Re: [PATCH v3] net: can: Introduce MEN 16Z192-00 CAN controller driver

From: Marc Kleine-Budde
Date: Tue Sep 15 2020 - 05:12:52 EST

On 7/7/20 5:35 PM, Abhijeet Badurkar wrote:
> 
> This CAN Controller is found on MEN Chameleon FPGAs.
>
> The driver/device supports the CAN2.0 specification.
> There are 255 RX and 255 Tx buffer within the IP. The
> pointer for the buffer are handled by HW to make the
> access from within the driver as simple as possible.
>
> The driver also supports parameters to configure the
> buffer level interrupt for RX/TX as well as a RX timeout
> interrupt.
>
> With this configuration options, the driver/device
> provides flexibility for different types of usecases.
>
> Changes in version 2:
> Since the hardware does not have TX-done notification,
> the local loopback mechanism is implemented using ECHO skbs.
> The skb is added to echo stack, upon packet reception,
> received and echo skb are matched.
>
> LED trigger support is added.

Please remove, as this is obsolete. There's generic CONFIG_LEDS_TRIGGER_NETDEV now.

> The other fixes are related to transmission and reception
> of remote frame, setting can state on CAN initialization,
> some minor fixes and code optimizations.
>
> Changes in version 3:
> Fixed compiler warning.
>
> Signed-off-by: Abhijeet Badurkar <abhijeet.badurkar@xxxxxxxxxx>
> ---
> drivers/net/can/Kconfig | 10 +
> drivers/net/can/Makefile | 1 +
> drivers/net/can/men_z192_can.c | 1055 ++++++++++++++++++++++++++++++++
> 3 files changed, 1066 insertions(+)
> create mode 100644 drivers/net/can/men_z192_can.c
>
> diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig
> index f07012a76c0c..df658ecefddb 100644
> --- a/drivers/net/can/Kconfig
> +++ b/drivers/net/can/Kconfig
> @@ -133,6 +133,16 @@ config CAN_KVASER_PCIEFD
> Kvaser Mini PCI Express HS v2
> Kvaser Mini PCI Express 2xHS v2
>
> +config CAN_MEN_Z192
> + depends on MCB
> + tristate "MEN 16Z192-00 CAN Controller"
> + help
> + Driver for MEN 16Z192-00 CAN Controller IP-Core, which
> + is connected to the MEN Chameleon Bus.
> +
> + This driver can also be built as a module. If so, the module will be
> + called men_z192_can.ko.
> +
> config CAN_SUN4I
> tristate "Allwinner A10 CAN controller"
> depends on MACH_SUN4I || MACH_SUN7I || COMPILE_TEST
> diff --git a/drivers/net/can/Makefile b/drivers/net/can/Makefile
> index 22164300122d..d874ab1b9f08 100644
> --- a/drivers/net/can/Makefile
> +++ b/drivers/net/can/Makefile
> @@ -26,6 +26,7 @@ obj-$(CONFIG_CAN_GRCAN) += grcan.o
> obj-$(CONFIG_CAN_IFI_CANFD) += ifi_canfd/
> obj-$(CONFIG_CAN_JANZ_ICAN3) += janz-ican3.o
> obj-$(CONFIG_CAN_KVASER_PCIEFD) += kvaser_pciefd.o
> +obj-$(CONFIG_CAN_MEN_Z192) += men_z192_can.o
> obj-$(CONFIG_CAN_MSCAN) += mscan/
> obj-$(CONFIG_CAN_M_CAN) += m_can/
> obj-$(CONFIG_CAN_PEAK_PCIEFD) += peak_canfd/
> diff --git a/drivers/net/can/men_z192_can.c b/drivers/net/can/men_z192_can.c
> new file mode 100644
> index 000000000000..a1e8be2dd94c
> --- /dev/null
> +++ b/drivers/net/can/men_z192_can.c
> @@ -0,0 +1,1055 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* MEN 16Z192 CAN Controller driver
> + *
> + * Copyright (C) 2016 MEN Mikroelektronik GmbH (www.men.de)
> + *
> + * Local loopback implementation in this driver is adapted from Janz MODULbus
> + * VMOD-ICAN3 CAN Interface Driver
> + * Copyright (c) 2010 Ira W. Snyder <iws@xxxxxxxxxxxxxxxx>
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/err.h>
> +#include <linux/bitops.h>
> +#include <linux/netdevice.h>
> +#include <linux/can.h>
> +#include <linux/can/dev.h>
> +#include <linux/can/error.h>
> +#include <linux/can/led.h>
> +#include <linux/mcb.h>
> +
> +#define DRV_NAME "z192_can"
> +
> +#define MEN_Z192_MODE_TOUT_US 40
> +
> +/* CTL/BTR Register Bits */
> +#define MEN_Z192_CTL0_INITRQ BIT(0)
> +#define MEN_Z192_CTL0_SLPRQ BIT(1)
> +#define MEN_Z192_CTL1_INITAK BIT(8)
> +#define MEN_Z192_CTL1_SLPAK BIT(9)
> +#define MEN_Z192_CTL1_LISTEN BIT(12)
> +#define MEN_Z192_CTL1_LOOPB BIT(13)
> +#define MEN_Z192_CTL1_CANE BIT(15)
> +#define MEN_Z192_BTR0_BRP(x) (((x) & 0x3f) << 16)
> +#define MEN_Z192_BTR0_SJW(x) (((x) & 0x03) << 22)
> +#define MEN_Z192_BTR1_TSEG1(x) (((x) & 0x0f) << 24)
> +#define MEN_Z192_BTR1_TSEG2(x) (((x) & 0x07) << 28)
> +#define MEN_Z192_BTR1_SAMP BIT(31)
> +
> +/* IER Interrupt Enable Register bits */
> +#define MEN_Z192_RXIE BIT(0)
> +#define MEN_Z192_OVRIE BIT(1)
> +#define MEN_Z192_CSCIE BIT(6)
> +#define MEN_Z192_TOUTE BIT(7)
> +#define MEN_Z192_TXIE BIT(16)
> +#define MEN_Z192_ERRIE BIT(17)
> +
> +#define MEN_Z192_IRQ_ALL \
> + (MEN_Z192_RXIE | MEN_Z192_OVRIE | \
> + MEN_Z192_CSCIE | MEN_Z192_TOUTE | \
only one space in front of the '|'

