[PATCH V5 3/4] Bluetooth: btnxpuart: Add M.2 Bluetooth device support using pwrseq

[Sherry Sun (OSS)]

From: Sherry Sun <sherry.sun@xxxxxxx>

Power supply to the M.2 Bluetooth device attached to the host using M.2
connector is controlled using the 'uart' pwrseq device. So add support
for getting the pwrseq device if the OF graph link is present.

Once obtained, pwrseq_power_on() is called to power up the M.2 Bluetooth
card. The power sequencer descriptor is obtained via devm_pwrseq_get()
with the UART controller device (serdev->ctrl->dev), since the OF graph
link is defined on the UART controller node.

The devm cleanup of the pwrseq descriptor is tied to the UART controller
device, not the serdev child device, so it does not fire when the serdev
probe fails and nxp_serdev_remove(), an explicit pwrseq_power_off() call
is added in probe error path and nxp_serdev_remove() to ensure the power
reference stay balanced.

Signed-off-by: Sherry Sun <sherry.sun@xxxxxxx>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>
Reviewed-by: Frank Li <Frank.Li@xxxxxxx>
---
Hi Frank and Bartosz, this V5 patch adds an explicit pwrseq_power_off()
call in both probe error path and nxp_serdev_remove() to properly handle
power references. I'm keeping your Reviewed-by tag. I can remove it if you
think it's inappropriate.
---
 drivers/bluetooth/btnxpuart.c | 34 ++++++++++++++++++++++++++++++----
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/drivers/bluetooth/btnxpuart.c b/drivers/bluetooth/btnxpuart.c
index 0bb300eef157..68f84c324113 100644
--- a/drivers/bluetooth/btnxpuart.c
+++ b/drivers/bluetooth/btnxpuart.c
@@ -9,6 +9,8 @@
 
 #include <linux/serdev.h>
 #include <linux/of.h>
+#include <linux/of_graph.h>
+#include <linux/pwrseq/consumer.h>
 #include <linux/skbuff.h>
 #include <linux/unaligned.h>
 #include <linux/firmware.h>
@@ -211,6 +213,7 @@ struct btnxpuart_dev {
 
 	struct ps_data psdata;
 	struct btnxpuart_data *nxp_data;
+	struct pwrseq_desc *pwrseq;
 	struct reset_control *pdn;
 	struct hci_uart hu;
 };
@@ -1872,11 +1875,26 @@ static int nxp_serdev_probe(struct serdev_device *serdev)
 		return err;
 	}
 
+	if (of_graph_is_present(dev_of_node(&serdev->ctrl->dev))) {
+		struct pwrseq_desc *pwrseq;
+
+		pwrseq = devm_pwrseq_get(&serdev->ctrl->dev, "uart");
+		if (IS_ERR(pwrseq))
+			return dev_err_probe(&serdev->dev, PTR_ERR(pwrseq),
+					     "failed to get pwrseq\n");
+
+		nxpdev->pwrseq = pwrseq;
+		err = pwrseq_power_on(pwrseq);
+		if (err)
+			return err;
+	}
+
 	/* Initialize and register HCI device */
 	hdev = hci_alloc_dev();
 	if (!hdev) {
 		dev_err(&serdev->dev, "Can't allocate HCI device\n");
-		return -ENOMEM;
+		err = -ENOMEM;
+		goto err_pwrseq_power_off;
 	}
 
 	reset_control_deassert(nxpdev->pdn);
@@ -1907,13 +1925,16 @@ static int nxp_serdev_probe(struct serdev_device *serdev)
 	if (bacmp(&ba, BDADDR_ANY))
 		hci_set_quirk(hdev, HCI_QUIRK_USE_BDADDR_PROPERTY);
 
-	if (hci_register_dev(hdev) < 0) {
+	err = hci_register_dev(hdev);
+	if (err < 0) {
 		dev_err(&serdev->dev, "Can't register HCI device\n");
 		goto probe_fail;
 	}
 
-	if (ps_setup(hdev))
+	if (ps_setup(hdev)) {
+		err = -ENODEV;
 		goto probe_fail_unregister;
+	}
 
 	hci_devcd_register(hdev, nxp_coredump, nxp_coredump_hdr,
 			   nxp_coredump_notify);
@@ -1925,7 +1946,10 @@ static int nxp_serdev_probe(struct serdev_device *serdev)
 probe_fail:
 	reset_control_assert(nxpdev->pdn);
 	hci_free_dev(hdev);
-	return -ENODEV;
+err_pwrseq_power_off:
+	if (nxpdev->pwrseq)
+		pwrseq_power_off(nxpdev->pwrseq);
+	return err;
 }
 
 static void nxp_serdev_remove(struct serdev_device *serdev)
@@ -1952,6 +1976,8 @@ static void nxp_serdev_remove(struct serdev_device *serdev)
 	ps_cleanup(nxpdev);
 	hci_unregister_dev(hdev);
 	reset_control_assert(nxpdev->pdn);
+	if (nxpdev->pwrseq)
+		pwrseq_power_off(nxpdev->pwrseq);
 	hci_free_dev(hdev);
 }
 
-- 
2.50.1