diff mbox series

[v7,3/3] platform/chrome: cros_ec_uart: Add DT enumeration support

Message ID 20221117114818.v7.3.Ie23c217d69ff25d7354db942613f143bbc8ef891@changeid (mailing list archive)
State Superseded
Headers show
Series [v7,1/3] platform/chrome: cros_ec_uart: Add cros-ec-uart transport layer | expand

Commit Message

Mark Hasemeyer Nov. 17, 2022, 6:48 p.m. UTC 
Existing firmware uses the "PRP0001" _HID and an associated compatible
string to enumerate the cros_ec_uart.

Add DT enumeration support for already shipped firmware.

Signed-off-by: Bhanu Prakash Maiya <bhanumaiya@chromium.org>
Signed-off-by: Mark Hasemeyer <markhas@chromium.org>
---

Changes in v7:
- Move PRP0001 enumeration support to its own commit

 drivers/platform/chrome/cros_ec_uart.c | 8 ++++++++
 1 file changed, 8 insertions(+)

Comments

Tzung-Bi Shih Nov. 18, 2022, 5:44 a.m. UTC | #1 
On Thu, Nov 17, 2022 at 11:48:48AM -0700, Mark Hasemeyer wrote:
> @@ -392,6 +393,12 @@ static int __maybe_unused cros_ec_uart_resume(struct device *dev)
>  static SIMPLE_DEV_PM_OPS(cros_ec_uart_pm_ops, cros_ec_uart_suspend,
>  			 cros_ec_uart_resume);
>  
> +static const struct of_device_id cros_ec_uart_of_match[] = {
> +	{ .compatible = "google,cros-ec-uart" },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, cros_ec_uart_of_match);

It would need a guard for checking CONFIG_OF.  Similar to what
`cros_ec_uart_acpi_id` does.

> @@ -405,6 +412,7 @@ static struct serdev_device_driver cros_ec_uart_driver = {
>  	.driver	= {
>  		.name	= "cros-ec-uart",
>  		.acpi_match_table = ACPI_PTR(cros_ec_uart_acpi_id),
> +		.of_match_table = cros_ec_uart_of_match,

It would need be wrapped by `of_match_ptr()`.  Similar to what
`ACPI_PTR()` does.
Mark Hasemeyer Nov. 29, 2022, 6:13 p.m. UTC | #2 
> > @@ -392,6 +393,12 @@ static int __maybe_unused cros_ec_uart_resume(struct device *dev)
> >  static SIMPLE_DEV_PM_OPS(cros_ec_uart_pm_ops, cros_ec_uart_suspend,
> >                        cros_ec_uart_resume);
> >
> > +static const struct of_device_id cros_ec_uart_of_match[] = {
> > +     { .compatible = "google,cros-ec-uart" },
> > +     {}
> > +};
> > +MODULE_DEVICE_TABLE(of, cros_ec_uart_of_match);
>
> It would need a guard for checking CONFIG_OF.  Similar to what
> `cros_ec_uart_acpi_id` does.
>
> > @@ -405,6 +412,7 @@ static struct serdev_device_driver cros_ec_uart_driver = {
> >       .driver = {
> >               .name   = "cros-ec-uart",
> >               .acpi_match_table = ACPI_PTR(cros_ec_uart_acpi_id),
> > +             .of_match_table = cros_ec_uart_of_match,
>
> It would need be wrapped by `of_match_ptr()`.  Similar to what
> `ACPI_PTR()` does.

I'm not sure we want a guard in this case because we compile the kernel without
CONFIG_OF enabled for (most?) x86 platforms. Yet we still need the device
tree code to enumerate using the PRP0001 _HID method.
Tzung-Bi Shih Nov. 30, 2022, 7:09 a.m. UTC | #3 
On Tue, Nov 29, 2022 at 11:13:04AM -0700, Mark Hasemeyer wrote:
> > > @@ -392,6 +393,12 @@ static int __maybe_unused cros_ec_uart_resume(struct device *dev)
> > >  static SIMPLE_DEV_PM_OPS(cros_ec_uart_pm_ops, cros_ec_uart_suspend,
> > >                        cros_ec_uart_resume);
> > >
> > > +static const struct of_device_id cros_ec_uart_of_match[] = {
> > > +     { .compatible = "google,cros-ec-uart" },
> > > +     {}
> > > +};
> > > +MODULE_DEVICE_TABLE(of, cros_ec_uart_of_match);
> >
> > It would need a guard for checking CONFIG_OF.  Similar to what
> > `cros_ec_uart_acpi_id` does.
> >
> > > @@ -405,6 +412,7 @@ static struct serdev_device_driver cros_ec_uart_driver = {
> > >       .driver = {
> > >               .name   = "cros-ec-uart",
> > >               .acpi_match_table = ACPI_PTR(cros_ec_uart_acpi_id),
> > > +             .of_match_table = cros_ec_uart_of_match,
> >
> > It would need be wrapped by `of_match_ptr()`.  Similar to what
> > `ACPI_PTR()` does.
> 
> I'm not sure we want a guard in this case because we compile the kernel without
> CONFIG_OF enabled for (most?) x86 platforms. Yet we still need the device
> tree code to enumerate using the PRP0001 _HID method.

