Re: [RFC 4/6] dma: Add Synopsys eDMA IP PCIe glue-logic

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Wed, Dec 12, 2018 at 12:13:24PM +0100, Gustavo Pimentel wrote:
> Synopsys eDMA IP is normally distributed along with Synopsys PCIe
> EndPoint IP (depends of the use and licensing agreement).
> 
> This IP requires some basic configurations, such as:
>  - eDMA registers BAR
>  - eDMA registers offset
>  - eDMA linked list BAR
>  - eDMA linked list offset
>  - eDMA linked list size
>  - eDMA version
>  - eDMA mode
> 
> As a working example, PCIe glue-logic will attach to a Synopsys PCIe
> EndPoint IP prototype kit (Vendor ID = 0x16c3, Device ID = 0xedda),
> which has built-in an eDMA IP with this default configuration:
>  - eDMA registers BAR = 0
>  - eDMA registers offset = 0x1000 (4 Kbytes)
>  - eDMA linked list BAR = 2
>  - eDMA linked list offset = 0x0 (0 Kbytes)
>  - eDMA linked list size = 0x20000 (128 Kbytes)
>  - eDMA version = 0
>  - eDMA mode = EDMA_MODE_UNROLL
> 
> This driver can be compile as built-in or external module in kernel.
> 
> To enable this driver just select DW_EDMA_PCIE option in kernel
> configuration, however it requires and selects automatically DW_EDMA
> option too.

It seems this driver somehow written as a copy-paste of existing pieces w/o good reasons to do such.

> +enum dw_edma_pcie_bar {
> +	BAR_0,
> +	BAR_1,
> +	BAR_2,
> +	BAR_3,
> +	BAR_4,
> +	BAR_5
> +};

Why do you need this at all?

> +static const struct dw_edma_pcie_data snps_edda_data = {
> +	// eDMA registers location
> +	.regs_bar			= BAR_0,
> +	.regs_off			= 0x1000,	//   4 KBytes
> +	// eDMA memory linked list location
> +	.ll_bar				= BAR_2,
> +	.ll_off				= 0,		//   0 KBytes
> +	.ll_sz				= 0x20000,	// 128 KBytes
> +	// Other
> +	.version			= 0,
> +	.mode				= EDMA_MODE_UNROLL,
> +};

Huh? Isn't this 

> +
> +static int dw_edma_pcie_probe(struct pci_dev *pdev,
> +			      const struct pci_device_id *pid)
> +{
> +	const struct dw_edma_pcie_data *pdata = (void *)pid->driver_data;
> +	struct device *dev = &pdev->dev;
> +	struct dw_edma_chip *chip;
> +	struct dw_edma *dw;
> +	void __iomem *reg;
> +	int err, irq = -1;
> +	u32 addr_hi, addr_lo;
> +	u16 flags;
> +	u8 cap_off;
> +
> +	if (!pdata) {
> +		dev_err(dev, "%s missing data struture\n",
> +			pci_name(pdev));
> +		return -EFAULT;
> +	}
> +
> +	err = pcim_enable_device(pdev);
> +	if (err) {
> +		dev_err(dev, "%s enabling device failed\n",
> +			pci_name(pdev));
> +		return err;
> +	}
> +

> +	err = pcim_iomap_regions(pdev, 1 << pdata->regs_bar, pci_name(pdev));
> +	if (err) {
> +		dev_err(dev, "%s eDMA register BAR I/O memory remapping failed\n",
> +			pci_name(pdev));
> +		return err;
> +	}
> +
> +	err = pcim_iomap_regions(pdev, 1 << pdata->ll_bar, pci_name(pdev));
> +	if (err) {
> +		dev_err(dev, "%s eDMA linked list BAR I/O remapping failed\n",
> +			pci_name(pdev));
> +		return err;
> +	}

This could be done in one call.

> +
> +	pci_set_master(pdev);
> +

> +	err = pci_try_set_mwi(pdev);
> +	if (err) {
> +		dev_err(dev, "%s DMA memory write invalidate\n",
> +			pci_name(pdev));
> +		return err;
> +	}

Are you sure you need this?

> +
> +	err = pci_set_dma_mask(pdev, DMA_BIT_MASK(32));
> +	if (err) {
> +		dev_err(dev, "%s DMA mask set failed\n",
> +			pci_name(pdev));
> +		return err;
> +	}
> +
> +	err = pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(32));
> +	if (err) {
> +		dev_err(dev, "%s consistent DMA mask set failed\n",
> +			pci_name(pdev));
> +		return err;
> +	}
> +
> +	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
> +	if (!chip)
> +		return -ENOMEM;
> +
> +	dw = devm_kzalloc(&pdev->dev, sizeof(*dw), GFP_KERNEL);
> +	if (!dw)
> +		return -ENOMEM;
> +
> +	irq = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI | PCI_IRQ_MSIX);
> +	if (irq < 0) {
> +		dev_err(dev, "%s failed to alloc IRQ vector\n",
> +			pci_name(pdev));
> +		return -EPERM;
> +	}
> +
> +	chip->dw = dw;
> +	chip->dev = dev;
> +	chip->id = pdev->devfn;
> +	chip->irq = pdev->irq;
> +
> +	dw->regs = pcim_iomap_table(pdev)[pdata->regs_bar];
> +	dw->regs += pdata->regs_off;
> +
> +	dw->va_ll = pcim_iomap_table(pdev)[pdata->ll_bar];
> +	dw->va_ll += pdata->ll_off;
> +	dw->pa_ll = pdev->resource[pdata->ll_bar].start;
> +	dw->pa_ll += pdata->ll_off;
> +	dw->ll_sz = pdata->ll_sz;
> +
> +	dw->msi_addr = 0;
> +	dw->msi_data = 0;
> +
> +	dw->version = pdata->version;
> +	dw->mode = pdata->mode;
> +
> +	dev_info(dev, "Version:\t%u\n", dw->version);
> +
> +	dev_info(dev, "Mode:\t%s\n",
> +		 dw->mode == EDMA_MODE_LEGACY ? "Legacy" : "Unroll");
> +


> +	dev_info(dev, "Registers:\tBAR=%u, off=0x%.16llx B, addr=0x%.8lx\n",
> +		 pdata->regs_bar, pdata->regs_off,
> +		 (unsigned long) dw->regs);

Oh, no, don't do casting when printing something. In only rare cases it's needed, not here.

