[PATCH v7 0/2] Add Loongson CAN-FD controller driver

[Binbin Zhou <zhoubinbin@loongson.cn>]

Hi all:

This patchset adds support for the CAN-FD controller found on Loongson
CPUs.

Patch 1 introduces the basic CAN-FD controller driver with support
for classic CAN and CAN FD, including bit timing, error handling,
NAPI-based RX, and multiple TX buffers.

Patch 2 adds optional DMA support for RX path using the Loongson APB
CMC DMA engine, which significantly reduces CPU load under high
receive throughput.

The driver has been tested on Loongson-2K3000 platforms with various
CAN/CAN FD traffic patterns.

Finally, I'd like to thank Bingxiong, the original author of this driver,
for his efforts in working on the patch.

Thanks.
Binbin

=========
V7:
Patch (1/2):
 - Fix can_bittiming_const->tseg1_max;
 - Fix TX buffer id in loongson_canfd_start_xmit();
 - Add rwcnt checking in loongson_canfd_rx()
 - Add netdev stats spinlock;
 - Add net_ratelimit() to control log output in
   loongson_canfd_err_interrupt);
 - Rewrite `loongson_canfd_rx_napi()` to clearly distinguish between the
   two scenarios: "no more data to process" and "quota exhausted".

Patch (2/2):
 - Put dmaengine_terminate_sync() before loongson_canfd_rxdma_free();

Link to V6:
https://lore.kernel.org/all/cover.1784597141.git.zhoubinbin@loongson.cn/

V6:
- Rebase on linux-can/master;
Patch (1/2):
 - Drop CAN_CTRLMODE_3_SAMPLES ctrlmode;
 - Replace kfree_skb() with dev_kfree_skb_any();
 - Drop REG_CMD_ERCRST operation;
 - Rewrite `loongson_canfd_tx_interrupt()` to prevent duplicate handling
   of TX completion';
Patch (2/2):
 - Added a fallback to true when dmaengine_tx_status() returns an error;
 - Replaced all direct regmap_read() from LOONGSON_CANFD_RX_DATA with
   the priv->get_rx_data() callback;
 - Release the DMA channel and clear priv->rx_ch on dma_alloc_coherent()
   failure;

Link to V5:
https://lore.kernel.org/all/cover.1783670733.git.zhoubinbin@loongson.cn/

V5:
Patch (1/2):
 - Fix tseg1_max const value;
 - Empty FIFO when SKB allocate failed.
 - Use REG_FRAME_META1_RWCNT as the playload read count value;
 - Only clean processed interrupt flags in
   loongson_canfd_err_interrupt();
 - Refact loongson_canfd_tx_interrupt();
 - Add LOONGSON_CANFD_TRV_DLY into loongson_canfd_volatile_reg();
Patch (2/2):
 - Fix dma_request_chan() error path;
 - Fix build error;
 - Fix loongson_canfd_rxdma_init() error path;

Link to V4:
https://lore.kernel.org/all/cover.1783391759.git.zhoubinbin@loongson.cn/

V4:
- Fix some issues from sashiko.
Patch (1/2):
 - Update commit message;
 - Use common APIs to calculate DLC;
 - Correct CAN_RTR_FLAG judgement;
 - Add skb check for CAN_STATE_ERROR_ACTIVE case;
 - Use regmap_write() rather than regmap_update_bits() to
   disable all interrupts;
 - Add napi_disable() in error paths;
 - Add `clock-frequency` return value check;
 - More comments for macros.

Link to V3:
https://lore.kernel.org/all/cover.1782787997.git.zhoubinbin@loongson.cn/

V3:
Patch (1/2):
 - Replace the switch-case statement with a calculated mask in
   `loongson_canfd_get_txbuf_sts()`;
 - Change `loongson_canfd_reset()` return type to `void`;
 - Drop old code in `loongson_canfd_set_btr()`;
 - Rename `loongson_canfd_set_mode()` to `loongson_canfd_set_conf_mode()`;
 - Drop `cf->__res*` usage;
 - Drop unnecessary macro definitions;
 - Add `netif_napi_del()` in probe error route path;
 - Replace ternary operator with `if-else`;
 - Drop stats->rx_packets and stats->rx_bytes count in CAN error frames;
 - Add ethtool_ops;
 - Add CAN_CTRLMODE_CC_LEN8_DLC;

Patch (2/2):
 - Fix W=2 warning;
 - Rename get_rx_frc() -> get_rxbuf_empty();
 - Put `loongson_canfd_rxdma_remove()` before free_candev();
 - Adjust the RXDMA probe process.

Link to V2:
https://lore.kernel.org/all/cover.1780908445.git.zhoubinbin@loongson.cn/

V2:
Patch (1/2):
 - Put all code into one file;
 - Add COMPILE_TEST Kconfig option;
 - Rewrite Kconfig description;
 - Use `regmap_test_bits()` to simplify bit field checks;
 - Drop odd FIELD_GET() usage;
 - Don't use FIELD_GET() for a single bit;
 - Use an if/else instead of the ternary operator;
 - Use the CAN TDC framework to get the SSP value;
 - Use guard(spinlock)/scoped_guard(spinlock);
 - Use netdev_debug() to be less verboss;
 - Check for memory allocation failure;
 - Add CAN_ERR_CNT flag;
 - Drop unused REG_DATA_xx_yy_W_DATA_yy definition;
 - Add more function comment;

Link to V1:
https://lore.kernel.org/all/cover.1777273055.git.zhoubinbin@loongson.cn/

Binbin Zhou (2):
  can: Add Loongson CAN-FD controller driver
  can: loongson_canfd: Add RXDMA support

 MAINTAINERS                      |    7 +
 drivers/net/can/Kconfig          |   11 +
 drivers/net/can/Makefile         |    1 +
 drivers/net/can/loongson_canfd.c | 1913 ++++++++++++++++++++++++++++++
 4 files changed, 1932 insertions(+)
 create mode 100644 drivers/net/can/loongson_canfd.c


base-commit: 3bd438a58e910db5dc369aa25dfed1fc95f1b596
-- 
2.52.0