mfd: cros_ec_dev: Only register PCHG device if present

Don't create a device for the peripheral charger (PCHG) if there aren't
any peripheral charger ports. This removes a device on most ChromeOS
systems, because the peripheral charger functionality isn't always
present.

Cc: Prashant Malani <pmalani@chromium.org>
Cc: Tzung-Bi Shih <tzungbi@kernel.org>
Cc: Daisuke Nojiri <dnojiri@chromium.org>
Cc: Benson Leung <bleung@chromium.org>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: <chrome-platform@lists.linux.dev>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Prashant Malani <pmalani@chromium.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20220419000408.3202635-1-swboyd@chromium.org

diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
index 546feef851abb5e7abc63c820322f0878220117b..596731caf4079f2d1a1d9d818de4362372cf7dc8 100644 (file)
--- a/drivers/mfd/cros_ec_dev.c
+++ b/drivers/mfd/cros_ec_dev.c
@@ -114,6 +114,9 @@ static const struct mfd_cell cros_ec_platform_cells[] = {
        { .name = "cros-ec-chardev", },
        { .name = "cros-ec-debugfs", },
        { .name = "cros-ec-sysfs", },
+};
+
+static const struct mfd_cell cros_ec_pchg_cells[] = {
        { .name = "cros-ec-pchg", },
 };
 
@@ -137,6 +140,7 @@ static int ec_device_probe(struct platform_device *pdev)
        struct device *dev = &pdev->dev;
        struct cros_ec_platform *ec_platform = dev_get_platdata(dev);
        struct cros_ec_dev *ec = kzalloc(sizeof(*ec), GFP_KERNEL);
+       struct ec_response_pchg_count pchg_count;
        int i;
 
        if (!ec)
@@ -242,6 +246,21 @@ static int ec_device_probe(struct platform_device *pdev)
                }
        }
 
+       /*
+        * The PCHG device cannot be detected by sending EC_FEATURE_GET_CMD, but
+        * it can be detected by querying the number of peripheral chargers.
+        */
+       retval = cros_ec_command(ec->ec_dev, 0, EC_CMD_PCHG_COUNT, NULL, 0,
+                                &pchg_count, sizeof(pchg_count));
+       if (retval >= 0 && pchg_count.port_count) {
+               retval = mfd_add_hotplug_devices(ec->dev,
+                                       cros_ec_pchg_cells,
+                                       ARRAY_SIZE(cros_ec_pchg_cells));
+               if (retval)
+                       dev_warn(ec->dev, "failed to add pchg: %d\n",
+                                retval);
+       }
+
        /*
         * The following subdevices cannot be detected by sending the
         * EC_FEATURE_GET_CMD to the Embedded Controller device.