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1// SPDX-License-Identifier: GPL-2.02//3// mcp251xfd - Microchip MCP251xFD Family CAN controller driver4//5// Copyright (c) 2019, 2020, 2021, 2023 Pengutronix,6// Marc Kleine-Budde <kernel@pengutronix.de>7//8// Based on:9//10// CAN bus driver for Microchip 25XXFD CAN Controller with SPI Interface11//12// Copyright (c) 2019 Martin Sperl <kernel@martin.sperl.org>13//14 15#include <linux/bitfield.h>16 17#include "mcp251xfd.h"18 19static inline bool mcp251xfd_tx_fifo_sta_empty(u32 fifo_sta)20{21 return fifo_sta & MCP251XFD_REG_FIFOSTA_TFERFFIF;22}23 24static inline int25mcp251xfd_tef_tail_get_from_chip(const struct mcp251xfd_priv *priv,26 u8 *tef_tail)27{28 u32 tef_ua;29 int err;30 31 err = regmap_read(priv->map_reg, MCP251XFD_REG_TEFUA, &tef_ua);32 if (err)33 return err;34 35 *tef_tail = tef_ua / sizeof(struct mcp251xfd_hw_tef_obj);36 37 return 0;38}39 40static int mcp251xfd_check_tef_tail(const struct mcp251xfd_priv *priv)41{42 u8 tef_tail_chip, tef_tail;43 int err;44 45 if (!IS_ENABLED(CONFIG_CAN_MCP251XFD_SANITY))46 return 0;47 48 err = mcp251xfd_tef_tail_get_from_chip(priv, &tef_tail_chip);49 if (err)50 return err;51 52 tef_tail = mcp251xfd_get_tef_tail(priv);53 if (tef_tail_chip != tef_tail) {54 netdev_err(priv->ndev,55 "TEF tail of chip (0x%02x) and ours (0x%08x) inconsistent.\n",56 tef_tail_chip, tef_tail);57 return -EILSEQ;58 }59 60 return 0;61}62 63static int64mcp251xfd_handle_tefif_one(struct mcp251xfd_priv *priv,65 const struct mcp251xfd_hw_tef_obj *hw_tef_obj,66 unsigned int *frame_len_ptr)67{68 struct net_device_stats *stats = &priv->ndev->stats;69 u32 seq, tef_tail_masked, tef_tail;70 struct sk_buff *skb;71 72 /* Use the MCP2517FD mask on the MCP2518FD, too. We only73 * compare 7 bits, this is enough to detect old TEF objects.74 */75 seq = FIELD_GET(MCP251XFD_OBJ_FLAGS_SEQ_MCP2517FD_MASK,76 hw_tef_obj->flags);77 tef_tail_masked = priv->tef->tail &78 field_mask(MCP251XFD_OBJ_FLAGS_SEQ_MCP2517FD_MASK);79 80 /* According to mcp2518fd erratum DS80000789E 6. the FIFOCI81 * bits of a FIFOSTA register, here the TX FIFO tail index82 * might be corrupted and we might process past the TEF FIFO's83 * head into old CAN frames.84 *85 * Compare the sequence number of the currently processed CAN86 * frame with the expected sequence number. Abort with87 * -EBADMSG if an old CAN frame is detected.88 */89 if (seq != tef_tail_masked) {90 netdev_dbg(priv->ndev, "%s: chip=0x%02x ring=0x%02x\n", __func__,91 seq, tef_tail_masked);92 stats->tx_fifo_errors++;93 94 return -EBADMSG;95 }96 97 tef_tail = mcp251xfd_get_tef_tail(priv);98 skb = priv->can.echo_skb[tef_tail];99 if (skb)100 mcp251xfd_skb_set_timestamp_raw(priv, skb, hw_tef_obj->ts);101 stats->tx_bytes +=102 can_rx_offload_get_echo_skb_queue_timestamp(&priv->offload,103 tef_tail, hw_tef_obj->ts,104 frame_len_ptr);105 stats->tx_packets++;106 priv->tef->tail++;107 108 return 0;109}110 111static int112mcp251xfd_get_tef_len(struct mcp251xfd_priv *priv, u8 *len_p)113{114 const struct mcp251xfd_tx_ring *tx_ring = priv->tx;115 const u8 shift = tx_ring->obj_num_shift_to_u8;116 u8 chip_tx_tail, tail, len;117 u32 fifo_sta;118 int err;119 120 err = regmap_read(priv->map_reg, MCP251XFD_REG_FIFOSTA(priv->tx->fifo_nr),121 &fifo_sta);122 if (err)123 return err;124 125 /* If the chip says the TX-FIFO is empty, but there are no TX126 * buffers free in the ring, we assume all have been sent.127 */128 if (mcp251xfd_tx_fifo_sta_empty(fifo_sta) &&129 mcp251xfd_get_tx_free(tx_ring) == 0) {130 *len_p = tx_ring->obj_num;131 return 0;132 }133 134 chip_tx_tail = FIELD_GET(MCP251XFD_REG_FIFOSTA_FIFOCI_MASK, fifo_sta);135 136 err = mcp251xfd_check_tef_tail(priv);137 if (err)138 return err;139 tail = mcp251xfd_get_tef_tail(priv);140 141 /* First shift to full u8. The subtraction works on signed142 * values, that keeps the difference steady around the u8143 * overflow. The right shift acts on len, which is an u8.144 */145 BUILD_BUG_ON(sizeof(tx_ring->obj_num) != sizeof(chip_tx_tail));146 BUILD_BUG_ON(sizeof(tx_ring->obj_num) != sizeof(tail));147 BUILD_BUG_ON(sizeof(tx_ring->obj_num) != sizeof(len));148 149 len = (chip_tx_tail << shift) - (tail << shift);150 *len_p = len >> shift;151 152 return 0;153}154 155static inline int156mcp251xfd_tef_obj_read(const struct mcp251xfd_priv *priv,157 struct mcp251xfd_hw_tef_obj *hw_tef_obj,158 const u8 offset, const u8 len)159{160 const struct mcp251xfd_tx_ring *tx_ring = priv->tx;161 const int val_bytes = regmap_get_val_bytes(priv->map_rx);162 163 if (IS_ENABLED(CONFIG_CAN_MCP251XFD_SANITY) &&164 (offset > tx_ring->obj_num ||165 len > tx_ring->obj_num ||166 offset + len > tx_ring->obj_num)) {167 netdev_err(priv->ndev,168 "Trying to read too many TEF objects (max=%d, offset=%d, len=%d).\n",169 tx_ring->obj_num, offset, len);170 return -ERANGE;171 }172 173 return regmap_bulk_read(priv->map_rx,174 mcp251xfd_get_tef_obj_addr(offset),175 hw_tef_obj,176 sizeof(*hw_tef_obj) / val_bytes * len);177}178 179static inline void mcp251xfd_ecc_tefif_successful(struct mcp251xfd_priv *priv)180{181 struct mcp251xfd_ecc *ecc = &priv->ecc;182 183 ecc->ecc_stat = 0;184}185 186int mcp251xfd_handle_tefif(struct mcp251xfd_priv *priv)187{188 struct mcp251xfd_hw_tef_obj hw_tef_obj[MCP251XFD_TX_OBJ_NUM_MAX];189 unsigned int total_frame_len = 0;190 u8 tef_tail, len, l;191 int err, i;192 193 err = mcp251xfd_get_tef_len(priv, &len);194 if (err)195 return err;196 197 tef_tail = mcp251xfd_get_tef_tail(priv);198 l = mcp251xfd_get_tef_linear_len(priv, len);199 err = mcp251xfd_tef_obj_read(priv, hw_tef_obj, tef_tail, l);200 if (err)201 return err;202 203 if (l < len) {204 err = mcp251xfd_tef_obj_read(priv, &hw_tef_obj[l], 0, len - l);205 if (err)206 return err;207 }208 209 for (i = 0; i < len; i++) {210 unsigned int frame_len = 0;211 212 err = mcp251xfd_handle_tefif_one(priv, &hw_tef_obj[i], &frame_len);213 /* -EBADMSG means we're affected by mcp2518fd erratum214 * DS80000789E 6., i.e. the Sequence Number in the TEF215 * doesn't match our tef_tail. Don't process any216 * further and mark processed frames as good.217 */218 if (err == -EBADMSG)219 goto out_netif_wake_queue;220 if (err)221 return err;222 223 total_frame_len += frame_len;224 }225 226out_netif_wake_queue:227 len = i; /* number of handled goods TEFs */228 if (len) {229 struct mcp251xfd_tef_ring *ring = priv->tef;230 struct mcp251xfd_tx_ring *tx_ring = priv->tx;231 int offset;232 233 ring->head += len;234 235 /* Increment the TEF FIFO tail pointer 'len' times in236 * a single SPI message.237 *238 * Note:239 * Calculate offset, so that the SPI transfer ends on240 * the last message of the uinc_xfer array, which has241 * "cs_change == 0", to properly deactivate the chip242 * select.243 */244 offset = ARRAY_SIZE(ring->uinc_xfer) - len;245 err = spi_sync_transfer(priv->spi,246 ring->uinc_xfer + offset, len);247 if (err)248 return err;249 250 tx_ring->tail += len;251 netdev_completed_queue(priv->ndev, len, total_frame_len);252 253 err = mcp251xfd_check_tef_tail(priv);254 if (err)255 return err;256 }257 258 mcp251xfd_ecc_tefif_successful(priv);259 260 if (mcp251xfd_get_tx_free(priv->tx)) {261 /* Make sure that anybody stopping the queue after262 * this sees the new tx_ring->tail.263 */264 smp_mb();265 netif_wake_queue(priv->ndev);266 }267 268 if (priv->tx_coalesce_usecs_irq)269 hrtimer_start(&priv->tx_irq_timer,270 ns_to_ktime(priv->tx_coalesce_usecs_irq *271 NSEC_PER_USEC),272 HRTIMER_MODE_REL);273 274 return 0;275}276