diff options
Diffstat (limited to 'drivers/net/can/at91_can.c')
| -rw-r--r-- | drivers/net/can/at91_can.c | 1186 |
1 files changed, 1186 insertions, 0 deletions
diff --git a/drivers/net/can/at91_can.c b/drivers/net/can/at91_can.c new file mode 100644 index 00000000000..f67ae285a35 --- /dev/null +++ b/drivers/net/can/at91_can.c @@ -0,0 +1,1186 @@ +/* + * at91_can.c - CAN network driver for AT91 SoC CAN controller + * + * (C) 2007 by Hans J. Koch <hjk@linutronix.de> + * (C) 2008, 2009 by Marc Kleine-Budde <kernel@pengutronix.de> + * + * This software may be distributed under the terms of the GNU General + * Public License ("GPL") version 2 as distributed in the 'COPYING' + * file from the main directory of the linux kernel source. + * + * Send feedback to <socketcan-users@lists.berlios.de> + * + * + * Your platform definition file should specify something like: + * + * static struct at91_can_data ek_can_data = { + * transceiver_switch = sam9263ek_transceiver_switch, + * }; + * + * at91_add_device_can(&ek_can_data); + * + */ + +#include <linux/clk.h> +#include <linux/errno.h> +#include <linux/if_arp.h> +#include <linux/init.h> +#include <linux/interrupt.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/netdevice.h> +#include <linux/platform_device.h> +#include <linux/skbuff.h> +#include <linux/spinlock.h> +#include <linux/string.h> +#include <linux/types.h> + +#include <linux/can.h> +#include <linux/can/dev.h> +#include <linux/can/error.h> + +#include <mach/board.h> + +#define DRV_NAME "at91_can" +#define AT91_NAPI_WEIGHT 12 + +/* + * RX/TX Mailbox split + * don't dare to touch + */ +#define AT91_MB_RX_NUM 12 +#define AT91_MB_TX_SHIFT 2 + +#define AT91_MB_RX_FIRST 0 +#define AT91_MB_RX_LAST (AT91_MB_RX_FIRST + AT91_MB_RX_NUM - 1) + +#define AT91_MB_RX_MASK(i) ((1 << (i)) - 1) +#define AT91_MB_RX_SPLIT 8 +#define AT91_MB_RX_LOW_LAST (AT91_MB_RX_SPLIT - 1) +#define AT91_MB_RX_LOW_MASK (AT91_MB_RX_MASK(AT91_MB_RX_SPLIT)) + +#define AT91_MB_TX_NUM (1 << AT91_MB_TX_SHIFT) +#define AT91_MB_TX_FIRST (AT91_MB_RX_LAST + 1) +#define AT91_MB_TX_LAST (AT91_MB_TX_FIRST + AT91_MB_TX_NUM - 1) + +#define AT91_NEXT_PRIO_SHIFT (AT91_MB_TX_SHIFT) +#define AT91_NEXT_PRIO_MASK (0xf << AT91_MB_TX_SHIFT) +#define AT91_NEXT_MB_MASK (AT91_MB_TX_NUM - 1) +#define AT91_NEXT_MASK ((AT91_MB_TX_NUM - 1) | AT91_NEXT_PRIO_MASK) + +/* Common registers */ +enum at91_reg { + AT91_MR = 0x000, + AT91_IER = 0x004, + AT91_IDR = 0x008, + AT91_IMR = 0x00C, + AT91_SR = 0x010, + AT91_BR = 0x014, + AT91_TIM = 0x018, + AT91_TIMESTP = 0x01C, + AT91_ECR = 0x020, + AT91_TCR = 0x024, + AT91_ACR = 0x028, +}; + +/* Mailbox registers (0 <= i <= 15) */ +#define AT91_MMR(i) (enum at91_reg)(0x200 + ((i) * 0x20)) +#define AT91_MAM(i) (enum at91_reg)(0x204 + ((i) * 0x20)) +#define AT91_MID(i) (enum at91_reg)(0x208 + ((i) * 0x20)) +#define AT91_MFID(i) (enum at91_reg)(0x20C + ((i) * 0x20)) +#define AT91_MSR(i) (enum at91_reg)(0x210 + ((i) * 0x20)) +#define AT91_MDL(i) (enum at91_reg)(0x214 + ((i) * 0x20)) +#define AT91_MDH(i) (enum at91_reg)(0x218 + ((i) * 0x20)) +#define AT91_MCR(i) (enum at91_reg)(0x21C + ((i) * 0x20)) + +/* Register bits */ +#define AT91_MR_CANEN BIT(0) +#define AT91_MR_LPM BIT(1) +#define AT91_MR_ABM BIT(2) +#define AT91_MR_OVL BIT(3) +#define AT91_MR_TEOF BIT(4) +#define AT91_MR_TTM BIT(5) +#define AT91_MR_TIMFRZ BIT(6) +#define AT91_MR_DRPT BIT(7) + +#define AT91_SR_RBSY BIT(29) + +#define AT91_MMR_PRIO_SHIFT (16) + +#define AT91_MID_MIDE BIT(29) + +#define AT91_MSR_MRTR BIT(20) +#define AT91_MSR_MABT BIT(22) +#define AT91_MSR_MRDY BIT(23) +#define AT91_MSR_MMI BIT(24) + +#define AT91_MCR_MRTR BIT(20) +#define AT91_MCR_MTCR BIT(23) + +/* Mailbox Modes */ +enum at91_mb_mode { + AT91_MB_MODE_DISABLED = 0, + AT91_MB_MODE_RX = 1, + AT91_MB_MODE_RX_OVRWR = 2, + AT91_MB_MODE_TX = 3, + AT91_MB_MODE_CONSUMER = 4, + AT91_MB_MODE_PRODUCER = 5, +}; + +/* Interrupt mask bits */ +#define