Subject: [PATCH v3 2/2] can: m_can: add Bosch M_CAN controller support

From: [email-masked] (Varka Bhadram)
Date: Fri, 11 Jul 2014 17:43:19 +0530

On 07/11/2014 05:33 PM, Marc Kleine-Budde wrote:
> On 07/11/2014 01:13 PM, Varka Bhadram wrote:
>> On 07/11/2014 03:59 PM, Dong Aisheng wrote:
>>
>> (...)
>>
>>> +/* m_can private data structure */
>>> +struct m_can_priv {
>>> +    struct can_priv can;    /* must be the first member */
>>> +    struct napi_struct napi;
>>> +    struct net_device *dev;
>>> +    struct device *device;
>>> +    struct clk *hclk;
>>> +    struct clk *cclk;
>>> +    void __iomem *base;
>>> +    u32 irqstatus;
>>> +
>>> +    /* message ram configuration */
>>> +    void __iomem *mram_base;
>>> +    struct mram_cfg mcfg[MRAM_CFG_NUM];
>>> +};
>>> +
>> It will be good if we write the comments for the driver private structure
>>
>>> +static inline u32 m_can_read(const struct m_can_priv *priv, enum
>>> m_can_reg reg)
>>> +{
>>> +    return readl(priv->base + reg);
>>> +}
>>> +
>> (...)
>>
>>> +static void free_m_can_dev(struct net_device *dev)
>>> +{
>>> +    free_candev(dev);
>>> +}
>>> +
>> Why do we need a separate function which calls a single function...  :-)
> To be symetric with alloc_m_can_dev()
>
>>> +static struct net_device *alloc_m_can_dev(void)
>>> +{
>>> +    struct net_device *dev;
>>> +    struct m_can_priv *priv;
>>> +
>>> +    dev = alloc_candev(sizeof(struct m_can_priv), 1);
>> sizeof(*priv)...?
>>
>>> +    if (!dev)
>>> +        return NULL;
>> Return value -ENOMEM ?
> I'm okay with NULL, however if we want to return an arror value, it must
> be ERR_PTR() wrapped.
>
>>> +
>>> +    priv = netdev_priv(dev);
>>> +    netif_napi_add(dev, &priv->napi, m_can_poll, M_CAN_NAPI_WEIGHT);
>>> +
>>> +    priv->dev = dev;
>>> +    priv->can.bittiming_const = &m_can_bittiming_const;
>>> +    priv->can.do_set_mode = m_can_set_mode;
>>> +    priv->can.do_get_berr_counter = m_can_get_berr_counter;
>>> +    priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
>>> +                    CAN_CTRLMODE_LISTENONLY |
>>> +                    CAN_CTRLMODE_BERR_REPORTING;
>>> +
>>> +    return dev;
>>> +}
>>> +
>>> +static int m_can_open(struct net_device *dev)
>>> +{
>>> +    struct m_can_priv *priv = netdev_priv(dev);
>>> +    int err;
>>> +
>>> +    err = clk_prepare_enable(priv->hclk);
>>> +    if (err)
>>> +        return err;
>>> +
>>> +    err = clk_prepare_enable(priv->cclk);
>>> +    if (err)
>>> +        goto exit_disable_hclk;
>>> +
>>> +    /* open the can device */
>>> +    err = open_candev(dev);
>>> +    if (err) {
>>> +        netdev_err(dev, "failed to open can device\n");
>>> +        goto exit_disable_cclk;
>>> +    }
>>> +
>>> +    /* register interrupt handler */
>>> +    err = request_irq(dev->irq, m_can_isr, IRQF_SHARED, dev->name,
>>> +              dev);
>> why don't we use devm_request_irq()...? If you use this no need to worry
>> about freeing the irq
> ...because the IRQ is allocated during ifup and released during ifdown.
>
>>> +    if (err < 0) {
>>> +        netdev_err(dev, "failed to request interrupt\n");
>>> +        goto exit_irq_fail;
>>> +    }
>>> +
>>> +    /* start the m_can controller */
>>> +    m_can_start(dev);
>>> +
>>> +    can_led_event(dev, CAN_LED_EVENT_OPEN);
>>> +    napi_enable(&priv->napi);
>>> +    netif_start_queue(dev);
>>> +
>>> +    return 0;
>>> +
>>> +exit_irq_fail:
>>> +    close_candev(dev);
>>> +exit_disable_cclk:
>>> +    clk_disable_unprepare(priv->cclk);
>>> +exit_disable_hclk:
>>> +    clk_disable_unprepare(priv->hclk);
>>> +    return err;
>>> +}
>>> +
>>> +static void m_can_stop(struct net_device *dev)
>>> +{
>>> +    struct m_can_priv *priv = netdev_priv(dev);
>>> +
>>> +    /* disable all interrupts */
>>> +    m_can_disable_all_interrupts(priv);
>>> +
>>> +    clk_disable_unprepare(priv->hclk);
>>> +    clk_disable_unprepare(priv->cclk);
>>> +
>>> +    /* set the state as STOPPED */
>>> +    priv->can.state = CAN_STATE_STOPPED;
>>> +}
>>> +
>>> +static int m_can_close(struct net_device *dev)
>>> +{
>>> +    struct m_can_priv *priv = netdev_priv(dev);
>>> +
>>> +    netif_stop_queue(dev);
>>> +    napi_disable(&priv->napi);
>>> +    m_can_stop(dev);
>>> +    free_irq(dev->irq, dev);
>> not required when you use devm_request_irq()
> No....see above.
>
>>> +    close_candev(dev);
>>> +    can_led_event(dev, CAN_LED_EVENT_STOP);
>>> +
>>> +    return 0;
>>> +}
>>> +
>> (...)
>>
>>> +
>>> +static const struct of_device_id m_can_of_table[] = {
>>> +    { .compatible = "bosch,m_can", .data = NULL },
>> we can simply give '0' . No need of .data = NULL. Things should be
>> simple right....  :-)
> .data should be a pointer, while "0" isn't. (Although 0 is valid C, we
> don't want a integer 0 to initialize a pointer.) However, you can omit
> .data = NULL completely. When initialzing via C99, any omited members of
> the struct will automatically be initialized with 0x0. I like to see the
> .data = NULL because it documents that there isn't any data (yet), once
> another compatible is added, we need the .data anyways.