I'm not familiar to ACPI.  However, I thought it should add the compatible
string in the _DSD instead of using of_match for the case.  See example
in [1].

[1]: https://www.kernel.org/doc/html/latest/firmware-guide/acpi/enumeration.html#device-tree-namespace-link-device-id
Raul Rangel Nov. 30, 2022, 4:52 p.m. UTC | #4 
On Wed, Nov 30, 2022 at 12:10 AM Tzung-Bi Shih <tzungbi@kernel.org> wrote:
>
> On Tue, Nov 29, 2022 at 11:13:04AM -0700, Mark Hasemeyer wrote:
> > > > @@ -392,6 +393,12 @@ static int __maybe_unused cros_ec_uart_resume(struct device *dev)
> > > >  static SIMPLE_DEV_PM_OPS(cros_ec_uart_pm_ops, cros_ec_uart_suspend,
> > > >                        cros_ec_uart_resume);
> > > >
> > > > +static const struct of_device_id cros_ec_uart_of_match[] = {
> > > > +     { .compatible = "google,cros-ec-uart" },
> > > > +     {}
> > > > +};
> > > > +MODULE_DEVICE_TABLE(of, cros_ec_uart_of_match);
> > >
> > > It would need a guard for checking CONFIG_OF.  Similar to what
> > > `cros_ec_uart_acpi_id` does.
> > >
> > > > @@ -405,6 +412,7 @@ static struct serdev_device_driver cros_ec_uart_driver = {
> > > >       .driver = {
> > > >               .name   = "cros-ec-uart",
> > > >               .acpi_match_table = ACPI_PTR(cros_ec_uart_acpi_id),
> > > > +             .of_match_table = cros_ec_uart_of_match,
> > >
> > > It would need be wrapped by `of_match_ptr()`.  Similar to what
> > > `ACPI_PTR()` does.
> >
> > I'm not sure we want a guard in this case because we compile the kernel without
> > CONFIG_OF enabled for (most?) x86 platforms. Yet we still need the device
> > tree code to enumerate using the PRP0001 _HID method.
>

> I'm not familiar to ACPI.  However, I thought it should add the compatible
> string in the _DSD instead of using of_match for the case.  See example
> in [1].
>
> [1]: https://www.kernel.org/doc/html/latest/firmware-guide/acpi/enumeration.html#device-tree-namespace-link-device-id

Correct, we need to add the compatible string inside the _DSD. This is
what we currently do for all of our released devices:
```
    Device (CRFP)
    {
        Name (_HID, "PRP0001")  // _HID: Hardware ID
        Name (_UID, Zero)  // _UID: Unique ID
        Name (_DDN, "Fingerprint Reader")  // _DDN: DOS Device Name
        Name (_DSD, Package (0x02)  // _DSD: Device-Specific Data
        {
            ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301") /* Device
Properties for _DSD */,
            Package (0x03)
            {
                Package (0x02)
                {
                    "compatible",
                    "google,cros-ec-uart"
                },
                ...
            }
        }
    }
```