> + MEN_Z192_TXIE)
> +
> +/* RX_TX_STAT RX/TX Status status register bits */
> +#define MEN_Z192_RX_BUF_CNT(x) ((x) & 0xff)
> +#define MEN_Z192_TX_BUF_CNT(x) (((x) & 0xff00) >> 8)
> +#define MEN_Z192_RFLG_RXIF BIT(16)
> +#define MEN_Z192_RFLG_OVRF BIT(17)
> +#define MEN_Z192_RFLG_TSTATE GENMASK(19, 18)
> +#define MEN_Z192_RFLG_RSTATE GENMASK(21, 20)
> +#define MEN_Z192_RFLG_CSCIF BIT(22)
> +#define MEN_Z192_RFLG_TOUTF BIT(23)
> +#define MEN_Z192_TFLG_TXIF BIT(24)
> +
> +#define MEN_Z192_GET_TSTATE(x) (((x) & MEN_Z192_RFLG_TSTATE) >> 18)
> +#define MEN_Z192_GET_RSTATE(x) (((x) & MEN_Z192_RFLG_RSTATE) >> 20)
> +
> +#define MEN_Z192_IRQ_NAPI (MEN_Z192_RXIE | MEN_Z192_TOUTE)
> +
> +#define MEN_Z192_IRQ_FLAGS_ALL \
> + (MEN_Z192_RFLG_RXIF | MEN_Z192_RFLG_OVRF | \
> + MEN_Z192_RFLG_TSTATE | MEN_Z192_RFLG_RSTATE | \
> + MEN_Z192_RFLG_CSCIF | MEN_Z192_RFLG_TOUTF | \
> + MEN_Z192_TFLG_TXIF)
> +
> +/* RX/TX Error counter bits */
> +#define MEN_Z192_GET_RX_ERR_CNT(x) ((x) & 0xff)
> +#define MEN_Z192_GET_TX_ERR_CNT(x) (((x) & 0x00ff0000) >> 16)

define a MASK using GENMASK and use FIELD_GET() in the code.

> +
> +/* Buffer level register bits */
> +#define MEN_Z192_RX_BUF_LVL GENMASK(15, 0)
> +#define MEN_Z192_TX_BUF_LVL GENMASK(31, 16)
> +
> +/* RX/TX Buffer register bits */
> +#define MEN_Z192_CFBUF_LEN GENMASK(3, 0)
> +#define MEN_Z192_CFBUF_ID1 GENMASK(31, 21)
> +#define MEN_Z192_CFBUF_ID2 GENMASK(18, 1)
> +#define MEN_Z192_CFBUF_TS GENMASK(31, 8)
> +#define MEN_Z192_CFBUF_E_RTR BIT(0)
> +#define MEN_Z192_CFBUF_IDE BIT(19)
> +#define MEN_Z192_CFBUF_SRR BIT(20)
> +#define MEN_Z192_CFBUF_S_RTR BIT(20)
> +#define MEN_Z192_CFBUF_ID2_SHIFT 1
> +#define MEN_Z192_CFBUF_ID1_SHIFT 21
> +
> +/* Global register offsets */
> +#define MEN_Z192_RX_BUF_START 0x0000
> +#define MEN_Z192_TX_BUF_START 0x1000
> +#define MEN_Z192_REGS_OFFS 0x2000
> +
> +/* Buffer level control values */
> +#define MEN_Z192_MIN_BUF_LVL 0
> +#define MEN_Z192_MAX_BUF_LVL 254
> +#define MEN_Z192_RX_BUF_LVL_DEF 5
> +#define MEN_Z192_TX_BUF_LVL_DEF 5
> +#define MEN_Z192_RX_TOUT_MIN 0
> +#define MEN_Z192_RX_TOUT_MAX 65535
> +#define MEN_Z192_RX_TOUT_DEF 1000

Please use a consistent indention scheme, I suggest only one space between name
and value/expression.
> +
> +static int txlvl = MEN_Z192_TX_BUF_LVL_DEF;
> +module_param(txlvl, int, 0444);
> +MODULE_PARM_DESC(txlvl, "TX IRQ trigger level (in frames) 0-254, default="
> + __MODULE_STRING(MEN_Z192_MIN_BUF_LVL) ")");

Please implement this via ethtool coalesce. See:

https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/ethtool.h#L389
https://elixir.bootlin.com/linux/latest/source/include/linux/ethtool.h#L392

Use an existing driver to follow, how to implement ethtool:

https://elixir.bootlin.com/linux/latest/source/drivers/net/ethernet/amd/xgbe/xgbe-ethtool.c#L815

> +/* Following parameters related to RX interrupt have impact on latency and
> + * provide the users full control over them.
> + *
> + * rxlvl: Receive buffer level or in other words, the number of frames to
> + * trigger RX interrupt
> + * When number of received valid CAN frames exceeds rxlvl and RX interrupt is
> + * enabled, an interrupt will be generated. For example, if rxlvl is 0 and one
> + * frame is received, an interrupt will be generated or if rxlvl is 254 and 255
> + * frames are received, an interrupt will be generated.

