Re: [PATCH 1/3] platform/chrome: Add Type C connector class driver

[Prashant Malani <pmalani@chromium.org>]

Hi Enric,

Thanks for taking a look at the patch. Please see my responses inline
(I will defer sending the next version till the one pending question I
had is resolved):

On Thu, Feb 6, 2020 at 8:19 AM Enric Balletbo i Serra
<enric.balletbo@collabora.corp-partner.google.com> wrote:
>
> Hi Prashant,
>
> On 5/2/20 21:59, Prashant Malani wrote:
> > Add a driver to implement the Type C connector class for Chrome OS
> > devices with ECs (Embedded Controllers).
> >
> > The driver relies on firmware device specifications for various port
> > attributes. On ACPI platforms, this is specified using the logical
> > device with HID GOOG0014. On DT platforms, this is specified using the
> > DT node with compatible string "google,cros-ec-typec".
> >
>
> If that's the case you should document this in a binding file.

Done. I will add this in the next version of the series.

> driver a replacement of the cros-ec-extcon driver or is a different thing?

Currently it is distinct. We're hoping to plug in to type C connector
class work which Heikki is working on (relating to Type C Mux agent).
Hopefully, we will gradually transition the extcon functionality to
the Type C port driver.

>
> There is a device where I can test this?

I think you can try it on kevin if you add the DT node for it (haven't
tried it myself on kevin). An example will be present in the DT
Documentation I provide in the next version.

>
> > This patch reads the device FW node and uses the port attributes to
> > register the typec ports with the Type C connector class framework, but
> > doesn't do much else.
> >
> > Subsequent patches will add more functionality to the driver, including
> > obtaining current port information (polarity, vconn role, current power
> > role etc.) after querying the EC.
> >
> > Signed-off-by: Prashant Malani <pmalani@chromium.org>
> > ---
> >  drivers/platform/chrome/Kconfig         |  11 ++
> >  drivers/platform/chrome/Makefile        |   1 +
> >  drivers/platform/chrome/cros_ec_typec.c | 228 ++++++++++++++++++++++++
> >  3 files changed, 240 insertions(+)
> >  create mode 100644 drivers/platform/chrome/cros_ec_typec.c
> >
> > diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
> > index 5f57282a28da00..1370dfd1ca1565 100644
> > --- a/drivers/platform/chrome/Kconfig
> > +++ b/drivers/platform/chrome/Kconfig
> > @@ -214,6 +214,17 @@ config CROS_EC_SYSFS
> >         To compile this driver as a module, choose M here: the
> >         module will be called cros_ec_sysfs.
> >
> > +config CROS_EC_TYPEC
> > +     tristate "ChromeOS EC Type-C Connector Control"
> > +     depends on MFD_CROS_EC_DEV && TYPEC
> > +     default n
>
> Default value is already n, so you don't need to put it here. But I'd say that
> we might be interested on have default MFD_CROS_EC_DEV like the other drivers.

Done.

>
> > +     help
> > +       If you say Y here, you get support for accessing Type C connector
> > +       information from the Chrome OS EC.
> > +
> > +       To compile this driver as a module, choose M here: the module will be
> > +       called cros_ec_typec.
> > +
> >  config CROS_USBPD_LOGGER
> >       tristate "Logging driver for USB PD charger"
> >       depends on CHARGER_CROS_USBPD
> > diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
> > index aacd5920d8a180..caf2a9cdb5e6d1 100644
> > --- a/drivers/platform/chrome/Makefile
> > +++ b/drivers/platform/chrome/Makefile
> > @@ -12,6 +12,7 @@ obj-$(CONFIG_CROS_EC_ISHTP)         += cros_ec_ishtp.o
> >  obj-$(CONFIG_CROS_EC_RPMSG)          += cros_ec_rpmsg.o
> >  obj-$(CONFIG_CROS_EC_SPI)            += cros_ec_spi.o
> >  cros_ec_lpcs-objs                    := cros_ec_lpc.o cros_ec_lpc_mec.o
> > +obj-$(CONFIG_CROS_EC_TYPEC)          += cros_ec_typec.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_typec.c b/drivers/platform/chrome/cros_ec_typec.c
> > new file mode 100644
> > index 00000000000000..fe5659171c2a85
> > --- /dev/null
> > +++ b/drivers/platform/chrome/cros_ec_typec.c
> > @@ -0,0 +1,228 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Copyright 2020 Google LLC
> > + *
> > + * This driver provides the ability to view and manage Type C ports through the
> > + * Chrome OS EC.
> > + */
> > +
> > +#include <linux/acpi.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_data/cros_ec_commands.h>
> > +#include <linux/platform_data/cros_ec_proto.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/usb/typec.h>
> > +
> > +#define DRV_NAME "cros-ec-typec"
> > +
> > +/* Platform-specific data for the Chrome OS EC Type C controller. */
> > +struct cros_typec_data {
> > +     struct device *dev;
> > +     struct cros_ec_device *ec;
> > +     int num_ports;
> > +     /* Array of ports, indexed by port number. */
> > +     struct typec_port *ports[EC_USB_PD_MAX_PORTS];
> > +};
> > +
> > +int cros_typec_parse_port_props(struct typec_capability *cap,
>
> static int

