[PATCH v11 7/9] mmc: cavium: Add scatter-gather DMA support

Jan Glauber
2017-02-06T13:40:28Z

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>
Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Steven J. Hill <steven.hill@cavium.com>
---
drivers/mmc/host/cavium-mmc.c | 105 ++++++++++++++++++++++++++++++++-
drivers/mmc/host/cavium-mmc.h | 58 ++++++++++++++++++
drivers/mmc/host/cavium-pci-thunderx.c | 3 +
3 files changed, 163 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/cavium-mmc.c b/drivers/mmc/host/cavium-mmc.c
index f1fe291..3d3c9c7 100644
--- a/drivers/mmc/host/cavium-mmc.c
+++ b/drivers/mmc/host/cavium-mmc.c
@@ -351,9 +351,31 @@ 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)
+{
+ union mio_emm_dma_fifo_cfg fifo_cfg;
+
+ /* Check if there are any pending requests left */
+ fifo_cfg.val = readq(host->dma_base + MIO_EMM_DMA_FIFO_CFG);
+ if (fifo_cfg.s.count)
+ dev_err(host->dev, "%u requests still pending\n",
+ fifo_cfg.s.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);
+ 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 bool bad_status(union mio_emm_rsp_sts *rsp_sts)
@@ -493,9 +515,83 @@ 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)
+{
+ union mio_emm_dma_fifo_cmd fifo_cmd;
+ struct scatterlist *sg;
+ int count, i;
+ u64 addr;
+
+ 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);
+
+ 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);
+
+ /*
+ * 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.
+ */
+ fifo_cmd.val = 0;
+ fifo_cmd.s.rw = (data->flags & MMC_DATA_WRITE) ? 1 : 0;
+
+ /* enable interrupts on the last element */
+ if (i + 1 == count)
+ fifo_cmd.s.intdis = 0;
+ else
+ fifo_cmd.s.intdis = 1;
+
+#ifdef __LITTLE_ENDIAN
+ fifo_cmd.s.endian = 1;
+#endif
+ fifo_cmd.s.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.val, host->dma_base + MIO_EMM_DMA_FIFO_CMD);
+ pr_debug("[%s] sg_dma_len: %u sg_elem: %d/%d\n",
+ (fifo_cmd.s.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);
+ 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 void prepare_ext_dma(struct mmc_host *mmc, struct mmc_request *mrq,
@@ -998,7 +1094,10 @@ int cvm_mmc_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 64a837c..04898b8 100644
--- a/drivers/mmc/host/cavium-mmc.h
+++ b/drivers/mmc/host/cavium-mmc.h
@@ -22,6 +22,10 @@
#define MIO_EMM_DMA_CFG 0x00
#define MIO_EMM_DMA_ADR 0x08

+#define MIO_EMM_DMA_FIFO_CFG 0x00
+#define MIO_EMM_DMA_FIFO_ADR 0x00
+#define MIO_EMM_DMA_FIFO_CMD 0x00
+
#define MIO_EMM_CFG 0x00
#define MIO_EMM_SWITCH 0x48
#define MIO_EMM_DMA 0x50
@@ -40,6 +44,9 @@

#elif CONFIG_MMC_CAVIUM_THUNDERX

+#define MIO_EMM_DMA_FIFO_CFG 0x160
+#define MIO_EMM_DMA_FIFO_ADR 0x170
+#define MIO_EMM_DMA_FIFO_CMD 0x178
#define MIO_EMM_DMA_CFG 0x180
#define MIO_EMM_DMA_ADR 0x188
#define MIO_EMM_DMA_INT 0x190
@@ -81,6 +88,7 @@ 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;
@@ -135,6 +143,56 @@ struct cvm_mmc_cr_mods {

/* Bitfield definitions */

+union mio_emm_dma_fifo_cfg {
+ u64 val;
+ struct mio_emm_dma_fifo_cfg_s {
+#ifdef __BIG_ENDIAN_BITFIELD
+ u64 :48;
+ u64 clr:1;
+ u64 :3;
+ u64 int_lvl:4;
+ u64 :3;
+ u64 count:5;
+#else
+ u64 count:5;
+ u64 :3;
+ u64 int_lvl:4;
+ u64 :3;
+ u64 clr:1;
+ u64 :48;
+#endif
+ } s;
+};
+
+union mio_emm_dma_fifo_cmd {
+ u64 val;
+ struct mio_emm_dma_fifo_cmd_s {
+#ifdef __BIG_ENDIAN_BITFIELD
+ u64 :1;
+ u64 rw:1;
+ u64 :1;
+ u64 intdis:1;
+ u64 swap32:1;
+ u64 swap16:1;
+ u64 swap8:1;
+ u64 endian:1;
+ u64 size:20;
+ u64 :36;
+#else
+ u64 :36;
+ u64 size:20;
+ u64 endian:1;
+ u64 swap8:1;
+ u64 swap16:1;
+ u64 swap32:1;
+ u64 intdis:1;
+ u64 :1;
+ u64 rw:1;
+ u64 :1;
+#endif
+ } s;
+};
+
union mio_emm_cmd {
u64 val;
struct mio_emm_cmd_s {
diff --git a/drivers/mmc/host/cavium-pci-thunderx.c b/drivers/mmc/host/cavium-pci-thunderx.c
index 5052c4e..579e063 100644
--- a/drivers/mmc/host/cavium-pci-thunderx.c
+++ b/drivers/mmc/host/cavium-pci-thunderx.c
@@ -109,6 +109,7 @@ 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;
@@ -123,6 +124,8 @@ static int thunder_mmc_probe(struct pci_dev *pdev,
*/
writeq(127, host->base + MIO_EMM_INT_EN);
writeq(3, host->base + MIO_EMM_DMA_INT_ENA_W1C);
+ /* Clear DMA FIFO */
+ writeq(BIT_ULL(16), host->base + MIO_EMM_DMA_FIFO_CFG);

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