This probably correspondes to ETHTOOL_COALESCE_RX_MAX_FRAMES

> + *
> + * rx_timeout: Read timeout for receive buffer
> + * When receive buffer is not empty and it has not been accessed since
> + * rx_timeout then TOUTF flag is set. If RX interrupt was already enabled and
> + * TOUTF flag is set, a RX interrupt will be generated. By defining this
> + * parameter, time of the interrupt generation can be controlled, if the RX
> + * buffer level is not reached within rx_timeout.

This probably correspondes to ETHTOOL_COALESCE_RX_USECS

> + *
> + * When an interrupt is generated for either of these parameters, NAPI poll is
> + * scheduled to read the recived CAN frames.
> + */
> +static int rxlvl = MEN_Z192_RX_BUF_LVL_DEF;
> +module_param(rxlvl, int, 0444);
> +MODULE_PARM_DESC(rxlvl, "RX IRQ trigger level (in frames) 0-254, default="
> + __MODULE_STRING(MEN_Z192_MIN_BUF_LVL) ")");
> +
> +static int rx_timeout = MEN_Z192_RX_TOUT_DEF;
> +module_param(rx_timeout, int, 0444);
> +MODULE_PARM_DESC(rx_timeout, "RX IRQ timeout (in 100usec steps), default="
> + __MODULE_STRING(MEN_Z192_RX_TOUT_DEF) ")");
> +
> +struct men_z192_regs {
> + u32 ctl_btr; /* Control and bus timing register */
> + u32 ier; /* Interrupt enable register */
> + u32 buf_lvl; /* Buffer level register */
> + u32 rxa; /* RX Data acknowledge register */
> + u32 txa; /* TX data acknowledge register */
> + u32 rx_tx_sts; /* RX/TX flags and buffer level */
> + u32 ovr_ecc_sts; /* Overrun/ECC status register */
> + u32 idac_ver; /* ID acceptance control / version */
> + u32 rx_tx_err; /* RX/TX error counter register */
> + u32 idar_0_to_3; /* ID acceptance register 0...3 */
> + u32 idar_4_to_7; /* ID acceptance register 4...7 */
> + u32 idmr_0_to_3; /* ID mask register 0...3 */
> + u32 idmr_4_to_7; /* ID mask register 4...7 */
> + u32 rx_timeout; /* receive timeout */
> + u32 timebase; /* Base frequency for baudrate calculation */
> +};
> +
> +struct men_z192 {
> + struct can_priv can;
> + struct napi_struct napi;
> + struct net_device *ndev;
> + struct device *dev;
> +
> + /* Lock for CTL_BTR register access. This register combines bittiming
> + * bits and the operation mode bits. It is also used for bit r/m/w
> + * access to all registers.
> + */
> + spinlock_t lock;
> + struct resource *mem;
> + struct men_z192_regs __iomem *regs;
> + void __iomem *dev_base;
> +
> + /* queue for echo packets */
> + struct sk_buff_head echoq;
> +};
> +
> +struct men_z192_cf_buf {
> + u32 can_id;
> + u32 data[2];
> + u32 length;
> +};
> +
> +enum men_z192_int_state {
> + MEN_Z192_CAN_DIS = 0,
> + MEN_Z192_CAN_EN,
> + MEN_Z192_CAN_NAPI_DIS,
> + MEN_Z192_CAN_NAPI_EN,
> +};
> +
> +static enum can_state bus_state_map[] = {
const
> + CAN_STATE_ERROR_ACTIVE,
> + CAN_STATE_ERROR_WARNING,
> + CAN_STATE_ERROR_PASSIVE,
> + CAN_STATE_BUS_OFF
> +};
> +
> +static const struct can_bittiming_const men_z192_bittiming_const = {
> + .name = DRV_NAME,
> + .tseg1_min = 4,
> + .tseg1_max = 16,
> + .tseg2_min = 2,
> + .tseg2_max = 8,
> + .sjw_max = 4,
> + .brp_min = 2,
> + .brp_max = 64,
> + .brp_inc = 1,
> +};
> +
> +static inline void men_z192_bit_clr(struct men_z192 *priv, void __iomem *addr,
> + u32 mask)
> +{
> + unsigned long flags;
> + u32 val;
> +
> + spin_lock_irqsave(&priv->lock, flags);
> +
> + val = readl(addr);
> + val &= ~mask;
> + writel(val, addr);
> +
> + spin_unlock_irqrestore(&priv->lock, flags);
> +}
> +
> +static inline void men_z192_bit_set(struct men_z192 *priv, void __iomem *addr,
> + u32 mask)
> +{
> + unsigned long flags;
> + u32 val;
> +
> + spin_lock_irqsave(&priv->lock, flags);
> +
> + val = readl(addr);
> + val |= mask;
> + writel(val, addr);
> +
> + spin_unlock_irqrestore(&priv->lock, flags);
> +}
> +
> +static inline void men_z192_ack_rx_pkg(struct men_z192 *priv,
> + unsigned int count)
> +{
> + writel(count, &priv->regs->rxa);
> +}
> +
> +static inline void men_z192_ack_tx_pkg(struct men_z192 *priv,
> + unsigned int count)
> +{
> + writel(count, &priv->regs->txa);
> +}
> +
> +static void men_z192_set_int(struct men_z192 *priv,
> + enum men_z192_int_state state)
> +{
> + struct men_z192_regs __iomem *regs = priv->regs;
> +
> + switch (state) {
> + case MEN_Z192_CAN_DIS:
> + men_z192_bit_clr(priv, &regs->ier, MEN_Z192_IRQ_ALL);
> + break;
> +
> + case MEN_Z192_CAN_EN:
> + men_z192_bit_set(priv, &regs->ier, MEN_Z192_IRQ_ALL);
> + break;
> +
> + case MEN_Z192_CAN_NAPI_DIS:
> + men_z192_bit_clr(priv, &regs->ier, MEN_Z192_IRQ_NAPI);
> + break;
> +
> + case MEN_Z192_CAN_NAPI_EN:
> + men_z192_bit_set(priv, &regs->ier, MEN_Z192_IRQ_NAPI);
> + break;
> +
> + default:
> + netdev_err(priv->ndev, "invalid interrupt state\n");
> + break;
> + }
> +}
> +
> +static int men_z192_get_berr_counter(const struct net_device *ndev,
> + struct can_berr_counter *bec)
> +{
> + struct men_z192 *priv = netdev_priv(ndev);
> + struct men_z192_regs __iomem *regs = priv->regs;
> + u32 err_cnt;
> +
> + err_cnt = readl(&regs->rx_tx_err);
> +
> + bec->txerr = MEN_Z192_GET_TX_ERR_CNT(err_cnt);
> + bec->rxerr = MEN_Z192_GET_RX_ERR_CNT(err_cnt);

