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Date:   Wed, 24 Aug 2022 17:22:37 +0300
From:   Serge Semin <fancer.lancer@gmail.com>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc:     Serge Semin <Sergey.Semin@baikalelectronics.ru>,
        Gustavo Pimentel <gustavo.pimentel@synopsys.com>,
        Vinod Koul <vkoul@kernel.org>, Rob Herring <robh@kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Jingoo Han <jingoohan1@gmail.com>, Frank Li <Frank.Li@nxp.com>,
        Lorenzo Pieralisi <lpieralisi@kernel.org>,
        Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kw@linux.com>,
        Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@baikalelectronics.ru>,
        linux-pci@vger.kernel.org, dmaengine@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH RESEND v5 24/24] PCI: dwc: Add DW eDMA engine support
Message-ID: <20220824142237.7ajdcbculdxp52kz@mobilestation>
References: <20220822185332.26149-1-Sergey.Semin@baikalelectronics.ru>
 <20220822185332.26149-25-Sergey.Semin@baikalelectronics.ru>
 <20220823154937.GC6371@thinkpad>
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In-Reply-To: <20220823154937.GC6371@thinkpad>
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On Tue, Aug 23, 2022 at 09:19:37PM +0530, Manivannan Sadhasivam wrote:
> On Mon, Aug 22, 2022 at 09:53:32PM +0300, Serge Semin wrote:
> > Since the DW eDMA driver now supports eDMA controllers embedded into the
> > locally accessible DW PCIe Root Ports and Endpoints, we can use the
> > updated interface to register DW eDMA as DMA engine device if it's
> > available. In order to successfully do that the DW PCIe core driver need
> > to perform some preparations first. First of all it needs to find out the
> > eDMA controller CSRs base address, whether they are accessible over the
> > Port Logic or iATU unrolled space. Afterwards it can try to auto-detect
> > the eDMA controller availability and number of it's read/write channels.
> > If none was found the procedure will just silently halt with no error
> > returned. Secondly the platform is supposed to provide either combined or
> > per-channel IRQ signals. If no valid IRQs set is found the procedure will
> > also halt with no error returned so to be backward compatible with the
> > platforms where DW PCIe controllers have eDMA embedded but lack of the
> > IRQs defined for them. Finally before actually probing the eDMA device we
> > need to allocate LLP items buffers. After that the DW eDMA can be
> > registered. If registration is successful the info-message regarding the
> > number of detected Read/Write eDMA channels will be printed to the system
> > log in the similar way as it's done for the iATU settings.
> > 
> > Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> > Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > Acked-By: Vinod Koul <vkoul@kernel.org>
> > 
> > ---
> > 
> > Changelog v2:
> > - Don't fail eDMA detection procedure if the DW eDMA driver couldn't probe
> >   device. That happens if the driver is disabled. (@Manivannan)
> > - Add "dma" registers resource mapping procedure. (@Manivannan)
> > - Move the eDMA CSRs space detection into the dw_pcie_map_detect() method.
> > - Remove eDMA on the dw_pcie_ep_init() internal errors. (@Manivannan)
> > - Remove eDMA in the dw_pcie_ep_exit() method.
> > - Move the dw_pcie_edma_detect() method execution to the tail of the
> >   dw_pcie_ep_init() function.
> > 
> > Changelog v3:
> > - Add more comprehensive and less regression prune eDMA block detection
> >   procedure.
> > - Remove Manivannan tb tag since the patch content has been changed.
> > ---
> >  .../pci/controller/dwc/pcie-designware-ep.c   |  12 +-
> >  .../pci/controller/dwc/pcie-designware-host.c |  13 +-
> >  drivers/pci/controller/dwc/pcie-designware.c  | 186 ++++++++++++++++++
> >  drivers/pci/controller/dwc/pcie-designware.h  |  20 ++
> >  4 files changed, 228 insertions(+), 3 deletions(-)
> > 
> 
> [...]
