[PATCH net-next v3 08/13] net: lan966x: add shutdown callback to stop FDMA on reboot

[Daniel Machon <daniel.machon@microchip.com>]

When lan966x is used as a PCIe endpoint, the FDMA engine runs on the
card and survives a host reboot. Without a shutdown callback, channels
stay active and interrupt sources stay armed across the reset, causing
the shared PCIe INTx to assert before the driver has re-probed.

Add a shutdown callback, shared by the platform and PCI paths, that
masks FDMA interrupts (FDMA_INTR_ENA and FDMA_INTR_DB_ENA) and disables
the RX and TX channels.

FDMA_INTR_ENA persists on the card across a warm reboot, so also
restore the full enable in lan966x_fdma_rx_start() to re-arm interrupts
after a previous shutdown(). rx_start() runs after both the RX and TX
rings are allocated, so the same single-site re-arm works for both the
platform and PCIe backends.

Tested-by: Herve Codina <herve.codina@bootlin.com>
Signed-off-by: Daniel Machon <daniel.machon@microchip.com>
---
 drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c |  4 ++++
 drivers/net/ethernet/microchip/lan966x/lan966x_main.c | 18 ++++++++++++++++++
 drivers/net/ethernet/microchip/lan966x/lan966x_regs.h | 15 +++++++++++++++
 3 files changed, 37 insertions(+)

diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c b/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c
index 9bb40383aa56..493aef5ba8d1 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c
@@ -146,6 +146,10 @@ void lan966x_fdma_rx_start(struct lan966x_rx *rx)
 	struct fdma *fdma = &rx->fdma;
 	u32 mask;
 
+	lan_wr(FDMA_INTR_ENA_INTR_PORT_ENA_SET(GENMASK(1, 0)) |
+	       FDMA_INTR_ENA_INTR_CH_ENA_SET(GENMASK(7, 0)),
+	       lan966x, FDMA_INTR_ENA);
+
 	lan_wr(FDMA_CH_CFG_CH_DCB_DB_CNT_SET(fdma->n_dbs) |
 	       FDMA_CH_CFG_CH_INTR_DB_EOF_ONLY_SET(1) |
 	       FDMA_CH_CFG_CH_INJ_PORT_SET(0) |
diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
index b3701953b090..271c023900db 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
@@ -1311,9 +1311,27 @@ static void lan966x_remove(struct platform_device *pdev)
 	debugfs_remove_recursive(lan966x->debugfs_root);
 }
 
+static void lan966x_shutdown(struct platform_device *pdev)
+{
+	struct lan966x *lan966x = platform_get_drvdata(pdev);
+
+	if (!lan966x->fdma)
+		return;
+
+	lan966x_fdma_rx_disable(&lan966x->rx);
+	lan966x_fdma_tx_disable(&lan966x->tx);
+
+	napi_synchronize(&lan966x->napi);
+	napi_disable(&lan966x->napi);
+
+	lan_wr(0, lan966x, FDMA_INTR_ENA);
+	lan_wr(0, lan966x, FDMA_INTR_DB_ENA);
+}
+
 static struct platform_driver lan966x_driver = {
 	.probe = lan966x_probe,
 	.remove = lan966x_remove,
+	.shutdown = lan966x_shutdown,
 	.driver = {
 		.name = "lan966x-switch",
 		.of_match_table = lan966x_match,
diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_regs.h b/drivers/net/ethernet/microchip/lan966x/lan966x_regs.h
index 4b553927d2e0..aba0d36ae6b5 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_regs.h
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_regs.h
@@ -1039,6 +1039,21 @@ enum lan966x_target {
 /*      FDMA:FDMA:FDMA_INTR_ERR */
 #define FDMA_INTR_ERR             __REG(TARGET_FDMA, 0, 1, 8, 0, 1, 428, 400, 0, 1, 4)
 
+/*      FDMA:FDMA:FDMA_INTR_ENA */
+#define FDMA_INTR_ENA             __REG(TARGET_FDMA, 0, 1, 8, 0, 1, 428, 404, 0, 1, 4)
+
+#define FDMA_INTR_ENA_INTR_PORT_ENA              GENMASK(9, 8)
+#define FDMA_INTR_ENA_INTR_PORT_ENA_SET(x)\
+	FIELD_PREP(FDMA_INTR_ENA_INTR_PORT_ENA, x)
+#define FDMA_INTR_ENA_INTR_PORT_ENA_GET(x)\
+	FIELD_GET(FDMA_INTR_ENA_INTR_PORT_ENA, x)
+
+#define FDMA_INTR_ENA_INTR_CH_ENA                GENMASK(7, 0)
+#define FDMA_INTR_ENA_INTR_CH_ENA_SET(x)\
+	FIELD_PREP(FDMA_INTR_ENA_INTR_CH_ENA, x)
+#define FDMA_INTR_ENA_INTR_CH_ENA_GET(x)\
+	FIELD_GET(FDMA_INTR_ENA_INTR_CH_ENA, x)
+
 /*      FDMA:FDMA:FDMA_ERRORS */
 #define FDMA_ERRORS               __REG(TARGET_FDMA, 0, 1, 8, 0, 1, 428, 412, 0, 1, 4)
 

-- 
2.34.1