[RFC PATCH 5/5] PCI: rcar-ep: Add support for DMAC

From: Lad Prabhakar
Date: Wed Jan 26 2022 - 14:51:54 EST

R-Car PCIe controller has an internal DMAC to support data transfer
between Internal Bus -> PCI Express and vice versa.

This patch fills in the required flags and ops for the PCIe EP to
support DMAC transfer.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
---
drivers/pci/controller/pcie-rcar-ep.c | 227 ++++++++++++++++++++++++++
drivers/pci/controller/pcie-rcar.h | 23 +++
2 files changed, 250 insertions(+)

diff --git a/drivers/pci/controller/pcie-rcar-ep.c b/drivers/pci/controller/pcie-rcar-ep.c
index f9682df1da61..c49b25069328 100644
--- a/drivers/pci/controller/pcie-rcar-ep.c
+++ b/drivers/pci/controller/pcie-rcar-ep.c
@@ -18,6 +18,21 @@

#define RCAR_EPC_MAX_FUNCTIONS 1

+#define RCAR_PCIE_MAX_DMAC_BYTE_COUNT 0x7FFFFFFU
+#define RCAR_PCIE_DMAC_BYTE_COUNT_MULTIPLE 8
+#define RCAR_PCIE_DMAC_TIMEOUT (msecs_to_jiffies(3 * 1000))
+#define RCAR_PCIE_DMAC_DEFAULT_CHANNEL 0
+
+enum rcar_pcie_ep_dmac_xfr_status {
+ RCAR_PCIE_DMA_XFR_SUCCESS,
+ RCAR_PCIE_DMA_XFR_ERROR,
+};
+
+struct rcar_pcie_ep_dmac_info {
+ enum rcar_pcie_ep_dmac_xfr_status status;
+ size_t bytes;
+};
+
/* Structure representing the PCIe interface */
struct rcar_pcie_endpoint {
struct rcar_pcie pcie;
@@ -28,8 +43,114 @@ struct rcar_pcie_endpoint {
unsigned long *ib_window_map;
u32 num_ib_windows;
u32 num_ob_windows;
+ struct completion irq_raised;
+ struct mutex dma_operation;
+ spinlock_t lock;
+ struct rcar_pcie_ep_dmac_info xfr;
};

