can: mcp251x: Move to threaded interrupts instead of workqueues.
authorChristian Pellegrin <chripell@fsfe.org>
Wed, 3 Feb 2010 07:39:54 +0000 (07:39 +0000)
committerDavid S. Miller <davem@davemloft.net>
Thu, 4 Feb 2010 04:32:28 +0000 (20:32 -0800)
This patch addresses concerns about efficiency of handling incoming
packets. Handling of interrupts is done in a threaded interrupt handler
which has a smaller latency than workqueues. This change needed a rework
of the locking scheme that was much simplified. Some other (more or less
longstanding) bugs are fixed: utilization of just half of the RX
buffers, useless wait for interrupt on open, more reliable reset
sequence. The MERR interrupt is not used anymore: it overloads the CPU
in error-passive state without any additional information. One shot mode
is disabled because it's not clear if it can be handled efficiently on
this CAN controller.

Signed-off-by: Christian Pellegrin <chripell@fsfe.org>
Acked-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
drivers/net/can/mcp251x.c

index bbe186b5a0ed76ab5c4b5dcd36224a18dcde5846..f8cc168ec76cd29db433bee4face5726c11bd43a 100644 (file)
 #define RXBEID0_OFF 4
 #define RXBDLC_OFF  5
 #define RXBDAT_OFF  6
+#define RXFSIDH(n) ((n) * 4)
+#define RXFSIDL(n) ((n) * 4 + 1)
+#define RXFEID8(n) ((n) * 4 + 2)
+#define RXFEID0(n) ((n) * 4 + 3)
+#define RXMSIDH(n) ((n) * 4 + 0x20)
+#define RXMSIDL(n) ((n) * 4 + 0x21)
+#define RXMEID8(n) ((n) * 4 + 0x22)
+#define RXMEID0(n) ((n) * 4 + 0x23)
 
 #define GET_BYTE(val, byte)                    \
        (((val) >> ((byte) * 8)) & 0xff)
@@ -219,7 +227,8 @@ struct mcp251x_priv {
        struct net_device *net;
        struct spi_device *spi;
 
-       struct mutex spi_lock; /* SPI buffer lock */
+       struct mutex mcp_lock; /* SPI device lock */
+
        u8 *spi_tx_buf;
        u8 *spi_rx_buf;
        dma_addr_t spi_tx_dma;
@@ -227,11 +236,11 @@ struct mcp251x_priv {
 
        struct sk_buff *tx_skb;
        int tx_len;
+
        struct workqueue_struct *wq;
        struct work_struct tx_work;
-       struct work_struct irq_work;
-       struct completion awake;
-       int wake;
+       struct work_struct restart_work;
+
        int force_quit;
        int after_suspend;
 #define AFTER_SUSPEND_UP 1
@@ -245,7 +254,8 @@ static void mcp251x_clean(struct net_device *net)
 {
        struct mcp251x_priv *priv = netdev_priv(net);
 
-       net->stats.tx_errors++;
+       if (priv->tx_skb || priv->tx_len)
+               net->stats.tx_errors++;
        if (priv->tx_skb)
                dev_kfree_skb(priv->tx_skb);
        if (priv->tx_len)
@@ -300,16 +310,12 @@ static u8 mcp251x_read_reg(struct spi_device *spi, uint8_t reg)
        struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
        u8 val = 0;
 
-       mutex_lock(&priv->spi_lock);
-
        priv->spi_tx_buf[0] = INSTRUCTION_READ;
        priv->spi_tx_buf[1] = reg;
 
        mcp251x_spi_trans(spi, 3);
        val = priv->spi_rx_buf[2];
 
-       mutex_unlock(&priv->spi_lock);
-
        return val;
 }
 
@@ -317,15 +323,11 @@ static void mcp251x_write_reg(struct spi_device *spi, u8 reg, uint8_t val)
 {
        struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
 
