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Subject[RFC v3 4/5] mfd: add EC host command support using rpmsg.
Date
Add EC host command support through rpmsg.

Cc: Enric Balletbo Serra <eballetbo@gmail.com>
Cc: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Pi-Hsun Shih <pihsun@chromium.org>
---
Changes from v2:
- Wait for ipi ack instead of depends on the behavior in mtk-rpmsg.

Changes from v1:
- Code format fix based on feedback for cros_ec_rpmsg.c.
- Extract feature detection for SCP into separate patch (Patch 6).
---
drivers/platform/chrome/Kconfig | 8 +
drivers/platform/chrome/Makefile | 1 +
drivers/platform/chrome/cros_ec_rpmsg.c | 186 ++++++++++++++++++++++++
3 files changed, 195 insertions(+)
create mode 100644 drivers/platform/chrome/cros_ec_rpmsg.c

diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
index 16b1615958aa2d..e3f63f3d67711b 100644
--- a/drivers/platform/chrome/Kconfig
+++ b/drivers/platform/chrome/Kconfig
@@ -72,6 +72,14 @@ config CROS_EC_SPI
response time cannot be guaranteed, we support ignoring
'pre-amble' bytes before the response actually starts.

+config CROS_EC_RPMSG
+ tristate "ChromeOS Embedded Controller (rpmsg)"
+ depends on MFD_CROS_EC && RPMSG && OF
+ help
+ If you say Y here, you get support for talking to the ChromeOS EC
+ through rpmsg. This uses a simple byte-level protocol with a
+ checksum.
+
config CROS_EC_LPC
tristate "ChromeOS Embedded Controller (LPC)"
depends on MFD_CROS_EC && ACPI && (X86 || COMPILE_TEST)
diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
index cd591bf872bbe9..3e3190af2b50f4 100644
--- a/drivers/platform/chrome/Makefile
+++ b/drivers/platform/chrome/Makefile
@@ -8,6 +8,7 @@ cros_ec_ctl-objs := cros_ec_sysfs.o cros_ec_lightbar.o \
obj-$(CONFIG_CROS_EC_CTL) += cros_ec_ctl.o
obj-$(CONFIG_CROS_EC_I2C) += cros_ec_i2c.o
obj-$(CONFIG_CROS_EC_SPI) += cros_ec_spi.o
+obj-$(CONFIG_CROS_EC_RPMSG) += cros_ec_rpmsg.o
cros_ec_lpcs-objs := cros_ec_lpc.o cros_ec_lpc_reg.o
cros_ec_lpcs-$(CONFIG_CROS_EC_LPC_MEC) += cros_ec_lpc_mec.o
obj-$(CONFIG_CROS_EC_LPC) += cros_ec_lpcs.o
diff --git a/drivers/platform/chrome/cros_ec_rpmsg.c b/drivers/platform/chrome/cros_ec_rpmsg.c
new file mode 100644
index 00000000000000..5354e56b362a0f
--- /dev/null
+++ b/drivers/platform/chrome/cros_ec_rpmsg.c
@@ -0,0 +1,186 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright 2018 Google LLC.
+
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mfd/cros_ec.h>
+#include <linux/mfd/cros_ec_commands.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/rpmsg.h>
+#include <linux/slab.h>
+
+#define EC_MSG_TIMEOUT_MS 200
+
+struct cros_ec_rpmsg {
+ struct rpmsg_device *rpdev;
+
+ wait_queue_head_t xfer_ack_wq;
+ bool xfer_acked;
+};
+
+/**
+ * cros_ec_cmd_xfer_rpmsg - Transfer a message over rpmsg and receive the reply
+ *
+ * This is only used for old EC proto version, and is not supported for this
+ * driver.
+ *
+ * @ec_dev: ChromeOS EC device
+ * @ec_msg: Message to transfer
+ */
+static int cros_ec_cmd_xfer_rpmsg(struct cros_ec_device *ec_dev,
+ struct cros_ec_command *ec_msg)
+{
+ return -EINVAL;
+}
+
+/**
+ * cros_ec_pkt_xfer_rpmsg - Transfer a packet over rpmsg and receive the reply
+ *
+ * @ec_dev: ChromeOS EC device
+ * @ec_msg: Message to transfer
+ */
+static int cros_ec_pkt_xfer_rpmsg(struct cros_ec_device *ec_dev,
+ struct cros_ec_command *ec_msg)
+{
+ struct ec_host_response *response;
+ struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;
