[PATCH 3/3] at91_can: add driver for Atmel's CAN controller on AT91SAM9263
Marc Kleine-Budde
mkl at pengutronix.de
Wed Sep 16 05:46:45 EDT 2009
This patch add the driver for the SoC CAN controller in Atmel's AT91SAM9263.
Signed-off-by: Marc Kleine-Budde <mkl at pengutronix.de>
---
drivers/net/can/Kconfig | 6 +
drivers/net/can/Makefile | 1 +
drivers/net/can/at91_can.c | 1177 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 1184 insertions(+), 0 deletions(-)
create mode 100644 drivers/net/can/at91_can.c
diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig
index 0900743..b6d2af1 100644
--- a/drivers/net/can/Kconfig
+++ b/drivers/net/can/Kconfig
@@ -82,6 +82,12 @@ config CAN_KVASER_PCI
This driver is for the the PCIcanx and PCIcan cards (1, 2 or
4 channel) from Kvaser (http://www.kvaser.com).
+config CAN_AT91
+ tristate "Atmel AT91 onchip CAN controller"
+ depends on CAN && ARCH_AT91SAM9263
+ ---help---
+ This is a driver for the SoC CAN controller in Atmel's AT91SAM9263.
+
config CAN_DEBUG_DEVICES
bool "CAN devices debugging messages"
depends on CAN
diff --git a/drivers/net/can/Makefile b/drivers/net/can/Makefile
index 523a941..3a54a12 100644
--- a/drivers/net/can/Makefile
+++ b/drivers/net/can/Makefile
@@ -8,5 +8,6 @@ obj-$(CONFIG_CAN_DEV) += can-dev.o
can-dev-y := dev.o
obj-$(CONFIG_CAN_SJA1000) += sja1000/
+obj-$(CONFIG_CAN_AT91) += at91_can.o
ccflags-$(CONFIG_CAN_DEBUG_DEVICES) := -DDEBUG
diff --git a/drivers/net/can/at91_can.c b/drivers/net/can/at91_can.c
new file mode 100644
index 0000000..cd1e8cb
--- /dev/null
+++ b/drivers/net/can/at91_can.c
@@ -0,0 +1,1177 @@
+/*
+ * at91_can.c - CAN network driver for AT91 SoC CAN controller
+ *
+ * (C) 2007 by Hans J. Koch <hjk at linutronix.de>
+ * (C) 2008, 2009 by Marc Kleine-Budde <kernel at 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 at lists.berlios.de>
+ *
+ */
+
+#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 at pengutronix.de>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION(DRV_NAME " CAN netdevice driver");
--
1.6.3.3
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