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Message-ID: <CABXOdTd9J6=M_-sx0us13++g2NLi_HcJDBOrqnDn6EjHoyvN=Q@mail.gmail.com>
Date: Thu, 3 Jan 2019 08:08:43 -0800
From: Guenter Roeck <groeck@...gle.com>
To: Enric Balletbo Serra <eballetbo@...il.com>
Cc: Pi-Hsun Shih <pihsun@...omium.org>,
Nicolas Boichat <drinkcat@...omium.org>,
Lee Jones <lee.jones@...aro.org>,
Benson Leung <bleung@...omium.org>,
Olof Johansson <olof@...om.net>,
open list <linux-kernel@...r.kernel.org>,
Guenter Roeck <groeck@...omium.org>
Subject: Re: [RFC,5/5] mfd: cros_ec: add EC host command support using rpmsg.
On Thu, Jan 3, 2019 at 8:06 AM Enric Balletbo Serra <eballetbo@...il.com> wrote:
>
> Hi,
>
> Many thanks for sending this. Please, add Guenter and me for next
> versions, we are interested in it, thanks :)
>
> Missatge de Pi-Hsun Shih <pihsun@...omium.org> del dia dc., 26 de des.
> 2018 a les 8:57:
> >
> > Add EC host command support through rpmsg.
> >
> > Signed-off-by: Pi-Hsun Shih <pihsun@...omium.org>
> > ---
> > drivers/mfd/cros_ec_dev.c | 9 ++
> > drivers/platform/chrome/Kconfig | 8 ++
> > drivers/platform/chrome/Makefile | 1 +
> > drivers/platform/chrome/cros_ec_rpmsg.c | 164 ++++++++++++++++++++++++
> > include/linux/mfd/cros_ec.h | 1 +
> > include/linux/mfd/cros_ec_commands.h | 2 +
> > 6 files changed, 185 insertions(+)
> > create mode 100644 drivers/platform/chrome/cros_ec_rpmsg.c
> >
> > diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
> > index 2d0fee488c5aa8..67983853413d07 100644
> > --- a/drivers/mfd/cros_ec_dev.c
> > +++ b/drivers/mfd/cros_ec_dev.c
> > @@ -414,6 +414,15 @@ static int ec_device_probe(struct platform_device *pdev)
> > device_initialize(&ec->class_dev);
> > cdev_init(&ec->cdev, &fops);
> >
> > + if (cros_ec_check_features(ec, EC_FEATURE_SCP)) {
> > + dev_info(dev, "SCP detected.\n");
> > + /*
> > + * Help userspace differentiating ECs from SCP,
> > + * regardless of the probing order.
> > + */
> > + ec_platform->ec_name = CROS_EC_DEV_SCP_NAME;
> > + }
> > +
>
> Why userspace should know that this is an SCP? From the userspace
> point of view shouldn't be this transparent, we don't do distinctions
> when the transport layer is i2c, spi or lpc, and I think that the
> cros_ec_rpmsg driver is a cros-ec transport layer, like these. So, I
> think that this is not needed.
>
> > /*
> > * Add the class device
> > * Link to the character device for creating the /dev entry
> > diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
> > index 16b1615958aa2d..b03d68eb732177 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
>
> I think that this driver is DT-only, && 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..f123ca6d1c029c
> > --- /dev/null
> > +++ b/drivers/platform/chrome/cros_ec_rpmsg.c
> > @@ -0,0 +1,164 @@
> > +// 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>
> > +
> > +/**
> > + * 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 rpmsg_device *rpdev = ec_dev->priv;
> > + int len;
> > + u8 sum;
> > + int ret;
> > + int i;
> > +
> > + ec_msg->result = 0;
> > + len = cros_ec_prepare_tx(ec_dev, ec_msg);
> > + dev_dbg(ec_dev->dev, "prepared, len=%d\n", len);
> > +
> > + // TODO: This currently relies on that mtk_rpmsg send actually blocks
> > + // until ack. Should do the wait here instead.
>
> Use standard C style comments.
>
> > + ret = rpmsg_send(rpdev->ept, ec_dev->dout, len);
> > +
>
> Remove that empty line.
>
> > + if (ret) {
> > + dev_err(ec_dev->dev, "rpmsg send failed\n");
> > + return ret;
> > + }
> > +
> > + /* 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);
>
> Can you explain why this sleep is needed?