> +
> +	dev_info(dev,
> +		"L. List:\tBAR=%u, off=0x%.16llx B, sz=0x%.8x B, vaddr=0x%.8lx, paddr=0x%.8lx",
> +		 pdata->ll_bar, pdata->ll_off, pdata->ll_sz,
> +		 (unsigned long) dw->va_ll,
> +		 (unsigned long) dw->pa_ll);

This is noise, either remove or move to dbg level.

> +	if (pdev->msi_cap && pdev->msi_enabled) {
> +		cap_off = pdev->msi_cap + PCI_MSI_FLAGS;
> +		pci_read_config_word(pdev, cap_off, &flags);
> +		if (flags & PCI_MSI_FLAGS_ENABLE) {
> +			cap_off = pdev->msi_cap + PCI_MSI_ADDRESS_LO;
> +			pci_read_config_dword(pdev, cap_off, &addr_lo);
> +
> +			if (flags & PCI_MSI_FLAGS_64BIT) {
> +				cap_off = pdev->msi_cap + PCI_MSI_ADDRESS_HI;
> +				pci_read_config_dword(pdev, cap_off, &addr_hi);
> +				cap_off = pdev->msi_cap + PCI_MSI_DATA_64;
> +			} else {
> +				addr_hi = 0;
> +				cap_off = pdev->msi_cap + PCI_MSI_DATA_32;
> +			}
> +
> +			dw->msi_addr = addr_hi;
> +			dw->msi_addr <<= 32;
> +			dw->msi_addr |= addr_lo;
> +
> +			pci_read_config_dword(pdev, cap_off, &(dw->msi_data));
> +			dw->msi_data &= 0xffff;
> +
> +			dev_info(dev,
> +				 "MSI:\t\taddr=0x%.16llx, data=0x%.8x, nr=%d\n",
> +				 dw->msi_addr, dw->msi_data, pdev->irq);
> +		}
> +	}
> +
> +	if (pdev->msix_cap && pdev->msix_enabled) {
> +		u32 offset;
> +		u8 bir;
> +
> +		cap_off = pdev->msix_cap + PCI_MSIX_FLAGS;
> +		pci_read_config_word(pdev, cap_off, &flags);
> +
> +		if (flags & PCI_MSIX_FLAGS_ENABLE) {
> +			cap_off = pdev->msix_cap + PCI_MSIX_TABLE;
> +			pci_read_config_dword(pdev, cap_off, &offset);
> +
> +			bir = offset & PCI_MSIX_TABLE_BIR;
> +			offset &= PCI_MSIX_TABLE_OFFSET;
> +
> +			reg = pcim_iomap_table(pdev)[bir];
> +			reg += offset;
> +
> +			addr_lo = readl(reg + PCI_MSIX_ENTRY_LOWER_ADDR);
> +			addr_hi = readl(reg + PCI_MSIX_ENTRY_UPPER_ADDR);
> +			dw->msi_addr = addr_hi;
> +			dw->msi_addr <<= 32;
> +			dw->msi_addr |= addr_lo;
> +
> +			dw->msi_data = readl(reg + PCI_MSIX_ENTRY_DATA);
> +
> +			dev_info(dev,
> +				 "MSI-X:\taddr=0x%.16llx, data=0x%.8x, nr=%d\n",
> +				 dw->msi_addr, dw->msi_data, pdev->irq);
> +		}
> +	}

What is this? Why?

> +
> +	if (!pdev->msi_enabled && !pdev->msix_enabled) {

There is a helper from PCI core for this.

> +		dev_err(dev, "%s enable interrupt failed\n",
> +			pci_name(pdev));
> +		return -EPERM;
> +	}
> +
> +	err = dw_edma_probe(chip);
> +	if (err) {
> +		dev_err(dev, "%s eDMA probe failed\n",
> +			pci_name(pdev));
> +		return err;
> +	}
> +
> +	pci_set_drvdata(pdev, chip);
> +
> +	dev_info(dev, "DesignWare eDMA PCIe driver loaded completely\n");
> +
> +	return 0;
> +}
> +
> +static void dw_edma_pcie_remove(struct pci_dev *pdev)
> +{
> +	struct dw_edma_chip *chip = pci_get_drvdata(pdev);
> +	struct device *dev = &pdev->dev;
> +	int err;
> +
> +	err = dw_edma_remove(chip);
> +	if (err) {
> +		dev_warn(dev, "%s can't remove device properly: %d\n",
> +			pci_name(pdev), err);

dev_warn + dev_name ?! Have you tried to see what would be the output?

> +	}
> +
> +	pci_free_irq_vectors(pdev);
> +
> +	dev_info(dev, "DesignWare eDMA PCIe driver unloaded completely\n");
> +}
> +

> +#ifdef CONFIG_PM_SLEEP

You can use __maybe_unused instead of this.

> +#endif /* CONFIG_PM_SLEEP */

-- 
With Best Regards,
Andy Shevchenko