static const struct of_device_id m_can_of_table[] = {
	{ .compatible = "bosch,m_can", },
};

This is enough... right ?

>>> +    { /* sentinel */ },
>>> +};
>>> +MODULE_DEVICE_TABLE(of, m_can_of_table);
>>> +
>>> +static int m_can_of_parse_mram(struct platform_device *pdev,
>>> +                   struct m_can_priv *priv)
>>> +{
>>> +    struct device_node *np = pdev->dev.of_node;
>>> +    struct resource *res;
>>> +    void __iomem *addr;
>>> +    u32 out_val[MRAM_CFG_LEN];
>>> +    int ret;
>>> +
>>> +    /* message ram could be shared */
>>> +    res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
>>> "message_ram");
>>> +    if (!res)
>>> +        return -ENODEV;
>>> +
>>> +    addr = devm_ioremap(&pdev->dev, res->start, resource_size(res));
>>> +    if (!addr)
>>> +        return -ENODEV;
>> Is this err return is appropriate ... ?
> -ENOMEM seems to be more commonly used.
>
>>> +
>>> +    /* get message ram configuration */
>>> +    ret = of_property_read_u32_array(np, "mram-cfg",
>>> +                     out_val, sizeof(out_val) / 4);
>>> +    if (ret) {
>>> +        dev_err(&pdev->dev, "can not get message ram configuration\n");
>>> +        return -ENODEV;
>>> +    }
>>> +
>> Is this err return is appropriate ... ?
> Whay do you suggest?
>
>>> +    priv->mram_base = addr;
>>> +    priv->mcfg[MRAM_SIDF].off = out_val[0];
>>> +    priv->mcfg[MRAM_SIDF].num = out_val[1];
>>> +    priv->mcfg[MRAM_XIDF].off = priv->mcfg[MRAM_SIDF].off +
>>> +            priv->mcfg[MRAM_SIDF].num * SIDF_ELEMENT_SIZE;
>>> +    priv->mcfg[MRAM_XIDF].num = out_val[2];
>>> +    priv->mcfg[MRAM_RXF0].off = priv->mcfg[MRAM_XIDF].off +
>>> +            priv->mcfg[MRAM_XIDF].num * XIDF_ELEMENT_SIZE;
>>> +    priv->mcfg[MRAM_RXF0].num = out_val[3] & RXFC_FS_MASK;
>>> +    priv->mcfg[MRAM_RXF1].off = priv->mcfg[MRAM_RXF0].off +
>>> +            priv->mcfg[MRAM_RXF0].num * RXF0_ELEMENT_SIZE;
>>> +    priv->mcfg[MRAM_RXF1].num = out_val[4] & RXFC_FS_MASK;
>>> +    priv->mcfg[MRAM_RXB].off = priv->mcfg[MRAM_RXF1].off +
>>> +            priv->mcfg[MRAM_RXF1].num * RXF1_ELEMENT_SIZE;
>>> +    priv->mcfg[MRAM_RXB].num = out_val[5];
>>> +    priv->mcfg[MRAM_TXE].off = priv->mcfg[MRAM_RXB].off +
>>> +            priv->mcfg[MRAM_RXB].num * RXB_ELEMENT_SIZE;
>>> +    priv->mcfg[MRAM_TXE].num = out_val[6];
>>> +    priv->mcfg[MRAM_TXB].off = priv->mcfg[MRAM_TXE].off +
>>> +            priv->mcfg[MRAM_TXE].num * TXE_ELEMENT_SIZE;
>>> +    priv->mcfg[MRAM_TXB].num = out_val[7] & TXBC_NDTB_MASK;
>>> +
>>> +    dev_dbg(&pdev->dev, "mram_base %p sidf 0x%x %d xidf 0x%x %d rxf0
>>> 0x%x %d rxf1 0x%x %d rxb 0x%x %d txe 0x%x %d txb 0x%x %d\n",
>>> +        priv->mram_base,
>>> +        priv->mcfg[MRAM_SIDF].off, priv->mcfg[MRAM_SIDF].num,
>>> +        priv->mcfg[MRAM_XIDF].off, priv->mcfg[MRAM_XIDF].num,
>>> +        priv->mcfg[MRAM_RXF0].off, priv->mcfg[MRAM_RXF0].num,
>>> +        priv->mcfg[MRAM_RXF1].off, priv->mcfg[MRAM_RXF1].num,
>>> +        priv->mcfg[MRAM_RXB].off, priv->mcfg[MRAM_RXB].num,
>>> +        priv->mcfg[MRAM_TXE].off, priv->mcfg[MRAM_TXE].num,
>>> +        priv->mcfg[MRAM_TXB].off, priv->mcfg[MRAM_TXB].num);
>>> +
>> dev_dbg() will insert the new lines in b/w. It wont print the values as
>> you expected.
>> Check this by enabling debug ...
> What do you mean by b/w?

