mmc: meson-gx: use memcpy_to/fromio for dram-access-quirk

It has been reported that usage of memcpy() to/from an iomem mapping is invalid,
and a recent arm64 memcpy update [1] triggers a memory abort when dram-access-quirk
is used on the G12A/G12B platforms.

This adds a local sg_copy_to_buffer which makes usage of io versions of memcpy
when dram-access-quirk is enabled.

[1] 285133040e6c ("arm64: Import latest memcpy()/memmove() implementation")

Fixes: acdc8e71d9bb ("mmc: meson-gx: add dram-access-quirk")
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20210609150230.9291-1-narmstrong@baylibre.com
Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
index 016a6106151a5bcdd75a66483ed2d57842c69124..3f28eb4d17fe79a9c13f37ff0d5cf5afb11a4db0 100644 (file)
--- a/drivers/mmc/host/meson-gx-mmc.c
+++ b/drivers/mmc/host/meson-gx-mmc.c
@@ -165,6 +165,7 @@ struct meson_host {
 
        unsigned int bounce_buf_size;
        void *bounce_buf;
+       void __iomem *bounce_iomem_buf;
        dma_addr_t bounce_dma_addr;
        struct sd_emmc_desc *descs;
        dma_addr_t descs_dma_addr;
@@ -745,6 +746,47 @@ 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 */
+static void meson_mmc_copy_buffer(struct meson_host *host, struct mmc_data *data,
+                                 size_t buflen, bool to_buffer)
+{
+       unsigned int sg_flags = SG_MITER_ATOMIC;
+       struct scatterlist *sgl = data->sg;
+       unsigned int nents = data->sg_len;
+       struct sg_mapping_iter miter;
+       unsigned int offset = 0;
+
+       if (to_buffer)
+               sg_flags |= SG_MITER_FROM_SG;
+       else
+               sg_flags |= SG_MITER_TO_SG;
+
+       sg_miter_start(&miter, sgl, nents, sg_flags);
+
+       while ((offset < buflen) && sg_miter_next(&miter)) {
+               unsigned int len;
+
+               len = min(miter.length, buflen - offset);
+
+               /* 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);
+               } else {
+                       if (to_buffer)
+                               memcpy(host->bounce_buf + offset, miter.addr, len);
+                       else
+                               memcpy(miter.addr, host->bounce_buf + offset, len);
+               }
+
+               offset += len;
+       }
+
+       sg_miter_stop(&miter);
+}
+
 static void meson_mmc_start_cmd(struct mmc_host *mmc, struct mmc_command *cmd)
 {
        struct meson_host *host = mmc_priv(mmc);
@@ -788,8 +830,7 @@ 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);
-                       sg_copy_to_buffer(data->sg, data->sg_len,
-                                         host->bounce_buf, xfer_bytes);
+                       meson_mmc_copy_buffer(host, data, xfer_bytes, true);
                        dma_wmb();
                }
 
@@ -958,8 +999,7 @@ 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);
-               sg_copy_from_buffer(data->sg, data->sg_len,
-                                   host->bounce_buf, xfer_bytes);
+               meson_mmc_copy_buffer(host, data, xfer_bytes, false);
        }
 
        next_cmd = meson_mmc_get_next_command(cmd);
@@ -1179,7 +1219,7 @@ static int meson_mmc_probe(struct platform_device *pdev)
                 * instead of the DDR memory
                 */
                host->bounce_buf_size = SD_EMMC_SRAM_DATA_BUF_LEN;
-               host->bounce_buf = host->regs + SD_EMMC_SRAM_DATA_BUF_OFF;
+               host->bounce_iomem_buf = host->regs + SD_EMMC_SRAM_DATA_BUF_OFF;
                host->bounce_dma_addr = res->start + SD_EMMC_SRAM_DATA_BUF_OFF;
        } else {
                /* data bounce buffer */