FIELD_GET()

> +
> + return 0;
> +}
> +
> +static int men_z192_req_run_mode(struct men_z192 *priv)
> +{
> + struct men_z192_regs __iomem *regs = priv->regs;
> + u32 val;
> +
> + men_z192_bit_clr(priv, &regs->ctl_btr, MEN_Z192_CTL0_INITRQ);
> +
> + return read_poll_timeout(readl, val, !(val & MEN_Z192_CTL1_INITAK), 10,

please use a define for the 10

> + MEN_Z192_MODE_TOUT_US, 0, &regs->ctl_btr);
> +}
> +
> +static int men_z192_req_init_mode(struct men_z192 *priv)
> +{
> + struct men_z192_regs __iomem *regs = priv->regs;
> + u32 val;
> +
> + men_z192_bit_set(priv, &regs->ctl_btr, MEN_Z192_CTL0_INITRQ);
> +
> + return read_poll_timeout(readl, val, val & MEN_Z192_CTL1_INITAK, 10,

same here

> + MEN_Z192_MODE_TOUT_US, 0, &regs->ctl_btr);
> +}
> +
> +static void z192_put_echo_skb(struct men_z192 *priv, struct sk_buff *skb)
> +{
> + skb = can_create_echo_skb(skb);
> + if (!skb)
> + return;
> +
> + /* save this skb for tx interrupt echo handling */
> + skb_queue_tail(&priv->echoq, skb);
> +}
> +
> +static unsigned int z192_get_echo_skb(struct men_z192 *priv)
> +{
> + struct sk_buff *skb = skb_dequeue(&priv->echoq);
> + struct can_frame *cf;
> + u8 dlc;
> +
> + /* this should never trigger unless there is a driver bug */
> + if (!skb) {
> + netdev_err(priv->ndev, "BUG: echo skb not occupied\n");
> + return 0;
> + }
> +
> + cf = (struct can_frame *)skb->data;
> + dlc = cf->can_dlc;
> +
> + /* check flag whether this packet has to be looped back */
> + if (skb->pkt_type != PACKET_LOOPBACK) {
> + kfree_skb(skb);
> + return dlc;
> + }
> +
> + skb->protocol = htons(ETH_P_CAN);
> + skb->pkt_type = PACKET_BROADCAST;
> + skb->ip_summed = CHECKSUM_UNNECESSARY;
> + skb->dev = priv->ndev;
> + netif_receive_skb(skb);
> + return dlc;
> +}
> +
> +static bool z192_echo_skb_matches(struct men_z192 *priv, struct sk_buff *skb)
> +{
> + struct can_frame *cf = (struct can_frame *)skb->data;
> + struct sk_buff *echo_skb = skb_peek(&priv->echoq);
> + struct can_frame *echo_cf;
> +
> + if (!echo_skb)
> + return false;
> +
> + echo_cf = (struct can_frame *)echo_skb->data;
> + if (cf->can_id != echo_cf->can_id)
> + return false;
> +
> + if (cf->can_dlc != echo_cf->can_dlc)
> + return false;
> +
> + return memcmp(cf->data, echo_cf->data, cf->can_dlc) == 0;
> +}
> +
> +static int men_z192_read_frame(struct net_device *ndev, unsigned int frame_nr)
> +{
> + struct net_device_stats *stats = &ndev->stats;
> + struct men_z192 *priv = netdev_priv(ndev);
> + struct men_z192_cf_buf __iomem *cf_buf;
> + struct can_frame *cf;
> + struct sk_buff *skb;
> + u32 cf_offset;
> + u32 length;
> + u32 id;
> +
> + skb = alloc_can_skb(ndev, &cf);
> + if (unlikely(!skb)) {
> + stats->rx_dropped++;
> + return 0;
> + }
> +
> + cf_offset = sizeof(struct men_z192_cf_buf) * frame_nr;
> +
> + cf_buf = priv->dev_base + MEN_Z192_RX_BUF_START + cf_offset;
> + length = readl(&cf_buf->length) & MEN_Z192_CFBUF_LEN;
> + id = readl(&cf_buf->can_id);
> +
> + if (id & MEN_Z192_CFBUF_IDE) {
> + /* Extended frame */
> + cf->can_id |=
> + (id & MEN_Z192_CFBUF_ID1) >> 3 |
> + ((id & MEN_Z192_CFBUF_ID2) >>
> + MEN_Z192_CFBUF_ID2_SHIFT) |

use FIELD_GET() here

> + CAN_EFF_FLAG;
> +
> + if (id & MEN_Z192_CFBUF_E_RTR)
> + cf->can_id |= CAN_RTR_FLAG;
> + } else {
> + /* Standard frame */
> + cf->can_id = (id & MEN_Z192_CFBUF_ID1) >>
> + MEN_Z192_CFBUF_ID1_SHIFT;