You are expecting the data to be print in format like:
pdev->dev/name: mram_base %p sidf 0x%x %d xidf 0x%x %d rxf0 0x%x %d rxf1 0x%x %d rxb 0x%x %d txe 0x%x %d txb 0x%x %d

But when we use the dev_dbg()/pr_debug()... It will put data like:
pdev->dev/name: mram_base %p sidf 0x%x
0x%x %d rxf0 0x%x
rxf1 0x%x %d rxb
....

check this by enable DEBUG...

>>> +    return 0;
>>> +}
>>> +
>> (...)
>>
>>> +
>>> +static void unregister_m_can_dev(struct net_device *dev)
>>> +{
>>> +    unregister_candev(dev);
>>> +}
>>> +
>> again a function which calls a single func.
>>
>>> +static int m_can_plat_remove(struct platform_device *pdev)
>>> +{
>>> +    struct net_device *dev = platform_get_drvdata(pdev);
>>> +
>>> +    unregister_m_can_dev(dev);
>>> +    platform_set_drvdata(pdev, NULL);
>>> +
>>> +    free_m_can_dev(dev);
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +static const struct dev_pm_ops m_can_pmops = {
>>> +    SET_SYSTEM_SLEEP_PM_OPS(m_can_suspend, m_can_resume)
>>> +};
>>> +
>>> +static struct platform_driver m_can_plat_driver = {
>>> +    .driver = {
>>> +        .name = KBUILD_MODNAME,
>>> +        .owner = THIS_MODULE,
>> No need to update .owner. module_platform_driver() will do for you.
>> see:http://lxr.free-electrons.com/source/include/linux/platform_device.h#L190
> Oh, right.
>
>>> +        .of_match_table = of_match_ptr(m_can_of_table),
>>> +        .pm     = &m_can_pmops,
>>> +    },
>>> +    .probe = m_can_plat_probe,
>>> +    .remove = m_can_plat_remove,
>>> +};
>>> +
>>> +module_platform_driver(m_can_plat_driver);
>>> +
>>> +MODULE_AUTHOR("Dong Aisheng <[email-masked]>");
>>> +MODULE_LICENSE("GPL v2");
>>> +MODULE_DESCRIPTION("CAN bus driver for Bosch M_CAN controller");
>>
> Marc
>

-- 
Regards,
Varka Bhadram.