[PATCH v2 3/3] platform/chrome: cros_ec_ucsi: Implement UCSI PDC driver

[Pavan Holla]

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

Signed-off-by: Pavan Holla <pholla@xxxxxxxxxxxx>
---
 drivers/platform/chrome/Kconfig                |  14 ++
 drivers/platform/chrome/Makefile               |   1 +
 drivers/platform/chrome/cros_ec_ucsi.c         | 247 +++++++++++++++++++++++++
 include/linux/platform_data/cros_ec_commands.h |  19 ++
 4 files changed, 281 insertions(+)

diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
index 7a83346bfa53..67ab79a6815b 100644
--- a/drivers/platform/chrome/Kconfig
+++ b/drivers/platform/chrome/Kconfig
@@ -238,6 +238,20 @@ config CROS_EC_TYPEC
 	  To compile this driver as a module, choose M here: the module will be
 	  called cros-ec-typec.
 
+config CROS_EC_UCSI
+	tristate "UCSI Driver for ChromeOS EC"
+	depends on MFD_CROS_EC_DEV
+	depends on CROS_USBPD_NOTIFY
+	depends on TYPEC_UCSI
+	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 CROS_HPS_I2C
 	tristate "ChromeOS HPS device"
 	depends on HID && I2C && PM
diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
index 2dcc6ccc2302..85964e165a70 100644
--- a/drivers/platform/chrome/Makefile
+++ b/drivers/platform/chrome/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_CROS_EC_UART)		+= cros_ec_uart.o
 cros_ec_lpcs-objs			:= cros_ec_lpc.o cros_ec_lpc_mec.o
 cros-ec-typec-objs			:= cros_ec_typec.o cros_typec_vdm.o
 obj-$(CONFIG_CROS_EC_TYPEC)		+= cros-ec-typec.o
+obj-$(CONFIG_CROS_EC_UCSI)		+= cros_ec_ucsi.o
 obj-$(CONFIG_CROS_EC_LPC)		+= cros_ec_lpcs.o
 obj-$(CONFIG_CROS_EC_PROTO)		+= cros_ec_proto.o cros_ec_trace.o
 obj-$(CONFIG_CROS_KBD_LED_BACKLIGHT)	+= cros_kbd_led_backlight.o
diff --git a/drivers/platform/chrome/cros_ec_ucsi.c b/drivers/platform/chrome/cros_ec_ucsi.c
new file mode 100644
index 000000000000..9fee300a3d93
--- /dev/null
+++ b/drivers/platform/chrome/cros_ec_ucsi.c
@@ -0,0 +1,247 @@
+// 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/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/usb/ucsi.h>
+#include <linux/wait.h>
+
+#define DRV_NAME "cros-ec-ucsi"
+
+#define MAX_EC_DATA_SIZE 256
+#define WRITE_TMO_MS 500
+
+#define COMMAND_PENDING 1
+#define ACK_PENDING     2
+
+#define UCSI_COMMAND(_cmd_) ((_cmd_) & 0xff)
+#define UCSI_ACK_CC_CI 0x04
+
+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);
+		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_ucsi_data *udata;
+	int ret;
+
+	udata = devm_kzalloc(dev, sizeof(*udata), GFP_KERNEL);
+	if (!udata)
+		return -ENOMEM;
+
+	udata->dev = dev;
+
+	udata->ec = ((struct cros_ec_dev *) dev_get_drvdata(pdev->dev.parent))->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);
+		udata->ucsi = NULL;
+		return ret;
+	}
+
+	udata->nb.notifier_call = cros_ucsi_event;
+	ret = cros_usbpd_register_notify(&udata->nb);
+	return ret;
+}
+
+static int cros_ucsi_remove(struct platform_device *dev)
+{
+	struct cros_ucsi_data *udata = platform_get_drvdata(dev);
+
+	if (udata->ucsi) {
+		ucsi_unregister(udata->ucsi);
+		ucsi_destroy(udata->ucsi);
+		udata->ucsi = NULL;
+	}
+	return 0;
+}
+
+static int cros_ucsi_suspend(struct device *dev)
+{
+	struct cros_ucsi_data *udata = dev_get_drvdata(dev);
+
+	cancel_work_sync(&udata->work);
+
+	return 0;
+}
+
+static int 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 struct platform_driver cros_ucsi_driver = {
+	.driver = {
+		.name = DRV_NAME,
+		.pm = &cros_ucsi_pm_ops,
+	},
+	.probe = cros_ucsi_probe,
+	.remove = cros_ucsi_remove,
+};
+
+module_platform_driver(cros_ucsi_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("UCSI driver for ChromeOS EC.");
+MODULE_ALIAS("platform:" DRV_NAME);
diff --git a/include/linux/platform_data/cros_ec_commands.h b/include/linux/platform_data/cros_ec_commands.h
index ecc47d5fe239..39f6f54bbe4c 100644
--- a/include/linux/platform_data/cros_ec_commands.h
+++ b/include/linux/platform_data/cros_ec_commands.h
@@ -4933,6 +4933,7 @@ struct ec_response_pd_status {
 #define PD_EVENT_POWER_CHANGE      BIT(1)
 #define PD_EVENT_IDENTITY_RECEIVED BIT(2)
 #define PD_EVENT_DATA_SWAP         BIT(3)
+#define PD_EVENT_PPM               BIT(5)
 struct ec_response_host_event_status {
 	uint32_t status;      /* PD MCU host event status */
 } __ec_align4;
@@ -5994,6 +5995,24 @@ struct ec_response_typec_vdm_response {
 
 #undef VDO_MAX_SIZE
 
+/*
+ * Read/write interface for UCSI OPM <-> PPM communication.
+ */
+#define EC_CMD_UCSI_PPM_SET 0x0140
+
+/* The data size is stored in the host command protocol header. */
+struct ec_params_ucsi_ppm_set {
+	uint16_t offset;
+	uint8_t data[];
+} __ec_align2;
+
+#define EC_CMD_UCSI_PPM_GET 0x0141
+
+struct ec_params_ucsi_ppm_get {
+	uint16_t offset;
+	uint8_t size;
+} __ec_align2;
+
 /*****************************************************************************/
 /* The command range 0x200-0x2FF is reserved for Rotor. */
 

-- 
2.44.0.396.g6e790dbe36-goog