same here

> +
> + if (id & MEN_Z192_CFBUF_S_RTR)
> + cf->can_id |= CAN_RTR_FLAG;
> + }
> +
> + cf->can_dlc = get_can_dlc(length);
> +
> + /* remote transmission request frame contains no data field even if the
> + * data length is set to a value > 0
> + */
> + if (!(cf->can_id & CAN_RTR_FLAG) && cf->can_dlc) {
> + *(__be32 *)cf->data = cpu_to_be32(readl(&cf_buf->data[0]));
> + if (cf->can_dlc > 4)
> + *(__be32 *)(cf->data + 4) =
> + cpu_to_be32(readl(&cf_buf->data[1]));
> + }
> +
> + if (z192_echo_skb_matches(priv, skb)) {
> + stats->tx_packets++;
> + stats->tx_bytes += z192_get_echo_skb(priv);
> + kfree_skb(skb);
> + goto led_event;
> + }
> +
> + stats->rx_bytes += cf->can_dlc;
> + stats->rx_packets++;
> + netif_receive_skb(skb);
> +
> +led_event:
> + can_led_event(ndev, CAN_LED_EVENT_RX);
> +
> + return 1;
> +}
> +
> +static int men_z192_poll(struct napi_struct *napi, int quota)
> +{
> + struct net_device *ndev = napi->dev;
> + struct men_z192 *priv = netdev_priv(ndev);
> + struct men_z192_regs __iomem *regs = priv->regs;
> + int work_done = 0;
> + u32 frame_cnt;
> + u32 status;
> +
> + status = readl(&regs->rx_tx_sts);
> +
> + frame_cnt = MEN_Z192_RX_BUF_CNT(status);
> +
> + while (frame_cnt-- && (work_done < quota)) {
> + work_done += men_z192_read_frame(ndev, 0);
> + men_z192_ack_rx_pkg(priv, 1);
> + }
> +
> + if (work_done < quota) {
> + napi_complete(napi);
> + men_z192_set_int(priv, MEN_Z192_CAN_NAPI_EN);
> + }
> +
> + return work_done;
> +}
> +
> +static int men_z192_xmit(struct sk_buff *skb, struct net_device *ndev)
> +{
> + struct can_frame *cf = (struct can_frame *)skb->data;
> + struct men_z192 *priv = netdev_priv(ndev);
> + struct men_z192_regs __iomem *regs = priv->regs;
> + struct men_z192_cf_buf __iomem *cf_buf;
> + int status;
> + u32 id;
> +
> + if (can_dropped_invalid_skb(ndev, skb))
> + return NETDEV_TX_OK;
> +
> + status = readl(&regs->rx_tx_sts);
> +
> + if (MEN_Z192_TX_BUF_CNT(status) == 254) {

please use a define for the 254

> + netif_stop_queue(ndev);
> + netdev_err(ndev, "not enough space in TX buffer\n");
> +
> + return NETDEV_TX_BUSY;
> + }
> +
> + cf_buf = priv->dev_base + MEN_Z192_TX_BUF_START;
> +
> + if (cf->can_id & CAN_EFF_FLAG) {
> + /* Extended frame */
> + id = ((cf->can_id & CAN_EFF_MASK) <<
> + MEN_Z192_CFBUF_ID2_SHIFT) & MEN_Z192_CFBUF_ID2;
> +
> + id |= (((cf->can_id & CAN_EFF_MASK) >>
> + (CAN_EFF_ID_BITS - CAN_SFF_ID_BITS)) <<
> + MEN_Z192_CFBUF_ID1_SHIFT) & MEN_Z192_CFBUF_ID1;
> +
> + id |= MEN_Z192_CFBUF_IDE | MEN_Z192_CFBUF_SRR;

use FIELD_GET()/FIELD_PREP()
> +
> + if (cf->can_id & CAN_RTR_FLAG)
> + id |= MEN_Z192_CFBUF_E_RTR;
> + } else {
> + /* Standard frame */
> + id = ((cf->can_id & CAN_SFF_MASK) <<
> + MEN_Z192_CFBUF_ID1_SHIFT) & MEN_Z192_CFBUF_ID1;

same here

> +
> + if (cf->can_id & CAN_RTR_FLAG)
> + id |= MEN_Z192_CFBUF_S_RTR;
> + }
> +
> + writel(id, &cf_buf->can_id);
> + writel(cf->can_dlc, &cf_buf->length);
> +
> + if (!(cf->can_id & CAN_RTR_FLAG) && cf->can_dlc) {
> + writel(be32_to_cpup((__be32 *)(cf->data)), &cf_buf->data[0]);
> + if (cf->can_dlc > 4)
> + writel(be32_to_cpup((__be32 *)(cf->data + 4)),
> + &cf_buf->data[1]);
> + }
> +
> + /* The 16z192 CAN IP doesn't have TX-done interrupts, so local
> + * loopback is emulated using ECHO skbs. Add the skb to the ECHO
> + * stack. Upon packet reception, check if the ECHO skb and received
> + * skb match, and use that to wake the queue.
> + */
> + z192_put_echo_skb(priv, skb);
> +
> + /* be sure everything is written to the
> + * device before acknowledge the data.

...triggerring the transmission?

You have to stop the queue, if the buffer in the device is full.

> + */
> + wmb();
> +
> + /* trigger the transmission */
> + men_z192_ack_tx_pkg(priv, 1);
> +
> + can_led_event(ndev, CAN_LED_EVENT_TX);
> +
> + return NETDEV_TX_OK;
> +}
> +
> +static void men_z192_err_interrupt(struct net_device *ndev, u32 status)
> +{
> + struct net_device_stats *stats = &ndev->stats;
> + struct men_z192 *priv = netdev_priv(ndev);
> + struct can_berr_counter bec;
> + struct can_frame *cf;
> + struct sk_buff *skb;
> + enum can_state rx_state = 0, tx_state = 0;
> +
> + skb = alloc_can_err_skb(ndev, &cf);
> + if (unlikely(!skb))
> + return;

please do the stats handling, regardless if the skb was allocated or not.