-       mutex_lock(&priv->spi_lock);
-
        priv->spi_tx_buf[0] = INSTRUCTION_WRITE;
        priv->spi_tx_buf[1] = reg;
        priv->spi_tx_buf[2] = val;
 
        mcp251x_spi_trans(spi, 3);
-
-       mutex_unlock(&priv->spi_lock);
 }
 
 static void mcp251x_write_bits(struct spi_device *spi, u8 reg,
@@ -333,16 +335,12 @@ static void mcp251x_write_bits(struct spi_device *spi, u8 reg,
 {
        struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
 
-       mutex_lock(&priv->spi_lock);
-
        priv->spi_tx_buf[0] = INSTRUCTION_BIT_MODIFY;
        priv->spi_tx_buf[1] = reg;
        priv->spi_tx_buf[2] = mask;
        priv->spi_tx_buf[3] = val;
 
        mcp251x_spi_trans(spi, 4);
-
-       mutex_unlock(&priv->spi_lock);
 }
 
 static void mcp251x_hw_tx_frame(struct spi_device *spi, u8 *buf,
@@ -358,10 +356,8 @@ static void mcp251x_hw_tx_frame(struct spi_device *spi, u8 *buf,
                        mcp251x_write_reg(spi, TXBCTRL(tx_buf_idx) + i,
                                          buf[i]);
        } else {
-               mutex_lock(&priv->spi_lock);
                memcpy(priv->spi_tx_buf, buf, TXBDAT_OFF + len);
                mcp251x_spi_trans(spi, TXBDAT_OFF + len);
-               mutex_unlock(&priv->spi_lock);
        }
 }
 
@@ -408,13 +404,9 @@ static void mcp251x_hw_rx_frame(struct spi_device *spi, u8 *buf,
                for (; i < (RXBDAT_OFF + len); i++)
                        buf[i] = mcp251x_read_reg(spi, RXBCTRL(buf_idx) + i);
        } else {
-               mutex_lock(&priv->spi_lock);
-
                priv->spi_tx_buf[RXBCTRL_OFF] = INSTRUCTION_READ_RXB(buf_idx);
                mcp251x_spi_trans(spi, SPI_TRANSFER_BUF_LEN);
                memcpy(buf, priv->spi_rx_buf, SPI_TRANSFER_BUF_LEN);
-
-               mutex_unlock(&priv->spi_lock);
        }
 }
 
@@ -467,21 +459,6 @@ static void mcp251x_hw_sleep(struct spi_device *spi)
        mcp251x_write_reg(spi, CANCTRL, CANCTRL_REQOP_SLEEP);
 }
 
-static void mcp251x_hw_wakeup(struct spi_device *spi)
-{
-       struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
-
-       priv->wake = 1;
-
-       /* Can only wake up by generating a wake-up interrupt. */
-       mcp251x_write_bits(spi, CANINTE, CANINTE_WAKIE, CANINTE_WAKIE);
-       mcp251x_write_bits(spi, CANINTF, CANINTF_WAKIF, CANINTF_WAKIF);
-
-       /* Wait until the device is awake */
-       if (!wait_for_completion_timeout(&priv->awake, HZ))
-               dev_err(&spi->dev, "MCP251x didn't wake-up\n");
-}
-
 static netdev_tx_t mcp251x_hard_start_xmit(struct sk_buff *skb,
                                           struct net_device *net)
 {
@@ -490,7 +467,6 @@ static netdev_tx_t mcp251x_hard_start_xmit(struct sk_buff *skb,
 
        if (priv->tx_skb || priv->tx_len) {
                dev_warn(&spi->dev, "hard_xmit called while tx busy\n");
-               netif_stop_queue(net);
                return NETDEV_TX_BUSY;
        }
 
