3] usb: typec: ucsi: Implement ChromeOS UCSI driver

From: Pavan Holla <pholla@chromium.org>

Implementation of a UCSI transport driver for ChromeOS.
This driver will be loaded if the ChromeOS EC implements a PPM.

Signed-off-by: Pavan Holla <pholla@chromium.org>
Co-developed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Co-developed-by: Łukasz Bartosik <ukaszb@chromium.org>
Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
---
 MAINTAINERS                           |   7 +
 drivers/usb/typec/ucsi/Kconfig        |  13 ++
 drivers/usb/typec/ucsi/Makefile       |   1 +
 drivers/usb/typec/ucsi/cros_ec_ucsi.c | 252 ++++++++++++++++++++++++++
 4 files changed, 273 insertions(+)
 create mode 100644 drivers/usb/typec/ucsi/cros_ec_ucsi.c

On Thu, Nov 28, 2024 at 11:20:34PM +0000, Łukasz Bartosik wrote:
> From: Pavan Holla <pholla@chromium.org>
> 
> Implementation of a UCSI transport driver for ChromeOS.
> This driver will be loaded if the ChromeOS EC implements a PPM.
> 
> Signed-off-by: Pavan Holla <pholla@chromium.org>
> Co-developed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> Co-developed-by: Łukasz Bartosik <ukaszb@chromium.org>
> Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> ---
>  MAINTAINERS                           |   7 +
>  drivers/usb/typec/ucsi/Kconfig        |  13 ++
>  drivers/usb/typec/ucsi/Makefile       |   1 +
>  drivers/usb/typec/ucsi/cros_ec_ucsi.c | 252 ++++++++++++++++++++++++++
>  4 files changed, 273 insertions(+)
>  create mode 100644 drivers/usb/typec/ucsi/cros_ec_ucsi.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index b878ddc99f94..b0542223579a 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -5389,6 +5389,13 @@ L:	chrome-platform@lists.linux.dev
>  S:	Maintained
>  F:	drivers/watchdog/cros_ec_wdt.c
>  
> +CHROMEOS UCSI DRIVER
> +M:	Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> +M:	Łukasz Bartosik <ukaszb@chromium.org>
> +L:	chrome-platform@lists.linux.dev
> +S:	Maintained
> +F:	drivers/usb/typec/ucsi/cros_ec_ucsi.c
> +
>  CHRONTEL CH7322 CEC DRIVER
>  M:	Joe Tessler <jrt@google.com>
>  L:	linux-media@vger.kernel.org
> diff --git a/drivers/usb/typec/ucsi/Kconfig b/drivers/usb/typec/ucsi/Kconfig
> index 680e1b87b152..75559601fe8f 100644
> --- a/drivers/usb/typec/ucsi/Kconfig
> +++ b/drivers/usb/typec/ucsi/Kconfig
> @@ -69,6 +69,19 @@ config UCSI_PMIC_GLINK
>  	  To compile the driver as a module, choose M here: the module will be
>  	  called ucsi_glink.
>  
> +config CROS_EC_UCSI
> +	tristate "UCSI Driver for ChromeOS EC"
> +	depends on MFD_CROS_EC_DEV
> +	depends on CROS_USBPD_NOTIFY
> +	depends on !EXTCON_TCSS_CROS_EC
> +	default MFD_CROS_EC_DEV
> +	help
> +	  This driver enables UCSI support for a ChromeOS EC. The EC is
> +	  expected to implement a PPM.
> +
> +	  To compile the driver as a module, choose M here: the module
> +	  will be called cros_ec_ucsi.
> +
>  config UCSI_LENOVO_YOGA_C630
>  	tristate "UCSI Interface Driver for Lenovo Yoga C630"
>  	depends on EC_LENOVO_YOGA_C630
> diff --git a/drivers/usb/typec/ucsi/Makefile b/drivers/usb/typec/ucsi/Makefile
> index aed41d23887b..be98a879104d 100644
> --- a/drivers/usb/typec/ucsi/Makefile
> +++ b/drivers/usb/typec/ucsi/Makefile
> @@ -21,4 +21,5 @@ obj-$(CONFIG_UCSI_ACPI)			+= ucsi_acpi.o
>  obj-$(CONFIG_UCSI_CCG)			+= ucsi_ccg.o
>  obj-$(CONFIG_UCSI_STM32G0)		+= ucsi_stm32g0.o
>  obj-$(CONFIG_UCSI_PMIC_GLINK)		+= ucsi_glink.o
> +obj-$(CONFIG_CROS_EC_UCSI)		+= cros_ec_ucsi.o
>  obj-$(CONFIG_UCSI_LENOVO_YOGA_C630)	+= ucsi_yoga_c630.o
> diff --git a/drivers/usb/typec/ucsi/cros_ec_ucsi.c b/drivers/usb/typec/ucsi/cros_ec_ucsi.c
> new file mode 100644
> index 000000000000..c588d9a57643
> --- /dev/null
> +++ b/drivers/usb/typec/ucsi/cros_ec_ucsi.c
> @@ -0,0 +1,252 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * UCSI driver for ChromeOS EC
> + *
> + * Copyright 2024 Google LLC.
