[alsa-devel] [PATCH 1/2] ASoC: rt5677: Add ACPI device probing

[Grant Likely]

On Sat, Nov 15, 2014 at 6:56 AM, Ben Zhang <benzh at chromium.org> wrote:
> The rt5677 codec driver looks for ACPI device ID "RT5677CE",
> which is specified in coreboot. This patch allows platform
> data to be obtained via ACPI
>
> Signed-off-by: Ben Zhang <benzh at chromium.org>

This looks like an ideal time to talk about shared DT and ACPI driver
bindings. This driver /already/ has a firmware binding. It is
documented in the kernel under
Documentation/bindings/sound/rt5677.txt. We now have a standard method
for sharing bindings between DT and ACPI in the _DSD method[1].
Support for DSD is in linux-next and getting merged into v3.19. This
is exactly the case that _DSD should be used for passing additional
data to the driver, and it should use the existing binding.

[1] http://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUID.pdf

For a long time we've had the rule on DT that new bindings must be
documented before we merge a patch. That rule I think has been a good
one, even if it is a little chaoitc. I think when it comes to ACPI
drivers that we should be requiring the same: Document the binding,
either in the kernel as a DT binding, or point to somewhere else that
has the binding documented.

Also, since this patch is targeted at v3.19 or later, the
device-properties API should be used. Don't create something custom.

g.

> ---
>  sound/soc/codecs/rt5677.c | 52 +++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 50 insertions(+), 2 deletions(-)
>
> diff --git a/sound/soc/codecs/rt5677.c b/sound/soc/codecs/rt5677.c
> index 5d317c68..384281d 100644
> --- a/sound/soc/codecs/rt5677.c
> +++ b/sound/soc/codecs/rt5677.c
> @@ -20,6 +20,7 @@
>  #include <linux/i2c.h>
>  #include <linux/platform_device.h>
>  #include <linux/spi/spi.h>
> +#include <linux/acpi.h>
>  #include <linux/firmware.h>
>  #include <linux/gpio.h>
>  #include <sound/core.h>
> @@ -4525,6 +4526,43 @@ static int rt5677_parse_dt(struct rt5677_priv *rt5677, struct device_node *np)
>         return 0;
>  }
>
> +#ifdef CONFIG_ACPI
> +
> +static unsigned long long rt5677_parse_acpi_entry(struct device *dev,
> +               acpi_string name)
> +{
> +       acpi_handle handle = ACPI_HANDLE(dev);
> +       unsigned long long val;
> +       acpi_status status;
> +
> +       status = acpi_evaluate_integer(handle, name, NULL, &val);
> +       if (ACPI_FAILURE(status)) {
> +               dev_err(dev, "Failed to parse ACPI entry %s, default to 0: %d\n",
> +                               name, status);
> +               return 0;
> +       }
> +       return val;
> +}
> +
> +static void rt5677_parse_acpi(struct rt5677_priv *rt5677, struct device *dev)
> +{
> +       rt5677->pdata.dmic2_clk_pin = (enum rt5677_dmic2_clk)
> +               rt5677_parse_acpi_entry(dev, "DCLK");
> +       rt5677->pdata.in1_diff = (bool)rt5677_parse_acpi_entry(dev, "IN1");
> +       rt5677->pdata.in2_diff = (bool)rt5677_parse_acpi_entry(dev, "IN2");
> +       rt5677->pdata.lout1_diff = (bool)rt5677_parse_acpi_entry(dev, "OUT1");
> +       rt5677->pdata.lout2_diff = (bool)rt5677_parse_acpi_entry(dev, "OUT2");
> +       rt5677->pdata.lout3_diff = (bool)rt5677_parse_acpi_entry(dev, "OUT3");
> +       rt5677->pdata.jd1_gpio = rt5677_parse_acpi_entry(dev, "JD1");
> +       rt5677->pdata.jd2_gpio = rt5677_parse_acpi_entry(dev, "JD2");
> +       rt5677->pdata.jd3_gpio = rt5677_parse_acpi_entry(dev, "JD3");
> +}
> +#else
> +static void rt5677_parse_acpi(struct rt5677_priv *rt5677, struct device *dev)
> +{
> +}
> +#endif
> +
>  static struct regmap_irq rt5677_irqs[] = {
>         [RT5677_IRQ_JD1] = {
>                 .reg_offset = 0,
> @@ -4604,6 +4642,7 @@ static int rt5677_i2c_probe(struct i2c_client *i2c,
>         if (pdata)
>                 rt5677->pdata = *pdata;
>
> +       rt5677->pow_ldo2 = -EINVAL;
>         if (i2c->dev.of_node) {
>                 ret = rt5677_parse_dt(rt5677, i2c->dev.of_node);
>                 if (ret) {
> @@ -4611,8 +4650,8 @@ static int rt5677_i2c_probe(struct i2c_client *i2c,
>                                 ret);
>                         return ret;
>                 }
> -       } else {
> -               rt5677->pow_ldo2 = -EINVAL;
> +       } else if (ACPI_HANDLE(&i2c->dev)) {
> +               rt5677_parse_acpi(rt5677, &i2c->dev);
>         }
>
>         if (gpio_is_valid(rt5677->pow_ldo2)) {
> @@ -4708,10 +4747,19 @@ static int rt5677_i2c_remove(struct i2c_client *i2c)
>         return 0;
>  }
>
> +#ifdef CONFIG_ACPI
> +static const struct acpi_device_id rt5677_acpi_id[] = {
> +       { "RT5677CE", 0 },
> +       { }
> +};
> +MODULE_DEVICE_TABLE(acpi, rt5677_acpi_id);
> +#endif
> +
>  static struct i2c_driver rt5677_i2c_driver = {
>         .driver = {
>                 .name = "rt5677",
>                 .owner = THIS_MODULE,
> +               .acpi_match_table = ACPI_PTR(rt5677_acpi_id),
>         },
>         .probe = rt5677_i2c_probe,
>         .remove   = rt5677_i2c_remove,
> --
> 2.1.0.rc2.206.gedb03e5
>
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