@@ -511,12 +487,13 @@ static int mcp251x_do_set_mode(struct net_device *net, enum can_mode mode)
 
        switch (mode) {
        case CAN_MODE_START:
+               mcp251x_clean(net);
                /* We have to delay work since SPI I/O may sleep */
                priv->can.state = CAN_STATE_ERROR_ACTIVE;
                priv->restart_tx = 1;
                if (priv->can.restart_ms == 0)
                        priv->after_suspend = AFTER_SUSPEND_RESTART;
-               queue_work(priv->wq, &priv->irq_work);
+               queue_work(priv->wq, &priv->restart_work);
                break;
        default:
                return -EOPNOTSUPP;
@@ -525,7 +502,7 @@ static int mcp251x_do_set_mode(struct net_device *net, enum can_mode mode)
        return 0;
 }
 
-static void mcp251x_set_normal_mode(struct spi_device *spi)
+static int mcp251x_set_normal_mode(struct spi_device *spi)
 {
        struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
        unsigned long timeout;
@@ -533,8 +510,7 @@ static void mcp251x_set_normal_mode(struct spi_device *spi)
        /* Enable interrupts */
        mcp251x_write_reg(spi, CANINTE,
                          CANINTE_ERRIE | CANINTE_TX2IE | CANINTE_TX1IE |
-                         CANINTE_TX0IE | CANINTE_RX1IE | CANINTE_RX0IE |
-                         CANINTF_MERRF);
+                         CANINTE_TX0IE | CANINTE_RX1IE | CANINTE_RX0IE);
 
        if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK) {
                /* Put device into loopback mode */
@@ -544,9 +520,7 @@ static void mcp251x_set_normal_mode(struct spi_device *spi)
                mcp251x_write_reg(spi, CANCTRL, CANCTRL_REQOP_LISTEN_ONLY);
        } else {
                /* Put device into normal mode */
-               mcp251x_write_reg(spi, CANCTRL, CANCTRL_REQOP_NORMAL |
-                                 (priv->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT ?
-                                  CANCTRL_OSM : 0));
+               mcp251x_write_reg(spi, CANCTRL, CANCTRL_REQOP_NORMAL);
 
                /* Wait for the device to enter normal mode */
                timeout = jiffies + HZ;
@@ -555,11 +529,12 @@ static void mcp251x_set_normal_mode(struct spi_device *spi)
                        if (time_after(jiffies, timeout)) {
                                dev_err(&spi->dev, "MCP251x didn't"
                                        " enter in normal mode\n");
-                               return;
+                               return -EBUSY;
                        }
                }
        }
        priv->can.state = CAN_STATE_ERROR_ACTIVE;
+       return 0;
 }
 
 static int mcp251x_do_set_bittiming(struct net_device *net)
@@ -590,33 +565,39 @@ static int mcp251x_setup(struct net_device *net, struct mcp251x_priv *priv,
 {
        mcp251x_do_set_bittiming(net);
 
-       /* Enable RX0->RX1 buffer roll over and disable filters */
-       mcp251x_write_bits(spi, RXBCTRL(0),
-                          RXBCTRL_BUKT | RXBCTRL_RXM0 | RXBCTRL_RXM1,
-                          RXBCTRL_BUKT | RXBCTRL_RXM0 | RXBCTRL_RXM1);
-       mcp251x_write_bits(spi, RXBCTRL(1),
-                          RXBCTRL_RXM0 | RXBCTRL_RXM1,
-                          RXBCTRL_RXM0 | RXBCTRL_RXM1);
+       mcp251x_write_reg(spi, RXBCTRL(0),
+                         RXBCTRL_BUKT | RXBCTRL_RXM0 | RXBCTRL_RXM1);
+       mcp251x_write_reg(spi, RXBCTRL(1),
+                         RXBCTRL_RXM0 | RXBCTRL_RXM1);
        return 0;
 }
 