AT91_IRQ_MB_RX ((1 << (AT91_MB_RX_LAST + 1)) \ + - (1 << AT91_MB_RX_FIRST)) +#define AT91_IRQ_MB_TX ((1 << (AT91_MB_TX_LAST + 1)) \ + - (1 << AT91_MB_TX_FIRST)) +#define AT91_IRQ_MB_ALL (AT91_IRQ_MB_RX | AT91_IRQ_MB_TX) + +#define AT91_IRQ_ERRA (1 << 16) +#define AT91_IRQ_WARN (1 << 17) +#define AT91_IRQ_ERRP (1 << 18) +#define AT91_IRQ_BOFF (1 << 19) +#define AT91_IRQ_SLEEP (1 << 20) +#define AT91_IRQ_WAKEUP (1 << 21) +#define AT91_IRQ_TOVF (1 << 22) +#define AT91_IRQ_TSTP (1 << 23) +#define AT91_IRQ_CERR (1 << 24) +#define AT91_IRQ_SERR (1 << 25) +#define AT91_IRQ_AERR (1 << 26) +#define AT91_IRQ_FERR (1 << 27) +#define AT91_IRQ_BERR (1 << 28) + +#define AT91_IRQ_ERR_ALL (0x1fff0000) +#define AT91_IRQ_ERR_FRAME (AT91_IRQ_CERR | AT91_IRQ_SERR | \ + AT91_IRQ_AERR | AT91_IRQ_FERR | AT91_IRQ_BERR) +#define AT91_IRQ_ERR_LINE (AT91_IRQ_ERRA | AT91_IRQ_WARN | \ + AT91_IRQ_ERRP | AT91_IRQ_BOFF) + +#define AT91_IRQ_ALL (0x1fffffff) + +struct at91_priv { + struct can_priv can; /* must be the first member! */ + struct net_device *dev; + struct napi_struct napi; + + void __iomem *reg_base; + + u32 reg_sr; + unsigned int tx_next; + unsigned int tx_echo; + unsigned int rx_next; + + struct clk *clk; + struct at91_can_data *pdata; +}; + +static struct can_bittiming_const at91_bittiming_const = { + .tseg1_min = 4, + .tseg1_max = 16, + .tseg2_min = 2, + .tseg2_max = 8, + .sjw_max = 4, + .brp_min = 2, + .brp_max = 128, + .brp_inc = 1, +}; + +static inline int get_tx_next_mb(const struct at91_priv *priv) +{ + return (priv->tx_next & AT91_NEXT_MB_MASK) + AT91_MB_TX_FIRST; +} + +static inline int get_tx_next_prio(const struct at91_priv *priv) +{ + return (priv->tx_next >> AT91_NEXT_PRIO_SHIFT) & 0xf; +} + +static inline int get_tx_echo_mb(const struct at91_priv *priv) +{ + return (priv->tx_echo & AT91_NEXT_MB_MASK) + AT91_MB_TX_FIRST; +} + +static inline u32 at91_read(const struct at91_priv *priv, enum at91_reg reg) +{ + return readl(priv->reg_base + reg); +} + +static inline void at91_write(const struct at91_priv *priv, enum at91_reg reg, + u32 value) +{ + writel(value, priv->reg_base + reg); +} + +static inline void set_mb_mode_prio(const struct at91_priv *priv, + unsigned int mb, enum at91_mb_mode mode, int prio) +{ + at91_write(priv, AT91_MMR(mb), (mode << 24) | (prio << 16)); +} + +static inline void set_mb_mode(const struct at91_priv *priv, unsigned int mb, + enum at91_mb_mode mode) +{ + set_mb_mode_prio(priv, mb, mode, 0); +} + +static struct sk_buff *alloc_can_skb(struct net_device *dev, + struct can_frame **cf) +{ + struct sk_buff *skb; + + skb = netdev_alloc_skb(dev, sizeof(struct can_frame)); + if (unlikely(!skb)) + return NULL; + + skb->protocol = htons(ETH_P_CAN); + skb->ip_summed = CHECKSUM_UNNECESSARY; + *cf = (struct can_frame *)skb_put(skb, sizeof(struct can_frame)); + + return skb; +} + +static struct sk_buff *alloc_can_err_skb(struct net_device *dev, + struct can_frame **cf) +{ + struct sk_buff *skb; + + skb = alloc_can_skb(dev, cf); + if (unlikely(!skb)) + return NULL; + + memset(*cf, 0, sizeof(struct can_frame)); + (*cf)->can_id = CAN_ERR_FLAG; + (*cf)->can_dlc = CAN_ERR_DLC; + + return skb; +} + +/* + * Swtich transceiver on or off + */ +static void at91_transceiver_switch(const struct at91_priv *priv, int on) +{ + if (priv->pdata && priv->pdata->transceiver_switch) + priv->pdata->transceiver_switch(on); +} + +static void at91_setup_mailboxes(struct net_device *dev) +{ + struct at91_priv *priv = netdev_priv(dev); + unsigned int i; + + /* + * The first 12 mailboxes are used as a reception FIFO. The + * last mailbox is configured with overwrite option. The + * overwrite flag indicates a FIFO overflow. + */ + for (i = AT91_MB_RX_FIRST; i < AT91_MB_RX_LAST; i++) + set_mb_mode(priv, i, AT91_MB_MODE_RX); + set_mb_mode(priv, AT91_MB_RX_LAST, AT91_MB_MODE_RX_OVRWR); + + /* The last 4 mailboxes are used for transmitting. */ + for (i = AT91_MB_TX_FIRST; i <= AT91_MB_TX_LAST; i++) + set_mb_mode_prio(priv, i, AT91_MB_MODE_TX, 0); + + /* Reset tx and rx helper pointers */ + priv->tx_next = priv->tx_echo = priv->rx_next = 0; +} + +static int at91_set_bittiming(struct net_device *dev) +{ + const struct at91_priv *priv = netdev_priv(dev); + const struct can_bittiming *bt = &priv->can.bittiming; + u32 reg_br; + + reg_br = ((priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES) << 24) | + ((bt->brp - 1) << 16) | ((bt->sjw - 1) << 12) | + ((bt->prop_seg - 1) << 8) | ((bt->phase_seg1 - 1) << 4) | + ((bt->phase_seg2 - 1) << 0); + + dev_info(dev->dev.parent, "writing AT91_BR: 0x%08x\n", reg_br); + + at91_write(priv, AT91_BR, reg_br); + + return 0; +} + +static void at91_chip_start(struct net_device *dev) +{ + struct at91_priv *priv = netdev_priv(dev); + u32 reg_mr, reg_ier; + + /* disable interrupts */ + at91_write(priv, AT91_IDR, AT91_IRQ_ALL); + + /* disable chip */ + reg_mr = at91_read(priv, AT91_MR); + at91_write(priv, AT91_MR, reg_mr & ~AT91_MR_CANEN); + + at91_setup_mailboxes(dev); + at91_transceiver_switch(priv, 1); + + /* enable chip */ + at91_write(priv, AT91_MR, AT91_MR_CANEN); + + priv->can.state = CAN_STATE_ERROR_ACTIVE; + + /* Enable interrupts */ + reg_ier = AT91_IRQ_MB_RX | AT91_IRQ_ERRP | AT91_IRQ_ERR_FRAME; + at91_write(priv, AT91_IDR, AT91_IRQ_ALL); + at91_write(priv, AT91_IER, reg_ier); +} + +static void at91_chip_stop(struct net_device *dev, enum can_state state) +{ + struct at91_priv *priv = netdev_priv(dev); + u32 reg_mr; + + /* disable interrupts */ + at91_write(priv, AT91_IDR, AT91_IRQ_ALL); + + reg_mr = at91_read(priv, AT91_MR); + at91_write(priv, AT91_MR, reg_mr & ~AT91_MR_CANEN); + + at91_transceiver_switch(priv, 0); + priv->can.state = state; +} + +/* + * theory of operation: + * + * According to the datasheet priority 0 is the highest priority, 15 + * is the lowest. If two mailboxes have the same priority level the + * message of the mailbox with the lowest number is sent first. + * + * We use the first TX mailbox (AT91_MB_TX_FIRST) with prio 0, then + * the next mailbox with prio 0, and so on, until all mailboxes are + * used. Then we start from the beginning with mailbox + * AT91_MB_TX_FIRST, but with prio 1, mailbox AT91_MB_TX_FIRST + 1 + * prio 1. When we reach the last mailbox with prio 15, we have to + * stop sending, waiting for all messages to be delivered, then start + * again with mailbox AT91_MB_TX_FIRST prio 0. + * + * We use the priv->tx_next as counter for the next transmission + * mailbox, but without the offset AT91_MB_TX_FIRST. The lower bits + * encode the mailbox number, the upper 4 bits the mailbox priority: + * + * priv->tx_next = (prio << AT91_NEXT_PRIO_SHIFT) || + * (mb - AT91_MB_TX_FIRST); + * + */ +static netdev_tx_t at91_start_xmit(struct sk_buff *skb, struct net_device *dev) +{ + struct at91_priv *priv = netdev_priv(dev); + struct net_device_stats *stats = &dev->stats; + struct can_frame *cf = (struct can_frame *)skb->data; + unsigned int mb, prio; + u32 reg_mid, reg_mcr; + + mb = get_tx_next_mb(priv); + prio = get_tx_next_prio(priv); + + if (unlikely(!(at91_read(priv, AT91_MSR(mb)) & AT91_MSR_MRDY))) { + netif_stop_queue(dev); + + dev_err(dev->dev.parent, + "BUG! TX buffer full when queue awake!\n"); + return NETDEV_TX_BUSY; + } + + if (cf->can_id & CAN_EFF_FLAG) + reg_mid = (cf->can_id & CAN_EFF_MASK) | AT91_MID_MIDE; + else + reg_mid = (cf->can_id & CAN_SFF_MASK) << 18; + + reg_mcr = ((cf->can_id & CAN_RTR_FLAG) ? AT91_MCR_MRTR : 0) | + (cf->can_dlc << 16) | AT91_MCR_MTCR; + + /* disable MB while writing ID (see datasheet) */ + set_mb_mode(priv, mb, AT91_MB_MODE_DISABLED); + at91_write(priv, AT91_MID(mb), reg_mid); + set_mb_mode_prio(priv, mb, AT91_MB_MODE_TX, prio); + + at91_write(priv, AT91_MDL(mb), *(u32 *)(cf->data + 0)); + at91_write(priv, AT91_MDH(mb), *(u32 *)(cf->data + 4)); + + /* This triggers transmission */ + at91_write(priv, AT91_MCR(mb), reg_mcr); + + stats->tx_bytes += cf->can_dlc; + dev->trans_start = jiffies; + + /* _NOTE_: substract AT91_MB_TX_FIRST offset from mb! */ + can_put_echo_skb(skb, dev, mb - AT91_MB_TX_FIRST); + + /* + * we have to stop the queue and deliver all messages in case + * of a prio+mb counter wrap around. This is the case if + * tx_next buffer prio and mailbox equals 0. + * + * also stop the queue if next buffer is still in use + * (== not ready) + */ + priv->tx_next++; + if (!