[PATCH v2] mfd: cros_ec_dev: Only register PCHG device if present

[Stephen Boyd <swboyd@chromium.org>]

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>
---

Changes from v1 (https://lore.kernel.org/r/20220415003253.1973106-1-swboyd@chromium.org):
 * Use cros_ec_command()
 * Drop the other patches that aren't needed anymore

 drivers/mfd/cros_ec_dev.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
index 546feef851ab..596731caf407 100644
--- 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.

base-commit: 3123109284176b1532874591f7c81f3837bbdc17
-- 
https://chromeos.dev