-static void mcp251x_hw_reset(struct spi_device *spi)
+static int mcp251x_hw_reset(struct spi_device *spi)
 {
        struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
        int ret;
-
-       mutex_lock(&priv->spi_lock);
+       unsigned long timeout;
 
        priv->spi_tx_buf[0] = INSTRUCTION_RESET;
-
        ret = spi_write(spi, priv->spi_tx_buf, 1);
-
-       mutex_unlock(&priv->spi_lock);
-
-       if (ret)
+       if (ret) {
                dev_err(&spi->dev, "reset failed: ret = %d\n", ret);
+               return -EIO;
+       }
+
        /* Wait for reset to finish */
+       timeout = jiffies + HZ;
        mdelay(10);
+       while ((mcp251x_read_reg(spi, CANSTAT) & CANCTRL_REQOP_MASK)
+              != CANCTRL_REQOP_CONF) {
+               schedule();
+               if (time_after(jiffies, timeout)) {
+                       dev_err(&spi->dev, "MCP251x didn't"
+                               " enter in conf mode after reset\n");
+                       return -EBUSY;
+               }
+       }
+       return 0;
 }
 
 static int mcp251x_hw_probe(struct spi_device *spi)
@@ -640,63 +621,17 @@ static int mcp251x_hw_probe(struct spi_device *spi)
        return (st1 == 0x80 && st2 == 0x07) ? 1 : 0;
 }
 
-static irqreturn_t mcp251x_can_isr(int irq, void *dev_id)
-{
-       struct net_device *net = (struct net_device *)dev_id;
-       struct mcp251x_priv *priv = netdev_priv(net);
-
-       /* Schedule bottom half */
-       if (!work_pending(&priv->irq_work))
-               queue_work(priv->wq, &priv->irq_work);
-
-       return IRQ_HANDLED;
-}
-
-static int mcp251x_open(struct net_device *net)
+static void mcp251x_open_clean(struct net_device *net)
 {
        struct mcp251x_priv *priv = netdev_priv(net);
        struct spi_device *spi = priv->spi;
        struct mcp251x_platform_data *pdata = spi->dev.platform_data;
-       int ret;
-
-       ret = open_candev(net);
-       if (ret) {
-               dev_err(&spi->dev, "unable to set initial baudrate!\n");
-               return ret;
-       }
 
+       free_irq(spi->irq, priv);
+       mcp251x_hw_sleep(spi);
        if (pdata->transceiver_enable)
-               pdata->transceiver_enable(1);
-
-       priv->force_quit = 0;
-       priv->tx_skb = NULL;
-       priv->tx_len = 0;
-
-       ret = request_irq(spi->irq, mcp251x_can_isr,
-                         IRQF_TRIGGER_FALLING, DEVICE_NAME, net);
-       if (ret) {
-               dev_err(&spi->dev, "failed to acquire irq %d\n", spi->irq);
-               if (pdata->transceiver_enable)
-                       pdata->transceiver_enable(0);
-               close_candev(net);
-               return ret;
-       }
-
-       mcp251x_hw_wakeup(spi);
-       mcp251x_hw_reset(spi);
-       ret = mcp251x_setup(net, priv, spi);
-       if (ret) {
-               free_irq(spi->irq, net);
-               mcp251x_hw_sleep(spi);
-               if (pdata->transceiver_enable)
-                       pdata->transceiver_enable(0);
-               close_candev(net);
-               return ret;
-       }
-       mcp251x_set_normal_mode(spi);
-       netif_wake_queue(net);
-
-       return 0;
+               pdata->transceiver_enable(0);
+       close_candev(net);
 }
 
 static int mcp251x_stop(struct net_device *net)
@@ -707,17 +642,19 @@ static int mcp251x_stop(struct net_device *net)
 
        close_candev(net);
 
+       priv->force_quit = 1;
+       free_irq(spi->irq, priv);
+       destroy_workqueue(priv->wq);
+       priv->wq = NULL;
+
+       mutex_lock(&priv->mcp_lock);
+
        /* Disable and clear pending interrupts */
        mcp251x_write_reg(spi, CANINTE, 0x00);
        mcp251x_write_reg(spi, CANINTF, 0x00);
 
