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Date:	Fri, 19 Mar 2010 08:19:14 -0700
From:	"Ira W. Snyder" <iws@...o.caltech.edu>
To:	Wolfgang Grandegger <wg@...ndegger.com>
Cc:	linux-kernel@...r.kernel.org, socketcan-core@...ts.berlios.de,
	netdev@...r.kernel.org, sameo@...ux.intel.com
Subject: Re: [PATCH 2/3] can: add support for Janz VMOD-ICAN3 Intelligent
 CAN	module

On Fri, Mar 19, 2010 at 10:01:14AM +0100, Wolfgang Grandegger wrote:
> Hi Ira,
> 
> we already discussed this patch on the SocketCAN mailing list and there
> are just a few minor issues and the request to add support for the new
> "berr-reporting" option, if feasible. See:
> 
>   commit 52c793f24054f5dc30d228e37e0e19cc8313f086
>   Author: Wolfgang Grandegger <wg@...ndegger.com>
>   Date:   Mon Feb 22 22:21:17 2010 +0000
> 
>     can: netlink support for bus-error reporting and counters
>     
>     This patch makes the bus-error reporting configurable and allows to
>     retrieve the CAN TX and RX bus error counters via netlink interface.
>     I have added support for the SJA1000. The TX and RX bus error counters
>     are also copied to the data fields 6..7 of error messages when state
>     changes are reported.
> 
> Should not be a big deal.
> 

I think this patch came along since my last post of the driver. I must
have missed it. I'll try and add support.

