--- /dev/null
+// 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/jiffies.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
+
+/* Number of times to attempt recovery from a write timeout before giving up. */
+#define WRITE_TMO_CTR_MAX 5
+
+struct cros_ucsi_data {
+ struct device *dev;
+ struct ucsi *ucsi;
+
+ struct cros_ec_device *ec;
+ struct notifier_block nb;
+ struct work_struct work;
+ struct delayed_work write_tmo;
+ int tmo_counter;
+
+ 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;
+}
+
+static int cros_ucsi_sync_control(struct ucsi *ucsi, u64 cmd)
+{
+ struct cros_ucsi_data *udata = ucsi_get_drvdata(ucsi);
+ int ret;
+
+ ret = ucsi_sync_control_common(ucsi, cmd);
+ switch (ret) {
+ case -EBUSY:
+ /* EC may return -EBUSY if CCI.busy is set.
+ * Convert this to a timeout.
+ */
+ case -ETIMEDOUT:
+ /* Schedule recovery attempt when we timeout
+ * or tried to send a command while still busy.
+ */
+ cancel_delayed_work_sync(&udata->write_tmo);
+ schedule_delayed_work(&udata->write_tmo,
+ msecs_to_jiffies(WRITE_TMO_MS));
+ break;
+ case 0:
+ /* Successful write. Cancel any pending recovery work. */
+ cancel_delayed_work_sync(&udata->write_tmo);
+ break;
+ }
+
+ return ret;
+}
+
+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 = cros_ucsi_sync_control,
+};
+
+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 void cros_ucsi_write_timeout(struct work_struct *work)
+{
+ struct cros_ucsi_data *udata =
+ container_of(work, struct cros_ucsi_data, write_tmo.work);
+ u32 cci;
+ u64 cmd;
+
+ if (cros_ucsi_read(udata->ucsi, UCSI_CCI, &cci, sizeof(cci))) {
+ dev_err(udata->dev,
+ "Reading CCI failed; no write timeout recovery possible.");
+ return;
+ }
+
+ if (cci & UCSI_CCI_BUSY) {
+ udata->tmo_counter++;
+
+ if (udata->tmo_counter <= WRITE_TMO_CTR_MAX)
+ schedule_delayed_work(&udata->write_tmo,
+ msecs_to_jiffies(WRITE_TMO_MS));
+ else
+ dev_err(udata->dev,
+ "PPM unresponsive - too many write timeouts.");
+
+ return;
+ }
+
+ /* No longer busy means we can reset our timeout counter. */
+ udata->tmo_counter = 0;
+
+ /* Need to ack previous command which may have timed out. */
+ if (cci & UCSI_CCI_COMMAND_COMPLETE) {
+ cmd = UCSI_ACK_CC_CI | UCSI_ACK_COMMAND_COMPLETE;
+ cros_ucsi_async_control(udata->ucsi, cmd);
+
+ /* Check again after a few seconds that the system has
+ * recovered to make sure our async write above was successful.
+ */
+ schedule_delayed_work(&udata->write_tmo,
+ msecs_to_jiffies(WRITE_TMO_MS));
+ return;
+ }
+
+ /* We recovered from a previous timeout. Treat this as a recovery from
+ * suspend and call resume.
+ */
+ ucsi_resume(udata->ucsi);
+}
+
+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_delayed_work_sync(&udata->write_tmo);
+ 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_DELAYED_WORK(&udata->write_tmo, cros_ucsi_write_timeout);
+ 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_delayed_work_sync(&udata->write_tmo);
+ 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");
projects / linux-block.git / commitdiff