[PATCH 07/11] mmc: mvsdio: handle highmem pages

[Christoph Hellwig]

Instead of setting up a kernel pointer to track the current PIO address,
track the offset in the current page, and do an atomic kmap for the page
while doing the actual PIO operations.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 drivers/mmc/host/mvsdio.c | 48 +++++++++++++++++++++++----------------
 1 file changed, 29 insertions(+), 19 deletions(-)

diff --git a/drivers/mmc/host/mvsdio.c b/drivers/mmc/host/mvsdio.c
index e22bbff89c8d..545e370d6dae 100644
--- a/drivers/mmc/host/mvsdio.c
+++ b/drivers/mmc/host/mvsdio.c
@@ -12,6 +12,7 @@
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/io.h>
+#include <linux/highmem.h>
 #include <linux/platform_device.h>
 #include <linux/mbus.h>
 #include <linux/delay.h>
@@ -42,7 +43,8 @@ struct mvsd_host {
 	unsigned int intr_en;
 	unsigned int ctrl;
 	unsigned int pio_size;
-	void *pio_ptr;
+	struct scatterlist *pio_sg;
+	unsigned int pio_offset; /* offset in words into the segment */
 	unsigned int sg_frags;
 	unsigned int ns_per_clk;
 	unsigned int clock;
@@ -96,9 +98,9 @@ static int mvsd_setup_data(struct mvsd_host *host, struct mmc_data *data)
 	if (tmout_index > MVSD_HOST_CTRL_TMOUT_MAX)
 		tmout_index = MVSD_HOST_CTRL_TMOUT_MAX;
 
-	dev_dbg(host->dev, "data %s at 0x%08x: blocks=%d blksz=%d tmout=%u (%d)\n",
+	dev_dbg(host->dev, "data %s at 0x%08llx: blocks=%d blksz=%d tmout=%u (%d)\n",
 		(data->flags & MMC_DATA_READ) ? "read" : "write",
-		(u32)sg_virt(data->sg), data->blocks, data->blksz,
+		(u64)sg_phys(data->sg), data->blocks, data->blksz,
 		tmout, tmout_index);
 
 	host->ctrl &= ~MVSD_HOST_CTRL_TMOUT_MASK;
@@ -118,10 +120,11 @@ static int mvsd_setup_data(struct mvsd_host *host, struct mmc_data *data)
 		 * boundary.
 		 */
 		host->pio_size = data->blocks * data->blksz;
-		host->pio_ptr = sg_virt(data->sg);
+		host->pio_sg = data->sg;
+		host->pio_offset = data->sg->offset / 2;
 		if (!nodma)
-			dev_dbg(host->dev, "fallback to PIO for data at 0x%p size %d\n",
-				host->pio_ptr, host->pio_size);
+			dev_dbg(host->dev, "fallback to PIO for data at 0x%x size %d\n",
+				host->pio_offset, host->pio_size);
 		return 1;
 	} else {
 		dma_addr_t phys_addr;
@@ -291,8 +294,9 @@ static u32 mvsd_finish_data(struct mvsd_host *host, struct mmc_data *data,
 {
 	void __iomem *iobase = host->base;
 
-	if (host->pio_ptr) {
-		host->pio_ptr = NULL;
+	if (host->pio_sg) {
+		host->pio_sg = NULL;
+		host->pio_offset = 0;
 		host->pio_size = 0;
 	} else {
 		dma_unmap_sg(mmc_dev(host->mmc), data->sg, host->sg_frags,
@@ -376,11 +380,12 @@ static irqreturn_t mvsd_irq(int irq, void *dev)
 	if (host->pio_size &&
 	    (intr_status & host->intr_en &
 	     (MVSD_NOR_RX_READY | MVSD_NOR_RX_FIFO_8W))) {
-		u16 *p = host->pio_ptr;
+		u16 *p = kmap_atomic(sg_page(host->pio_sg));
+		unsigned int o = host->pio_offset;
 		int s = host->pio_size;
 		while (s >= 32 && (intr_status & MVSD_NOR_RX_FIFO_8W)) {
-			readsw(iobase + MVSD_FIFO, p, 16);
-			p += 16;
+			readsw(iobase + MVSD_FIFO, p + o, 16);
+			o += 16;
 			s -= 32;
 			intr_status = mvsd_read(MVSD_NOR_INTR_STATUS);
 		}
@@ -391,8 +396,10 @@ static irqreturn_t mvsd_irq(int irq, void *dev)
 		 */
 		if (s <= 32) {
 			while (s >= 4 && (intr_status & MVSD_NOR_RX_READY)) {
-				put_unaligned(mvsd_read(MVSD_FIFO), p++);
-				put_unaligned(mvsd_read(MVSD_FIFO), p++);
+				put_unaligned(mvsd_read(MVSD_FIFO), p + o);
+				o++;
+				put_unaligned(mvsd_read(MVSD_FIFO), p + o);
+				o++;
 				s -= 4;
 				intr_status = mvsd_read(MVSD_NOR_INTR_STATUS);
 			}
@@ -400,7 +407,7 @@ static irqreturn_t mvsd_irq(int irq, void *dev)
 				u16 val[2] = {0, 0};
 				val[0] = mvsd_read(MVSD_FIFO);
 				val[1] = mvsd_read(MVSD_FIFO);
-				memcpy(p, ((void *)&val) + 4 - s, s);
+				memcpy(p + o, ((void *)&val) + 4 - s, s);
 				s = 0;
 				intr_status = mvsd_read(MVSD_NOR_INTR_STATUS);
 			}
@@ -416,13 +423,14 @@ static irqreturn_t mvsd_irq(int irq, void *dev)
 		}
 		dev_dbg(host->dev, "pio %d intr 0x%04x hw_state 0x%04x\n",
 			s, intr_status, mvsd_read(MVSD_HW_STATE));
-		host->pio_ptr = p;
+		host->pio_offset = o;
 		host->pio_size = s;
 		irq_handled = 1;
 	} else if (host->pio_size &&
 		   (intr_status & host->intr_en &
 		    (MVSD_NOR_TX_AVAIL | MVSD_NOR_TX_FIFO_8W))) {
-		u16 *p = host->pio_ptr;
+		u16 *p = kmap_atomic(sg_page(host->pio_sg));
+		unsigned int o = host->pio_offset;
 		int s = host->pio_size;
 		/*
 		 * The TX_FIFO_8W bit is unreliable. When set, bursting
@@ -431,8 +439,10 @@ static irqreturn_t mvsd_irq(int irq, void *dev)
 		 * TX_FIFO_8W remains set.
 		 */
 		while (s >= 4 && (intr_status & MVSD_NOR_TX_AVAIL)) {
-			mvsd_write(MVSD_FIFO, get_unaligned(p++));
-			mvsd_write(MVSD_FIFO, get_unaligned(p++));
+			mvsd_write(MVSD_FIFO, get_unaligned(p + o));
+			o++;
+			mvsd_write(MVSD_FIFO, get_unaligned(p + o));
+			o++;
 			s -= 4;
 			intr_status = mvsd_read(MVSD_NOR_INTR_STATUS);
 		}
@@ -453,7 +463,7 @@ static irqreturn_t mvsd_irq(int irq, void *dev)
 		}
 		dev_dbg(host->dev, "pio %d intr 0x%04x hw_state 0x%04x\n",
 			s, intr_status, mvsd_read(MVSD_HW_STATE));
-		host->pio_ptr = p;
+		host->pio_offset = o;
 		host->pio_size = s;
 		irq_handled = 1;
 	}
-- 
2.20.1