[PATCH v9 27/27] PCI: dwc: Add DW eDMA engine support

Serge Semin
2023-01-13T17:24:55Z

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 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
as is 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.

Changelog v6:
- Fix some patchlog and in-line comments misspells. (@Bjorn)

Changelog v7:
- Activate the mapping auto-detection procedure for IP-cores older than
5.40a since the viewport-based access has been removed since that
version. (@Yoshihiro)
---
.../pci/controller/dwc/pcie-designware-ep.c | 12 +-
.../pci/controller/dwc/pcie-designware-host.c | 13 +-
drivers/pci/controller/dwc/pcie-designware.c | 195 ++++++++++++++++++
drivers/pci/controller/dwc/pcie-designware.h | 21 ++
4 files changed, 238 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index d06654895eba..f9182f8d552f 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -612,8 +612,11 @@ int dw_pcie_ep_raise_msix_irq(struct dw_pcie_ep *ep, u8 func_no,

void dw_pcie_ep_exit(struct dw_pcie_ep *ep)
{
+ struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
struct pci_epc *epc = ep->epc;

+ dw_pcie_edma_remove(pci);
+
pci_epc_mem_free_addr(epc, ep->msi_mem_phys, ep->msi_mem,
epc->mem->window.page_size);

@@ -785,6 +788,10 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
goto err_exit_epc_mem;
}

+ ret = dw_pcie_edma_detect(pci);
+ if (ret)
+ goto err_free_epc_mem;
+
if (ep->ops->get_features) {
epc_features = ep->ops->get_features(ep);
if (epc_features->core_init_notifier)
@@ -793,10 +800,13 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)

ret = dw_pcie_ep_init_complete(ep);
if (ret)
- goto err_free_epc_mem;
+ goto err_remove_edma;

return 0;

+err_remove_edma:
+ dw_pcie_edma_remove(pci);
+
err_free_epc_mem:
pci_epc_mem_free_addr(epc, ep->msi_mem_phys, ep->msi_mem,
epc->mem->window.page_size);
diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index e10608af39b4..a9e3dda36c21 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -476,14 +476,18 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)

dw_pcie_iatu_detect(pci);

- ret = dw_pcie_setup_rc(pp);
+ ret = dw_pcie_edma_detect(pci);
if (ret)
goto err_free_msi;

+ ret = dw_pcie_setup_rc(pp);
+ if (ret)
+ goto err_remove_edma;
+
if (!dw_pcie_link_up(pci)) {
ret = dw_pcie_start_link(pci);
if (ret)
- goto err_free_msi;
+ goto err_remove_edma;
}

/* Ignore errors, the link may come up later */
@@ -500,6 +504,9 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
err_stop_link:
dw_pcie_stop_link(pci);

+err_remove_edma:
+ dw_pcie_edma_remove(pci);
+
err_free_msi:
if (pp->has_msi_ctrl)
dw_pcie_free_msi(pp);
@@ -521,6 +528,8 @@ void dw_pcie_host_deinit(struct dw_pcie_rp *pp)

dw_pcie_stop_link(pci);

+ dw_pcie_edma_remove(pci);
+
if (pp->has_msi_ctrl)
dw_pcie_free_msi(pp);

diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index 6d5d619ab2e9..53a16b8b6ac2 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 +795,188 @@ 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;
+
+ /*
+ * Indirect eDMA CSRs access has been completely removed since v5.40a
+ * thus no space is now reserved for the eDMA channels viewport and
+ * former DMA CTRL register is no longer fixed to FFs.
+ */
+ if (dw_pcie_ver_is_ge(pci, 540A))
+ val = 0xFFFFFFFF;
+ else
+ val = dw_pcie_readl_dbi(pci, PCIE_DMA_VIEWPORT_BASE + PCIE_DMA_CTRL);
+
+ if (val == 0xFFFFFFFF && pci->edma.reg_base) {
+ 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.mem = dmam_alloc_coherent(pci->dev, ll->sz,
+ &paddr, GFP_KERNEL);
+ if (!ll->vaddr.mem)
+ 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.mem = dmam_alloc_coherent(pci->dev, ll->sz,
+ &paddr, GFP_KERNEL);
+ if (!ll->vaddr.mem)
+ 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 393dfb931df6..79713ce075cc 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>
@@ -31,6 +32,7 @@
#define DW_PCIE_VER_480A 0x3438302a
#define DW_PCIE_VER_490A 0x3439302a
#define DW_PCIE_VER_520A 0x3532302a
+#define DW_PCIE_VER_540A 0x3534302a

#define __dw_pcie_ver_cmp(_pci, _ver, _op) \
((_pci)->version _op DW_PCIE_VER_ ## _ver)
@@ -167,6 +169,18 @@
#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. Afterwards 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 +229,7 @@
* 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 +241,9 @@
#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;
@@ -369,6 +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];
@@ -408,6 +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)
{
--
2.39.0