Sorry, done.

>
> > +                             struct fwnode_handle *fwnode,
> > +                             struct device *dev)
> > +{
> > +     const char *buf;
> > +     int ret;
> > +
> > +     memset(cap, 0, sizeof(*cap));
> > +     ret = fwnode_property_read_string(fwnode, "power-role", &buf);
> > +     if (ret) {
> > +             dev_err(dev, "power-role not found: %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     ret = typec_find_port_power_role(buf);
> > +     if (ret < 0)
> > +             return ret;
> > +     cap->type = ret;
> > +
> > +     ret = fwnode_property_read_string(fwnode, "data-role", &buf);
> > +     if (ret) {
> > +             dev_err(dev, "data-role not found: %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     ret = typec_find_port_data_role(buf);
> > +     if (ret < 0)
> > +             return ret;
> > +     cap->data = ret;
> > +
> > +     ret = fwnode_property_read_string(fwnode, "try-power-role", &buf);
> > +     if (ret) {
> > +             dev_err(dev, "try-power-role not found: %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     ret = typec_find_power_role(buf);
> > +     if (ret < 0)
> > +             return ret;
> > +     cap->prefer_role = ret;
> > +
> > +     cap->fwnode = fwnode;
> > +
> > +     return 0;
> > +}
> > +
> > +static int cros_typec_init_ports(struct cros_typec_data *typec)
> > +{
> > +     struct device *dev = typec->dev;
> > +     struct typec_capability cap;
> > +     struct fwnode_handle *fwnode;
> > +     int ret;
> > +     int i;
> > +     int nports;
> > +     u32 port_num;
> > +
> > +     nports = device_get_child_node_count(dev);
> > +     if (nports == 0) {
> > +             dev_err(dev, "No port entries found.\n");
> > +             return -ENODEV;
> > +     }
> > +
> > +     device_for_each_child_node(dev, fwnode) {
> > +             if (fwnode_property_read_u32(fwnode, "port-number",
> > +                                          &port_num)) {
> > +                     dev_err(dev, "No port-number for port, skipping.\n");
> > +                     ret = -EINVAL;
> > +                     goto unregister_ports;
> > +             }
> > +
> > +             if (port_num >= typec->num_ports) {
> > +                     dev_err(dev, "Invalid port number.\n");
> > +                     ret = -EINVAL;
> > +                     goto unregister_ports;
> > +             }
> > +
> > +             dev_dbg(dev, "Registering port %d\n", port_num);
> > +             ret = cros_typec_parse_port_props(&cap, fwnode, dev);
> > +             if (ret < 0)
> > +                     goto unregister_ports;
> > +             typec->ports[port_num] = typec_register_port(dev, &cap);
> > +             if (IS_ERR(typec->ports[port_num])) {
> > +                     dev_err(dev, "Failed to register port %d\n", port_num);
> > +                     ret = PTR_ERR(typec->ports[port_num]);
> > +                     goto unregister_ports;
> > +             }
> > +     }
> > +
> > +     return 0;
> > +
> > +unregister_ports:
> > +     for (i = 0; i < typec->num_ports; i++)
> > +             typec_unregister_port(typec->ports[i]);
> > +     return ret;
> > +}
> > +
> > +static int cros_typec_ec_command(struct cros_typec_data *typec,
> > +                              unsigned int version,
> > +                              unsigned int command,
> > +                              void *outdata,
> > +                              unsigned int outsize,
> > +                              void *indata,
> > +                              unsigned int insize)
> > +{
> > +     struct cros_ec_command *msg;
> > +     int ret;
> > +
> > +     msg = kzalloc(sizeof(*msg) + max(outsize, insize), GFP_KERNEL);
> > +     if (!msg)
> > +             return -ENOMEM;
> > +
> > +     msg->version = version;
> > +     msg->command = command;
> > +     msg->outsize = outsize;
> > +     msg->insize = insize;
> > +
> > +     if (outsize)
> > +             memcpy(msg->data, outdata, outsize);
> > +
> > +     ret = cros_ec_cmd_xfer_status(typec->ec, msg);
> > +     if (ret >= 0 && insize)
> > +             memcpy(indata, msg->data, insize);
> > +
> > +     kfree(msg);
> > +     return ret;
> > +}
> > +
> > +
> > +static int cros_typec_get_num_ports(struct cros_typec_data *typec)
> > +{
>
> This functions is only called once at probe, you can just put the code there. I
> had some readibility problems trying to follow de code.

