mmc: davinci_mmc: Use sg_miter for PIO

Use the scatterlist memory iterator instead of just
dereferencing virtual memory using sg_virt().
This make highmem references work properly.

Suggested-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/linux-mmc/20240122073423.GA25859@lst.de/
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20240127-mmc-proper-kmap-v2-1-d8e732aa97d1@linaro.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/host/davinci_mmc.c b/drivers/mmc/host/davinci_mmc.c
index ee3b1a4e08485b16893192bc72b4e9d25a6a04df..c4657730513871ffa561f6ae42bb2593f048bd4d 100644 (file)
--- a/drivers/mmc/host/davinci_mmc.c
+++ b/drivers/mmc/host/davinci_mmc.c
@@ -180,12 +180,6 @@ struct mmc_davinci_host {
 #define DAVINCI_MMC_DATADIR_WRITE      2
        unsigned char data_dir;
 
-       /* buffer is used during PIO of one scatterlist segment, and
-        * is updated along with buffer_bytes_left.  bytes_left applies
-        * to all N blocks of the PIO transfer.
-        */
-       u8 *buffer;
-       u32 buffer_bytes_left;
        u32 bytes_left;
 
        struct dma_chan *dma_tx;
@@ -196,8 +190,8 @@ struct mmc_davinci_host {
        bool active_request;
 
        /* For PIO we walk scatterlists one segment at a time. */
+       struct sg_mapping_iter sg_miter;
        unsigned int            sg_len;
-       struct scatterlist *sg;
 
        /* Version of the MMC/SD controller */
        u8 version;
@@ -213,30 +207,24 @@ struct mmc_davinci_host {
 static irqreturn_t mmc_davinci_irq(int irq, void *dev_id);
 
 /* PIO only */
-static void mmc_davinci_sg_to_buf(struct mmc_davinci_host *host)
-{
-       host->buffer_bytes_left = sg_dma_len(host->sg);
-       host->buffer = sg_virt(host->sg);
-       if (host->buffer_bytes_left > host->bytes_left)
-               host->buffer_bytes_left = host->bytes_left;
-}
-
 static void davinci_fifo_data_trans(struct mmc_davinci_host *host,
                                        unsigned int n)
 {
+       struct sg_mapping_iter *sgm = &host->sg_miter;
+       size_t sglen;
        u8 *p;
        unsigned int i;
 
-       if (host->buffer_bytes_left == 0) {
-               host->sg = sg_next(host->data->sg);
-               mmc_davinci_sg_to_buf(host);
+       /*
+        * By adjusting sgm->consumed this will give a pointer to the
+        * current index into the sgm.
+        */
+       if (!sg_miter_next(sgm)) {
+               dev_err(mmc_dev(host->mmc), "ran out of sglist prematurely\n");
+               return;
        }
-
-       p = host->buffer;
-       if (n > host->buffer_bytes_left)
-               n = host->buffer_bytes_left;
-       host->buffer_bytes_left -= n;
-       host->bytes_left -= n;
+       p = sgm->addr;
+       sglen = sgm->length;
 
        /* NOTE:  we never transfer more than rw_threshold bytes
         * to/from the fifo here; there's no I/O overlap.
@@ -261,7 +249,9 @@ static void davinci_fifo_data_trans(struct mmc_davinci_host *host,
                        p = p + (n & 3);
                }
        }
-       host->buffer = p;
+
+       sgm->consumed = n;
+       host->bytes_left -= n;
 }
 
 static void mmc_davinci_start_command(struct mmc_davinci_host *host,
@@ -517,6 +507,7 @@ mmc_davinci_prepare_data(struct mmc_davinci_host *host, struct mmc_request *req)
        int fifo_lev = (rw_threshold == 32) ? MMCFIFOCTL_FIFOLEV : 0;
        int timeout;
        struct mmc_data *data = req->data;
+       unsigned int flags = SG_MITER_ATOMIC; /* Used from IRQ */
 
        if (host->version == MMC_CTLR_VERSION_2)
                fifo_lev = (rw_threshold == 64) ? MMCFIFOCTL_FIFOLEV : 0;
@@ -545,12 +536,14 @@ mmc_davinci_prepare_data(struct mmc_davinci_host *host, struct mmc_request *req)
 
        /* Configure the FIFO */
        if (data->flags & MMC_DATA_WRITE) {
+               flags |= SG_MITER_FROM_SG;
                host->data_dir = DAVINCI_MMC_DATADIR_WRITE;
                writel(fifo_lev | MMCFIFOCTL_FIFODIR_WR | MMCFIFOCTL_FIFORST,
                        host->base + DAVINCI_MMCFIFOCTL);
                writel(fifo_lev | MMCFIFOCTL_FIFODIR_WR,
                        host->base + DAVINCI_MMCFIFOCTL);
        } else {
+               flags |= SG_MITER_TO_SG;
                host->data_dir = DAVINCI_MMC_DATADIR_READ;
                writel(fifo_lev | MMCFIFOCTL_FIFODIR_RD | MMCFIFOCTL_FIFORST,
                        host->base + DAVINCI_MMCFIFOCTL);
@@ -558,7 +551,6 @@ mmc_davinci_prepare_data(struct mmc_davinci_host *host, struct mmc_request *req)
                        host->base + DAVINCI_MMCFIFOCTL);
        }
 
-       host->buffer = NULL;
        host->bytes_left = data->blocks * data->blksz;
 
        /* For now we try to use DMA whenever we won't need partial FIFO
@@ -576,8 +568,7 @@ mmc_davinci_prepare_data(struct mmc_davinci_host *host, struct mmc_request *req)
        } else {
                /* Revert to CPU Copy */
                host->sg_len = data->sg_len;
-               host->sg = host->data->sg;
-               mmc_davinci_sg_to_buf(host);
+               sg_miter_start(&host->sg_miter, data->sg, data->sg_len, flags);
        }
 }
 
@@ -843,6 +834,8 @@ davinci_abort_data(struct mmc_davinci_host *host, struct mmc_data *data)
 {
        mmc_davinci_reset_ctrl(host, 1);
        mmc_davinci_reset_ctrl(host, 0);
+       if (!host->do_dma)
+               sg_miter_stop(&host->sg_miter);
 }
 
 static irqreturn_t mmc_davinci_sdio_irq(int irq, void *dev_id)
@@ -919,11 +912,13 @@ static irqreturn_t mmc_davinci_irq(int irq, void *dev_id)
        if (qstatus & MMCST0_DATDNE) {
                /* All blocks sent/received, and CRC checks passed */
                if (data != NULL) {
-                       if ((host->do_dma == 0) && (host->bytes_left > 0)) {
-                               /* if datasize < rw_threshold
-                                * no RX ints are generated
-                                */
-                               davinci_fifo_data_trans(host, host->bytes_left);
+                       if (!host->do_dma) {
+                               if (host->bytes_left > 0)
+                                       /* if datasize < rw_threshold
+                                        * no RX ints are generated
+                                        */
+                                       davinci_fifo_data_trans(host, host->bytes_left);
+                               sg_miter_stop(&host->sg_miter);
                        }
                        end_transfer = 1;
                        data->bytes_xfered = data->blocks * data->blksz;