> 
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> > index 1e06ccf2dc9e..3dcbdaf980e4 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware.c
> > @@ -12,6 +12,7 @@
> >  #include <linux/bitops.h>
> >  #include <linux/clk.h>
> >  #include <linux/delay.h>
> > +#include <linux/dma/edma.h>
> >  #include <linux/gpio/consumer.h>
> >  #include <linux/ioport.h>
> >  #include <linux/of.h>
> > @@ -142,6 +143,18 @@ int dw_pcie_get_resources(struct dw_pcie *pci)
> >  	if (!pci->atu_size)
> >  		pci->atu_size = SZ_4K;
> >  
> > +	/* eDMA region can be mapped to a custom base address */
> > +	if (!pci->edma.reg_base) {
> > +		res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dma");
> > +		if (res) {
> > +			pci->edma.reg_base = devm_ioremap_resource(pci->dev, res);
> > +			if (IS_ERR(pci->edma.reg_base))
> > +				return PTR_ERR(pci->edma.reg_base);
> > +		} else if (pci->atu_size >= 2 * DEFAULT_DBI_DMA_OFFSET) {
> > +			pci->edma.reg_base = pci->atu_base + DEFAULT_DBI_DMA_OFFSET;
> > +		}
> > +	}
> > +
> >  	/* LLDD is supposed to manually switch the clocks and resets state */
> >  	if (dw_pcie_cap_is(pci, REQ_RES)) {
> >  		ret = dw_pcie_get_clocks(pci);
> > @@ -782,6 +795,179 @@ void dw_pcie_iatu_detect(struct dw_pcie *pci)
> >  		 pci->region_align / SZ_1K, (pci->region_limit + 1) / SZ_1G);
> >  }
> >  
> > +static u32 dw_pcie_readl_dma(struct dw_pcie *pci, u32 reg)
> > +{
> > +	u32 val = 0;
> > +	int ret;
> > +
> > +	if (pci->ops && pci->ops->read_dbi)
> > +		return pci->ops->read_dbi(pci, pci->edma.reg_base, reg, 4);
> > +
> > +	ret = dw_pcie_read(pci->edma.reg_base + reg, 4, &val);
> > +	if (ret)
> > +		dev_err(pci->dev, "Read DMA address failed\n");
> > +
> > +	return val;
> > +}
> > +
> > +static int dw_pcie_edma_irq_vector(struct device *dev, unsigned int nr)
> > +{
> > +	struct platform_device *pdev = to_platform_device(dev);
> > +	char name[6];
> > +	int ret;
> > +
> > +	if (nr >= EDMA_MAX_WR_CH + EDMA_MAX_RD_CH)
> > +		return -EINVAL;
> > +
> > +	ret = platform_get_irq_byname_optional(pdev, "dma");
> > +	if (ret > 0)
> > +		return ret;
> > +
> > +	snprintf(name, sizeof(name), "dma%u", nr);
> > +
> > +	return platform_get_irq_byname_optional(pdev, name);
> > +}
> > +
> > +static struct dw_edma_core_ops dw_pcie_edma_ops = {
> > +	.irq_vector = dw_pcie_edma_irq_vector,
> > +};
> > +
> > +static int dw_pcie_edma_find_chip(struct dw_pcie *pci)
> > +{
> > +	u32 val;
> > +
> > +	val = dw_pcie_readl_dbi(pci, PCIE_DMA_VIEWPORT_BASE + PCIE_DMA_CTRL);
> > +	if (val == 0xFFFFFFFF && pci->edma.reg_base) {
> 

> Nit: Lower case for hex here and below?

I would have fully agreed with you if the rest of the file had the
lower-cased literals. But in this case it uses the upper-case hexes.
So IMO we'd better stick to the convention specific to the file for
now. If it gets to be that much required somebody will perform the
conversion at once in the framework of another cleanup patch(set).

