[PATCH v6 2/4] can: rockchip: add RK3588 CAN support

Add support for the RK3588 CAN controller by introducing a dedicated
model ID and OF match entry.

The block is closely related to the existing RK3568 variants, but it
cannot reuse their match data unchanged. In particular, RK3588
encodes RX_FIFO_CNT in bits 7:5 instead of 6:4, so the RX path needs
SoC-specific handling.

The RX FIFO count bitfield difference was found by comparing Rockchip's
vendor kernel 6.1 CAN support for RK3568 and RK3588. Runtime testing on
RK3588 also confirms that bits 7:5 are needed.

Enable the existing erratum 5 empty-FIFO workaround for RK3588.
Heiko reproduced erratum 6 on RK3588, so enable that workaround as
well.

CAN-FD is enabled for RK3588. The BRS bus-off issue seen in earlier
testing was caused by the transmit delay compensation setting. With
RKCANFD_REG_TRANSMIT_DELAY_COMPENSATION programmed to 0 on RK3588,
CAN-FD with BRS works in local testing.

Tested on an embedfire,rk3588-lubancat-5io board with can0/can1
directly connected, no other device on the bus, 60 Ohm bus
termination, and a 300 MHz CAN clock. Runtime testing used 500 kbit/s
arbitration bitrate and 1, 3 and 5 Mbit/s data bitrates. The 5 Mbit/s
data phase test ran for 15 minutes with cangen using BRS and
cansequence on the receiver. Both interfaces reported 9528377 packets
and 150667356 bytes, with 0 bus-errors, 0 error-warn, 0 error-pass and
0 bus-off events.

Co-developed-by: Heiko Stuebner <[email protected]>
Signed-off-by: Heiko Stuebner <[email protected]>
Tested-by: Heiko Stuebner <[email protected]>
Reviewed-by: Heiko Stuebner <[email protected]>
Signed-off-by: Cunhao Lu <[email protected]>
---
v3 -> v4:
- Disable TDC on RK3588 by programming
  RKCANFD_REG_TRANSMIT_DELAY_COMPENSATION to 0.
- Drop RKCANFD_QUIRK_CANFD_BROKEN for RK3588 and enable CAN-FD support.
- Document successful RK3588 CAN-FD/BRS testing.
v2 -> v3:
- Use Co-developed-by for Heiko's RK3588 contributions and add his
  Signed-off-by
- Collect Heiko's Reviewed-by and Tested-by tags
---
 drivers/net/can/rockchip/rockchip_canfd-core.c | 17 +++++++++++++++++
 drivers/net/can/rockchip/rockchip_canfd-rx.c   |  5 ++++-
 drivers/net/can/rockchip/rockchip_canfd.h      | 14 +++++++++++++-
 3 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/drivers/net/can/rockchip/rockchip_canfd-core.c b/drivers/net/can/rockchip/rockchip_canfd-core.c
index 29de0c01e4ed..37c1c22c40c9 100644
--- a/drivers/net/can/rockchip/rockchip_canfd-core.c
+++ b/drivers/net/can/rockchip/rockchip_canfd-core.c
@@ -50,6 +50,12 @@ static const struct rkcanfd_devtype_data rkcanfd_devtype_data_rk3568v3 = {
 		RKCANFD_QUIRK_CANFD_BROKEN,
 };
 
+static const struct rkcanfd_devtype_data rkcanfd_devtype_data_rk3588 = {
+	.model = RKCANFD_MODEL_RK3588,
+	.quirks = RKCANFD_QUIRK_RK3568_ERRATUM_5 |
+		RKCANFD_QUIRK_RK3568_ERRATUM_6,
+};
+
 static const char *__rkcanfd_get_model_str(enum rkcanfd_model model)
 {
 	switch (model) {
@@ -57,6 +63,8 @@ static const char *__rkcanfd_get_model_str(enum rkcanfd_model model)
 		return "rk3568v2";
 	case RKCANFD_MODEL_RK3568V3:
 		return "rk3568v3";
+	case RKCANFD_MODEL_RK3588:
+		return "rk3588";
 	}
 
 	return "<unknown>";
@@ -148,6 +156,12 @@ static int rkcanfd_set_bittiming(struct rkcanfd_priv *priv)
 
 	rkcanfd_write(priv, RKCANFD_REG_FD_DATA_BITTIMING, reg_dbt);
 
+	/* RK3588 CAN-FD BRS works with TDC disabled. */
+	if (priv->devtype_data.model == RKCANFD_MODEL_RK3588) {
+		rkcanfd_write(priv, RKCANFD_REG_TRANSMIT_DELAY_COMPENSATION, 0);
+		return 0;
+	}
+
 	tdco = (priv->can.clock.freq / dbt->bitrate) * 2 / 3;
 	tdco = min(tdco, FIELD_MAX(RKCANFD_REG_TRANSMIT_DELAY_COMPENSATION_TDC_OFFSET));
 