> + */
> +
> +#include <linux/container_of.h>
> +#include <linux/dev_printk.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/platform_data/cros_ec_commands.h>
> +#include <linux/platform_data/cros_usbpd_notify.h>
> +#include <linux/platform_data/cros_ec_proto.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/wait.h>
> +
> +#include "ucsi.h"
> +
> +/*
> + * Maximum size in bytes of a UCSI message between AP and EC
> + */
> +#define MAX_EC_DATA_SIZE	256
> +
> +/*
> + * Maximum time in milliseconds the cros_ec_ucsi driver
> + * will wait for a response to a command or and ack.
> + */
> +#define WRITE_TMO_MS		5000
> +
> +struct cros_ucsi_data {
> +	struct device *dev;
> +	struct ucsi *ucsi;
> +
> +	struct cros_ec_device *ec;
> +	struct notifier_block nb;
> +	struct work_struct work;
> +
> +	struct completion complete;
> +	unsigned long flags;
> +};
> +
> +static int cros_ucsi_read(struct ucsi *ucsi, unsigned int offset, void *val,
> +			  size_t val_len)
> +{
> +	struct cros_ucsi_data *udata = ucsi_get_drvdata(ucsi);
> +	struct ec_params_ucsi_ppm_get req = {
> +		.offset = offset,
> +		.size = val_len,
> +	};
> +	int ret;
> +
> +	if (val_len > MAX_EC_DATA_SIZE) {
> +		dev_err(udata->dev, "Can't read %zu bytes. Too big.", val_len);
> +		return -EINVAL;
> +	}
> +
> +	ret = cros_ec_cmd(udata->ec, 0, EC_CMD_UCSI_PPM_GET,
> +			  &req, sizeof(req), val, val_len);
> +	if (ret < 0) {
> +		dev_warn(udata->dev, "Failed to send EC message UCSI_PPM_GET: error=%d", ret);
> +		return ret;
> +	}
> +	return 0;
> +}
> +
> +static int cros_ucsi_read_version(struct ucsi *ucsi, u16 *version)
> +{
> +	return cros_ucsi_read(ucsi, UCSI_VERSION, version, sizeof(*version));
> +}
> +
> +static int cros_ucsi_read_cci(struct ucsi *ucsi, u32 *cci)
> +{
> +	return cros_ucsi_read(ucsi, UCSI_CCI, cci, sizeof(*cci));
> +}
> +
> +static int cros_ucsi_read_message_in(struct ucsi *ucsi, void *val,
> +				     size_t val_len)
> +{
> +	return cros_ucsi_read(ucsi, UCSI_MESSAGE_IN, val, val_len);
> +}
> +
> +static int cros_ucsi_async_control(struct ucsi *ucsi, u64 cmd)
> +{
> +	struct cros_ucsi_data *udata = ucsi_get_drvdata(ucsi);
> +	u8 ec_buf[sizeof(struct ec_params_ucsi_ppm_set) + sizeof(cmd)];
> +	struct ec_params_ucsi_ppm_set *req = (struct ec_params_ucsi_ppm_set *) ec_buf;
> +	int ret;
> +
> +	req->offset = UCSI_CONTROL;
> +	memcpy(req->data, &cmd, sizeof(cmd));
> +	ret = cros_ec_cmd(udata->ec, 0, EC_CMD_UCSI_PPM_SET,
> +			  req, sizeof(ec_buf), NULL, 0);
> +	if (ret < 0) {
> +		dev_warn(udata->dev, "Failed to send EC message UCSI_PPM_SET: error=%d", ret);
> +		return ret;
> +	}
> +	return 0;
> +}
> +
> +struct ucsi_operations cros_ucsi_ops = {
> +	.read_version = cros_ucsi_read_version,
> +	.read_cci = cros_ucsi_read_cci,
> +	.read_message_in = cros_ucsi_read_message_in,
> +	.async_control = cros_ucsi_async_control,
> +	.sync_control = ucsi_sync_control_common,
> +};
> +
> +static void cros_ucsi_work(struct work_struct *work)
> +{
> +	struct cros_ucsi_data *udata = container_of(work, struct cros_ucsi_data, work);
> +	u32 cci;
> +
> +	if (cros_ucsi_read_cci(udata->ucsi, &cci))
> +		return;
> +
> +	ucsi_notify_common(udata->ucsi, cci);
> +}
> +
> +static int cros_ucsi_event(struct notifier_block *nb,
> +			   unsigned long host_event, void *_notify)
> +{
> +	struct cros_ucsi_data *udata = container_of(nb, struct cros_ucsi_data, nb);
> +
> +	if (!(host_event & PD_EVENT_PPM))
> +		return NOTIFY_OK;