Done.

>
> > +     struct ec_response_usb_pd_ports resp;
> > +     int ret;
> > +
> > +     ret = cros_typec_ec_command(typec, 0, EC_CMD_USB_PD_PORTS, NULL, 0,
> > +                                 &resp, sizeof(resp));
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     typec->num_ports = resp.num_ports;
> > +     if (typec->num_ports > EC_USB_PD_MAX_PORTS) {
> > +             dev_warn(typec->dev,
> > +                      "Too many ports reported: %d, limiting to max: %d\n",
> > +                      typec->num_ports, EC_USB_PD_MAX_PORTS);
>
> You say that you are limiting the number of ports to max but typec->num_ports is
> still resp.num_ports, is that correct?
>

Sorry, thanks for catching this, it should be set to
EC_USB_PD_MAX_PORTS. I will fix this in the next version.

> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +#ifdef CONFIG_ACPI
> > +static const struct acpi_device_id cros_typec_acpi_id[] = {
> > +     { "GOOG0014", 0 },
> > +     { /* sentinel */ }
>
> No need to add /* sentinel */ here, is obvious.

Done.

>
> > +};
> > +MODULE_DEVICE_TABLE(acpi, cros_typec_acpi_id);
> > +#endif
> > +
> > +#ifdef CONFIG_OF
> > +static const struct of_device_id cros_typec_of_match[] = {
> > +     { .compatible = "google,cros-ec-typec", },
> > +     { /* sentinel */ },
>
> No need to add /* sentinel */ here, is obvious. And no need for the colon at the
> end.

Done.
>
> > +};
> > +MODULE_DEVICE_TABLE(of, cros_typec_of_match);
> > +#endif
> > +
> > +static int cros_typec_probe(struct platform_device *pdev)
> > +{
> > +     struct device *dev = &pdev->dev;
> > +     struct cros_typec_data *typec;
> > +     int ret;
> > +
> > +     typec = devm_kzalloc(dev, sizeof(*typec), GFP_KERNEL);
> > +     if (!typec)
> > +             return -ENOMEM;
> > +     typec->dev = dev;
> > +     typec->ec = dev_get_drvdata(pdev->dev.parent);
> > +     platform_set_drvdata(pdev, typec);
> > +
> > +     ret = cros_typec_get_num_ports(typec);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     ret = cros_typec_init_ports(typec);
>
> both, cros_typec_get_num_ports and cros_typec_init_ports are only called once,
> as I said I had some problems of readibility because typec->num_ports is set in
> one function and unregister in another function when fails.

Can we keep cros_typec_init_ports() as a separate function? I was
hoping to avoid cluttering the _probe() with FW node parsing logic.
cros_typec_init_ports() registers the ports (and unregisters on
failure), so seems fairly self-contained.
Of course, happy to place everything in probe if you still prefer that.

>
> I'd just remove those two functions and put the code directly here.
>
> > +     if (!ret)
> > +             return ret;
> > +
> > +     return 0;
> > +}
> > +
> > +static struct platform_driver cros_typec_driver = {
> > +     .driver = {
> > +             .name   = DRV_NAME,
>
> no tab, just space after .-name

Done.
>
> > +             .acpi_match_table = ACPI_PTR(cros_typec_acpi_id),
> > +             .of_match_table = of_match_ptr(cros_typec_of_match),
> > +     },
> > +     .probe          = cros_typec_probe,
>
> no tab, just space after .probe

Done.

>
> > +};
> > +
> > +module_platform_driver(cros_typec_driver);
> > +
> > +MODULE_LICENSE("GPL");
> > +MODULE_DESCRIPTION("Chrome OS EC Type C control");
> >
>
> You probably want to add the MODULE_AUTHOR here

Done.

Best regards,