-       priv->force_quit = 1;
-       free_irq(spi->irq, net);
-       flush_workqueue(priv->wq);
-
        mcp251x_write_reg(spi, TXBCTRL(0), 0);
-       if (priv->tx_skb || priv->tx_len)
-               mcp251x_clean(net);
+       mcp251x_clean(net);
 
        mcp251x_hw_sleep(spi);
 
@@ -726,9 +663,27 @@ static int mcp251x_stop(struct net_device *net)
 
        priv->can.state = CAN_STATE_STOPPED;
 
+       mutex_unlock(&priv->mcp_lock);
+
        return 0;
 }
 
+static void mcp251x_error_skb(struct net_device *net, int can_id, int data1)
+{
+       struct sk_buff *skb;
+       struct can_frame *frame;
+
+       skb = alloc_can_err_skb(net, &frame);
+       if (skb) {
+               frame->can_id = can_id;
+               frame->data[1] = data1;
+               netif_rx(skb);
+       } else {
+               dev_err(&net->dev,
+                       "cannot allocate error skb\n");
+       }
+}
+
 static void mcp251x_tx_work_handler(struct work_struct *ws)
 {
        struct mcp251x_priv *priv = container_of(ws, struct mcp251x_priv,
@@ -737,33 +692,32 @@ static void mcp251x_tx_work_handler(struct work_struct *ws)
        struct net_device *net = priv->net;
        struct can_frame *frame;
 
+       mutex_lock(&priv->mcp_lock);
        if (priv->tx_skb) {
-               frame = (struct can_frame *)priv->tx_skb->data;
-
                if (priv->can.state == CAN_STATE_BUS_OFF) {
                        mcp251x_clean(net);
-                       netif_wake_queue(net);
-                       return;
+               } else {
+                       frame = (struct can_frame *)priv->tx_skb->data;
+
+                       if (frame->can_dlc > CAN_FRAME_MAX_DATA_LEN)
+                               frame->can_dlc = CAN_FRAME_MAX_DATA_LEN;
+                       mcp251x_hw_tx(spi, frame, 0);
+                       priv->tx_len = 1 + frame->can_dlc;
+                       can_put_echo_skb(priv->tx_skb, net, 0);
+                       priv->tx_skb = NULL;
                }
-               if (frame->can_dlc > CAN_FRAME_MAX_DATA_LEN)
-                       frame->can_dlc = CAN_FRAME_MAX_DATA_LEN;
-               mcp251x_hw_tx(spi, frame, 0);
-               priv->tx_len = 1 + frame->can_dlc;
-               can_put_echo_skb(priv->tx_skb, net, 0);
-               priv->tx_skb = NULL;
        }
+       mutex_unlock(&priv->mcp_lock);
 }
 
-static void mcp251x_irq_work_handler(struct work_struct *ws)
+static void mcp251x_restart_work_handler(struct work_struct *ws)
 {
        struct mcp251x_priv *priv = container_of(ws, struct mcp251x_priv,
-                                                irq_work);
+                                                restart_work);
        struct spi_device *spi = priv->spi;
        struct net_device *net = priv->net;
-       u8 txbnctrl;
-       u8 intf;
-       enum can_state new_state;
 
+       mutex_lock(&priv->mcp_lock);
        if (priv->after_suspend) {
                mdelay(10);
                mcp251x_hw_reset(spi);
@@ -772,45 +726,54 @@ static void mcp251x_irq_work_handler(struct work_struct *ws)
                        mcp251x_set_normal_mode(spi);
                } else if (priv->after_suspend & AFTER_SUSPEND_UP) {
                        netif_device_attach(net);
-                       /* Clean since we lost tx buffer */
-                       if (priv->tx_skb || priv->tx_len) {
-                               mcp251x_clean(net);
-                               netif_wake_queue(net);
-                       }
+                       mcp251x_clean(net);
                        mcp251x_set_normal_mode(spi);
+                       netif_wake_queue(net);
                } else {
                        mcp251x_hw_sleep(spi);
                }
                priv->after_suspend = 0;
+               priv->force_quit = 0;
        }
 