(at91_read(priv, AT91_MSR(get_tx_next_mb(priv))) & + AT91_MSR_MRDY) || + (priv->tx_next & AT91_NEXT_MASK) == 0) + netif_stop_queue(dev); + + /* Enable interrupt for this mailbox */ + at91_write(priv, AT91_IER, 1 << mb); + + return NETDEV_TX_OK; +} + +/** + * at91_activate_rx_low - activate lower rx mailboxes + * @priv: a91 context + * + * Reenables the lower mailboxes for reception of new CAN messages + */ +static inline void at91_activate_rx_low(const struct at91_priv *priv) +{ + u32 mask = AT91_MB_RX_LOW_MASK; + at91_write(priv, AT91_TCR, mask); +} + +/** + * at91_activate_rx_mb - reactive single rx mailbox + * @priv: a91 context + * @mb: mailbox to reactivate + * + * Reenables given mailbox for reception of new CAN messages + */ +static inline void at91_activate_rx_mb(const struct at91_priv *priv, + unsigned int mb) +{ + u32 mask = 1 << mb; + at91_write(priv, AT91_TCR, mask); +} + +/** + * at91_rx_overflow_err - send error frame due to rx overflow + * @dev: net device + */ +static void at91_rx_overflow_err(struct net_device *dev) +{ + struct net_device_stats *stats = &dev->stats; + struct sk_buff *skb; + struct can_frame *cf; + + dev_dbg(dev->dev.parent, "RX buffer overflow\n"); + stats->rx_over_errors++; + stats->rx_errors++; + + skb = alloc_can_err_skb(dev, &cf); + if (unlikely(!skb)) + return; + + cf->can_id |= CAN_ERR_CRTL; + cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW; + netif_receive_skb(skb); + + stats->rx_packets++; + stats->rx_bytes += cf->can_dlc; +} + +/** + * at91_read_mb - read CAN msg from mailbox (lowlevel impl) + * @dev: net device + * @mb: mailbox number to read from + * @cf: can frame where to store message + * + * Reads a CAN message from the given mailbox and stores data into + * given can frame. "mb" and "cf" must be valid. + */ +static void at91_read_mb(struct net_device *dev, unsigned int mb, + struct can_frame *cf) +{ + const struct at91_priv *priv = netdev_priv(dev); + u32 reg_msr, reg_mid; + + reg_mid = at91_read(priv, AT91_MID(mb)); + if (reg_mid & AT91_MID_MIDE) + cf->can_id = ((reg_mid >> 0) & CAN_EFF_MASK) | CAN_EFF_FLAG; + else + cf->can_id = (reg_mid >> 18) & CAN_SFF_MASK; + + reg_msr = at91_read(priv, AT91_MSR(mb)); + if (reg_msr & AT91_MSR_MRTR) + cf->can_id |= CAN_RTR_FLAG; + cf->can_dlc = min_t(__u8, (reg_msr >> 16) & 0xf, 8); + + *(u32 *)(cf->data + 0) = at91_read(priv, AT91_MDL(mb)); + *(u32 *)(cf->data + 4) = at91_read(priv, AT91_MDH(mb)); + + if (unlikely(mb == AT91_MB_RX_LAST && reg_msr & AT91_MSR_MMI)) + at91_rx_overflow_err(dev); +} + +/** + * at91_read_msg - read CAN message from mailbox + * @dev: net device + * @mb: mail box to read from + * + * Reads a CAN message from given mailbox, and put into linux network + * RX queue, does all housekeeping chores (stats, ...) + */ +static void at91_read_msg(struct net_device *dev, unsigned int mb) +{ + struct net_device_stats *stats = &dev->stats; + struct can_frame *cf; + struct sk_buff *skb; + + skb = alloc_can_skb(dev, &cf); + if (unlikely(!skb)) { + stats->rx_dropped++; + return; + } + + at91_read_mb(dev, mb, cf); + netif_receive_skb(skb); + + stats->rx_packets++; + stats->rx_bytes += cf->can_dlc; +} + +/** + * at91_poll_rx - read multiple CAN messages from mailboxes + * @dev: net device + * @quota: max number of pkgs we're allowed to receive + * + * Theory of Operation: + * + * 12 of the 16 mailboxes on the chip are reserved for RX. we split + * them into 2 groups. The lower group holds 8 and upper 4 mailboxes. + * + * Like it or not, but the chip always saves a received CAN message + * into the first free mailbox it finds (starting with the + * lowest). This makes it very difficult to read the messages in the + * right order from the chip. This is how we work around that problem: + * + * The first message goes into mb nr. 0 and issues an interrupt. All + * rx ints are disabled in the interrupt handler and a napi poll is + * scheduled. We read the mailbox, but do _not_ reenable the mb (to + * receive another message). + * + * lower mbxs upper + * ______^______ __^__ + * / \ / \ + * +-+-+-+-+-+-+-+-++-+-+-+-+ + * |x|x|x|x|x|x|x|x|| | | | | + * +-+-+-+-+-+-+-+-++-+-+-+-+ + * 0 0 0 0 0 0 0 0 0 0 1 1 \ mail + * 0 1 2 3 4 5 6 7 8 9 0 1 / box + * + * The variable priv->rx_next points to the next mailbox to read a + * message from. As long we're in the lower mailboxes we just read the + * mailbox but not reenable it. + * + * With completion of the last of the lower mailboxes, we reenable the + * whole first group, but continue to look for filled mailboxes in the + * upper mailboxes. Imagine the second group like overflow mailboxes, + * which takes CAN messages if the lower goup is full. While in the + * upper group we reenable the mailbox right after reading it. Giving + * the chip more room to store messages. + * + * After finishing we look again in the lower group if we've still + * quota. + * + */ +static int at91_poll_rx(struct net_device *dev, int quota) +{ + struct at91_priv *priv = netdev_priv(dev); + u32 reg_sr = at91_read(priv, AT91_SR); + const unsigned long *addr = (unsigned long *)®_sr; + unsigned int mb; + int received = 0; + + if (priv->rx_next > AT91_MB_RX_LOW_LAST && + reg_sr & AT91_MB_RX_LOW_MASK) + dev_info(dev->dev.parent, + "order of incoming frames cannot be guaranteed\n"); + + again: + for (mb = find_next_bit(addr, AT91_MB_RX_NUM, priv->rx_next); + mb < AT91_MB_RX_NUM && quota > 0; + reg_sr = at91_read(priv, AT91_SR), + mb = find_next_bit(addr, AT91_MB_RX_NUM, ++priv->rx_next)) { + at91_read_msg(dev, mb); + + /* reactivate mailboxes */ + if (mb == AT91_MB_RX_LOW_LAST) + /* all lower mailboxed, if just finished it */ + at91_activate_rx_low(priv); + else if (mb > AT91_MB_RX_LOW_LAST) + /* only the mailbox we read */ + at91_activate_rx_mb(priv, mb); + + received++; + quota--; + } + + /* upper group completed, look again in lower */ + if (priv->rx_next > AT91_MB_RX_LOW_LAST && + quota > 0 && mb >= AT91_MB_RX_NUM) { + priv->rx_next = 0; + goto again; + } + + return received; +} + +static void at91_poll_err_frame(struct net_device *dev, + struct can_frame *cf, u32 reg_sr) +{ + struct at91_priv *priv = netdev_priv(dev); + + /* CRC error */ + if (reg_sr & AT91_IRQ_CERR) { + dev_dbg(dev->dev.parent, "CERR irq\n"); + dev->stats.rx_errors++; + priv->can.can_stats.bus_error++; + cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR; + } + + /* Stuffing Error */ + if (reg_sr & AT91_IRQ_SERR) { + dev_dbg(dev->dev.parent, "SERR irq\n"); + dev->stats.rx_errors++; + priv->can.can_stats.bus_error++; + cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR; + cf->data[2] |= CAN_ERR_PROT_STUFF; + } + + /* Acknowledgement Error */ + if (reg_sr & AT91_IRQ_AERR) { + dev_dbg(dev->dev.parent, "AERR irq\n"); + dev->stats.tx_errors++; + cf->can_id |= CAN_ERR_ACK; + } + + /* Form error */ + if (reg_sr & AT91_IRQ_FERR) { + dev_dbg(dev->dev.parent, "FERR irq\n"); + dev->stats.rx_errors++; + priv->can.can_stats.bus_error++; + cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR; + cf->data[2] |= CAN_ERR_PROT_FORM; + } + + /* Bit Error */ + if (reg_sr & AT91_IRQ_BERR) { + dev_dbg(dev->dev.parent, "BERR irq\n"); + dev->stats.tx_errors++; + priv->can.can_stats.bus_error++; + cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR; + cf->data[2] |= CAN_ERR_PROT_BIT; + } +} + +static int