[PATCH v2] mmc: meson-gx: do not use memcpy_to/fromio for dram-access-quirk

---
Changes since v1:
- added sg pre-validation at meson_mmc_request and dropped checks in meson_mmc_copy_buffer

 drivers/mmc/host/meson-gx-mmc.c | 73 ++++++++++++++++++++++++++-------
 1 file changed, 59 insertions(+), 14 deletions(-)

diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
index 3f28eb4d17fe..8f36536cb1b6 100644
--- a/drivers/mmc/host/meson-gx-mmc.c
+++ b/drivers/mmc/host/meson-gx-mmc.c

@@ -746,7 +746,7 @@ static void meson_mmc_desc_chain_transfer(struct mmc_host *mmc, u32 cmd_cfg)
        writel(start, host->regs + SD_EMMC_START);
 }

-/* local sg copy to buffer version with _to/fromio usage for dram_access_quirk */
+/* local sg copy for dram_access_quirk */
 static void meson_mmc_copy_buffer(struct meson_host *host, struct mmc_data *data,
                                  size_t buflen, bool to_buffer)
 {

@@ -764,21 +764,27 @@ static void meson_mmc_copy_buffer(struct meson_host *host, struct mmc_data *data
        sg_miter_start(&miter, sgl, nents, sg_flags);

        while ((offset < buflen) && sg_miter_next(&miter)) {
-               unsigned int len;
+               unsigned int buf_offset = 0;
+               unsigned int len, left;
+               u32 *buf = miter.addr;

                len = min(miter.length, buflen - offset);
+               left = len;

-               /* When dram_access_quirk, the bounce buffer is a iomem mapping */
-               if (host->dram_access_quirk) {
-                       if (to_buffer)
-                               memcpy_toio(host->bounce_iomem_buf + offset, miter.addr, len);
-                       else
-                               memcpy_fromio(miter.addr, host->bounce_iomem_buf + offset, len);
+               if (to_buffer) {
+                       do {
+                               writel(*buf++, host->bounce_iomem_buf + offset + buf_offset);
+
+                               buf_offset += 4;
+                               left -= 4;
+                       } while (left);
                } else {
-                       if (to_buffer)
-                               memcpy(host->bounce_buf + offset, miter.addr, len);
-                       else
-                               memcpy(miter.addr, host->bounce_buf + offset, len);
+                       do {
+                               *buf++ = readl(host->bounce_iomem_buf + offset + buf_offset);
+
+                               buf_offset += 4;
+                               left -= 4;
+                       } while (left);
                }

                offset += len;

@@ -830,7 +836,11 @@ static void meson_mmc_start_cmd(struct mmc_host *mmc, struct mmc_command *cmd)
                if (data->flags & MMC_DATA_WRITE) {
                        cmd_cfg |= CMD_CFG_DATA_WR;
                        WARN_ON(xfer_bytes > host->bounce_buf_size);
-                       meson_mmc_copy_buffer(host, data, xfer_bytes, true);
+                       if (host->dram_access_quirk)
+                               meson_mmc_copy_buffer(host, data, xfer_bytes, true);
+                       else
+                               sg_copy_to_buffer(data->sg, data->sg_len,
+                                                 host->bounce_buf, xfer_bytes);
                        dma_wmb();
                }

@@ -849,12 +859,43 @@ static void meson_mmc_start_cmd(struct mmc_host *mmc, struct mmc_command *cmd)
        writel(cmd->arg, host->regs + SD_EMMC_CMD_ARG);
 }

+static int meson_mmc_validate_dram_access(struct mmc_host *mmc, struct mmc_data *data)
+{
+       struct scatterlist *sg;
+       int i;
+
+       /* Reject request if any element offset or size is not 32bit aligned */
+       for_each_sg(data->sg, sg, data->sg_len, i) {
+               if (!IS_ALIGNED(sg->offset, sizeof(u32)) ||
+                   !IS_ALIGNED(sg->length, sizeof(u32))) {
+                       dev_err(mmc_dev(mmc), "unaligned sg offset %u len %u\n",
+                               data->sg->offset, data->sg->length);
+                       return -EINVAL;
+               }
+       }
+
+       return 0;
+}
+
 static void meson_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
 {
        struct meson_host *host = mmc_priv(mmc);
        bool needs_pre_post_req = mrq->data &&
                        !(mrq->data->host_cookie & SD_EMMC_PRE_REQ_DONE);

+       /*
+        * The memory at the end of the controller used as bounce buffer for
+        * the dram_access_quirk only accepts 32bit read/write access,
+        * check the aligment and length of the data before starting the request.
+        */
+       if (host->dram_access_quirk && mrq->data) {
+               mrq->cmd->error = meson_mmc_validate_dram_access(mmc, mrq->data);
+               if (mrq->cmd->error) {
+                       mmc_request_done(mmc, mrq);
+                       return;
+               }
+       }
+
        if (needs_pre_post_req) {
                meson_mmc_get_transfer_mode(mmc, mrq);
                if (!meson_mmc_desc_chain_mode(mrq->data))

@@ -999,7 +1040,11 @@ static irqreturn_t meson_mmc_irq_thread(int irq, void *dev_id)
        if (meson_mmc_bounce_buf_read(data)) {
                xfer_bytes = data->blksz * data->blocks;
                WARN_ON(xfer_bytes > host->bounce_buf_size);
-               meson_mmc_copy_buffer(host, data, xfer_bytes, false);
+               if (host->dram_access_quirk)
+                       meson_mmc_copy_buffer(host, data, xfer_bytes, false);
+               else
+                       sg_copy_from_buffer(data->sg, data->sg_len,
+                                           host->bounce_buf, xfer_bytes);
        }

        next_cmd = meson_mmc_get_next_command(cmd);
--

2.25.1