+static inline bool rcar_pcie_ep_is_dmac_active(struct rcar_pcie_endpoint *ep)
+{
+ if (rcar_pci_read_reg(&ep->pcie, PCIEDMAOR) & PCIEDMAOR_DMAACT)
+ return true;
+
+ return false;
+}
+
+static void
+rcar_pcie_ep_setup_dmac_request(struct rcar_pcie_endpoint *ep,
+ dma_addr_t dma_dst, dma_addr_t dma_src,
+ size_t len, enum pci_epf_xfr_direction dir, u8 ch)
+{
+ struct rcar_pcie *pcie = &ep->pcie;
+ u32 val;
+
+ ep->xfr.status = RCAR_PCIE_DMA_XFR_ERROR;
+ ep->xfr.bytes = RCAR_PCIE_MAX_DMAC_BYTE_COUNT;
+
+ /* swap values if xfr is from pcie to internal */
+ if (dir == PCIE_TO_INTERNAL)
+ swap(dma_dst, dma_src);
+
+ /* Configure the PCI Express lower */
+ rcar_pci_write_reg(pcie, lower_32_bits(dma_dst), PCIEDMPALR(ch));
+
+ /* Configure the PCI Express upper */
+ rcar_pci_write_reg(pcie, upper_32_bits(dma_dst), PCIEDMPAUR(ch));
+
+ /* Configure the internal bus address */
+ rcar_pci_write_reg(pcie, lower_32_bits(dma_src), PCIEDMIAR(ch));
+
+ /* Configure the byte count values */
+ rcar_pci_write_reg(pcie, len, PCIEDMBCNTR(ch));
+
+ /* Enable interrupts */
+ val = rcar_pci_read_reg(pcie, PCIEDMCHSR(ch));
+
+ /* set enable flags */
+ val |= PCIEDMCHSR_IE;
+ val |= PCIEDMCHSR_IBEE;
+ val |= PCIEDMCHSR_PEEE;
+ val |= PCIEDMCHSR_CHTCE;
+
+ /* Clear error flags */
+ val &= ~PCIEDMCHSR_TE;
+ val &= ~PCIEDMCHSR_PEE;
+ val &= ~PCIEDMCHSR_IBE;
+ val &= ~PCIEDMCHSR_CHTC;
+
+ rcar_pci_write_reg(pcie, val, PCIEDMCHSR(ch));
+
+ wmb(); /* flush the settings */
+}
+
+static void rcar_pcie_ep_execute_dmac_request(struct rcar_pcie_endpoint *ep,
+ enum pci_epf_xfr_direction dir, u8 ch)
+{
+ struct rcar_pcie *pcie = &ep->pcie;
+ u32 val;
+
+ /* Enable DMA */
+ val = rcar_pci_read_reg(pcie, PCIEDMAOR);
+ val |= PCIEDMAOR_DMAE;
+ rcar_pci_write_reg(pcie, val, PCIEDMAOR);
+
+ /* Configure the DMA direction */
+ val = rcar_pci_read_reg(pcie, PCIEDMCHCR(ch));
+ if (dir == INTERNAL_TO_PCIE)
+ val |= PCIEDMCHCR_DIR;
+ else
+ val &= ~PCIEDMCHCR_DIR;
+
+ val |= PCIEDMCHCR_CHE;
+ rcar_pci_write_reg(pcie, val, PCIEDMCHCR(ch));
+
+ wmb(); /* flush the settings */
+}
+
+static enum rcar_pcie_ep_dmac_xfr_status
+rcar_pcie_ep_get_dmac_status(struct rcar_pcie_endpoint *ep,
+ size_t *count, u8 ch)
+{
+ *count = ep->xfr.bytes;
+ return ep->xfr.status;
+}
+
+static void rcar_pcie_ep_stop_dmac_request(struct rcar_pcie_endpoint *ep, u8 ch)
+{
+ struct rcar_pcie *pcie = &ep->pcie;
+ u32 val;
+
+ val = rcar_pci_read_reg(pcie, PCIEDMCHCR(ch));
+ val &= ~PCIEDMCHCR_CHE;
+ rcar_pci_write_reg(pcie, val, PCIEDMCHCR(ch));
+
+ /* Disable interrupt */
+ val = rcar_pci_read_reg(pcie, PCIEDMAOR);
+ val &= ~PCIEDMAOR_DMAE;
+ rcar_pci_write_reg(pcie, val, PCIEDMAOR);
+}
+
static void rcar_pcie_ep_hw_init(struct rcar_pcie *pcie)
{
u32 val;
@@ -419,6 +540,44 @@ static int rcar_pcie_ep_raise_irq(struct pci_epc *epc, u8 fn, u8 vfn,
}
}

+static int rcar_pcie_ep_data_transfer(struct pci_epc *epc, struct pci_epf *epf,
+ dma_addr_t dma_dst, dma_addr_t dma_src,
+ size_t len, enum pci_epf_xfr_direction dir)
+{
+ struct rcar_pcie_endpoint *ep = epc_get_drvdata(epc);
+ u8 ch = RCAR_PCIE_DMAC_DEFAULT_CHANNEL;
+ enum rcar_pcie_ep_dmac_xfr_status stat;
+ int ret = -EINVAL;
+ long wait_status;
+ size_t count;
+
+ if (len > RCAR_PCIE_MAX_DMAC_BYTE_COUNT ||
+ (len % RCAR_PCIE_DMAC_BYTE_COUNT_MULTIPLE) != 0)
+ return -EINVAL;
+
+ if (mutex_is_locked(&ep->dma_operation) || rcar_pcie_ep_is_dmac_active(ep))
+ return -EBUSY;
+
+ mutex_lock(&ep->dma_operation);
+
+ rcar_pcie_ep_setup_dmac_request(ep, dma_dst, dma_src, len, dir, ch);
+
+ rcar_pcie_ep_execute_dmac_request(ep, dir, ch);
+
+ wait_status = wait_for_completion_interruptible_timeout(&ep->irq_raised,
+ RCAR_PCIE_DMAC_TIMEOUT);
+ if (wait_status <= 0) {
+ rcar_pcie_ep_stop_dmac_request(ep, ch);
+ } else {
+ stat = rcar_pcie_ep_get_dmac_status(ep, &count, ch);
+ if (stat == RCAR_PCIE_DMA_XFR_SUCCESS && !count)
+ ret = 0;
+ }
+
+ mutex_unlock(&ep->dma_operation);
+ return ret;
+}
+
static int rcar_pcie_ep_start(struct pci_epc *epc)
{
struct rcar_pcie_endpoint *ep = epc_get_drvdata(epc);
@@ -429,6 +588,55 @@ static int rcar_pcie_ep_start(struct pci_epc *epc)
return 0;
}