> More inline...
> 
> Ira W. Snyder wrote:
> > The Janz VMOD-ICAN3 is a MODULbus daughterboard which fits onto any
> > MODULbus carrier board. It is an intelligent CAN controller with a
> > microcontroller and associated firmware.
> > 
> > Signed-off-by: Ira W. Snyder <iws@...o.caltech.edu>
> > Cc: socketcan-core@...ts.berlios.de
> > Cc: netdev@...r.kernel.org
> > ---
> >  drivers/net/can/Kconfig      |   10 +
> >  drivers/net/can/Makefile     |    1 +
> >  drivers/net/can/janz-ican3.c | 1659 ++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 1670 insertions(+), 0 deletions(-)
> >  create mode 100644 drivers/net/can/janz-ican3.c
> > 
> > diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig
> > index 05b7517..2c5227c 100644
> > --- a/drivers/net/can/Kconfig
> > +++ b/drivers/net/can/Kconfig
> > @@ -63,6 +63,16 @@ config CAN_BFIN
> >  	  To compile this driver as a module, choose M here: the
> >  	  module will be called bfin_can.
> >  
> > +config CAN_JANZ_ICAN3
> > +	tristate "Janz VMOD-ICAN3 Intelligent CAN controller"
> > +	depends on CAN_DEV && MFD_JANZ_CMODIO
> > +	---help---
> > +	  Driver for Janz VMOD-ICAN3 Intelligent CAN controller module, which
> > +	  connects to a MODULbus carrier board.
> > +
> > +	  This driver can also be built as a module. If so, the module will be
> > +	  called janz-ican3.ko.
> > +
> >  source "drivers/net/can/mscan/Kconfig"
> >  
> >  source "drivers/net/can/sja1000/Kconfig"
> > diff --git a/drivers/net/can/Makefile b/drivers/net/can/Makefile
> > index 7a702f2..9047cd0 100644
> > --- a/drivers/net/can/Makefile
> > +++ b/drivers/net/can/Makefile
> > @@ -15,5 +15,6 @@ obj-$(CONFIG_CAN_AT91)		+= at91_can.o
> >  obj-$(CONFIG_CAN_TI_HECC)	+= ti_hecc.o
> >  obj-$(CONFIG_CAN_MCP251X)	+= mcp251x.o
> >  obj-$(CONFIG_CAN_BFIN)		+= bfin_can.o
> > +obj-$(CONFIG_CAN_JANZ_ICAN3)	+= janz-ican3.o
> >  
> >  ccflags-$(CONFIG_CAN_DEBUG_DEVICES) := -DDEBUG
> > diff --git a/drivers/net/can/janz-ican3.c b/drivers/net/can/janz-ican3.c
> > new file mode 100644
> > index 0000000..94d4995
> > --- /dev/null
> > +++ b/drivers/net/can/janz-ican3.c
> [snip]
>  +struct ican3_dev {
> > +
> > +	/* must be the first member */
> > +	struct can_priv can;
> > +
> > +	/* CAN network device */
> > +	struct net_device *ndev;
> > +	struct napi_struct napi;
> > +
> > +	/* Device for printing */
> > +	struct device *dev;
> > +
> > +	/* module number */
> > +	unsigned int num;
> > +
> > +	/* base address of registers and IRQ */
> > +	struct janz_cmodio_onboard_regs __iomem *ctrl;
> > +	struct ican3_dpm_control *dpmctrl;
> > +	void __iomem *dpm;
> > +	int irq;
> > +
> > +	/* old and new style host interface */
> > +	unsigned int iftype;
> > +	spinlock_t lock;
> 
> Please describe what the lock is used for.
> 
> > +	/* new host interface */
> > +	unsigned int rx_int;
> > +	unsigned int rx_num;
> > +	unsigned int tx_num;
> > +
> > +	/* fast host interface */
> > +	unsigned int fastrx_start;
> > +	unsigned int fastrx_int;
> > +	unsigned int fastrx_num;
> > +	unsigned int fasttx_start;
> > +	unsigned int fasttx_num;
> > +
> > +	/* first free DPM page */
> > +	unsigned int free_page;
> > +};
> 
> [snip]
> > +static void ican3_to_can_frame(struct ican3_dev *mod,
> > +			       struct ican3_fast_desc *desc,
> > +			       struct can_frame *cf)
> > +{
> > +	if ((desc->command & ICAN3_CAN_TYPE_MASK) == ICAN3_CAN_TYPE_SFF) {
> > +		dev_dbg(mod->dev, "%s: old frame format\n", __func__);
> 
> This prints a debug message for every message which is not really
> useful for the user. Please remove.
> 
> > +		if (desc->data[1] & ICAN3_SFF_RTR)
> > +			cf->can_id |= CAN_RTR_FLAG;
> > +
> > +		cf->can_id |= desc->data[0] << 3;
> > +		cf->can_id |= (desc->data[1] & 0xe0) >> 5;
> > +		cf->can_dlc = desc->data[1] & ICAN3_CAN_DLC_MASK;
