[PATCH v12 7/9] mmc: cavium: Add scatter-gather DMA support

Jan Glauber
2017-03-10T13:25:05Z

Add Support for the scatter-gather DMA available in the
ThunderX MMC units. Up to 16 DMA requests can be processed
together.

Signed-off-by: Jan Glauber <jglauber@cavium.com>
---
drivers/mmc/host/cavium-mmc.c | 104 ++++++++++++++++++++++++++++++++-
drivers/mmc/host/cavium-mmc.h | 16 +++++
drivers/mmc/host/cavium-pci-thunderx.c | 3 +
3 files changed, 120 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/cavium-mmc.c b/drivers/mmc/host/cavium-mmc.c
index c57abed..fb6e1c1 100644
--- a/drivers/mmc/host/cavium-mmc.c
+++ b/drivers/mmc/host/cavium-mmc.c
@@ -377,9 +377,32 @@ static int finish_dma_single(struct cvm_mmc_host *host, struct mmc_data *data)
return 1;
}

+static int finish_dma_sg(struct cvm_mmc_host *host, struct mmc_data *data)
+{
+ u64 fifo_cfg;
+ int count;
+
+ /* Check if there are any pending requests left */
+ fifo_cfg = readq(host->dma_base + MIO_EMM_DMA_FIFO_CFG(host));
+ count = FIELD_GET(MIO_EMM_DMA_FIFO_CFG_COUNT, fifo_cfg);
+ if (count)
+ dev_err(host->dev, "%u requests still pending\n", count);
+
+ data->bytes_xfered = data->blocks * data->blksz;
+ data->error = 0;
+
+ /* Clear and disable FIFO */
+ writeq(BIT_ULL(16), host->dma_base + MIO_EMM_DMA_FIFO_CFG(host));
+ dma_unmap_sg(host->dev, data->sg, data->sg_len, get_dma_dir(data));
+ return 1;
+}
+
static int finish_dma(struct cvm_mmc_host *host, struct mmc_data *data)
{
- return finish_dma_single(host, data);
+ if (host->use_sg && data->sg_len > 1)
+ return finish_dma_sg(host, data);
+ else
+ return finish_dma_single(host, data);
}

static int check_status(u64 rsp_sts)
@@ -522,9 +545,81 @@ static u64 prepare_dma_single(struct cvm_mmc_host *host, struct mmc_data *data)
return addr;
}

+/*
+ * Queue complete sg list into the FIFO.
+ * Returns 0 on error, 1 otherwise.
+ */
+static u64 prepare_dma_sg(struct cvm_mmc_host *host, struct mmc_data *data)
+{
+ struct scatterlist *sg;
+ u64 fifo_cmd, addr;
+ int count, i, rw;
+
+ count = dma_map_sg(host->dev, data->sg, data->sg_len,
+ get_dma_dir(data));
+ if (!count)
+ return 0;
+ if (count > 16)
+ goto error;
+
+ /* Enable FIFO by removing CLR bit */
+ writeq(0, host->dma_base + MIO_EMM_DMA_FIFO_CFG(host));
+
+ for_each_sg(data->sg, sg, count, i) {
+ /* Program DMA address */
+ addr = sg_dma_address(sg);
+ if (addr & 7)
+ goto error;
+ writeq(addr, host->dma_base + MIO_EMM_DMA_FIFO_ADR(host));
+
+ /*
+ * If we have scatter-gather support we also have an extra
+ * register for the DMA addr, so no need to check
+ * host->big_dma_addr here.
+ */
+ rw = (data->flags & MMC_DATA_WRITE) ? 1 : 0;
+ fifo_cmd = FIELD_PREP(MIO_EMM_DMA_FIFO_CMD_RW, rw);
+
+ /* enable interrupts on the last element */
+ fifo_cmd |= FIELD_PREP(MIO_EMM_DMA_FIFO_CMD_INTDIS,
+ (i + 1 == count) ? 0 : 1);
+
+#ifdef __LITTLE_ENDIAN
+ fifo_cmd |= FIELD_PREP(MIO_EMM_DMA_FIFO_CMD_ENDIAN, 1);
+#endif
+ fifo_cmd |= FIELD_PREP(MIO_EMM_DMA_FIFO_CMD_SIZE,
+ sg_dma_len(sg) / 8 - 1);
+ /*
+ * The write copies the address and the command to the FIFO
+ * and increments the FIFO's COUNT field.
+ */
+ writeq(fifo_cmd, host->dma_base + MIO_EMM_DMA_FIFO_CMD(host));
+ pr_debug("[%s] sg_dma_len: %u sg_elem: %d/%d\n",
+ (rw) ? "W" : "R", sg_dma_len(sg), i, count);
+ }
+
+ /*
+ * In difference to prepare_dma_single we don't return the
+ * address here, as it would not make sense for scatter-gather.
+ * The dma fixup is only required on models that don't support
+ * scatter-gather, so that is not a problem.
+ */
+ return 1;
+
+error:
+ WARN_ON_ONCE(1);
+ dma_unmap_sg(host->dev, data->sg, data->sg_len, get_dma_dir(data));
+ /* Disable FIFO */
+ writeq(BIT_ULL(16), host->dma_base + MIO_EMM_DMA_FIFO_CFG(host));
+ return 0;
+}
+
static u64 prepare_dma(struct cvm_mmc_host *host, struct mmc_data *data)
{
- return prepare_dma_single(host, data);
+ if (host->use_sg && data->sg_len > 1)
+ return prepare_dma_sg(host, data);
+ else
+ return prepare_dma_single(host, data);
}