+ struct rpmsg_device *rpdev = ec_rpmsg->rpdev;
+ int len;
+ u8 sum;
+ int ret;
+ int i;
+ unsigned long timeout;
+
+ ec_msg->result = 0;
+ len = cros_ec_prepare_tx(ec_dev, ec_msg);
+ dev_dbg(ec_dev->dev, "prepared, len=%d\n", len);
+
+ ec_rpmsg->xfer_acked = false;
+ ret = rpmsg_send(rpdev->ept, ec_dev->dout, len);
+ if (ret) {
+ dev_err(ec_dev->dev, "rpmsg send failed\n");
+ return ret;
+ }
+
+ timeout = msecs_to_jiffies(EC_MSG_TIMEOUT_MS);
+ ret = wait_event_timeout(ec_rpmsg->xfer_ack_wq, ec_rpmsg->xfer_acked,
+ timeout);
+ if (!ret) {
+ dev_err(ec_dev->dev, "rpmsg send timeout\n");
+ return -EIO;
+ }
+
+ /* check response error code */
+ response = (struct ec_host_response *)ec_dev->din;
+ ec_msg->result = response->result;
+
+ ret = cros_ec_check_result(ec_dev, ec_msg);
+ if (ret)
+ goto exit;
+
+ if (response->data_len > ec_msg->insize) {
+ dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
+ response->data_len, ec_msg->insize);
+ ret = -EMSGSIZE;
+ goto exit;
+ }
+
+ /* copy response packet payload and compute checksum */
+ memcpy(ec_msg->data, ec_dev->din + sizeof(*response),
+ response->data_len);
+
+ sum = 0;
+ for (i = 0; i < sizeof(*response) + response->data_len; i++)
+ sum += ec_dev->din[i];
+
+ if (sum) {
+ dev_err(ec_dev->dev, "bad packet checksum, calculated %x\n",
+ sum);
+ ret = -EBADMSG;
+ goto exit;
+ }
+
+ ret = response->data_len;
+exit:
+ if (ec_msg->command == EC_CMD_REBOOT_EC)
+ msleep(EC_REBOOT_DELAY_MS);
+
+ return ret;
+}
+
+static int cros_ec_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
+ int len, void *priv, u32 src)
+{
+ struct cros_ec_device *ec_dev = dev_get_drvdata(&rpdev->dev);
+ struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;
+
+ if (len > ec_dev->din_size) {
+ dev_warn(ec_dev->dev,
+ "ipi received length %d > din_size, truncating", len);
+ len = ec_dev->din_size;
+ }
+
+ memcpy(ec_dev->din, data, len);
+ ec_rpmsg->xfer_acked = true;
+ wake_up(&ec_rpmsg->xfer_ack_wq);
+
+ return 0;
+}
+
+static int cros_ec_rpmsg_probe(struct rpmsg_device *rpdev)
+{
+ struct device *dev = &rpdev->dev;
+ struct cros_ec_device *ec_dev;
+ struct cros_ec_rpmsg *ec_rpmsg;
+ int ret;
+
+ ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
+ if (!ec_dev)
+ return -ENOMEM;
+
+ ec_rpmsg = devm_kzalloc(dev, sizeof(*ec_rpmsg), GFP_KERNEL);
+ if (!ec_rpmsg)
+ return -ENOMEM;
+
+ ec_dev->dev = dev;
+ ec_dev->priv = ec_rpmsg;
+ ec_dev->cmd_xfer = cros_ec_cmd_xfer_rpmsg;
+ ec_dev->pkt_xfer = cros_ec_pkt_xfer_rpmsg;
+ ec_dev->phys_name = dev_name(&rpdev->dev);
+ ec_dev->din_size = sizeof(struct ec_host_response) +
+ sizeof(struct ec_response_get_protocol_info);
+ ec_dev->dout_size = sizeof(struct ec_host_request);
+ dev_set_drvdata(dev, ec_dev);
+
+ ec_rpmsg->rpdev = rpdev;
+ init_waitqueue_head(&ec_rpmsg->xfer_ack_wq);
+
+ ret = cros_ec_register(ec_dev);
+ if (ret) {
+ dev_err(dev, "cannot register EC\n");
+ return ret;
+ }
+
+ return 0;
+}
+
+static const struct rpmsg_device_id cros_ec_rpmsg_device_id[] = {
+ { .name = "cros-ec-rpmsg", },
+ { }
+};
+MODULE_DEVICE_TABLE(rpmsg, cros_ec_rpmsg_device_id);
+
+static struct rpmsg_driver cros_ec_driver_rpmsg = {
+ .drv.name = KBUILD_MODNAME,
+ .id_table = cros_ec_rpmsg_device_id,
+ .probe = cros_ec_rpmsg_probe,
+ .callback = cros_ec_rpmsg_callback,
+};
+
+module_rpmsg_driver(cros_ec_driver_rpmsg);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("ChromeOS EC multi function device (rpmsg)");
--
2.20.1.321.g9e740568ce-goog
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