> +
> + /* put the rx/tx error counter to
> + * the additional controller specific
> + * section of the error frame.
> + */
> + men_z192_get_berr_counter(ndev, &bec);
> + cf->data[6] = bec.txerr;
> + cf->data[7] = bec.rxerr;
> +
> + /* overrun interrupt */
> + if (status & MEN_Z192_RFLG_OVRF) {
> + cf->can_id |= CAN_ERR_CRTL;
> + cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
> + stats->rx_over_errors++;
> + stats->rx_errors++;
> + }
> +
> + /* bus change interrupt */
> + if (status & MEN_Z192_RFLG_CSCIF) {
> + rx_state = bus_state_map[MEN_Z192_GET_RSTATE(status)];
> + tx_state = bus_state_map[MEN_Z192_GET_TSTATE(status)];
> + can_change_state(ndev, cf, tx_state, rx_state);
> +
> + if (priv->can.state == CAN_STATE_BUS_OFF)
> + can_bus_off(ndev);
> + }
> +
> + stats->rx_packets++;
> + stats->rx_bytes += cf->can_dlc;
> + netif_receive_skb(skb);
> +}
> +
> +static irqreturn_t men_z192_isr(int irq, void *dev_id)
> +{
> + struct net_device *ndev = dev_id;
> + struct men_z192 *priv = netdev_priv(ndev);
> + struct men_z192_regs __iomem *regs = priv->regs;
> + bool handled = false;
> + u32 irq_flags;
> + u32 status;
> +
> + status = readl(&regs->rx_tx_sts);
> +
> + irq_flags = status & MEN_Z192_IRQ_FLAGS_ALL;
> + if (!irq_flags)
> + goto out;
> +
> + /* It is safe to write to RX_TS_STS[15:0] */
> + writel(irq_flags, &regs->rx_tx_sts);
> +
> + if (irq_flags & MEN_Z192_TFLG_TXIF) {
> + netif_wake_queue(ndev);
> + handled = true;
> + }
> +
> + /* handle errors */
> + if ((irq_flags & MEN_Z192_RFLG_OVRF) ||
> + (irq_flags & MEN_Z192_RFLG_CSCIF)) {
> + men_z192_err_interrupt(ndev, status);
> + handled = true;
> + }
> +
> + /* schedule NAPI if:
> + * - rx IRQ
> + * - rx timeout IRQ
> + */
> + if ((irq_flags & MEN_Z192_RFLG_RXIF) ||
> + (irq_flags & MEN_Z192_RFLG_TOUTF)) {
> + men_z192_set_int(priv, MEN_Z192_CAN_NAPI_DIS);
> + napi_schedule(&priv->napi);
> + handled = true;
> + }
> +
> +out:
> + return IRQ_RETVAL(handled);
> +}
> +
> +static int men_z192_set_bittiming(struct net_device *ndev)
> +{
> + struct men_z192 *priv = netdev_priv(ndev);
> + const struct can_bittiming *bt = &priv->can.bittiming;
> + unsigned long flags;
> + u32 ctlbtr;
> + int ret = 0;
> +
> + spin_lock_irqsave(&priv->lock, flags);
> +
> + ctlbtr = readl(&priv->regs->ctl_btr);
> +
> + if (!(ctlbtr & MEN_Z192_CTL1_INITAK)) {
> + netdev_alert(ndev,
> + "cannot set bittiminig while in running mode\n");
> + ret = -EPERM;
> + goto out_restore;
> + }
> +
> + ctlbtr &= ~(MEN_Z192_BTR0_BRP(0x3f) |
> + MEN_Z192_BTR0_SJW(0x03) |
> + MEN_Z192_BTR1_TSEG1(0x0f) |
> + MEN_Z192_BTR1_TSEG2(0x07) |
> + MEN_Z192_CTL1_LISTEN |
> + MEN_Z192_CTL1_LOOPB |
> + MEN_Z192_BTR1_SAMP);
> +
> + ctlbtr |= MEN_Z192_BTR0_BRP(bt->brp - 1) |
> + MEN_Z192_BTR0_SJW(bt->sjw - 1) |
> + MEN_Z192_BTR1_TSEG1(bt->phase_seg1 + bt->prop_seg - 1) |
> + MEN_Z192_BTR1_TSEG2(bt->phase_seg2 - 1);

FIELD_PREP()

