linux-kernel - [PATCH 03/11] mmc: omap: handle highmem pages

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Message-Id: <20190114095804.27978-4-hch@lst.de>
Date:   Mon, 14 Jan 2019 10:57:56 +0100
From:   Christoph Hellwig <hch@....de>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Russell King <linux@...linux.org.uk>,
        Nicolas Pitre <nico@...xnic.net>,
        Aaro Koskinen <aaro.koskinen@....fi>,
        Ben Dooks <ben-linux@...ff.org>, linux-mmc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: [PATCH 03/11] mmc: omap: handle highmem pages

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@....de>
---
 drivers/mmc/host/omap.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/mmc/host/omap.c b/drivers/mmc/host/omap.c
index c60a7625b1fa..0377ac6194a0 100644
--- a/drivers/mmc/host/omap.c
+++ b/drivers/mmc/host/omap.c
@@ -13,6 +13,7 @@
 
 #include <linux/module.h>
 #include <linux/moduleparam.h>
+#include <linux/highmem.h>
 #include <linux/init.h>
 #include <linux/ioport.h>
 #include <linux/platform_device.h>
@@ -148,7 +149,7 @@ struct mmc_omap_host {
 
 	unsigned int		sg_len;
 	int			sg_idx;
-	u16 *			buffer;
+	u32			buffer_offset;
 	u32			buffer_bytes_left;
 	u32			total_bytes_left;
 
@@ -649,7 +650,7 @@ mmc_omap_sg_to_buf(struct mmc_omap_host *host)
 
 	sg = host->data->sg + host->sg_idx;
 	host->buffer_bytes_left = sg->length;
-	host->buffer = sg_virt(sg);
+	host->buffer_offset = sg->offset;
 	if (host->buffer_bytes_left > host->total_bytes_left)
 		host->buffer_bytes_left = host->total_bytes_left;
 }
@@ -666,7 +667,9 @@ mmc_omap_clk_timer(struct timer_list *t)
 static void
 mmc_omap_xfer_data(struct mmc_omap_host *host, int write)
 {
+	struct scatterlist *sg = host->data->sg + host->sg_idx;
 	int n, nwords;
+	void *p;
 
 	if (host->buffer_bytes_left == 0) {
 		host->sg_idx++;
@@ -684,15 +687,17 @@ mmc_omap_xfer_data(struct mmc_omap_host *host, int write)
 	host->total_bytes_left -= n;
 	host->data->bytes_xfered += n;
 
+	p = kmap_atomic(sg_page(sg));
 	if (write) {
 		__raw_writesw(host->virt_base + OMAP_MMC_REG(host, DATA),
-			      host->buffer, nwords);
+			      p + host->buffer_offset, nwords);
 	} else {
 		__raw_readsw(host->virt_base + OMAP_MMC_REG(host, DATA),
-			     host->buffer, nwords);
+			     p + host->buffer_offset, nwords);
 	}
+	kunmap_atomic(p);
 
-	host->buffer += nwords;
+	host->buffer_offset += nwords;
 }
 
 #ifdef CONFIG_MMC_DEBUG
-- 
2.20.1