at91_poll_err(struct net_device *dev, int quota, u32 reg_sr) +{ + struct sk_buff *skb; + struct can_frame *cf; + + if (quota == 0) + return 0; + + skb = alloc_can_err_skb(dev, &cf); + if (unlikely(!skb)) + return 0; + + at91_poll_err_frame(dev, cf, reg_sr); + netif_receive_skb(skb); + + dev->last_rx = jiffies; + dev->stats.rx_packets++; + dev->stats.rx_bytes += cf->can_dlc; + + return 1; +} + +static int at91_poll(struct napi_struct *napi, int quota) +{ + struct net_device *dev = napi->dev; + const struct at91_priv *priv = netdev_priv(dev); + u32 reg_sr = at91_read(priv, AT91_SR); + int work_done = 0; + + if (reg_sr & AT91_IRQ_MB_RX) + work_done += at91_poll_rx(dev, quota - work_done); + + /* + * The error bits are clear on read, + * so use saved value from irq handler. + */ + reg_sr |= priv->reg_sr; + if (reg_sr & AT91_IRQ_ERR_FRAME) + work_done += at91_poll_err(dev, quota - work_done, reg_sr); + + if (work_done < quota) { + /* enable IRQs for frame errors and all mailboxes >= rx_next */ + u32 reg_ier = AT91_IRQ_ERR_FRAME; + reg_ier |= AT91_IRQ_MB_RX & ~AT91_MB_RX_MASK(priv->rx_next); + + napi_complete(napi); + at91_write(priv, AT91_IER, reg_ier); + } + + return work_done; +} + +/* + * theory of operation: + * + * priv->tx_echo holds the number of the oldest can_frame put for + * transmission into the hardware, but not yet ACKed by the CAN tx + * complete IRQ. + * + * We iterate from priv->tx_echo to priv->tx_next and check if the + * packet has been transmitted, echo it back to the CAN framework. If + * we discover a not yet transmitted package, stop looking for more. + * + */ +static void at91_irq_tx(struct net_device *dev, u32 reg_sr) +{ + struct at91_priv *priv = netdev_priv(dev); + u32 reg_msr; + unsigned int mb; + + /* masking of reg_sr not needed, already done by at91_irq */ + + for (/* nix */; (priv->tx_next - priv->tx_echo) > 0; priv->tx_echo++) { + mb = get_tx_echo_mb(priv); + + /* no event in mailbox? */ + if (!(reg_sr & (1 << mb))) + break; + + /* Disable irq for this TX mailbox */ + at91_write(priv, AT91_IDR, 1 << mb); + + /* + * only echo if mailbox signals us a transfer + * complete (MSR_MRDY). Otherwise it's a tansfer + * abort. "can_bus_off()" takes care about the skbs + * parked in the echo queue. + */ + reg_msr = at91_read(priv, AT91_MSR(mb)); + if (likely(reg_msr & AT91_MSR_MRDY && + ~reg_msr & AT91_MSR_MABT)) { + /* _NOTE_: substract AT91_MB_TX_FIRST offset from mb! */ + can_get_echo_skb(dev, mb - AT91_MB_TX_FIRST); + dev->stats.tx_packets++; + } + } + + /* + * restart queue if we don't have a wrap around but restart if + * we get a TX int for the last can frame directly before a + * wrap around. + */ + if ((priv->tx_next & AT91_NEXT_MASK) != 0 || + (priv->tx_echo & AT91_NEXT_MASK) == 0) + netif_wake_queue(dev); +} + +static void at91_irq_err_state(struct net_device *dev, + struct can_frame *cf, enum can_state new_state) +{ + struct at91_priv *priv = netdev_priv(dev); + u32 reg_idr, reg_ier, reg_ecr; + u8 tec, rec; + + reg_ecr = at91_read(priv, AT91_ECR); + rec = reg_ecr & 0xff; + tec = reg_ecr >> 16; + + switch (priv->can.state) { + case CAN_STATE_ERROR_ACTIVE: + /* + * from: ERROR_ACTIVE + * to : ERROR_WARNING, ERROR_PASSIVE, BUS_OFF + * => : there was a warning int + */ + if (new_state >= CAN_STATE_ERROR_WARNING && + new_state <= CAN_STATE_BUS_OFF) { + dev_dbg(dev->dev.parent, "Error Warning IRQ\n"); + priv->can.can_stats.error_warning++; + + cf->can_id |= CAN_ERR_CRTL; + cf->data[1] = (tec > rec) ? + CAN_ERR_CRTL_TX_WARNING : + CAN_ERR_CRTL_RX_WARNING; + } + case CAN_STATE_ERROR_WARNING: /* fallthrough */ + /* + * from: ERROR_ACTIVE, ERROR_WARNING + * to : ERROR_PASSIVE, BUS_OFF + * => : error passive int + */ + if (new_state >= CAN_STATE_ERROR_PASSIVE && + new_state <= CAN_STATE_BUS_OFF) { + dev_dbg(dev->dev.parent, "Error Passive IRQ\n"); + priv->can.can_stats.error_passive++; + + cf->can_id |= CAN_ERR_CRTL; + cf->data[1] = (tec > rec) ? + CAN_ERR_CRTL_TX_PASSIVE : + CAN_ERR_CRTL_RX_PASSIVE; + } + break; + case CAN_STATE_BUS_OFF: + /* + * from: BUS_OFF + * to : ERROR_ACTIVE, ERROR_WARNING, ERROR_PASSIVE + */ + if (new_state <= CAN_STATE_ERROR_PASSIVE) { + cf->can_id |= CAN_ERR_RESTARTED; + + dev_dbg(dev->dev.parent, "restarted\n"); + priv->can.can_stats.restarts++; + + netif_carrier_on(dev); + netif_wake_queue(dev); + } + break; + default: + break; + } + + + /* process state changes depending on the new state */ + switch (new_state) { + case CAN_STATE_ERROR_ACTIVE: + /* + * actually we want to enable AT91_IRQ_WARN here, but + * it screws up the system under certain + * circumstances. so just enable AT91_IRQ_ERRP, thus + * the "fallthrough" + */ + dev_dbg(dev->dev.parent, "Error Active\n"); + cf->can_id |= CAN_ERR_PROT; + cf->data[2] = CAN_ERR_PROT_ACTIVE; + case CAN_STATE_ERROR_WARNING: /* fallthrough */ + reg_idr = AT91_IRQ_ERRA | AT91_IRQ_WARN | AT91_IRQ_BOFF; + reg_ier = AT91_IRQ_ERRP; + break; + case CAN_STATE_ERROR_PASSIVE: + reg_idr = AT91_IRQ_ERRA | AT91_IRQ_WARN | AT91_IRQ_ERRP; + reg_ier = AT91_IRQ_BOFF; + break; + case CAN_STATE_BUS_OFF: + reg_idr = AT91_IRQ_ERRA | AT91_IRQ_ERRP | + AT91_IRQ_WARN | AT91_IRQ_BOFF; + reg_ier = 0; + + cf->can_id |= CAN_ERR_BUSOFF; + + dev_dbg(dev->dev.parent, "bus-off\n"); + netif_carrier_off(dev); + priv->can.can_stats.bus_off++; + + /* turn off chip, if restart is disabled */ + if (!priv->can.restart_ms) { + at91_chip_stop(dev, CAN_STATE_BUS_OFF); + return; + } + break; + default: + break; + } + + at91_write(priv, AT91_IDR, reg_idr); + at91_write(priv, AT91_IER, reg_ier); +} + +static void at91_irq_err(struct net_device *dev) +{ + struct at91_priv *priv = netdev_priv(dev); + struct sk_buff *skb; + struct can_frame *cf; + enum can_state new_state; + u32 reg_sr; + + reg_sr = at91_read(priv, AT91_SR); + + /* we need to look at the unmasked reg_sr */ + if (unlikely(reg_sr & AT91_IRQ_BOFF)) + new_state = CAN_STATE_BUS_OFF; + else if (unlikely(reg_sr & AT91_IRQ_ERRP)) + new_state = CAN_STATE_ERROR_PASSIVE; + else if (unlikely(reg_sr & AT91_IRQ_WARN)) + new_state = CAN_STATE_ERROR_WARNING; + else if (likely(reg_sr & AT91_IRQ_ERRA)) + new_state = CAN_STATE_ERROR_ACTIVE; + else { + dev_err(dev->dev.parent, "BUG! hardware in undefined state\n"); + return; + } + + /* state hasn't changed */ + if (likely(new_state == priv->can.state)) + return; + + skb = alloc_can_err_skb(dev, &cf); + if (unlikely(!skb)) + return; + + at91_irq_err_state(dev, cf, new_state); + netif_rx(skb); + + dev->last_rx = jiffies; + dev->stats.rx_packets++; + dev->stats.rx_bytes += cf->can_dlc; + + priv->can.state = new_state; +} + +/* + * interrupt handler + */ +static irqreturn_t at91_irq(int irq, void *dev_id) +{ + struct net_device *dev = dev_id; + struct at91_priv *priv = netdev_priv(dev); + irqreturn_t handled = IRQ_NONE; + u32 reg_sr, reg_imr; + + reg_sr = at91_read(priv, AT91_SR); + reg_imr = at91_read(priv, AT91_IMR); + + /* Ignore masked interrupts */ + reg_sr &= reg_imr; + if (!reg_sr) + goto exit; + + handled = IRQ_HANDLED; + + /* Receive or error interrupt? -> napi */ + if (reg_sr & (AT91_IRQ_MB_RX | AT91_IRQ_ERR_FRAME)) { + /* + * The error bits are clear on read, + * save for later use. + */ + priv->reg_sr = reg_sr; + at91_write(priv, AT91_IDR, + AT91_IRQ_MB_RX | AT91_IRQ_ERR_FRAME); + napi_schedule(&priv->napi); + } + + /* Transmission complete interrupt */ + if (reg_sr & AT91_IRQ_MB_TX) + at91_irq_tx(dev, reg_sr); + + at91_irq_err(dev); + + exit: + return handled; +} + +static int at91_open(struct net_device *dev) +{ + struct at91_priv *priv = netdev_priv(dev); + int err; + + clk_enable(priv->clk); + + /* check or determine and set bittime */ + err = open_candev(dev); + if (err) + goto out; + + /* register interrupt handler */ + if (request_irq(dev->irq, at91_irq, IRQF_SHARED, + dev->name, dev)) { + err = -EAGAIN; + goto