> > +		memcpy(cf->data, &desc->data[2], sizeof(cf->data));
> > +	} else {
> > +		dev_dbg(mod->dev, "%s: new frame format\n", __func__);
> 
> Ditto.
> 
> > +		cf->can_dlc = desc->data[0] & ICAN3_CAN_DLC_MASK;
> > +		if (desc->data[0] & ICAN3_EFF_RTR)
> > +			cf->can_id |= CAN_RTR_FLAG;
> > +
> > +		if (desc->data[0] & ICAN3_EFF) {
> > +			cf->can_id |= CAN_EFF_FLAG;
> > +			cf->can_id |= desc->data[2] << 21; /* 28-21 */
> > +			cf->can_id |= desc->data[3] << 13; /* 20-13 */
> > +			cf->can_id |= desc->data[4] << 5;  /* 12-5  */
> > +			cf->can_id |= (desc->data[5] & 0xf8) >> 3;
> > +		} else {
> > +			cf->can_id |= desc->data[2] << 3;  /* 10-3  */
> > +			cf->can_id |= desc->data[3] >> 5;  /* 2-0   */
> > +		}
> > +
> > +		memcpy(cf->data, &desc->data[6], sizeof(cf->data));
> > +	}
> > +}
> > +
> > +static void can_frame_to_ican3(struct ican3_dev *mod,
> > +			       struct can_frame *cf,
> > +			       struct ican3_fast_desc *desc)
> > +{
> > +	/* clear out any stale data in the descriptor */
> > +	memset(desc->data, 0, sizeof(desc->data));
> > +
> > +	/* we always use the extended format, with the ECHO flag set */
> > +	desc->command = ICAN3_CAN_TYPE_EFF;
> > +	desc->data[0] |= cf->can_dlc;
> > +	desc->data[1] |= ICAN3_ECHO;
> > +
> > +	if (cf->can_id & CAN_RTR_FLAG)
> > +		desc->data[0] |= ICAN3_EFF_RTR;
> > +
> > +	/* pack the id into the correct places */
> > +	if (cf->can_id & CAN_EFF_FLAG) {
> > +		dev_dbg(mod->dev, "%s: extended frame\n", __func__);
> 
> Ditto.
> 
> > +		desc->data[0] |= ICAN3_EFF;
> > +		desc->data[2] = (cf->can_id & 0x1fe00000) >> 21; /* 28-21 */
> > +		desc->data[3] = (cf->can_id & 0x001fe000) >> 13; /* 20-13 */
> > +		desc->data[4] = (cf->can_id & 0x00001fe0) >> 5;  /* 12-5  */
> > +		desc->data[5] = (cf->can_id & 0x0000001f) << 3;  /* 4-0   */
> > +	} else {
> > +		dev_dbg(mod->dev, "%s: standard frame\n", __func__);
> 
> Ditto.
> 
> > +		desc->data[2] = (cf->can_id & 0x7F8) >> 3; /* bits 10-3 */
> > +		desc->data[3] = (cf->can_id & 0x007) << 5; /* bits 2-0  */
> > +	}
> > +
> > +	/* copy the data bits into the descriptor */
> > +	memcpy(&desc->data[6], cf->data, sizeof(cf->data));
> > +}
> 
> [snip]
> > +/*
> > + * Handle CAN Event Indication Messages from the firmware
> > + *
> > + * The ICAN3 firmware provides the values of some SJA1000 registers when it
> > + * generates this message. The code below is largely copied from the
> > + * drivers/net/can/sja1000/sja1000.c file, and adapted as necessary
> > + */
> > +static int ican3_handle_cevtind(struct ican3_dev *mod, struct ican3_msg *msg)
> > +{
> > +	struct net_device *dev = mod->ndev;
> > +	struct net_device_stats *stats = &dev->stats;
> > +	enum can_state state = mod->can.state;
> > +	struct can_frame *cf;
> > +	struct sk_buff *skb;
> > +	u8 status, isrc;
> > +
> > +	/* we can only handle the SJA1000 part */
> > +	if (msg->data[1] != CEVTIND_CHIP_SJA1000) {
> > +		dev_err(mod->dev, "unable to handle errors on non-SJA1000\n");
> > +		return -ENODEV;
> > +	}
> > +
> > +	/* check the message length for sanity */
> > +	if (msg->len < 6) {
> > +		dev_err(mod->dev, "error message too short\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	skb = alloc_can_err_skb(dev, &cf);
> > +	if (skb == NULL)
> > +		return -ENOMEM;
> > +
> > +	isrc = msg->data[0];
> > +	status = msg->data[3];
> > +
> > +	/* data overrun interrupt */
> > +	if (isrc == CEVTIND_DOI || isrc == CEVTIND_LOST) {
> 
> Here and for the other errors below a dev_dbg() would be useful. Please
> check sja1000.c.
> 
> > +		cf->can_id |= CAN_ERR_CRTL;
> > +		cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
> > +		stats->rx_over_errors++;
> > +		stats->rx_errors++;
> > +		dev_info(mod->dev, "%s: overflow frame generated\n", __func__);
> 
> s/dev_info/dev_dbg/ ?
> 

