can: mcp251x: Move to threaded interrupts instead of workqueues.

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>

1 files changed, 203 insertions, 218 deletions

diff --git a/drivers/net/can/mcp251x.c b/drivers/net/can/mcp251x.c
index bbe186b5a0ed..f8cc168ec76c 100644
--- a/drivers/net/can/mcp251x.c
+++ b/drivers/net/can/mcp251x.c
@@ -180,6 +180,14 @@
 #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