Re: [PATCH 1/3] i3c: master: Add driver for Synopsys DesignWare IP

[Boris Brezillon]

Hi Victor,

On Fri, 20 Jul 2018 21:57:50 +0100
Vitor soares <Vitor.Soares@xxxxxxxxxxxx> wrote:

> This patch add driver for Synopsys DesignWare IP on top of
> I3C subsystem patchset proposal V6

The fact that you based your work on v6 of the I3C patchset should be
placed ....

> 
> Signed-off-by: Vitor soares <soares@xxxxxxxxxxxx>
> ---

... here, so that it does not appear in the final commit message.


[...]

> +static int dw_i3c_master_get_free_pos(struct dw_i3c_master *master)
> +{
> +	if (!(master->free_pos & GENMASK(master->maxdevs - 1, 0)))
> +		return -ENOSPC;
> +
> +	return ffs(master->free_pos) - 1;
> +}

Okay, maybe we can have a generic infrastructure for that part (I have
the same logic in the Cadence driver), but let's keep that for later.

> +
> +static void dw_i3c_master_wr_tx_fifo(struct dw_i3c_master *master,
> +				     const u8 *bytes, int nbytes)
> +{
> +	int i, j;
> +
> +	for (i = 0; i < nbytes; i += 4) {
> +		u32 data = 0;
> +
> +		for (j = 0; j < 4 && (i + j) < nbytes; j++)
> +			data |= (u32)bytes[i + j] << (j * 8);
> +
> +		writel(data, master->regs + RX_TX_DATA_PORT);

Maybe you can use writesl() as suggested by Arnd in his review of the
Cadence driver.

> +	}
> +}
> +

[...]

> +
> +static void dw_i3c_master_detach_i2c_dev(struct i2c_dev_desc *dev)
> +{
> +	struct dw_i3c_i2c_dev_data *data = i2c_dev_get_master_data(dev);
> +	struct i3c_master_controller *m = i2c_dev_get_master(dev);
> +	struct dw_i3c_master *master = to_dw_i3c_master(m);
> +
> +	writel(NULL,

		^ 0 not NULL

> +	       master->regs +
> +	       DEV_ADDR_TABLE_LOC(master->datstartaddr, data->index));
> +
> +	i2c_dev_set_master_data(dev, NULL);
> +	master->addrs[data->index] = 0;
> +	master->free_pos |= BIT(data->index);
> +	kfree(data);
> +}
> +

> +static int dw_i3c_probe(struct platform_device *pdev)
> +{
> +	struct dw_i3c_master *master;
> +	struct resource *res;
> +	int ret, irq;
> +
> +	master = devm_kzalloc(&pdev->dev, sizeof(*master), GFP_KERNEL);
> +	if (!master)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	master->regs = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(master->regs))
> +		return PTR_ERR(master->regs);
> +
> +	master->core_clk = devm_clk_get(&pdev->dev, "core_clk");
> +	if (IS_ERR(master->core_clk))
> +		return PTR_ERR(master->core_clk);
> +
> +	master->core_rst = devm_reset_control_get_optional_exclusive(&pdev->dev,
> +								    "core_rst");
> +	if (IS_ERR(master->core_rst))
> +		return PTR_ERR(master->core_rst);
> +
> +	ret = clk_prepare_enable(master->core_clk);
> +	if (ret)
> +		goto err_disable_core_clk;
> +
> +	reset_control_deassert(master->core_rst);
> +
> +	spin_lock_init(&master->xferqueue.lock);
> +	INIT_LIST_HEAD(&master->xferqueue.list);
> +
> +	writel(INTR_ALL, master->regs + INTR_STATUS);
> +	irq = platform_get_irq(pdev, 0);
> +	ret = devm_request_irq(&pdev->dev, irq,
> +			       dw_i3c_master_irq_handler, 0,
> +			       dev_name(&pdev->dev), master);
> +	if (ret)
> +		goto err_assert_rst;
> +
> +	platform_set_drvdata(pdev, master);
> +
> +	ret = readl(master->regs + QUEUE_STATUS_LEVEL);
> +	master->caps.cmdfifodepth = QUEUE_STATUS_LEVEL_CMD(ret);
> +
> +	ret = readl(master->regs + DATA_BUFFER_STATUS_LEVEL);
> +	master->caps.datafifodepth = DATA_BUFFER_STATUS_LEVEL_TX(ret);
> +
> +	ret = readl(master->regs + DEVICE_ADDR_TABLE_POINTER);
> +	master->datstartaddr = ret;
> +	master->maxdevs = ret >> 16;
> +	master->free_pos = GENMASK(master->maxdevs - 1, 0);
> +
> +	/* read controller version */
> +	ret = readl(master->regs + I3C_VER_ID);
> +	master->version[0] = (char)(ret >> 24);
> +	master->version[1] = '.';
> +	master->version[2] = (char)(ret >> 16);
> +	master->version[3] = (char)(ret >> 8);
> +	master->version[4] = '\0';
> +
> +	/* read controller type */
> +	ret = readl(master->regs + I3C_VER_TYPE);
> +	master->type[0] = (char)(ret >> 24);
> +	master->type[1] = (char)(ret >> 16);
> +	master->type[2] = (char)(ret >> 8);
> +	master->type[3] = (char) ret;
> +	master->type[4] = '\0';

Hm, do you really intend to read these as strings? If you do, maybe you
can use sprintf() here:

	sprintf(master->version, "%c.%c%c", ...)
	sprintf(master->type, "%c%c%c%c", ...)


> +
> +	ret = i3c_master_register(&master->base, &pdev->dev,
> +				  &dw_mipi_i3c_ops, false);
> +	if (ret)
> +		goto err_assert_rst;
> +
> +	dev_info(&pdev->dev, "Synopsys DW MIPI I3C Master: version %s-%s\n",
> +		 master->version, master->type);
> +
> +	return 0;
> +
> +err_assert_rst:
> +	reset_control_assert(master->core_rst);
> +
> +err_disable_core_clk:
> +	clk_disable_unprepare(master->core_clk);
> +
> +	return ret;
> +}

The driver looks pretty good already, and I'm pleasantly surprised to
see that the Synopsys IP works pretty much the same way the Cadence one
does. I could find some of the logic I implemented in the Cadence
driver almost directly applied to this one, so I think there's room for
code factorization. Anyway, let's see what the next controller looks
like before doing that.

Thanks for sharing your work early and for reviewing the previous
versions of the I3C patchset.

Regards,

Boris