> +
> +	dev_dbg(udata->dev, "UCSI notification received");
> +	flush_work(&udata->work);
> +	schedule_work(&udata->work);
> +
> +	return NOTIFY_OK;
> +}
> +
> +static void cros_ucsi_destroy(struct cros_ucsi_data *udata)
> +{
> +	cros_usbpd_unregister_notify(&udata->nb);
> +	cancel_work_sync(&udata->work);
> +	ucsi_destroy(udata->ucsi);
> +}
> +
> +static int cros_ucsi_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct cros_ec_dev *ec_data = dev_get_drvdata(dev->parent);
> +	struct cros_ucsi_data *udata;
> +	int ret;
> +
> +	udata = devm_kzalloc(dev, sizeof(*udata), GFP_KERNEL);
> +	if (!udata)
> +		return -ENOMEM;
> +
> +	udata->dev = dev;
> +
> +	udata->ec = ec_data->ec_dev;
> +	if (!udata->ec) {
> +		dev_err(dev, "couldn't find parent EC device");
> +		return -ENODEV;
> +	}
> +
> +	platform_set_drvdata(pdev, udata);
> +
> +	INIT_WORK(&udata->work, cros_ucsi_work);
> +	init_completion(&udata->complete);
> +
> +	udata->ucsi = ucsi_create(dev, &cros_ucsi_ops);
> +	if (IS_ERR(udata->ucsi)) {
> +		dev_err(dev, "failed to allocate UCSI instance");
> +		return PTR_ERR(udata->ucsi);
> +	}
> +
> +	ucsi_set_drvdata(udata->ucsi, udata);
> +
> +	udata->nb.notifier_call = cros_ucsi_event;
> +	ret = cros_usbpd_register_notify(&udata->nb);
> +	if (ret) {
> +		dev_err(dev, "failed to register notifier: error=%d", ret);
> +		ucsi_destroy(udata->ucsi);
> +		return ret;
> +	}
> +
> +	ret = ucsi_register(udata->ucsi);
> +	if (ret) {
> +		dev_err(dev, "failed to register UCSI: error=%d", ret);
> +		cros_ucsi_destroy(udata);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void cros_ucsi_remove(struct platform_device *dev)
> +{
> +	struct cros_ucsi_data *udata = platform_get_drvdata(dev);
> +
> +	ucsi_unregister(udata->ucsi);
> +	cros_ucsi_destroy(udata);
> +}
> +
> +static int __maybe_unused cros_ucsi_suspend(struct device *dev)
> +{
> +	struct cros_ucsi_data *udata = dev_get_drvdata(dev);
> +
> +	cancel_work_sync(&udata->work);
> +
> +	return 0;
> +}
> +
> +static void __maybe_unused cros_ucsi_complete(struct device *dev)
> +{
> +	struct cros_ucsi_data *udata = dev_get_drvdata(dev);
> +
> +	ucsi_resume(udata->ucsi);
> +}
> +
> +/*
> + * UCSI protocol is also used on ChromeOS platforms which reply on
> + * cros_ec_lpc.c driver for communication with embedded controller (EC).
> + * On such platforms communication with the EC is not available until
> + * the .complete() callback of the cros_ec_lpc driver is executed.
> + * For this reason we delay ucsi_resume() until the .complete() stage
> + * otherwise UCSI SET_NOTIFICATION_ENABLE command will fail and we won't
> + * receive any UCSI notifications from the EC where PPM is implemented.
> + */
> +static const struct dev_pm_ops cros_ucsi_pm_ops = {
> +#ifdef CONFIG_PM_SLEEP
> +	.suspend = cros_ucsi_suspend,
> +	.complete = cros_ucsi_complete,
> +#endif
> +};
> +
> +static const struct platform_device_id cros_ucsi_id[] = {
> +	{ KBUILD_MODNAME, 0 },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(platform, cros_ucsi_id);
> +
> +static struct platform_driver cros_ucsi_driver = {
> +	.driver = {
> +		.name = KBUILD_MODNAME,
> +		.pm = &cros_ucsi_pm_ops,
> +	},
> +	.id_table = cros_ucsi_id,
> +	.probe = cros_ucsi_probe,
> +	.remove = cros_ucsi_remove,
> +};
> +
> +module_platform_driver(cros_ucsi_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("UCSI driver for ChromeOS EC");
> -- 
> 2.47.0.338.g60cca15819-goog