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linux-stable/drivers/net/can/at91_can.c
Marc Kleine-Budde 5613fff2dc can: at91_can: fix comment about priv->tx_next 
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
2011-06-06 11:00:10 +02:00

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/*
* at91_can.c - CAN network driver for AT91 SoC CAN controller
*
* (C) 2007 by Hans J. Koch <hjk@hansjkoch.de>
* (C) 2008, 2009, 2010, 2011 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/rtnetlink.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/can/dev.h>
#include <linux/can/error.h>
#include <mach/board.h>
#define AT91_NAPI_WEIGHT 11
/*
* RX/TX Mailbox split
* don't dare to touch
*/
#define AT91_MB_RX_NUM 11
#define AT91_MB_TX_SHIFT 2
#define AT91_MB_RX_FIRST 1
#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) & \
~AT91_MB_RX_MASK(AT91_MB_RX_FIRST))
#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;
canid_t mb0_id;
};
static struct can_bittiming_const at91_bittiming_const = {
.name = KBUILD_MODNAME,
.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 __raw_readl(priv->reg_base + reg);
}
static inline void at91_write(const struct at91_priv *priv, enum at91_reg reg,
u32 value)
{
__raw_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 inline u32 at91_can_id_to_reg_mid(canid_t can_id)
{
u32 reg_mid;
if (can_id & CAN_EFF_FLAG)
reg_mid = (can_id & CAN_EFF_MASK) | AT91_MID_MIDE;
else
reg_mid = (can_id & CAN_SFF_MASK) << 18;
return reg_mid;
}
/*
* 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;
u32 reg_mid;
/*
* Due to a chip bug (errata 50.2.6.3 & 50.3.5.3) the first
* mailbox is disabled. The next 11 mailboxes are used as a
* reception FIFO. The last mailbox is configured with
* overwrite option. The overwrite flag indicates a FIFO
* overflow.
*/
reg_mid = at91_can_id_to_reg_mid(priv->mb0_id);
for (i = 0; i < AT91_MB_RX_FIRST; i++) {
set_mb_mode(priv, i, AT91_MB_MODE_DISABLED);
at91_write(priv, AT91_MID(i), reg_mid);
at91_write(priv, AT91_MCR(i), 0x0); /* clear dlc */
}
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);
/* reset acceptance mask and id register */
for (i = AT91_MB_RX_FIRST; i <= AT91_MB_RX_LAST; i++) {
at91_write(priv, AT91_MAM(i), 0x0);
at91_write(priv, AT91_MID(i), AT91_MID_MIDE);
}
/* 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 = 0;
priv->rx_next = AT91_MB_RX_FIRST;
}
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) ? 1 << 24 : 0) |
((bt->brp - 1) << 16) | ((bt->sjw - 1) << 12) |
((bt->prop_seg - 1) << 8) | ((bt->phase_seg1 - 1) << 4) |
((bt->phase_seg2 - 1) << 0);
netdev_info(dev, "writing AT91_BR: 0x%08x\n", reg_br);
at91_write(priv, AT91_BR, reg_br);
return 0;
}
static int at91_get_berr_counter(const struct net_device *dev,
struct can_berr_counter *bec)
{
const struct at91_priv *priv = netdev_priv(dev);
u32 reg_ecr = at91_read(priv, AT91_ECR);
bec->rxerr = reg_ecr & 0xff;
bec->txerr = reg_ecr >> 16;
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_set_bittiming(dev);
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;
if (can_dropped_invalid_skb(dev, skb))
return NETDEV_TX_OK;
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);
netdev_err(dev, "BUG! TX buffer full when queue awake!\n");
return NETDEV_TX_BUSY;
}
reg_mid = at91_can_id_to_reg_mid(cf->can_id);
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;
/* _NOTE_: subtract 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;
netdev_dbg(dev, "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 = get_can_dlc((reg_msr >> 16) & 0xf);
*(u32 *)(cf->data + 0) = at91_read(priv, AT91_MDL(mb));
*(u32 *)(cf->data + 4) = at91_read(priv, AT91_MDH(mb));
/* allow RX of extended frames */
at91_write(priv, AT91_MID(mb), AT91_MID_MIDE);
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:
*
* 11 of the 16 mailboxes on the chip are reserved for RX. we split
* them into 2 groups. The lower group holds 7 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. 1 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|| | | | |
* +-+-+-+-+-+-+-+-++-+-+-+-+
* 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
* ^
* |
* \
* unused, due to chip bug
*
* 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 *)&reg_sr;
unsigned int mb;
int received = 0;
if (priv->rx_next > AT91_MB_RX_LOW_LAST &&
reg_sr & AT91_MB_RX_LOW_MASK)
netdev_info(dev,
"order of incoming frames cannot be guaranteed\n");
again:
for (mb = find_next_bit(addr, AT91_MB_RX_LAST + 1, priv->rx_next);
mb < AT91_MB_RX_LAST + 1 && quota > 0;
reg_sr = at91_read(priv, AT91_SR),
mb = find_next_bit(addr, AT91_MB_RX_LAST + 1, ++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_LAST) {
priv->rx_next = AT91_MB_RX_FIRST;
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) {
netdev_dbg(dev, "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) {
netdev_dbg(dev, "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) {
netdev_dbg(dev, "AERR irq\n");
dev->stats.tx_errors++;
cf->can_id |= CAN_ERR_ACK;
}
/* Form error */
if (reg_sr & AT91_IRQ_FERR) {
netdev_dbg(dev, "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) {
netdev_dbg(dev, "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->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_: subtract 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 = 0, reg_ier = 0;
struct can_berr_counter bec;
at91_get_berr_counter(dev, &bec);
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) {
netdev_dbg(dev, "Error Warning IRQ\n");
priv->can.can_stats.error_warning++;
cf->can_id |= CAN_ERR_CRTL;
cf->data[1] = (bec.txerr > bec.rxerr) ?