-Sergey

> 
> Thanks,
> Mani
> 
> > +		pci->edma.mf = EDMA_MF_EDMA_UNROLL;
> > +
> > +		val = dw_pcie_readl_dma(pci, PCIE_DMA_CTRL);
> > +	} else if (val != 0xFFFFFFFF) {
> > +		pci->edma.mf = EDMA_MF_EDMA_LEGACY;
> > +
> > +		pci->edma.reg_base = pci->dbi_base + PCIE_DMA_VIEWPORT_BASE;
> > +	} else {
> > +		return -ENODEV;
> > +	}
> > +
> > +	pci->edma.dev = pci->dev;
> > +
> > +	if (!pci->edma.ops)
> > +		pci->edma.ops = &dw_pcie_edma_ops;
> > +
> > +	pci->edma.flags |= DW_EDMA_CHIP_LOCAL;
> > +
> > +	pci->edma.ll_wr_cnt = FIELD_GET(PCIE_DMA_NUM_WR_CHAN, val);
> > +	pci->edma.ll_rd_cnt = FIELD_GET(PCIE_DMA_NUM_RD_CHAN, val);
> > +
> > +	/* Sanity check the channels count if the mapping was incorrect */
> > +	if (!pci->edma.ll_wr_cnt || pci->edma.ll_wr_cnt > EDMA_MAX_WR_CH ||
> > +	    !pci->edma.ll_rd_cnt || pci->edma.ll_rd_cnt > EDMA_MAX_RD_CH)
> > +		return -EINVAL;
> > +
> > +	return 0;
> > +}
> > +
> > +static int dw_pcie_edma_irq_verify(struct dw_pcie *pci)
> > +{
> > +	struct platform_device *pdev = to_platform_device(pci->dev);
> > +	u16 ch_cnt = pci->edma.ll_wr_cnt + pci->edma.ll_rd_cnt;
> > +	char name[6];
> > +	int ret;
> > +
> > +	if (pci->edma.nr_irqs == 1)
> > +		return 0;
> > +	else if (pci->edma.nr_irqs > 1)
> > +		return pci->edma.nr_irqs != ch_cnt ? -EINVAL : 0;
> > +
> > +	ret = platform_get_irq_byname_optional(pdev, "dma");
> > +	if (ret > 0) {
> > +		pci->edma.nr_irqs = 1;
> > +		return 0;
> > +	}
> > +
> > +	for (; pci->edma.nr_irqs < ch_cnt; pci->edma.nr_irqs++) {
> > +		snprintf(name, sizeof(name), "dma%d", pci->edma.nr_irqs);
> > +
> > +		ret = platform_get_irq_byname_optional(pdev, name);
> > +		if (ret <= 0)
> > +			return -EINVAL;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int dw_pcie_edma_ll_alloc(struct dw_pcie *pci)
> > +{
> > +	struct dw_edma_region *ll;
> > +	dma_addr_t paddr;
> > +	int i;
> > +
> > +	for (i = 0; i < pci->edma.ll_wr_cnt; i++) {
> > +		ll = &pci->edma.ll_region_wr[i];
> > +		ll->sz = DMA_LLP_MEM_SIZE;
> > +		ll->vaddr = dmam_alloc_coherent(pci->dev, ll->sz,
> > +						&paddr, GFP_KERNEL);
> > +		if (!ll->vaddr)
> > +			return -ENOMEM;
> > +
> > +		ll->paddr = paddr;
> > +	}
> > +
> > +	for (i = 0; i < pci->edma.ll_rd_cnt; i++) {
> > +		ll = &pci->edma.ll_region_rd[i];
> > +		ll->sz = DMA_LLP_MEM_SIZE;
> > +		ll->vaddr = dmam_alloc_coherent(pci->dev, ll->sz,
> > +						&paddr, GFP_KERNEL);
> > +		if (!ll->vaddr)
> > +			return -ENOMEM;
> > +
> > +		ll->paddr = paddr;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +int dw_pcie_edma_detect(struct dw_pcie *pci)
> > +{
> > +	int ret;
> > +
> > +	/* Don't fail if no eDMA was found (for the backward compatibility) */
> > +	ret = dw_pcie_edma_find_chip(pci);
> > +	if (ret)
> > +		return 0;
> > +
> > +	/* Don't fail on the IRQs verification (for the backward compatibility) */
> > +	ret = dw_pcie_edma_irq_verify(pci);
> > +	if (ret) {
> > +		dev_err(pci->dev, "Invalid eDMA IRQs found\n");
> > +		return 0;
> > +	}
> > +
> > +	ret = dw_pcie_edma_ll_alloc(pci);
> > +	if (ret) {
> > +		dev_err(pci->dev, "Couldn't allocate LLP memory\n");
> > +		return ret;
> > +	}
> > +