static u64 prepare_ext_dma(struct mmc_host *mmc, struct mmc_request *mrq)
@@ -965,7 +1060,10 @@ int cvm_mmc_of_slot_probe(struct device *dev, struct cvm_mmc_host *host)
mmc->caps |= MMC_CAP_MMC_HIGHSPEED | MMC_CAP_SD_HIGHSPEED |
MMC_CAP_ERASE | MMC_CAP_CMD23 | MMC_CAP_POWER_OFF_CARD;

- mmc->max_segs = 1;
+ if (host->use_sg)
+ mmc->max_segs = 16;
+ else
+ mmc->max_segs = 1;

/* DMA size field can address up to 8 MB */
mmc->max_seg_size = 8 * 1024 * 1024;
diff --git a/drivers/mmc/host/cavium-mmc.h b/drivers/mmc/host/cavium-mmc.h
index fb82aee..5893f3a 100644
--- a/drivers/mmc/host/cavium-mmc.h
+++ b/drivers/mmc/host/cavium-mmc.h
@@ -22,6 +22,9 @@
#define CAVIUM_MAX_MMC 4

/* DMA register addresses */
+#define MIO_EMM_DMA_FIFO_CFG(x) (0x00 + x->reg_off_dma)
+#define MIO_EMM_DMA_FIFO_ADR(x) (0x10 + x->reg_off_dma)
+#define MIO_EMM_DMA_FIFO_CMD(x) (0x18 + x->reg_off_dma)
#define MIO_EMM_DMA_CFG(x) (0x20 + x->reg_off_dma)
#define MIO_EMM_DMA_ADR(x) (0x28 + x->reg_off_dma)
#define MIO_EMM_DMA_INT(x) (0x30 + x->reg_off_dma)
@@ -63,6 +66,7 @@ struct cvm_mmc_host {
struct mmc_request *current_req;
struct sg_mapping_iter smi;
bool dma_active;
+ bool use_sg;

bool has_ciu3;
bool big_dma_addr;
@@ -110,6 +114,18 @@ struct cvm_mmc_cr_mods {
};

/* Bitfield definitions */
+#define MIO_EMM_DMA_FIFO_CFG_CLR BIT_ULL(16)
+#define MIO_EMM_DMA_FIFO_CFG_INT_LVL GENMASK_ULL(12, 8)
+#define MIO_EMM_DMA_FIFO_CFG_COUNT GENMASK_ULL(4, 0)
+
+#define MIO_EMM_DMA_FIFO_CMD_RW BIT_ULL(62)
+#define MIO_EMM_DMA_FIFO_CMD_INTDIS BIT_ULL(60)
+#define MIO_EMM_DMA_FIFO_CMD_SWAP32 BIT_ULL(59)
+#define MIO_EMM_DMA_FIFO_CMD_SWAP16 BIT_ULL(58)
+#define MIO_EMM_DMA_FIFO_CMD_SWAP8 BIT_ULL(57)
+#define MIO_EMM_DMA_FIFO_CMD_ENDIAN BIT_ULL(56)
+#define MIO_EMM_DMA_FIFO_CMD_SIZE GENMASK_ULL(55, 36)
+
#define MIO_EMM_CMD_SKIP_BUSY BIT_ULL(62)
#define MIO_EMM_CMD_BUS_ID GENMASK_ULL(61, 60)
#define MIO_EMM_CMD_VAL BIT_ULL(59)
diff --git a/drivers/mmc/host/cavium-pci-thunderx.c b/drivers/mmc/host/cavium-pci-thunderx.c
index 6ad36b4..5b93a7b 100644
--- a/drivers/mmc/host/cavium-pci-thunderx.c
+++ b/drivers/mmc/host/cavium-pci-thunderx.c
@@ -104,6 +104,7 @@ static int thunder_mmc_probe(struct pci_dev *pdev,
host->release_bus = thunder_mmc_release_bus;
host->int_enable = thunder_mmc_int_enable;

+ host->use_sg = true;
host->big_dma_addr = true;
host->need_irq_handler_lock = true;
host->last_slot = -1;
@@ -118,6 +119,8 @@ static int thunder_mmc_probe(struct pci_dev *pdev,
*/
writeq(127, host->base + MIO_EMM_INT_EN(host));
writeq(3, host->base + MIO_EMM_DMA_INT_ENA_W1C(host));
+ /* Clear DMA FIFO */
+ writeq(BIT_ULL(16), host->base + MIO_EMM_DMA_FIFO_CFG(host));

ret = thunder_mmc_register_interrupts(host, pdev);
if (ret)
--
2.9.0.rc0.21.g7777322