> +
> + if (priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES)
> + ctlbtr |= MEN_Z192_BTR1_SAMP;
> +
> + if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
> + ctlbtr |= MEN_Z192_CTL1_LISTEN;
> +
> + if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
> + ctlbtr |= MEN_Z192_CTL1_LOOPB;
> +
> + netdev_dbg(ndev, "CTL_BTR=0x%08x\n", ctlbtr);
> +
> + writel(ctlbtr, &priv->regs->ctl_btr);
> +
> +out_restore:
> + spin_unlock_irqrestore(&priv->lock, flags);
> +
> + return ret;
> +}
> +
> +static void men_z192_init_idac(struct net_device *ndev)
> +{
> + struct men_z192 *priv = netdev_priv(ndev);
> + struct men_z192_regs __iomem *regs = priv->regs;
> +
> + /* hardware filtering (accept everything) */
> + writel(0x00000000, &regs->idar_0_to_3);
> + writel(0x00000000, &regs->idar_4_to_7);
> + writel(0xffffffff, &regs->idmr_0_to_3);
> + writel(0xffffffff, &regs->idmr_4_to_7);
> +}
> +
> +static void men_z192_set_can_state(struct net_device *ndev)
> +{
> + struct men_z192 *priv = netdev_priv(ndev);
> + struct men_z192_regs __iomem *regs = priv->regs;
> + enum can_state rx_state, tx_state;
> + u32 status;
> +
> + status = readl(&regs->rx_tx_sts);
> +
> + rx_state = bus_state_map[MEN_Z192_GET_RSTATE(status)];
> + tx_state = bus_state_map[MEN_Z192_GET_TSTATE(status)];
> +
> + can_change_state(ndev, NULL, tx_state, rx_state);
> +}
> +
> +static int men_z192_start(struct net_device *ndev)
> +{
> + struct men_z192 *priv = netdev_priv(ndev);
> + int ret;
> +
> + ret = men_z192_req_init_mode(priv);
> + if (ret)
> + return ret;
> +
> + ret = men_z192_set_bittiming(ndev);
> + if (ret)
> + return ret;
> +
> + ret = men_z192_req_run_mode(priv);
> + if (ret)
> + return ret;
> +
> + men_z192_init_idac(ndev);
> +
> + /* The 16z192 CAN IP does not reset the can bus state if we enter the
> + * init mode. There is also no software reset to reset the state
> + * machine. We need to read the current state, and inform the upper
> + * layer about the current state.
> + */
> + men_z192_set_can_state(ndev);
> +
> + men_z192_set_int(priv, MEN_Z192_CAN_EN);
> +
> + return 0;
> +}
> +
> +static int men_z192_open(struct net_device *ndev)
> +{
> + struct men_z192 *priv = netdev_priv(ndev);
> + int ret;
> +
> + ret = open_candev(ndev);
> + if (ret)
> + return ret;
> +
> + ret = request_irq(ndev->irq, men_z192_isr, IRQF_SHARED,
> + ndev->name, ndev);
> + if (ret)
> + goto out_close;
> +
> + ret = men_z192_start(ndev);
> + if (ret)
> + goto out_free_irq;
> +
> + napi_enable(&priv->napi);
> + netif_start_queue(ndev);
> +
> + can_led_event(ndev, CAN_LED_EVENT_OPEN);
> +
> + return 0;
> +
> +out_free_irq:
> + free_irq(ndev->irq, ndev);
> +out_close:
> + close_candev(ndev);
> + return ret;
> +}
> +
> +static int men_z192_stop(struct net_device *ndev)
> +{
> + struct men_z192 *priv = netdev_priv(ndev);
> + int ret;
> +
> + men_z192_set_int(priv, MEN_Z192_CAN_DIS);
> +
> + ret = men_z192_req_init_mode(priv);
> + if (ret)
> + return ret;
> +
> + priv->can.state = CAN_STATE_STOPPED;
> +
> + can_led_event(ndev, CAN_LED_EVENT_STOP);
> +
> + return 0;
> +}
> +
> +static int men_z192_close(struct net_device *ndev)
> +{
> + struct men_z192 *priv = netdev_priv(ndev);
> + int ret;
> +
> + netif_stop_queue(ndev);
> +
> + napi_disable(&priv->napi);
> +
> + ret = men_z192_stop(ndev);
> +
> + free_irq(ndev->irq, ndev);
> +
> + /* drop all outstanding echo skbs */
> + skb_queue_purge(&priv->echoq);
> +
> + close_candev(ndev);
> +
> + return ret;
> +}
> +
> +static int men_z192_set_mode(struct net_device *ndev, enum can_mode mode)
> +{
> + int ret;
> +
> + switch (mode) {
> + case CAN_MODE_START:
> + ret = men_z192_start(ndev);
> + if (ret)
> + return ret;
> +
> + netif_wake_queue(ndev);
> + break;
> + default:
> + return -EOPNOTSUPP;
> + }
> +
> + return 0;
> +}
> +
> +static const struct net_device_ops men_z192_netdev_ops = {
> + .ndo_open = men_z192_open,
> + .ndo_stop = men_z192_close,
> + .ndo_start_xmit = men_z192_xmit,
> + .ndo_change_mtu = can_change_mtu,
> +};
> +
> +static int men_z192_verify_buf_lvl(int buffer_lvl)
> +{
> + if (buffer_lvl < MEN_Z192_MIN_BUF_LVL ||
> + buffer_lvl > MEN_Z192_MAX_BUF_LVL)
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> +static void men_z192_set_buf_lvl_irq(struct net_device *ndev, int rxlvl,
> + int txlvl)
> +{
> + struct men_z192 *priv = netdev_priv(ndev);
> + struct men_z192_regs __iomem *regs = priv->regs;
> + int reg_val;
> +
> + if (men_z192_verify_buf_lvl(rxlvl))
> + reg_val = MEN_Z192_RX_BUF_LVL_DEF & MEN_Z192_RX_BUF_LVL;
> + else
> + reg_val = rxlvl & MEN_Z192_RX_BUF_LVL;
> +
> + if (men_z192_verify_buf_lvl(txlvl))
> + reg_val |= (MEN_Z192_TX_BUF_LVL_DEF << 16) &
> + MEN_Z192_TX_BUF_LVL;
> + else
> + reg_val |= (txlvl << 16) & MEN_Z192_TX_BUF_LVL;
> +
> + dev_info(priv->dev, "RX IRQ Level: %d TX IRQ Level: %d\n",
