linux-kernel - [PATCH v1 3/6] PCI: dwc: Add HDMA support

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Date: Fri, 19 Jan 2024 18:30:19 +0530
From: Mrinmay Sarkar <quic_msarkar@...cinc.com>
To: vkoul@...nel.org, jingoohan1@...il.com, conor+dt@...nel.org,
        konrad.dybcio@...aro.org, manivannan.sadhasivam@...aro.org,
        robh+dt@...nel.org
Cc: quic_shazhuss@...cinc.com, quic_nitegupt@...cinc.com,
        quic_ramkri@...cinc.com, quic_nayiluri@...cinc.com,
        dmitry.baryshkov@...aro.org, quic_krichai@...cinc.com,
        quic_vbadigan@...cinc.com, quic_parass@...cinc.com,
        quic_schintav@...cinc.com, quic_shijjose@...cinc.com,
        Mrinmay Sarkar <quic_msarkar@...cinc.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Serge Semin <fancer.lancer@...il.com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
        Kishon Vijay Abraham I <kishon@...nel.org>, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, mhi@...ts.linux.dev
Subject: [PATCH v1 3/6] PCI: dwc: Add HDMA support

From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>

Hyper DMA (HDMA) is already supported by the dw-edma dmaengine driver.
Unlike it's predecessor Embedded DMA (eDMA), HDMA supports only the
unrolled mapping format. So the platform drivers need to provide a valid
base address of the CSRs. Also, there is no standard way to auto detect
the number of available read/write channels in a platform. So the platform
drivers has to provide that information as well.

For adding HDMA support, the mapping format set by the platform drivers is
used to detect whether eDMA or HDMA is being used, since we cannot auto
detect it in a sane way.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Signed-off-by: Mrinmay Sarkar <quic_msarkar@...cinc.com>
---
 drivers/pci/controller/dwc/pcie-designware.c | 55 ++++++++++++++++++++++++----
 1 file changed, 47 insertions(+), 8 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index 96575b8..07a1f2d 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -880,7 +880,29 @@ static struct dw_edma_plat_ops dw_pcie_edma_ops = {
 	.irq_vector = dw_pcie_edma_irq_vector,
 };
 
-static int dw_pcie_edma_find_chip(struct dw_pcie *pci)
+static int dw_pcie_find_hdma(struct dw_pcie *pci)
+{
+	/*
+	 * Since HDMA supports only unrolled mapping, platform drivers need to
+	 * provide a valid base address.
+	 */
+	if (!pci->edma.reg_base)
+		return -ENODEV;
+
+	/*
+	 * Since there is no standard way to detect the number of read/write
+	 * HDMA channels, platform drivers are expected to provide the channel
+	 * count. Let's also do a sanity check of them to make sure that the
+	 * counts are within the limit specified by the spec.
+	 */
+	if (!pci->edma.ll_wr_cnt || pci->edma.ll_wr_cnt > dw_edma_get_max_wr_ch(pci->edma.mf) ||
+	    !pci->edma.ll_rd_cnt || pci->edma.ll_rd_cnt > dw_edma_get_max_rd_ch(pci->edma.mf))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int dw_pcie_find_edma(struct dw_pcie *pci)
 {
 	u32 val;
 
@@ -912,13 +934,6 @@ static int dw_pcie_edma_find_chip(struct dw_pcie *pci)
 		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);
 
@@ -930,6 +945,30 @@ static int dw_pcie_edma_find_chip(struct dw_pcie *pci)
 	return 0;
 }
 
+static int dw_pcie_edma_find_chip(struct dw_pcie *pci)
+{
+	int ret;
+
+	if (pci->edma.mf == EDMA_MF_HDMA_NATIVE) {
+		ret = dw_pcie_find_hdma(pci);
+		if (ret)
+			return ret;
+	} else {
+		ret = dw_pcie_find_edma(pci);
+		if (ret)
+			return ret;
+	}
+
+	pci->edma.dev = pci->dev;
+
+	if (!pci->edma.ops)
+		pci->edma.ops = &dw_pcie_edma_ops;
+
+	pci->edma.flags |= DW_EDMA_CHIP_LOCAL;
+
+	return 0;
+}
+
 static int dw_pcie_edma_irq_verify(struct dw_pcie *pci)
 {
 	struct platform_device *pdev = to_platform_device(pci->dev);
-- 
2.7.4