Whoops, a leftover from debugging. Will change to dev_dbg().

> > +	}
> > +
> > +	/* error warning interrupt */
> > +	if (isrc == CEVTIND_EI) {
> > +		if (status & SR_BS) {
> > +			state = CAN_STATE_BUS_OFF;
> > +			cf->can_id |= CAN_ERR_BUSOFF;
> > +			can_bus_off(dev);
> > +		} else if (status & SR_ES) {
> > +			state = CAN_STATE_ERROR_WARNING;
> > +		} else {
> > +			state = CAN_STATE_ERROR_ACTIVE;
> > +		}
> > +	}
> > +
> > +	/* bus error interrupt */
> > +	if (isrc == CEVTIND_BEI) {
> > +		u8 ecc = msg->data[2];
> 
> Add an empty line, please.
> 
> > +		mod->can.can_stats.bus_error++;
> > +		stats->rx_errors++;
> > +		cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
> > +
> > +		switch (ecc & ECC_MASK) {
> > +		case ECC_BIT:
> > +			cf->data[2] |= CAN_ERR_PROT_BIT;
> > +			break;
> > +		case ECC_FORM:
> > +			cf->data[2] |= CAN_ERR_PROT_FORM;
> > +			break;
> > +		case ECC_STUFF:
> > +			cf->data[2] |= CAN_ERR_PROT_STUFF;
> > +			break;
> > +		default:
> > +			cf->data[2] |= CAN_ERR_PROT_UNSPEC;
> > +			cf->data[3] = ecc & ECC_SEG;
> > +			break;
> > +		}
> > +
> > +		if ((ecc & ECC_DIR) == 0)
> > +			cf->data[2] |= CAN_ERR_PROT_TX;
> > +	}
> > +
> > +	if (state != mod->can.state && (state == CAN_STATE_ERROR_WARNING ||
> > +					state == CAN_STATE_ERROR_PASSIVE)) {
> > +		u8 rxerr = msg->data[4];
> > +		u8 txerr = msg->data[5];
> 
> Ditto.
> 
> > +		cf->can_id |= CAN_ERR_CRTL;
> > +		if (state == CAN_STATE_ERROR_WARNING) {
> > +			mod->can.can_stats.error_warning++;
> > +			cf->data[1] = (txerr > rxerr) ?
> > +				CAN_ERR_CRTL_TX_WARNING :
> > +				CAN_ERR_CRTL_RX_WARNING;
> > +		} else {
> > +			mod->can.can_stats.error_passive++;
> > +			cf->data[1] = (txerr > rxerr) ?
> > +				CAN_ERR_CRTL_TX_PASSIVE :
> > +				CAN_ERR_CRTL_RX_PASSIVE;
> > +		}
> > +	}
> > +
> > +	mod->can.state = state;
> > +	stats->rx_errors++;
> > +	stats->rx_bytes += cf->can_dlc;
> > +	netif_rx(skb);
> > +	return 0;
> > +}
> 
> [snip]
> > +static irqreturn_t ican3_irq(int irq, void *dev_id)
> > +{
> > +	struct ican3_dev *mod = dev_id;
> > +	u8 stat;
> > +
> > +	/*
> > +	 * The interrupt status register on this device reports interrupts
> > +	 * as zeroes instead of using ones like most other devices
> > +	 */
> > +	stat = ioread8(&mod->ctrl->int_disable) & (1 << mod->num);
> > +	if (stat == (1 << mod->num))
> > +		return IRQ_NONE;
> > +
> > +	dev_dbg(mod->dev, "IRQ: module %d\n", mod->num);
> 
> Please remove this dev_dbg() as well.
> 
> [snip]
> > +/*
> > + * Startup an ICAN module, bringing it into fast mode
> > + */
> > +static int __devinit ican3_startup_module(struct ican3_dev *mod)
> > +{
> > +	int ret;
> > +
> > +	ret = ican3_reset_module(mod);
> > +	if (ret) {
> > +		dev_err(mod->dev, "unable to reset module\n");
> > +		return ret;
> > +	}
> > +
> > +	/* re-enable interrupts so we can send messages */
> > +	iowrite8(1 << mod->num, &mod->ctrl->int_enable);
> > +
> > +	ret = ican3_msg_connect(mod);
> > +	if (ret) {
> > +		dev_err(mod->dev, "unable to connect to module\n");
> > +		return ret;
> > +	}
> > +
> > +	ican3_init_new_host_interface(mod);
> > +	ret = ican3_msg_newhostif(mod);
> > +	if (ret) {
> > +		dev_err(mod->dev, "unable to switch to new-style interface\n");
> > +		return ret;
> > +	}
> > +
> > +	ret = ican3_set_termination(mod, true);
> > +	if (ret) {
> > +		dev_err(mod->dev, "unable to enable termination\n");
> > +		return ret;
> > +	}
> 
> 
> Could you please allow the user to disable termination, e.g. via module parameter
> "bus_termination=0" in case he uses a cable with built-in termination.
> 

What would you think about a sysfs node instead, so it could be changed
at runtime, on a per-daughtercard basis? Do you think enabling bus
termination is a good default? IMO, it is a pretty safe default for most
users.

> [snip]
> > +static int __devinit ican3_probe(struct platform_device *pdev)
> > +{
> > +	struct janz_platform_data *pdata;
> > +	struct net_device *ndev;
> > +	struct ican3_dev *mod;
> > +	struct resource *res;
> > +	struct device *dev;
> > +	int ret;
> > +
> > +	pdata = pdev->dev.platform_data;
> > +	if (!pdata)
> > +		return -ENXIO;
> > +
> > +	dev_dbg(&pdev->dev, "probe: module number %d\n", pdata->modno);
> > +
> > +	/* save the struct device for printing */
> > +	dev = &pdev->dev;
> > +
> > +	/* allocate the CAN device and private data */
> > +	ndev = alloc_candev(sizeof(*mod), 0);
> > +	if (!ndev) {
> > +		dev_err(dev, "unable to allocate CANdev\n");
> > +		ret = -ENOMEM;
> > +		goto out_return;
> > +	}
> > +
> > +	platform_set_drvdata(pdev, ndev);
> > +	mod = netdev_priv(ndev);
> > +	mod->ndev = ndev;
> > +	mod->dev = &pdev->dev;
> > +	mod->num = pdata->modno;
> > +	netif_napi_add(ndev, &mod->napi, ican3_napi, ICAN3_RX_BUFFERS);
> > +	spin_lock_init(&mod->lock);
> > +
> > +	/* the first unallocated page in the DPM is 9 */
> > +	mod->free_page = DPM_FREE_START;
> > +
> > +	ndev->netdev_ops = &ican3_netdev_ops;
> > +	ndev->flags |= IFF_ECHO;
> > +	SET_NETDEV_DEV(ndev, &pdev->dev);
> > +
> > +	mod->can.clock.freq = 8000000;
> 
> Please use a constant here.
> [snip]
> 
> Please fix and resubmit with my:
> 
> "Acked-by: Wolfgang Grandegger <wg@...ndegger.com>"
> 
> for the SocketCAN part.
> 

Thanks for the review!
Ira
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