-       if (priv->can.restart_ms == 0 && priv->can.state == CAN_STATE_BUS_OFF)
-               return;
+       if (priv->restart_tx) {
+               priv->restart_tx = 0;
+               mcp251x_write_reg(spi, TXBCTRL(0), 0);
+               mcp251x_clean(net);
+               netif_wake_queue(net);
+               mcp251x_error_skb(net, CAN_ERR_RESTARTED, 0);
+       }
+       mutex_unlock(&priv->mcp_lock);
+}
 
-       while (!priv->force_quit && !freezing(current)) {
-               u8 eflag = mcp251x_read_reg(spi, EFLG);
-               int can_id = 0, data1 = 0;
+static irqreturn_t mcp251x_can_ist(int irq, void *dev_id)
+{
+       struct mcp251x_priv *priv = dev_id;
+       struct spi_device *spi = priv->spi;
+       struct net_device *net = priv->net;
 
-               mcp251x_write_reg(spi, EFLG, 0x00);
+       mutex_lock(&priv->mcp_lock);
+       while (!priv->force_quit) {
+               enum can_state new_state;
+               u8 intf = mcp251x_read_reg(spi, CANINTF);
+               u8 eflag;
+               int can_id = 0, data1 = 0;
 
-               if (priv->restart_tx) {
-                       priv->restart_tx = 0;
-                       mcp251x_write_reg(spi, TXBCTRL(0), 0);
-                       if (priv->tx_skb || priv->tx_len)
-                               mcp251x_clean(net);
-                       netif_wake_queue(net);
-                       can_id |= CAN_ERR_RESTARTED;
+               if (intf & CANINTF_RX0IF) {
+                       mcp251x_hw_rx(spi, 0);
+                       /* Free one buffer ASAP */
+                       mcp251x_write_bits(spi, CANINTF, intf & CANINTF_RX0IF,
+                                          0x00);
                }
 
-               if (priv->wake) {
-                       /* Wait whilst the device wakes up */
-                       mdelay(10);
-                       priv->wake = 0;
-               }
+               if (intf & CANINTF_RX1IF)
+                       mcp251x_hw_rx(spi, 1);
 
-               intf = mcp251x_read_reg(spi, CANINTF);
                mcp251x_write_bits(spi, CANINTF, intf, 0x00);
 
+               eflag = mcp251x_read_reg(spi, EFLG);
+               mcp251x_write_reg(spi, EFLG, 0x00);
+
                /* Update can state */
                if (eflag & EFLG_TXBO) {
                        new_state = CAN_STATE_BUS_OFF;
@@ -851,59 +814,31 @@ static void mcp251x_irq_work_handler(struct work_struct *ws)
                }
                priv->can.state = new_state;
 
-               if ((intf & CANINTF_ERRIF) || (can_id & CAN_ERR_RESTARTED)) {
-                       struct sk_buff *skb;
-                       struct can_frame *frame;
-
-                       /* Create error frame */
-                       skb = alloc_can_err_skb(net, &frame);
-                       if (skb) {
-                               /* Set error frame flags based on bus state */
-                               frame->can_id = can_id;
-                               frame->data[1] = data1;
-
-                               /* Update net stats for overflows */
-                               if (eflag & (EFLG_RX0OVR | EFLG_RX1OVR)) {
-                                       if (eflag & EFLG_RX0OVR)
-                                               net->stats.rx_over_errors++;
-                                       if (eflag & EFLG_RX1OVR)
-                                               net->stats.rx_over_errors++;
-                                       frame->can_id |= CAN_ERR_CRTL;
-                                       frame->data[1] |=
-                                               CAN_ERR_CRTL_RX_OVERFLOW;
-                               }
-
-                               netif_rx(skb);
-                       } else {
-                               dev_info(&spi->dev,
-                                        "cannot allocate error skb\n");
+               if (intf & CANINTF_ERRIF) {
+                       /* Handle overflow counters */
+                       if (eflag & (EFLG_RX0OVR | EFLG_RX1OVR)) {
+                               if (eflag & EFLG_RX0OVR)
+                                       net->stats.rx_over_errors++;
+                               if (eflag & EFLG_RX1OVR)
+                                       net->stats.rx_over_errors++;
+                               can_id |= CAN_ERR_CRTL;
+                               data1 |= CAN_ERR_CRTL_RX_OVERFLOW;
                        }
+                       mcp251x_error_skb(net, can_id, data1);
                }
 