> > +	/* Don't fail if the DW eDMA driver can't find the device */
> > +	ret = dw_edma_probe(&pci->edma);
> > +	if (ret && ret != -ENODEV) {
> > +		dev_err(pci->dev, "Couldn't register eDMA device\n");
> > +		return ret;
> > +	}
> > +
> > +	dev_info(pci->dev, "eDMA: unroll %s, %hu wr, %hu rd\n",
> > +		 pci->edma.mf == EDMA_MF_EDMA_UNROLL ? "T" : "F",
> > +		 pci->edma.ll_wr_cnt, pci->edma.ll_rd_cnt);
> > +
> > +	return 0;
> > +}
> > +
> > +void dw_pcie_edma_remove(struct dw_pcie *pci)
> > +{
> > +	dw_edma_remove(&pci->edma);
> > +}
> > +
> >  void dw_pcie_setup(struct dw_pcie *pci)
> >  {
> >  	u32 val;
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> > index f5530069a204..d11c246b9bc1 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.h
> > +++ b/drivers/pci/controller/dwc/pcie-designware.h
> > @@ -15,6 +15,7 @@
> >  #include <linux/bitops.h>
> >  #include <linux/clk.h>
> >  #include <linux/dma-mapping.h>
> > +#include <linux/dma/edma.h>
> >  #include <linux/gpio/consumer.h>
> >  #include <linux/irq.h>
> >  #include <linux/msi.h>
> > @@ -167,6 +168,18 @@
> >  #define PCIE_MSIX_DOORBELL		0x948
> >  #define PCIE_MSIX_DOORBELL_PF_SHIFT	24
> >  
> > +/*
> > + * eDMA CSRs. DW PCIe IP-core v4.70a and older had the eDMA registers accessible
> > + * over the Port Logic registers space. Afterwords the unrolled mapping was
> > + * introduced so eDMA and iATU could be accessed via a dedicated registers
> > + * space.
> > + */
> > +#define PCIE_DMA_VIEWPORT_BASE		0x970
> > +#define PCIE_DMA_UNROLL_BASE		0x80000
> > +#define PCIE_DMA_CTRL			0x008
> > +#define PCIE_DMA_NUM_WR_CHAN		GENMASK(3, 0)
> > +#define PCIE_DMA_NUM_RD_CHAN		GENMASK(19, 16)
> > +
> >  #define PCIE_PL_CHK_REG_CONTROL_STATUS			0xB20
> >  #define PCIE_PL_CHK_REG_CHK_REG_START			BIT(0)
> >  #define PCIE_PL_CHK_REG_CHK_REG_CONTINUOUS		BIT(1)
> > @@ -215,6 +228,7 @@
> >   * this offset, if atu_base not set.
> >   */
> >  #define DEFAULT_DBI_ATU_OFFSET (0x3 << 20)
> > +#define DEFAULT_DBI_DMA_OFFSET PCIE_DMA_UNROLL_BASE
> >  
> >  #define MAX_MSI_IRQS			256
> >  #define MAX_MSI_IRQS_PER_CTRL		32
> > @@ -226,6 +240,9 @@
> >  #define MAX_IATU_IN			256
> >  #define MAX_IATU_OUT			256
> >  
> > +/* Default eDMA LLP memory size */
> > +#define DMA_LLP_MEM_SIZE		PAGE_SIZE
> > +
> >  struct dw_pcie;
> >  struct dw_pcie_rp;
> >  struct dw_pcie_ep;
> > @@ -370,6 +387,7 @@ struct dw_pcie {
> >  	int			num_lanes;
> >  	int			link_gen;
> >  	u8			n_fts[2];
> > +	struct dw_edma_chip	edma;
> >  	struct clk_bulk_data	app_clks[DW_PCIE_NUM_APP_CLKS];
> >  	struct clk_bulk_data	core_clks[DW_PCIE_NUM_CORE_CLKS];
> >  	struct reset_control_bulk_data	app_rsts[DW_PCIE_NUM_APP_RSTS];
> > @@ -409,6 +427,8 @@ int dw_pcie_prog_ep_inbound_atu(struct dw_pcie *pci, u8 func_no, int index,
> >  void dw_pcie_disable_atu(struct dw_pcie *pci, u32 dir, int index);
> >  void dw_pcie_setup(struct dw_pcie *pci);
> >  void dw_pcie_iatu_detect(struct dw_pcie *pci);
> > +int dw_pcie_edma_detect(struct dw_pcie *pci);
> > +void dw_pcie_edma_remove(struct dw_pcie *pci);
> >  
> >  static inline void dw_pcie_writel_dbi(struct dw_pcie *pci, u32 reg, u32 val)
> >  {
> > -- 
> > 2.35.1
> > 
> 
> -- 
> மணிவண்ணன் சதாசிவம்