>
> > +
> > + 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);
> > +
> > + 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);
> > +
> > + return 0;
> > +}
> > +
> > +static int cros_ec_rpmsg_probe(struct rpmsg_device *rpdev)
> > +{
> > + struct device *dev = &rpdev->dev;
> > +
> Remove that empty line
>
> > + struct cros_ec_device *ec_dev;
> > + int ret;
> > +
> > + ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
> > + if (!ec_dev)
> > + return -ENOMEM;
> > +
> > + ec_dev->dev = dev;
> > + ec_dev->priv = rpdev;
> > + 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);
> > +
> > + ret = cros_ec_register(ec_dev);
> > + if (ret)
>
> I'd add an error message here
>
> dev_err(dev, "cannot register EC\n"
>
> > + return ret;
> > +
> > + return 0;
> > +}
> > +
> > +static void cros_ec_rpmsg_remove(struct rpmsg_device *rpdev)
>
> This function will not be needed after apply [1]. I would recommend
> base your patches on top of [2]
>
> [1] https://lkml.org/lkml/2018/12/12/672
> [2] https://lkml.org/lkml/2018/12/12/679
>
> > +{
> > + struct cros_ec_device *ec_dev = dev_get_drvdata(&rpdev->dev);
> > +
> > + cros_ec_remove(ec_dev);
> > +}
> > +
>
> How this driver is instantiated?
>
> I expect something like this here (like the other transport layers)
>
> static const struct of_device_id cros_ec_rpmsg_of_match[] = {
> { .compatible = "google,cros-ec-rpmsg", },
> { }
> };
> MODULE_DEVICE_TABLE(of, cros_ec_rpmsg_of_match);
>
> And the DT containing the compatible = "google,cros-ec-rpmsg" like the
> other cros-ec transport layers.
>
> > +static const struct rpmsg_device_id cros_ec_rpmsg_device_id[] = {
> > + { .name = "cros-ec-rpmsg", },
> > + { /* sentinel */ },
>
> I got convinced that the '/* sentinel */' comment doesn't means
> anything, so use { } only here, remove the comment and the last comma
> (there is nothing to separate)
> + { }
>
> > +};
> > +
> > +static struct rpmsg_driver cros_ec_driver_rpmsg = {
> > + .drv.name = KBUILD_MODNAME,
>
> And something like this here
> .drv = {
> .name = "cros-ec-rpmsg",
> .of_match_table = cros_ec_rpmsg_of_match,
> },
>
> > + .id_table = cros_ec_rpmsg_device_id,
> > + .probe = cros_ec_rpmsg_probe,
> > + .remove = cros_ec_rpmsg_remove,
> > + .callback = cros_ec_rpmsg_callback,
> > +};
> > +
> > +module_rpmsg_driver(cros_ec_driver_rpmsg);
> > +
> > +MODULE_LICENSE("GPL v2");
> > +MODULE_DESCRIPTION("ChromeOS EC multi function device (rpmsg)");
> > diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
> > index de8b588c8776da..fd297cf8f97295 100644
> > --- a/include/linux/mfd/cros_ec.h
> > +++ b/include/linux/mfd/cros_ec.h
> > @@ -24,6 +24,7 @@
> >
> > #define CROS_EC_DEV_NAME "cros_ec"
> > #define CROS_EC_DEV_PD_NAME "cros_pd"
> > +#define CROS_EC_DEV_SCP_NAME "cros_scp"
>
> I think this definition is not needed.
>
> >
> > /*
> > * The EC is unresponsive for a time after a reboot command. Add a
> > diff --git a/include/linux/mfd/cros_ec_commands.h b/include/linux/mfd/cros_ec_commands.h
> > index fc91082d4c357b..3e5da6e93b2f42 100644
> > --- a/include/linux/mfd/cros_ec_commands.h
> > +++ b/include/linux/mfd/cros_ec_commands.h
> > @@ -856,6 +856,8 @@ enum ec_feature_code {
> > EC_FEATURE_RTC = 27,
> > /* EC supports CEC commands */
> > EC_FEATURE_CEC = 35,
> > + /* The MCU exposes a SCP */
> > + EC_FEATURE_SCP = 39,
>
> Same here, I think this is not needed.
It might be needed for instantiation, ie instantiate only if the
feature is supported.
Guenter
> > };
> >
> > #define EC_FEATURE_MASK_0(event_code) (1UL << (event_code % 32))
> > --
> > 2.20.1.415.g653613c723-goog
> >
>
> Thanks,
> Enric
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