Date:   Fri, 7 Feb 2020 12:28:00 -0800
From:   Prashant Malani <pmalani@...omium.org>
To:     Enric Balletbo i Serra <enric.balletbo@...labora.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        heikki.krogerus@...el.com, Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>
Subject: Re: [PATCH 1/3] platform/chrome: Add Type C connector class driver

On Fri, Feb 7, 2020 at 9:00 AM Enric Balletbo i Serra
<enric.balletbo@...labora.com> wrote:
>
> Hi Prashant,
>
> On 7/2/20 0:30, Prashant Malani wrote:
> > 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@...labora.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@...omium.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 don't mind clutter probe if is more readable but try it, and lets see how
> looks like. You are also registering and unregistering the typec ports there,
> not only parsing. Usually what we have is parsing the firmware or dt and then
> register and unregister the typec ports, all mixed. I'm more in favour of have
> it separated, IMHO.
Sounds good, I'll push another version with cros_typec_init_ports()
distinct and we can check how it looks.
If it's still not readable, I'll push version with the code directly in probe()

>
> >>
> >> 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,
> >

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