@@ -846,6 +860,9 @@ static const struct of_device_id rkcanfd_of_match[] = {
 	}, {
 		.compatible = "rockchip,rk3568v3-canfd",
 		.data = &rkcanfd_devtype_data_rk3568v3,
+	}, {
+		.compatible = "rockchip,rk3588-canfd",
+		.data = &rkcanfd_devtype_data_rk3588,
 	}, {
 		/* sentinel */
 	},
diff --git a/drivers/net/can/rockchip/rockchip_canfd-rx.c b/drivers/net/can/rockchip/rockchip_canfd-rx.c
index 475c0409e215..24e87daa1df0 100644
--- a/drivers/net/can/rockchip/rockchip_canfd-rx.c
+++ b/drivers/net/can/rockchip/rockchip_canfd-rx.c
@@ -281,7 +281,10 @@ rkcanfd_rx_fifo_get_len(const struct rkcanfd_priv *priv)
 {
 	const u32 reg = rkcanfd_read(priv, RKCANFD_REG_RX_FIFO_CTRL);
 
-	return FIELD_GET(RKCANFD_REG_RX_FIFO_CTRL_RX_FIFO_CNT, reg);
+	if (priv->devtype_data.model == RKCANFD_MODEL_RK3588)
+		return FIELD_GET(RKCANFD_REG_RX_FIFO_CTRL_RX_FIFO_CNT_RK3588, reg);
+
+	return FIELD_GET(RKCANFD_REG_RX_FIFO_CTRL_RX_FIFO_CNT_RK3568, reg);
 }
 
 int rkcanfd_handle_rx_int(struct rkcanfd_priv *priv)
diff --git a/drivers/net/can/rockchip/rockchip_canfd.h b/drivers/net/can/rockchip/rockchip_canfd.h
index 93131c7d7f54..95bea9bfd8a2 100644
--- a/drivers/net/can/rockchip/rockchip_canfd.h
+++ b/drivers/net/can/rockchip/rockchip_canfd.h
@@ -214,7 +214,8 @@
 #define RKCANFD_REG_TXEVENT_FIFO_CTRL_TXE_FIFO_ENABLE BIT(0)
 
 #define RKCANFD_REG_RX_FIFO_CTRL 0x118
-#define RKCANFD_REG_RX_FIFO_CTRL_RX_FIFO_CNT GENMASK(6, 4)
+#define RKCANFD_REG_RX_FIFO_CTRL_RX_FIFO_CNT_RK3568 GENMASK(6, 4)
+#define RKCANFD_REG_RX_FIFO_CTRL_RX_FIFO_CNT_RK3588 GENMASK(7, 5)
 #define RKCANFD_REG_RX_FIFO_CTRL_RX_FIFO_FULL_WATERMARK GENMASK(3, 1)
 #define RKCANFD_REG_RX_FIFO_CTRL_RX_FIFO_ENABLE BIT(0)
 
@@ -331,6 +332,11 @@
  * rarely with the standard clock of 300 MHz, but almost immediately
  * at 80 MHz.
  *
+ * Tests on the rk3588 show the same empty FIFO condition.
+ * In that setup rx_fifo_empty_errors increments when the bus
+ * transitions from idle to high CAN-FD load and stops growing once
+ * the bus reaches a steady state.
+ *
  * To workaround this problem, check for empty FIFO with
  * rkcanfd_fifo_header_empty() in rkcanfd_handle_rx_int_one() and exit
  * early.
@@ -344,6 +350,8 @@
 /* Erratum 6: The CAN controller's transmission of extended frames may
  * intermittently change into standard frames
  *
+ * Tests on the rk3588 show the same problem.
+ *
  * Work around this issue by activating self reception (RXSTX). If we
  * have pending TX CAN frames, check all RX'ed CAN frames in
  * rkcanfd_rxstx_filter().
@@ -424,6 +432,9 @@
  *     cansequence -rv -i 1
  *
  * - TX starvation after repeated Bus-Off
+ *   Tests on the rk3588 show the same problem. In a
+ *   10-cycle Bus-Off recovery test, 9 cycles failed to send after the
+ *   controller restarted.
  *   To reproduce:
  *   host:
  *     sleep 3 && cangen can0 -I2 -Li -Di -p10 -g 0.0
@@ -434,6 +445,7 @@
 enum rkcanfd_model {
 	RKCANFD_MODEL_RK3568V2 = 0x35682,
 	RKCANFD_MODEL_RK3568V3 = 0x35683,
+	RKCANFD_MODEL_RK3588 = 0x3588,
 };
 
 struct rkcanfd_devtype_data {

-- 
2.34.1