+static irqreturn_t rcar_pcie_ep_dmac_irq_handler(int irq, void *arg)
+{
+ u8 ch = RCAR_PCIE_DMAC_DEFAULT_CHANNEL;
+ struct rcar_pcie_endpoint *ep = arg;
+ struct rcar_pcie *pcie = &ep->pcie;
+ unsigned long flags;
+ u32 chsr_val;
+ u32 chcr_val;
+ u32 bytes;
+
+ spin_lock_irqsave(&ep->lock, flags);
+
+ chsr_val = rcar_pci_read_reg(pcie, PCIEDMCHSR(ch));
+
+ chcr_val = rcar_pci_read_reg(pcie, PCIEDMCHCR(ch));
+
+ if (mutex_is_locked(&ep->dma_operation)) {
+ if ((chsr_val & PCIEDMCHSR_PEE) ||
+ (chsr_val & PCIEDMCHSR_IBE) ||
+ (chsr_val & PCIEDMCHSR_CHTC))
+ ep->xfr.status = RCAR_PCIE_DMA_XFR_ERROR;
+ else if (chsr_val & PCIEDMCHSR_TE)
+ ep->xfr.status = RCAR_PCIE_DMA_XFR_SUCCESS;
+
+ /* get byte count */
+ bytes = rcar_pci_read_reg(pcie, PCIEDMBCNTR(ch));
+ ep->xfr.bytes = bytes;
+
+ if ((chsr_val & PCIEDMCHSR_PEE) || (chsr_val & PCIEDMCHSR_IBE) ||
+ (chsr_val & PCIEDMCHSR_TE) || (chsr_val & PCIEDMCHSR_CHTC)) {
+ complete(&ep->irq_raised);
+ }
+ } else {
+ spin_unlock_irqrestore(&ep->lock, flags);
+ return IRQ_NONE;
+ }
+
+ if (chcr_val & PCIEDMCHCR_CHE)
+ chcr_val &= ~PCIEDMCHCR_CHE;
+ rcar_pci_write_reg(pcie, chcr_val, PCIEDMCHCR(ch));
+
+ /* Clear DMA interrupt source */
+ rcar_pci_write_reg(pcie, chsr_val, PCIEDMCHSR(ch));
+
+ spin_unlock_irqrestore(&ep->lock, flags);
+
+ return IRQ_HANDLED;
+}
+
static void rcar_pcie_ep_stop(struct pci_epc *epc)
{
struct rcar_pcie_endpoint *ep = epc_get_drvdata(epc);
@@ -446,6 +654,8 @@ static const struct pci_epc_features rcar_pcie_epc_features = {
.bar_fixed_size[0] = 128,
.bar_fixed_size[2] = 256,
.bar_fixed_size[4] = 256,
+ .internal_dmac = true,
+ .internal_dmac_mask = DMA_BIT_MASK(32),
};

