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Message-ID: <3ezjocthsigo3t746slmgzffnmpxw7wwf3s535basiaf2qy6io@7ocxva6ndsbt>
Date: Wed, 3 Apr 2024 21:58:33 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Pavan Holla <pholla@...omium.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Heikki Krogerus <heikki.krogerus@...ux.intel.com>, Benson Leung <bleung@...omium.org>,
Tzung-Bi Shih <tzungbi@...nel.org>, Guenter Roeck <groeck@...omium.org>,
linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
Abhishek Pandit-Subedi <abhishekpandit@...omium.org>, chrome-platform@...ts.linux.dev
Subject: Re: [PATCH v3 2/2] usb: typec: ucsi: Implement ChromeOS UCSI driver
On Wed, Apr 03, 2024 at 06:05:22PM +0000, Pavan Holla wrote:
> 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@...omium.org>
> ---
> drivers/usb/typec/ucsi/Kconfig | 13 ++
> drivers/usb/typec/ucsi/Makefile | 1 +
> drivers/usb/typec/ucsi/cros_ec_ucsi.c | 245 ++++++++++++++++++++++++++++++++++
> 3 files changed, 259 insertions(+)
>
> diff --git a/drivers/usb/typec/ucsi/Kconfig b/drivers/usb/typec/ucsi/Kconfig
> index bdcb1764cfae..4dceb14a66ee 100644
> --- a/drivers/usb/typec/ucsi/Kconfig
> +++ b/drivers/usb/typec/ucsi/Kconfig
> @@ -69,4 +69,17 @@ 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.
> +
> endif
> diff --git a/drivers/usb/typec/ucsi/Makefile b/drivers/usb/typec/ucsi/Makefile
> index b4679f94696b..cb336eee055c 100644
> --- a/drivers/usb/typec/ucsi/Makefile
> +++ b/drivers/usb/typec/ucsi/Makefile
> @@ -21,3 +21,4 @@ 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
> 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..dd46b46d430f
> --- /dev/null
> +++ b/drivers/usb/typec/ucsi/cros_ec_ucsi.c
> @@ -0,0 +1,245 @@
> +// 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"
> +
> +#define DRV_NAME "cros-ec-ucsi"
> +
> +#define MAX_EC_DATA_SIZE 256
> +#define WRITE_TMO_MS 500
> +
> +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_async_write(struct ucsi *ucsi, unsigned int offset,
> + const void *val, size_t val_len)
> +{
> + struct cros_ucsi_data *udata = ucsi_get_drvdata(ucsi);
> + uint8_t ec_buffer[MAX_EC_DATA_SIZE + sizeof(struct ec_params_ucsi_ppm_set)];
> + struct ec_params_ucsi_ppm_set *req = (struct ec_params_ucsi_ppm_set *)ec_buffer;
> + int ret = 0;
> +
> + if (val_len > MAX_EC_DATA_SIZE) {
> + dev_err(udata->dev, "Can't write %zu bytes. Too big.", val_len);
I think it's better be written as
if (WARN_ON_ONCE(val_len > MAX_EC_DATA_SIZE))
return -EINVAL;
Same applies to reading.