                if (priv->can.state == CAN_STATE_BUS_OFF) {
                        if (priv->can.restart_ms == 0) {
+                               priv->force_quit = 1;
                                can_bus_off(net);
                                mcp251x_hw_sleep(spi);
-                               return;
+                               break;
                        }
                }
 
                if (intf == 0)
                        break;
 
-               if (intf & CANINTF_WAKIF)
-                       complete(&priv->awake);
-
-               if (intf & CANINTF_MERRF) {
-                       /* If there are pending Tx buffers, restart queue */
-                       txbnctrl = mcp251x_read_reg(spi, TXBCTRL(0));
-                       if (!(txbnctrl & TXBCTRL_TXREQ)) {
-                               if (priv->tx_skb || priv->tx_len)
-                                       mcp251x_clean(net);
-                               netif_wake_queue(net);
-                       }
-               }
-
                if (intf & (CANINTF_TX2IF | CANINTF_TX1IF | CANINTF_TX0IF)) {
                        net->stats.tx_packets++;
                        net->stats.tx_bytes += priv->tx_len - 1;
@@ -914,12 +849,66 @@ static void mcp251x_irq_work_handler(struct work_struct *ws)
                        netif_wake_queue(net);
                }
 
-               if (intf & CANINTF_RX0IF)
-                       mcp251x_hw_rx(spi, 0);
+       }
+       mutex_unlock(&priv->mcp_lock);
+       return IRQ_HANDLED;
+}
 
-               if (intf & CANINTF_RX1IF)
-                       mcp251x_hw_rx(spi, 1);
+static int mcp251x_open(struct net_device *net)
+{
+       struct mcp251x_priv *priv = netdev_priv(net);
+       struct spi_device *spi = priv->spi;
+       struct mcp251x_platform_data *pdata = spi->dev.platform_data;
+       int ret;
+
+       ret = open_candev(net);
+       if (ret) {
+               dev_err(&spi->dev, "unable to set initial baudrate!\n");
+               return ret;
+       }
+
+       mutex_lock(&priv->mcp_lock);
+       if (pdata->transceiver_enable)
+               pdata->transceiver_enable(1);
+
+       priv->force_quit = 0;
+       priv->tx_skb = NULL;
+       priv->tx_len = 0;
+
+       ret = request_threaded_irq(spi->irq, NULL, mcp251x_can_ist,
+                         IRQF_TRIGGER_FALLING, DEVICE_NAME, priv);
+       if (ret) {
+               dev_err(&spi->dev, "failed to acquire irq %d\n", spi->irq);
+               if (pdata->transceiver_enable)
+                       pdata->transceiver_enable(0);
+               close_candev(net);
+               goto open_unlock;
+       }
+
+       priv->wq = create_freezeable_workqueue("mcp251x_wq");
+       INIT_WORK(&priv->tx_work, mcp251x_tx_work_handler);
+       INIT_WORK(&priv->restart_work, mcp251x_restart_work_handler);
+
+       ret = mcp251x_hw_reset(spi);
+       if (ret) {
+               mcp251x_open_clean(net);
+               goto open_unlock;
+       }
+       ret = mcp251x_setup(net, priv, spi);
+       if (ret) {
+               mcp251x_open_clean(net);
+               goto open_unlock;
        }
+       ret = mcp251x_set_normal_mode(spi);
+       if (ret) {
+               mcp251x_open_clean(net);
+               goto open_unlock;
+       }
+       netif_wake_queue(net);
+
+open_unlock:
+       mutex_unlock(&priv->mcp_lock);
+       return ret;
 }
 