out_close; + } + + /* start chip and queuing */ + at91_chip_start(dev); + napi_enable(&priv->napi); + netif_start_queue(dev); + + return 0; + + out_close: + close_candev(dev); + out: + clk_disable(priv->clk); + + return err; +} + +/* + * stop CAN bus activity + */ +static int at91_close(struct net_device *dev) +{ + struct at91_priv *priv = netdev_priv(dev); + + netif_stop_queue(dev); + napi_disable(&priv->napi); + at91_chip_stop(dev, CAN_STATE_STOPPED); + + free_irq(dev->irq, dev); + clk_disable(priv->clk); + + close_candev(dev); + + return 0; +} + +static int at91_set_mode(struct net_device *dev, enum can_mode mode) +{ + switch (mode) { + case CAN_MODE_START: + at91_chip_start(dev); + netif_wake_queue(dev); + break; + + default: + return -EOPNOTSUPP; + } + + return 0; +} + +static const struct net_device_ops at91_netdev_ops = { + .ndo_open = at91_open, + .ndo_stop = at91_close, + .ndo_start_xmit = at91_start_xmit, +}; + +static int __init at91_can_probe(struct platform_device *pdev) +{ + struct net_device *dev; + struct at91_priv *priv; + struct resource *res; + struct clk *clk; + void __iomem *addr; + int err, irq; + + clk = clk_get(&pdev->dev, "can_clk"); + if (IS_ERR(clk)) { + dev_err(&pdev->dev, "no clock defined\n"); + err = -ENODEV; + goto exit; + } + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + irq = platform_get_irq(pdev, 0); + if (!res || !irq) { + err = -ENODEV; + goto exit_put; + } + + if (!request_mem_region(res->start, + resource_size(res), + pdev->name)) { + err = -EBUSY; + goto exit_put; + } + + addr = ioremap_nocache(res->start, resource_size(res)); + if (!addr) { + err = -ENOMEM; + goto exit_release; + } + + dev = alloc_candev(sizeof(struct at91_priv)); + if (!dev) { + err = -ENOMEM; + goto exit_iounmap; + } + + dev->netdev_ops = &at91_netdev_ops; + dev->irq = irq; + dev->flags |= IFF_ECHO; + + priv = netdev_priv(dev); + priv->can.clock.freq = clk_get_rate(clk); + priv->can.bittiming_const = &at91_bittiming_const; + priv->can.do_set_bittiming = at91_set_bittiming; + priv->can.do_set_mode = at91_set_mode; + priv->reg_base = addr; + priv->dev = dev; + priv->clk = clk; + priv->pdata = pdev->dev.platform_data; + + netif_napi_add(dev, &priv->napi, at91_poll, AT91_NAPI_WEIGHT); + + dev_set_drvdata(&pdev->dev, dev); + SET_NETDEV_DEV(dev, &pdev->dev); + + err = register_candev(dev); + if (err) { + dev_err(&pdev->dev, "registering netdev failed\n"); + goto exit_free; + } + + dev_info(&pdev->dev, "device registered (reg_base=%p, irq=%d)\n", + priv->reg_base, dev->irq); + + return 0; + + exit_free: + free_netdev(dev); + exit_iounmap: + iounmap(addr); + exit_release: + release_mem_region(res->start, resource_size(res)); + exit_put: + clk_put(clk); + exit: + return err; +} + +static int __devexit at91_can_remove(struct platform_device *pdev) +{ + struct net_device *dev = platform_get_drvdata(pdev); + struct at91_priv *priv = netdev_priv(dev); + struct resource *res; + + unregister_netdev(dev); + + platform_set_drvdata(pdev, NULL); + + free_netdev(dev); + + iounmap(priv->reg_base); + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + release_mem_region(res->start, resource_size(res)); + + clk_put(priv->clk); + + return 0; +} + +static struct platform_driver at91_can_driver = { + .probe = at91_can_probe, + .remove = __devexit_p(at91_can_remove), + .driver = { + .name = DRV_NAME, + .owner = THIS_MODULE, + }, +}; + +static int __init at91_can_module_init(void) +{ + printk(KERN_INFO "%s netdevice driver\n", DRV_NAME); + return platform_driver_register(&at91_can_driver); +} + +static void __exit at91_can_module_exit(void) +{ + platform_driver_unregister(&at91_can_driver); + printk(KERN_INFO "%s: driver removed\n", DRV_NAME); +} + +module_init(at91_can_module_init); +module_exit(at91_can_module_exit); + +MODULE_AUTHOR("Marc Kleine-Budde <mkl@pengutronix.de>"); +MODULE_LICENSE("GPL v2"); +MODULE_DESCRIPTION(DRV_NAME " CAN netdevice driver"); |