static const struct pci_epc_features*
@@ -466,6 +676,7 @@ static const struct pci_epc_ops rcar_pcie_epc_ops = {
.start = rcar_pcie_ep_start,
.stop = rcar_pcie_ep_stop,
.get_features = rcar_pcie_ep_get_features,
+ .dmac_transfer = rcar_pcie_ep_data_transfer,
};

static const struct of_device_id rcar_pcie_ep_of_match[] = {
@@ -480,6 +691,7 @@ static int rcar_pcie_ep_probe(struct platform_device *pdev)
struct rcar_pcie_endpoint *ep;
struct rcar_pcie *pcie;
struct pci_epc *epc;
+ int dmac_irq;
int err;

ep = devm_kzalloc(dev, sizeof(*ep), GFP_KERNEL);
@@ -502,6 +714,14 @@ static int rcar_pcie_ep_probe(struct platform_device *pdev)
goto err_pm_put;
}

+ dmac_irq = platform_get_irq(pdev, 1);
+ if (dmac_irq < 0)
+ goto err_pm_put;
+
+ init_completion(&ep->irq_raised);
+ mutex_init(&ep->dma_operation);
+ spin_lock_init(&ep->lock);
+
ep->num_ib_windows = MAX_NR_INBOUND_MAPS;
ep->ib_window_map =
devm_kcalloc(dev, BITS_TO_LONGS(ep->num_ib_windows),
@@ -533,6 +753,13 @@ static int rcar_pcie_ep_probe(struct platform_device *pdev)

rcar_pcie_ep_hw_init(pcie);

+ err = devm_request_irq(dev, dmac_irq, rcar_pcie_ep_dmac_irq_handler,
+ 0, "pcie-rcar-ep-dmac", pcie);
+ if (err) {
+ dev_err(dev, "failed to request dmac irq\n");
+ goto err_pm_put;
+ }
+
err = pci_epc_multi_mem_init(epc, ep->ob_window, ep->num_ob_windows);
if (err < 0) {
dev_err(dev, "failed to initialize the epc memory space\n");
diff --git a/drivers/pci/controller/pcie-rcar.h b/drivers/pci/controller/pcie-rcar.h
index 9bb125db85c6..874f8a384e6d 100644
--- a/drivers/pci/controller/pcie-rcar.h
+++ b/drivers/pci/controller/pcie-rcar.h
@@ -54,6 +54,29 @@
#define PAR_ENABLE BIT(31)
#define IO_SPACE BIT(8)

+/* PCIe DMAC control reg & mask */
+#define PCIEDMAOR 0x04000
+#define PCIEDMAOR_DMAE BIT(31)
+#define PCIEDMAOR_DMAACT BIT(16)
+#define PCIEDMPALR(x) (0x04100 + ((x) * 0x40))
+#define PCIEDMPAUR(x) (0x04104 + ((x) * 0x40))
+#define PCIEDMIAR(x) (0x04108 + ((x) * 0x40))
+#define PCIEDMBCNTR(x) (0x04110 + ((x) * 0x40))
+#define PCIEDMCCAR(x) (0x04120 + ((x) * 0x40))
+#define PCIEDMCHCR(x) (0x04128 + ((x) * 0x40))
+#define PCIEDMCHCR_CHE BIT(31)
+#define PCIEDMCHCR_DIR BIT(30)
+#define PCIEDMCHSR(x) (0x0412c + ((x) * 0x40))
+#define PCIEDMCHSR_CHTCE BIT(28)
+#define PCIEDMCHSR_PEEE BIT(27)
+#define PCIEDMCHSR_IBEE BIT(25)
+#define PCIEDMCHSR_CHTC BIT(12)
+#define PCIEDMCHSR_PEE BIT(11)
+#define PCIEDMCHSR_IBE BIT(9)
+#define PCIEDMCHSR_IE BIT(3)
+#define PCIEDMCHSR_TE BIT(0)
+#define PCIEDMCHC2R(x) (0x04130 + ((x) * 0x40))
+
/* Configuration */
#define PCICONF(x) (0x010000 + ((x) * 0x4))
#define INTDIS BIT(10)
--
2.25.1