 static const struct net_device_ops mcp251x_netdev_ops = {
@@ -955,13 +944,11 @@ static int __devinit mcp251x_can_probe(struct spi_device *spi)
        priv->can.clock.freq = pdata->oscillator_frequency / 2;
        priv->can.ctrlmode_supported = CAN_CTRLMODE_3_SAMPLES |
                CAN_CTRLMODE_LOOPBACK | CAN_CTRLMODE_LISTENONLY;
-       if (pdata->model == CAN_MCP251X_MCP2515)
-               priv->can.ctrlmode_supported |= CAN_CTRLMODE_ONE_SHOT;
        priv->net = net;
        dev_set_drvdata(&spi->dev, priv);
 
        priv->spi = spi;
-       mutex_init(&priv->spi_lock);
+       mutex_init(&priv->mcp_lock);
 
        /* If requested, allocate DMA buffers */
        if (mcp251x_enable_dma) {
@@ -1010,18 +997,12 @@ static int __devinit mcp251x_can_probe(struct spi_device *spi)
 
        SET_NETDEV_DEV(net, &spi->dev);
 
-       priv->wq = create_freezeable_workqueue("mcp251x_wq");
-
-       INIT_WORK(&priv->tx_work, mcp251x_tx_work_handler);
-       INIT_WORK(&priv->irq_work, mcp251x_irq_work_handler);
-
-       init_completion(&priv->awake);
-
        /* Configure the SPI bus */
        spi->mode = SPI_MODE_0;
        spi->bits_per_word = 8;
        spi_setup(spi);
 
+       /* Here is OK to not lock the MCP, no one knows about it yet */
        if (!mcp251x_hw_probe(spi)) {
                dev_info(&spi->dev, "Probe failed\n");
                goto error_probe;
@@ -1064,10 +1045,6 @@ static int __devexit mcp251x_can_remove(struct spi_device *spi)
        unregister_candev(net);
        free_candev(net);
 
-       priv->force_quit = 1;
-       flush_workqueue(priv->wq);
-       destroy_workqueue(priv->wq);
-
        if (mcp251x_enable_dma) {
                dma_free_coherent(&spi->dev, PAGE_SIZE,
                                  priv->spi_tx_buf, priv->spi_tx_dma);
@@ -1089,6 +1066,12 @@ static int mcp251x_can_suspend(struct spi_device *spi, pm_message_t state)
        struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
        struct net_device *net = priv->net;
 
+       priv->force_quit = 1;
+       disable_irq(spi->irq);
+       /*
+        * Note: at this point neither IST nor workqueues are running.
+        * open/stop cannot be called anyway so locking is not needed
+        */
        if (netif_running(net)) {
                netif_device_detach(net);
 
@@ -1115,16 +1098,18 @@ static int mcp251x_can_resume(struct spi_device *spi)
 
        if (priv->after_suspend & AFTER_SUSPEND_POWER) {
                pdata->power_enable(1);
-               queue_work(priv->wq, &priv->irq_work);
+               queue_work(priv->wq, &priv->restart_work);
        } else {
                if (priv->after_suspend & AFTER_SUSPEND_UP) {
                        if (pdata->transceiver_enable)
                                pdata->transceiver_enable(1);
-                       queue_work(priv->wq, &priv->irq_work);
+                       queue_work(priv->wq, &priv->restart_work);
                } else {
                        priv->after_suspend = 0;
                }
        }
+       priv->force_quit = 0;
+       enable_irq(spi->irq);
        return 0;
 }
 #else