[PATCH v4 11/25] 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>

Activate the function after administrative context setup, polling for
GSV_ACTIVE or GSV_ERROR with a one-second timeout. Stop the function during
PCI removal.

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 | 53 ++++++++++++++++++++++++++++++++++++++++++++++-
 drivers/dma/sdxi/pci.c    |  1 +
 drivers/dma/sdxi/sdxi.h   |  1 +
 3 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/sdxi/device.c b/drivers/dma/sdxi/device.c
index f9787d7190d4..d5a5b8d43391 100644
--- a/drivers/dma/sdxi/device.c
+++ b/drivers/dma/sdxi/device.c
@@ -212,6 +212,36 @@ static int sdxi_dev_stop(struct sdxi_dev *sdxi)
 	return sdxi->bus_ops->reset ? sdxi->bus_ops->reset(sdxi) : -EIO;
 }
 
+/*
+ * Activate a stopped function. GSRV_ACTIVE takes it through the
+ * transient GSV_INIT state to GSV_ACTIVE or GSV_ERROR. See SDXI 1.0
+ * 4.1.8.9.
+ */
+static int sdxi_dev_start(struct sdxi_dev *sdxi)
+{
+	const unsigned long settled = BIT(SDXI_GSV_ACTIVE) | BIT(SDXI_GSV_ERROR);
+	enum sdxi_fn_gsv gsv = sdxi_dev_gsv(sdxi);
+
+	if (gsv != SDXI_GSV_STOP) {
+		dev_err(sdxi->dev,
+			"start: MMIO_STS0.fn_gsv = %#x (%s) on entry\n",
+			gsv, gsv_str(gsv));
+		return -EBUSY;
+	}
+
+	sdxi_write_fn_gsr(sdxi, SDXI_GSRV_ACTIVE);
+
+	if (sdxi_dev_gsv_poll(sdxi, gsv, BIT(gsv) & settled) ||
+	    gsv != SDXI_GSV_ACTIVE) {
+		dev_err(sdxi->dev,
+			"start: MMIO_STS0.fn_gsv = %#x (%s) after activate\n",
+			gsv, gsv_str(gsv));
+		return -EIO;
+	}
+
+	return 0;
+}
+
 /* Stop the function and discard inherited MMIO configuration. */
 static int sdxi_fn_prepare(struct sdxi_dev *sdxi)
 {
@@ -361,7 +391,20 @@ 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.
+	 *
+	 * We haven't queued any descriptors to the admin context at
+	 * this point, so the admin context jump start (SDXI 1.0
+	 * 4.1.8.10.b) is accomplished later when other
+	 * code starts client contexts.
+	 */
+	err = sdxi_dev_start(sdxi);
+	if (err)
+		sdxi_dev_stop(sdxi);
+
+	return err;
 }
 
 static int sdxi_device_init(struct sdxi_dev *sdxi)
@@ -407,6 +450,14 @@ int sdxi_register(struct device *dev, const struct sdxi_bus_ops *ops)
 }
 EXPORT_SYMBOL_NS_GPL(sdxi_register, "SDXI");
 
+void sdxi_unregister(struct device *dev)
+{
+	struct sdxi_dev *sdxi = dev_get_drvdata(dev);
+
+	sdxi_dev_stop(sdxi);
+}
+EXPORT_SYMBOL_NS_GPL(sdxi_unregister, "SDXI");
+
 MODULE_AUTHOR("Wei Huang");
 MODULE_AUTHOR("Nathan Lynch");
 MODULE_DESCRIPTION("SDXI core");
diff --git a/drivers/dma/sdxi/pci.c b/drivers/dma/sdxi/pci.c
index 6a293db69199..d196ab5cf6f1 100644
--- a/drivers/dma/sdxi/pci.c
+++ b/drivers/dma/sdxi/pci.c
@@ -99,6 +99,7 @@ static int sdxi_pci_probe(struct pci_dev *pdev,
 
 static void sdxi_pci_remove(struct pci_dev *pdev)
 {
+	sdxi_unregister(&pdev->dev);
 	pci_disable_sriov(pdev);
 }
 
diff --git a/drivers/dma/sdxi/sdxi.h b/drivers/dma/sdxi/sdxi.h
index 525473029987..631a605ea62f 100644
--- a/drivers/dma/sdxi/sdxi.h
+++ b/drivers/dma/sdxi/sdxi.h
@@ -68,6 +68,7 @@ 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)
 {

-- 
2.56.0