Since we define our `_HID` as `PRP0001` we need the `of_match_table`
so the ACPI node can bind.
Tzung-Bi Shih Dec. 1, 2022, 3:07 a.m. UTC | #5 
On Wed, Nov 30, 2022 at 09:52:29AM -0700, Raul Rangel wrote:
> On Wed, Nov 30, 2022 at 12:10 AM Tzung-Bi Shih <tzungbi@kernel.org> wrote:
> >
> > On Tue, Nov 29, 2022 at 11:13:04AM -0700, Mark Hasemeyer wrote:
> > > > > @@ -392,6 +393,12 @@ static int __maybe_unused cros_ec_uart_resume(struct device *dev)
> > > > >  static SIMPLE_DEV_PM_OPS(cros_ec_uart_pm_ops, cros_ec_uart_suspend,
> > > > >                        cros_ec_uart_resume);
> > > > >
> > > > > +static const struct of_device_id cros_ec_uart_of_match[] = {
> > > > > +     { .compatible = "google,cros-ec-uart" },
> > > > > +     {}
> > > > > +};
> > > > > +MODULE_DEVICE_TABLE(of, cros_ec_uart_of_match);
> > > >
> > > > It would need a guard for checking CONFIG_OF.  Similar to what
> > > > `cros_ec_uart_acpi_id` does.
> > > >
> > > > > @@ -405,6 +412,7 @@ static struct serdev_device_driver cros_ec_uart_driver = {
> > > > >       .driver = {
> > > > >               .name   = "cros-ec-uart",
> > > > >               .acpi_match_table = ACPI_PTR(cros_ec_uart_acpi_id),
> > > > > +             .of_match_table = cros_ec_uart_of_match,
> > > >
> > > > It would need be wrapped by `of_match_ptr()`.  Similar to what
> > > > `ACPI_PTR()` does.
> > >
> > > I'm not sure we want a guard in this case because we compile the kernel without
> > > CONFIG_OF enabled for (most?) x86 platforms. Yet we still need the device
> > > tree code to enumerate using the PRP0001 _HID method.
> >
> 
> > I'm not familiar to ACPI.  However, I thought it should add the compatible
> > string in the _DSD instead of using of_match for the case.  See example
> > in [1].
> >
> > [1]: https://www.kernel.org/doc/html/latest/firmware-guide/acpi/enumeration.html#device-tree-namespace-link-device-id
> 
> Correct, we need to add the compatible string inside the _DSD. This is
> what we currently do for all of our released devices:
> ```
>     Device (CRFP)
>     {
>         Name (_HID, "PRP0001")  // _HID: Hardware ID
>         Name (_UID, Zero)  // _UID: Unique ID
>         Name (_DDN, "Fingerprint Reader")  // _DDN: DOS Device Name
>         Name (_DSD, Package (0x02)  // _DSD: Device-Specific Data
>         {
>             ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301") /* Device
> Properties for _DSD */,
>             Package (0x03)
>             {
>                 Package (0x02)
>                 {
>                     "compatible",
>                     "google,cros-ec-uart"
>                 },
>                 ...
>             }
>         }
>     }
> ```
> 
> Since we define our `_HID` as `PRP0001` we need the `of_match_table`
> so the ACPI node can bind.

I see.  I also found some more examples:
- 3c3969a0c99b ("iio:adc:ti-adc12138: Switch to generic firmware properties
                 and drop of_match_ptr")
- a70bbbe387d0 ("nfc: pn533: drop of_match_ptr from device ID table")
diff mbox series

Patch

diff --git a/drivers/platform/chrome/cros_ec_uart.c b/drivers/platform/chrome/cros_ec_uart.c
index b5f72f0104985..d44efb78bc881 100644
--- a/drivers/platform/chrome/cros_ec_uart.c
+++ b/drivers/platform/chrome/cros_ec_uart.c
@@ -11,6 +11,7 @@ 
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/acpi.h>
+#include <linux/of.h>
 #include <linux/platform_data/cros_ec_commands.h>
 #include <linux/platform_data/cros_ec_proto.h>
 #include <linux/serdev.h>
@@ -392,6 +393,12 @@  static int __maybe_unused cros_ec_uart_resume(struct device *dev)
 static SIMPLE_DEV_PM_OPS(cros_ec_uart_pm_ops, cros_ec_uart_suspend,
 			 cros_ec_uart_resume);
 
+static const struct of_device_id cros_ec_uart_of_match[] = {
+	{ .compatible = "google,cros-ec-uart" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, cros_ec_uart_of_match);
+
 #ifdef CONFIG_ACPI
 static const struct acpi_device_id cros_ec_uart_acpi_id[] = {
 	{ "GOOG0019", 0 },
@@ -405,6 +412,7 @@  static struct serdev_device_driver cros_ec_uart_driver = {
 	.driver	= {
 		.name	= "cros-ec-uart",
 		.acpi_match_table = ACPI_PTR(cros_ec_uart_acpi_id),
+		.of_match_table = cros_ec_uart_of_match,
 		.pm	= &cros_ec_uart_pm_ops,
 	},
 	.probe		= cros_ec_uart_probe,