> + rxlvl, txlvl);
> +
> + writel(reg_val, &regs->buf_lvl);
> +}
> +
> +static void men_z192_set_rx_tout(struct net_device *ndev, int tout)
> +{
> + struct men_z192 *priv = netdev_priv(ndev);
> + struct men_z192_regs __iomem *regs = priv->regs;
> + int reg_val;
> +
> + if (tout < MEN_Z192_RX_TOUT_MIN || tout > MEN_Z192_RX_TOUT_MAX)
> + reg_val = MEN_Z192_RX_TOUT_MAX;
> + else
> + reg_val = tout;
> +
> + dev_info(priv->dev, "RX IRQ timeout set to: %d\n", reg_val);
> +
> + writel(reg_val, &regs->rx_timeout);
> +}
> +
> +static int men_z192_register(struct net_device *ndev)
> +{
> + struct men_z192 *priv = netdev_priv(ndev);
> + struct men_z192_regs __iomem *regs = priv->regs;
> + u32 ctl_btr;
> + int ret;
> +
> + /* The CAN controller should be always enabled.
> + * There is no way to enable it if disabled.
> + */
> + ctl_btr = readl(&regs->ctl_btr);
> + if (!(ctl_btr & MEN_Z192_CTL1_CANE))
> + return -ENODEV;
> +
> + men_z192_set_buf_lvl_irq(ndev, rxlvl, txlvl);
> + men_z192_set_rx_tout(ndev, rx_timeout);
> +
> + ret = men_z192_req_init_mode(priv);
> + if (ret) {
> + dev_err(priv->dev, "failed to request init mode\n");
> + return ret;
> + }
> +
> + return register_candev(ndev);
> +}
> +
> +static int men_z192_probe(struct mcb_device *mdev,
> + const struct mcb_device_id *id)
> +{
> + struct device *dev = &mdev->dev;
> + struct men_z192 *priv;
> + struct net_device *ndev;
> + void __iomem *dev_base;
> + struct resource *mem;
> + u32 timebase;
> + int ret = 0;
> + int irq;
> +
> + mem = mcb_request_mem(mdev, dev_name(dev));
> + if (IS_ERR(mem)) {
> + dev_err(dev, "failed to request device memory");
> + return PTR_ERR(mem);
> + }
> +
> + dev_base = ioremap(mem->start, resource_size(mem));
> + if (!dev_base) {
> + dev_err(dev, "failed to ioremap device memory");
> + ret = -ENXIO;
> + goto out_release;
> + }
> +
> + irq = mcb_get_irq(mdev);
> + if (irq <= 0) {
> + ret = -ENODEV;
> + goto out_unmap;
> + }
> +
> + ndev = alloc_candev(sizeof(struct men_z192), 0);
> + if (!ndev) {
> + dev_err(dev, "failed to allocat the can device");
> + ret = -ENOMEM;
> + goto out_unmap;
> + }
> +
> + ndev->netdev_ops = &men_z192_netdev_ops;
> + ndev->irq = irq;
> + ndev->flags |= IFF_ECHO;
> +
> + priv = netdev_priv(ndev);
> + priv->ndev = ndev;
> + priv->dev = dev;
> +
> + priv->mem = mem;
> + priv->dev_base = dev_base;
> + priv->regs = priv->dev_base + MEN_Z192_REGS_OFFS;
> +
> + timebase = readl(&priv->regs->timebase);
> + if (!timebase) {
> + dev_err(dev, "invalid timebase configured (timebase=%d)\n",
> + timebase);
> + ret = -EINVAL;
> + goto out_free_candev;
> + }
> +
> + priv->can.clock.freq = timebase;
> + priv->can.bittiming_const = &men_z192_bittiming_const;
> + priv->can.do_set_mode = men_z192_set_mode;
> + priv->can.do_get_berr_counter = men_z192_get_berr_counter;
> + priv->can.ctrlmode_supported = CAN_CTRLMODE_LISTENONLY |
> + CAN_CTRLMODE_3_SAMPLES |
> + CAN_CTRLMODE_LOOPBACK;
> +
> + spin_lock_init(&priv->lock);
> +
> + netif_napi_add(ndev, &priv->napi, men_z192_poll,
> + NAPI_POLL_WEIGHT);
> +
> + skb_queue_head_init(&priv->echoq);
> +
> + mcb_set_drvdata(mdev, ndev);
> + SET_NETDEV_DEV(ndev, dev);
> +
> + ret = men_z192_register(ndev);
> + if (ret) {
> + dev_err(dev, "failed to register CAN device");
> + goto out_free_candev;
> + }
> +
> + devm_can_led_init(ndev);
> +
> + dev_info(dev, "MEN 16z192 CAN driver successfully registered\n");
> +
> + return 0;
> +
> +out_free_candev:
> + netif_napi_del(&priv->napi);
> + free_candev(ndev);
> +out_unmap:
> + iounmap(dev_base);
> +out_release:
> + mcb_release_mem(mem);
> + return ret;
> +}
> +
> +static void men_z192_remove(struct mcb_device *mdev)
> +{
> + struct net_device *ndev = mcb_get_drvdata(mdev);
> + struct men_z192 *priv = netdev_priv(ndev);
> +
> + unregister_candev(ndev);
> + netif_napi_del(&priv->napi);
> +
> + iounmap(priv->dev_base);
> + mcb_release_mem(priv->mem);
> +
> + free_candev(ndev);
> +}
> +
> +static const struct mcb_device_id men_z192_ids[] = {
> + { .device = 0xc0 },
> + { }
> +};
> +MODULE_DEVICE_TABLE(mcb, men_z192_ids);
> +
> +static struct mcb_driver men_z192_driver = {
> + .driver = {
> + .name = DRV_NAME,
> + .owner = THIS_MODULE,
> + },
> + .probe = men_z192_probe,
> + .remove = men_z192_remove,
> + .id_table = men_z192_ids,
> +};
> +module_mcb_driver(men_z192_driver);
> +
> +MODULE_AUTHOR("Andreas Werner <andreas.werner@xxxxxx>");
> +MODULE_DESCRIPTION("MEN 16z192 CAN Controller");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("mcb:16z192");
> +MODULE_IMPORT_NS(MCB);
>
> base-commit: dcb7fd82c75ee2d6e6f9d8cc71c52519ed52e258
>

regards,
Marc

--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
Vertretung West/Dortmund | Phone: +49-231-2826-924 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |

Attachment: signature.asc
Description: OpenPGP digital signature