[PATCH v6 2/5] usb: cdns3-ti: run HW init at resume() if HW was reset

Théo Lebrun
2024-12-10T17:13:44Z

At runtime_resume(), read the W1 (Wrapper Register 1) register to detect
if an hardware reset occurred. If it did, run the hardware init sequence.

This callback will be called at system-wide resume. Previously, if a
reset occurred during suspend, we would crash. The wrapper config had
not been written, leading to invalid register accesses inside cdns3.

Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
---
drivers/usb/cdns3/cdns3-ti.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)

diff --git a/drivers/usb/cdns3/cdns3-ti.c b/drivers/usb/cdns3/cdns3-ti.c
index d704eb39820ad08a8774be7f00aa473c3ff267c0..d35be7db7616ef5e5bed7dbd53b78a094809f7cc 100644
--- a/drivers/usb/cdns3/cdns3-ti.c
+++ b/drivers/usb/cdns3/cdns3-ti.c
@@ -188,6 +188,12 @@ static int cdns_ti_probe(struct platform_device *pdev)
data->vbus_divider = device_property_read_bool(dev, "ti,vbus-divider");
data->usb2_only = device_property_read_bool(dev, "ti,usb2-only");

+ /*
+ * The call below to pm_runtime_get_sync() MIGHT reset hardware, if it
+ * detects it as uninitialised. We want to enforce a reset at probe,
+ * and so do it manually here. This means the first runtime_resume()
+ * will be a no-op.
+ */
cdns_ti_reset_and_init_hw(data);

pm_runtime_enable(dev);
@@ -232,6 +238,24 @@ static void cdns_ti_remove(struct platform_device *pdev)
platform_set_drvdata(pdev, NULL);
}

+static int cdns_ti_runtime_resume(struct device *dev)
+{
+ const u32 mask = USBSS_W1_PWRUP_RST | USBSS_W1_MODESTRAP_SEL;
+ struct cdns_ti *data = dev_get_drvdata(dev);
+ u32 w1;
+
+ w1 = cdns_ti_readl(data, USBSS_W1);
+ if ((w1 & mask) != mask)
+ cdns_ti_reset_and_init_hw(data);
+
+ return 0;
+}
+
+static const struct dev_pm_ops cdns_ti_pm_ops = {
+ RUNTIME_PM_OPS(NULL, cdns_ti_runtime_resume, NULL)
+ SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, pm_runtime_force_resume)
+};
+
static const struct of_device_id cdns_ti_of_match[] = {
{ .compatible = "ti,j721e-usb", },
{ .compatible = "ti,am64-usb", },
@@ -245,6 +269,7 @@ static struct platform_driver cdns_ti_driver = {
.driver = {
.name = "cdns3-ti",
.of_match_table = cdns_ti_of_match,
+ .pm = pm_ptr(&cdns_ti_pm_ops),
},
};

--
2.47.1