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

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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...  :-)

+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 ?

+
+	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

+	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()

+	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....  :-)

+	{ /* 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 ... ?

+
+	/* 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 ... ?

+	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 ...

+	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

+		.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 <b29396@xxxxxxxxxxxxx>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("CAN bus driver for Bosch M_CAN controller");


--
Regards,
Varka Bhadram.

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