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) {
netdev_dbg(dev, "Error Passive IRQ\n");
priv->can.can_stats.error_passive++;
cf->can_id |= CAN_ERR_CRTL;
cf->data[1] = (bec.txerr > bec.rxerr) ?
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;
netdev_dbg(dev, "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"
*/
netdev_dbg(dev, "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;
netdev_dbg(dev, "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 {
netdev_err(dev, "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->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 ssize_t at91_sysfs_show_mb0_id(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct at91_priv *priv = netdev_priv(to_net_dev(dev));
if (priv->mb0_id & CAN_EFF_FLAG)
return snprintf(buf, PAGE_SIZE, "0x%08x\n", priv->mb0_id);
else
return snprintf(buf, PAGE_SIZE, "0x%03x\n", priv->mb0_id);
}
static ssize_t at91_sysfs_set_mb0_id(struct device *dev,
struct device_attribute *attr, const char *buf, size_t count)
{
struct net_device *ndev = to_net_dev(dev);
struct at91_priv *priv = netdev_priv(ndev);
unsigned long can_id;
ssize_t ret;
int err;
rtnl_lock();
if (ndev->flags & IFF_UP) {
ret = -EBUSY;
goto out;
}
err = strict_strtoul(buf, 0, &can_id);
if (err) {
ret = err;
goto out;
}
if (can_id & CAN_EFF_FLAG)
can_id &= CAN_EFF_MASK | CAN_EFF_FLAG;
else
can_id &= CAN_SFF_MASK;
priv->mb0_id = can_id;
ret = count;
out:
rtnl_unlock();
return ret;
}
static DEVICE_ATTR(mb0_id, S_IWUSR | S_IRUGO,
at91_sysfs_show_mb0_id, at91_sysfs_set_mb0_id);
static struct attribute *at91_sysfs_attrs[] = {
&dev_attr_mb0_id.attr,
NULL,
};
static struct attribute_group at91_sysfs_attr_group = {
.attrs = at91_sysfs_attrs,
};
static int __devinit 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 <= 0) {
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), AT91_MB_TX_NUM);
if (!dev) {
err = -ENOMEM;
goto exit_iounmap;
}
dev->netdev_ops = &at91_netdev_ops;
dev->irq = irq;
dev->flags |= IFF_ECHO;
dev->sysfs_groups[0] = &at91_sysfs_attr_group;
priv = netdev_priv(dev);
priv->can.clock.freq = clk_get_rate(clk);
priv->can.bittiming_const = &at91_bittiming_const;
priv->can.do_set_mode = at91_set_mode;
priv->can.do_get_berr_counter = at91_get_berr_counter;
priv->can.ctrlmode_supported = CAN_CTRLMODE_3_SAMPLES;
priv->reg_base = addr;
priv->dev = dev;
priv->clk = clk;
priv->pdata = pdev->dev.platform_data;
priv->mb0_id = 0x7ff;
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_candev(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);
iounmap(priv->reg_base);
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
release_mem_region(res->start, resource_size(res));
clk_put(priv->clk);
free_candev(dev);
return 0;
}
static struct platform_driver at91_can_driver = {
.probe = at91_can_probe,
.remove = __devexit_p(at91_can_remove),
.driver = {
.name = KBUILD_MODNAME,
.owner = THIS_MODULE,
},
};
static int __init at91_can_module_init(void)
{
return platform_driver_register(&at91_can_driver);
}
static void __exit at91_can_module_exit(void)
{
platform_driver_unregister(&at91_can_driver);
}
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(KBUILD_MODNAME " CAN netdevice driver");
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