> + return -EINVAL;
> + }
> +
> + memset(req, 0, sizeof(ec_buffer));
> + req->offset = offset;
> + memcpy(req->data, val, val_len);
> + ret = cros_ec_cmd(udata->ec, 0, EC_CMD_UCSI_PPM_SET,
> + req, sizeof(struct ec_params_ucsi_ppm_set) + val_len, NULL, 0);
> +
> + if (ret < 0) {
> + dev_warn(udata->dev, "Failed to send EC message UCSI_PPM_SET: error=%d", ret);
> + return ret;
> + }
> + return 0;
> +}
> +
> +static int cros_ucsi_sync_write(struct ucsi *ucsi, unsigned int offset,
> + const void *val, size_t val_len)
> +{
> + struct cros_ucsi_data *udata = ucsi_get_drvdata(ucsi);
> + bool ack = UCSI_COMMAND(*(u64 *)val) == UCSI_ACK_CC_CI;
> + int ret;
> +
> + if (ack)
> + set_bit(ACK_PENDING, &udata->flags);
> + else
> + set_bit(COMMAND_PENDING, &udata->flags);
> +
> + ret = cros_ucsi_async_write(ucsi, offset, val, val_len);
> + if (ret)
> + goto out;
> +
> + if (!wait_for_completion_timeout(&udata->complete, WRITE_TMO_MS))
> + ret = -ETIMEDOUT;
> +
> +out:
> + if (ack)
> + clear_bit(ACK_PENDING, &udata->flags);
> + else
> + clear_bit(COMMAND_PENDING, &udata->flags);
> + return ret;
> +}
> +
> +struct ucsi_operations cros_ucsi_ops = {
> + .read = cros_ucsi_read,
> + .async_write = cros_ucsi_async_write,
> + .sync_write = cros_ucsi_sync_write,
> +};
> +
> +static void cros_ucsi_work(struct work_struct *work)
> +{
> + struct cros_ucsi_data *udata = container_of(work, struct cros_ucsi_data, work);
> + u32 cci;
> + int ret;
> +
> + ret = cros_ucsi_read(udata->ucsi, UCSI_CCI, &cci, sizeof(cci));
> + if (ret)
> + return;
> +
> + if (UCSI_CCI_CONNECTOR(cci))
> + ucsi_connector_change(udata->ucsi, UCSI_CCI_CONNECTOR(cci));
> +
> + if (cci & UCSI_CCI_ACK_COMPLETE && test_bit(ACK_PENDING, &udata->flags))
> + complete(&udata->complete);
> + if (cci & UCSI_CCI_COMMAND_COMPLETE &&
> + test_bit(COMMAND_PENDING, &udata->flags))
> + complete(&udata->complete);
> +}
> +
> +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 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\n");
> + return -ENODEV;
> + }
> +
> + platform_set_drvdata(pdev, udata);
> +
> + INIT_WORK(&udata->work, cros_ucsi_work);
> + init_completion(&udata->complete);
> +
> + udata->ucsi = ucsi_create(udata->dev, &cros_ucsi_ops);
> + if (IS_ERR(udata->ucsi)) {
> + dev_err(dev, "failed to allocate UCSI instance\n");
> + return PTR_ERR(udata->ucsi);
> + }
> +
> + ucsi_set_drvdata(udata->ucsi, udata);
> +
> + ret = ucsi_register(udata->ucsi);
> + if (ret) {
> + ucsi_destroy(udata->ucsi);
> + return ret;
> + }
> +
> + udata->nb.notifier_call = cros_ucsi_event;
> + return cros_usbpd_register_notify(&udata->nb);
I think you should register notifier before calling ucsi_register().
Otherwise you have a window when the UCSI can attempt to communitcate
with the hardware, but it will not get its notifications.
> +}
> +
> +static int cros_ucsi_remove(struct platform_device *dev)
> +{
> + struct cros_ucsi_data *udata = platform_get_drvdata(dev);
> +
> + ucsi_unregister(udata->ucsi);
> + ucsi_destroy(udata->ucsi);
> + return 0;
> +}
> +
> +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 int __maybe_unused cros_ucsi_resume(struct device *dev)
> +{
> + struct cros_ucsi_data *udata = dev_get_drvdata(dev);
> +
> + return ucsi_resume(udata->ucsi);
> +}
> +
> +static SIMPLE_DEV_PM_OPS(cros_ucsi_pm_ops, cros_ucsi_suspend,
> + cros_ucsi_resume);
> +
> +static const struct platform_device_id cros_ec_ucsi_id[] = {
> + { "cros-ec-ucsi"},
> + {}
> +};
> +MODULE_DEVICE_TABLE(platform, cros_ec_ucsi_id);
> +
> +static struct platform_driver cros_ucsi_driver = {
> + .driver = {
> + .name = DRV_NAME,
> + .pm = &cros_ucsi_pm_ops,
> + },
> + .id_table = cros_ec_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");
>
> --
> 2.44.0.478.gd926399ef9-goog
>
--
With best wishes
Dmitry
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