[PATCH v2 09/23] dmaengine: sdxi: Start functions on probe, stop on remove

[Nathan Lynch via B4 Relay <devnull+nathan.lynch.amd.com@kernel.org>]

From: Nathan Lynch <nathan.lynch@amd.com>

Following admin context setup in the previous patch, drive each SDXI
function to active state during probe. This is done by writing
GSRV_ACTIVE to MMIO_CTL0.fn_gsr and polling MMIO_STS0.fn_gsv until the
function reaches GSV_ACTIVE or an error state. A 1-second timeout has
been sufficient in practice so far.

Introduce sdxi_unregister() to stop the function during remove and wire
it up via the pci_driver .remove callback.

Co-developed-by: Wei Huang <wei.huang2@amd.com>
Signed-off-by: Wei Huang <wei.huang2@amd.com>
Signed-off-by: Nathan Lynch <nathan.lynch@amd.com>
---
 drivers/dma/sdxi/device.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++-
 drivers/dma/sdxi/pci.c    |  6 ++++++
 drivers/dma/sdxi/sdxi.h   |  1 +
 3 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/sdxi/device.c b/drivers/dma/sdxi/device.c
index 9d8729b62685..204841afa5b7 100644
--- a/drivers/dma/sdxi/device.c
+++ b/drivers/dma/sdxi/device.c
@@ -89,6 +89,42 @@ static void sdxi_write_fn_gsr(struct sdxi_dev *sdxi, enum sdxi_fn_gsr cmd)
 	sdxi_write64(sdxi, SDXI_MMIO_CTL0, ctl0);
 }
 
+/*
+ * Transition the function from stopped state to active.
+ * See SDXI 1.0 4.1 SDXI Function State.
+ */
+static int sdxi_dev_start(struct sdxi_dev *sdxi)
+{
+	enum sdxi_fn_gsv status = sdxi_dev_gsv(sdxi);
+	int ret;
+
+	if (status != SDXI_GSV_STOP) {
+		dev_err(sdxi->dev,
+			"can't activate busy device (unexpected gsv: %s)\n",
+			gsv_str(status));
+		return -EBUSY;
+	}
+
+	sdxi_write_fn_gsr(sdxi, SDXI_GSRV_ACTIVE);
+
+	ret = sdxi_dev_gsv_poll(sdxi, status,
+				status == SDXI_GSV_ACTIVE ||
+				status == SDXI_GSV_ERROR);
+	if (ret) {
+		dev_err(sdxi->dev, "activation timed out, current state: %s\n",
+			gsv_str(status));
+		return ret;
+	}
+
+	if (status == SDXI_GSV_ERROR) {
+		dev_err(sdxi->dev, "went to error state during activation\n");
+		return -EIO;
+	}
+
+	dev_dbg(sdxi->dev, "activated\n");
+	return 0;
+}
+
 /* Get the device to the GSV_STOP state. */
 static int sdxi_dev_stop(struct sdxi_dev *sdxi)
 {
@@ -222,7 +258,11 @@ static int sdxi_fn_activate(struct sdxi_dev *sdxi)
 	if (err)
 		return err;
 
-	return 0;
+	/*
+	 * SDXI 1.0 4.1.8.9: Set MMIO_CTL0.fn_gsr to GSRV_ACTIVE and
+	 * wait for MMIO_STS0.fn_gsv to reach GSV_ACTIVE or GSV_ERROR.
+	 */
+	return sdxi_dev_start(sdxi);
 }
 
 static int sdxi_device_init(struct sdxi_dev *sdxi)
@@ -281,3 +321,10 @@ int sdxi_register(struct device *dev, const struct sdxi_bus_ops *ops)
 
 	return sdxi_device_init(sdxi);
 }
+
+void sdxi_unregister(struct device *dev)
+{
+	struct sdxi_dev *sdxi = dev_get_drvdata(dev);
+
+	sdxi_dev_stop(sdxi);
+}
diff --git a/drivers/dma/sdxi/pci.c b/drivers/dma/sdxi/pci.c
index 9ac94d6f8b96..0f72cd359cf5 100644
--- a/drivers/dma/sdxi/pci.c
+++ b/drivers/dma/sdxi/pci.c
@@ -63,6 +63,11 @@ static int sdxi_pci_probe(struct pci_dev *pdev,
 	return sdxi_register(&pdev->dev, &sdxi_pci_ops);
 }
 
+static void sdxi_pci_remove(struct pci_dev *pdev)
+{
+	sdxi_unregister(&pdev->dev);
+}
+
 static const struct pci_device_id sdxi_id_table[] = {
 	{ PCI_DEVICE_CLASS(PCI_CLASS_ACCELERATOR_SDXI, 0xffffff) },
 	{ }
@@ -73,6 +78,7 @@ static struct pci_driver sdxi_driver = {
 	.name = "sdxi",
 	.id_table = sdxi_id_table,
 	.probe = sdxi_pci_probe,
+	.remove = sdxi_pci_remove,
 	.sriov_configure = pci_sriov_configure_simple,
 };
 
diff --git a/drivers/dma/sdxi/sdxi.h b/drivers/dma/sdxi/sdxi.h
index a0fef057b00b..7462fb912dc6 100644
--- a/drivers/dma/sdxi/sdxi.h
+++ b/drivers/dma/sdxi/sdxi.h
@@ -64,6 +64,7 @@ struct sdxi_dev {
 };
 
 int sdxi_register(struct device *dev, const struct sdxi_bus_ops *ops);
+void sdxi_unregister(struct device *dev);
 
 static inline u64 sdxi_read64(const struct sdxi_dev *sdxi, enum sdxi_reg reg)
 {

-- 
2.54.0